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Control methods against invasive Aedes mosquitoes in Europe: A review
Pest Management Science
Abstract
Five species of invasive Aedes mosquitoes have recently become established in Europe: Aedes albopictus, Aedes aegypti, Aedes japonicus japonicus, Aedes koreicus and Aedes atropalpus. These mosquitoes are a serious nuisance for people and are also competent vectors for several exotic pathogens such as dengue and chikungunya viruses. As they are a growing public health concern, methods to control these mosquitoes need to be implemented to reduce their biting and their potential for disease transmission. There is a crucial need to evaluate methods as part of an integrated invasive mosquito species control strategy in different European countries, taking into account local Aedes infestations and European regulations. This review presents the control methods available or in development against invasive Aedes mosquitoes with a particular focus on those which can be implemented in Europe. These control methods are divided into five categories: environmental (source reduction), mechanical (trapping), biological (e.g. copepods, Bti, Wolbachia), chemical (insect growth regulators, pyrethroids) and genetic (sterile insect technique and genetically modified mosquitoes). We discuss the effectiveness, ecological impact, sustainability and stage of development of each control method.
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... Notably, though, community participation through educational campaigns did not cause an impact on the number of Ae. albopictus breeding sites in New Jersey (USA) [21]. Additionally, source reduction as a unique intervention appears to be insufficient despite widespread campaigns being conducted by municipalities [22]. ...
... Additionally, SCBs were treated with a combined application of the microbial control agents Bti and Lsph. While Bti presents a rapid larvicidal effect within 24 h after treatment and an estimated four-week residual effect in treated sites, Lsph extends the larvicide effect due to the recirculation of the bacteria in dead larvae, especially of Culex spp [22]. ...
... Additionally, most surveyed citizens with AOTs (Sector 2) reported a perceived reduction of mosquito abundance in comparison to previous years, with such perceptions differing greatly from the responses given by participants in the control area (Figure 5d). The observed association of neighbors' perceptions and entomological parameters was also found in other studies related to Ae. albopictus control [22,40]. ...
Aedes albopictus has established populations in several European countries with a sustained spreading pattern through the continent. This invasive mosquito is a public health threat due to its vector competence for multiple arboviruses. Notably, the peri-domestic habits of this hematophagous insect greatly diminish the efficacy of regular control activities, as individuals may harbor in private areas. The oviposition behavior can be exploited for targeting adults and immature stages through different types of traps. An experimental integrated control program, which included a community-based mass trapping intervention in private areas, control of public street-catch basins, and an educational campaign, was developed in an infested residential area in Valencia (Eastern Spain). Focusing on mass trapping, participating residents deployed traps belonging to three modes of action in their gardens during the mosquito season. A total of 1028 families participated in the project, and 2884 traps were deployed. The study sector where adult lethal ovitraps were used showed the lowest adult collections, and residents living in this sector reported the highest satisfaction rates in a perception survey. The mass deployment through a community-based approach of the adulticidal oviposition trap type appears to be a promising tool for controlling Ae. albopictus in residential areas.
... Due to a lack of commercially applicable vaccines or effective antiviral treatments for fighting dengue [2], current efforts to curb dengue epidemics focus on controlling mosquito vectors. Killing mosquitoes through the use of insecticides [6,31] or the elimination of mosquito breeding sites [39] has been prioritized, however, neither method has been proven to be consistently effective or sustainable [6,21]. To enhance the control of mosquitoes, researchers from the World Mosquito Program have been working on a breakthrough that introduces the maternally inherited Wolbachia into Aedes mosquitoes, and then replacing them with ones infected by Wolbachia. ...
... Due to a lack of commercially applicable vaccines or effective antiviral treatments for fighting dengue [2], current efforts to curb dengue epidemics focus on controlling mosquito vectors. Killing mosquitoes through the use of insecticides [6,31] or the elimination of mosquito breeding sites [39] has been prioritized, however, neither method has been proven to be consistently effective or sustainable [6,21]. To enhance the control of mosquitoes, researchers from the World Mosquito Program have been working on a breakthrough that introduces the maternally inherited Wolbachia into Aedes mosquitoes, and then replacing them with ones infected by Wolbachia. ...
... There is currently a lack of commercially viable vaccines and treatments for such infections. Traditional prevention methods have failed to effectively against the consistent emergence of dengue due to insecticide resistance or the creation of ubiquitous larval sources during favorable seasons [6,31,39]. Wolbachia-driven mosquito control technique aims to reduce mosquito-borne diseases by controlling mosquitoes, which has been developed through rigorous research over decades. The functions of Wolbachia include CI, maternal transmission, and blocking dengue virus replication, providing an effective method for reducing disease transmission. ...
... When immersed in water, the eggs may hatch within 2 to 4 days, but in the absence of water, high resistance to drying allows the eggs remain viable for weeks, months or even one year (Faull and Williams, 2015). The resistance of eggs to periods of drought, added to the transport of objects that were previously used for oviposition by A. aegypti, are factors that influence the high invasive potential of mosquitoes, allowing the passive dissemination of eggs to new environments (Baldacchino et al., 2015). ...
... There are still no cases of resistance to Bti, but there are for Lsp and to circumvent this problem, the use of Lsp must be done in an intercalated way or associated with other larvicides, such as Bti itself. (Baldacchino et al., 2015). However, the low residual effect of marketed formulations results in the need for several applications of the product (Moreira et al., 2012). ...
... The use of EOs as vector controls substance is considered economically viable as plant species that give them are locally available in most world regions affected by arboviruses (Silva et al., 2008). They are commonly cheaper than individual components that must be isolated or synthesized (Baldacchino et al., 2015). Importantly, as derived from renewable sources they are widely accepted by the population (Baldacchino et al., 2015;Dias and Moraes, 2014). ...
Despite the global burden of viral diseases transmitted by Aedes aegypti, there is a lack of effective means of prevention and treatment. Strategies for vector control include chemical and biological approaches such as organophosphates and Bacillus thuringiensis var. israelensis (Bti), among others. However, important concerns are associated, such as resistance in mosquito larvae and deleterious effects on non-target organisms. In this scenario, novel approaches against A. aegypti have been investigated, including natural products (e.g. vegetable oil and extracts) and nanostructured systems. This review focuses on potential strategies for fighting A. aegypti, highlighting plant-based materials and nanomaterials able to induce toxic effects on egg, larva, pupa and adult mosquitoes. Issues including aspects of conventional vector control strategies are presented, and finally new insights on development of eco-friendly nanoformulations against A. aegypti are discussed.
... For juvenile stages, the use of a new entomopathogenic fungi (Cafarchia et al. 2022) or autodissemination (such as pyriproxyfen) (Pleydell and Bouyer 2019) are proposed alternative strategies (Achee et al. 2019). Biological mosquito control is so far mainly based on predatory copepods, Toxorhynchites larvae and fish; however, none of these control agents is currently used in Europe (Baldacchino et al. 2015;Achee et al. 2019). ...
... Biological vector control increases the necessity to identify the most locally effective natural predators of Culicidae, which is especially true for areas recently invaded by Aedes albopictus (Younes 2008;Bofill and Yee 2019). The use of native cyclopoid copepods already proved to be a successful method to control first larval instars of A. albopictus (Pauly et al. 2022) and is applied in the Americas, Asia and Oceania (Baldacchino et al. 2015). Toxorhynchites species show positive results in the control of Aedes species, but they are native to the Tropics with some species found in Asia and North America (Donald et al. 2020;Malla et al. 2023). ...
The invasive mosquito species Aedes albopictus (Skuse, 1894) is rapidly spreading in Europe, posing an increasing threat because of its high vector competence for chikungunya and dengue virus. An integrative and eco-friendly control of these populations is required to prevent mosquito-borne disease outbreaks. Traditionally-used insecticides or other chemical control agents are often expensive, harmful to the environment, strictly controlled or completely banned in several countries. Additionally, insecticide resistance is a potential threat. One possibility for biological control agents is the use of native aquatic beetles as natural predators of mosquitoes to boost Bacillus thuringiensis israelensis (Bti) interventions. Thirty predatory aquatic beetle taxa were caught in Belgium and kept at the Institute of Tropical Medicine’s insectary to test predation rate and prey choice on Aedes albopictus and Culex pipiens Linnaeus, 1758. Predation rates suggest at least four efficient dytiscid predators that are known to inhabit small, temporary habitats in Europe. Further experiments on prey choice reveal a clear preference for Aedes albopictus over alternative larval prey (Culex pipiens, Daphnia sp., Chaoboridae). We found a strong ecological overlap of the feeding niche of A. albopictus and the hunting zone of dytiscid predators in the benthic layer of small waterbodies. Our findings on the efficacy are very encouraging to further assess the potential of native predacious diving beetles as a biological control agent against the invasive A. albopictus in Europe.
... Traditional mosquito control methods, such as chemical adulticidal products, are not recommended in botanical gardens due to their toxicity, ecotoxicity, potential to generate resistance, and potential adverse effects on the diverse plant and animal life present in these gardens. Their use is only recommended in the event of arbovirus transmission outbreaks or very high densities causing significant discomfort (WHO, 2004;Baldacchino et al., 2015;ECDC, 2017). Therefore, adopting more environmentally friendly and targeted strategies, such as integrated invasive mosquito species control strategy techniques, is essential (Baldacchino et al., 2015). ...
... Their use is only recommended in the event of arbovirus transmission outbreaks or very high densities causing significant discomfort (WHO, 2004;Baldacchino et al., 2015;ECDC, 2017). Therefore, adopting more environmentally friendly and targeted strategies, such as integrated invasive mosquito species control strategy techniques, is essential (Baldacchino et al., 2015). There is no silver bullet for Aedes control, but more targeted approaches in these highly infested areas, based on routinely easy measures such as regular inspections, removal of standing water, and promoting water circulation in ponds and fountains, are desired. ...
... Treatment of breeding habitats with larvicide (e.g., Spinosad, Bacillus thuringensis israelensis and Lysinibacillus sphaericus) can effectively target immature stages and reduce adult abundance. These bioagents are safer options in terms of their impact on non-target organisms and the environment [22]. There are few reports of resistance to the larvicides [20] and such resistance development is a major constraint of their efficacy leading to undesired results in reducing mosquito population density. ...
... It is critical to find alternatives to conventional insecticides and alternatives include insect growth regulators (IGRs), B. thuringiensis israelensis (Bti), L. sphaericus (Ls) and Spinosad, which target mosquito immatures. These products have attracted lots of interest as they are safe to humans and the environmental [22]. So far no reports of insect field resistance to Bti have been made but there are reports of resistance to Bti and Ls in laboratory colonies of certain mosquito species, like Culex quinquefasciatus [42][43][44], and Cx. ...
Novel control products are needed in the control of important insects like mosquitoes which are developing resistance to insecticides and larvicides currently in the market. Boron compounds have been demonstrated to exhibit antibacterial and anticancer effects. 1,2-diboranes with a long history and importance in boron chemistry have been described. These compounds are synthesized from reactions of 1,2-dichlordiborane derivatives with lidium amides (ArNHLi/Et2NLi, etc.). In addition to the three previously synthesized diborane compounds, five novel 1,2-diborane compounds were synthesized in good yield using the same method for the first time. The structures of the novel derivatives were characterized by nuclear magnetic resonance spectroscopy, and the molecular structure of one of them (2a) was also demonstrated using single crystal X-ray diffraction. In this preliminary study, the ovicidal and larvicidal effects of new 1,2-diamino-1,2-diborane derivatives against Aedes aegypti and Aedes albopictus eggs and larvae were investigated for the first time. Of these, 2a and 2e showed the highest ovicidal activity against both species, while 7, 4 and 2d showed particularly high larvicidal activity. Some 1,2-diborane derivatives were found to be significantly toxic, with LC50 values ranging from 14,930 to 27,975 μg/mL. Some derivatives (6, 2a, 2c) were less effective against mosquito larvae. 1,2-Diborane derivatives have high ovicidal and larvicidal effects on mosquitoes and are therefore potential candidates for the development of new larvicides. Further studies are needed to evaluate its mode of action and safety. Understanding their mode of action against mosquito development is crucial to optimizing their use and reducing the potential development of resistance. Their potential effects on other mosquito species and non-target organisms need to be investigated.
... Due to the increasing public health concern coupled with the relevant nuisance related to the anthropophilic behaviour of Ae. albopictus, a plethora of population control approaches have been developed; including environmental, mechanical, biological, chemical, and genetic methods [7]. However, currently available control approaches were insufficient in reducing local population levels of the tiger mosquito [7][8][9][10]. ...
... Due to the increasing public health concern coupled with the relevant nuisance related to the anthropophilic behaviour of Ae. albopictus, a plethora of population control approaches have been developed; including environmental, mechanical, biological, chemical, and genetic methods [7]. However, currently available control approaches were insufficient in reducing local population levels of the tiger mosquito [7][8][9][10]. Among the newly proposed mosquito control methods, the "Sterile Insect Technique" (SIT) is emerging as one of the most promising. ...
The “Sterile Insect Technique” (SIT), a promising method to control Aedes albopictus, the Asian tiger mosquito, is gaining increasing interest. Recently, the role of microbiota in mosquito fitness received attention, but the link between microbiota and larval diet in mass rearing programs for SIT remains largely unexplored. We characterized the microbiota of four larval instars, pupae and eggs of non-wild (NW) lab-reared Ae. albopictus fed with a diet based on Black soldier fly (Hermetia illucens) larvae powder and fish food KOI pellets. We compared it with wild (W) field-collected individuals and the bacterial community occurring in rearing water-diet (DIET). A total of 18 bacterial classes with > 0.10% abundance were found overall in the samples, with seven classes being especially abundant. Overall, the microbiota profile significantly differed among NW, W and DIET. Verrucomicrobiae were significantly more abundant in W and DIET, Bacteroidia were more abundant in NW and DIET, and Gammaproteobacteria were only more abundant in W than in DIET. W-eggs microbiota differed from all the other groups. Large differences also appeared at the bacterial genus-level, with the abundance of 14 genera differing among groups. Three ASVs of Acinetobacter, known to have positive effects on tiger mosquitoes, were more abundant in NW than in W, while Serratia, known to have negative or neutral effects on another Aedes species, was less abundant in NW than in W. The bacterial community of W-eggs was the richest in species, while dominance and diversity did not differ among groups. Our data show that the diet based on Black soldier fly powder and fish food KOI influences the microbiota of NW tiger mosquito immature stages, but not in a way that may suggest a negative impact on their quality in SIT programs.
... To control mosquitoes, different methods are used, which are characterized by different efficiencies. For this purpose, methods of mosquito reduction, pesticide use, public education and biological control can be used, and the integration of these techniques can ensure an optimal control strategy [46]. The introduction of controls has led to the elimination of newly-created mosquito populations in some places [50]. ...
... The implementation of an integrated strategy to combat invasive mosquito species (IMS) should take into account the species, their ecology and the threat to public health, i.e. nuisance and disease transmission. An integrated control strategy for IMS requires coordinated involvement of local authorities and organizations of the entire society [46]. ...
... Aedes aegypti (Linnaeus) and Aedes albopictus (Skuse) are vectors of arboviruses such as dengue virus, yellow fever virus, chikungunya virus, and Zika virus (Jansen et al. 2010, Gubler 2011, Higgs and Vanlandingham 2015, Kauffman and Kramer 2017. These species are known to be invasive (Juliano et al. 2005, Baldacchino et al. 2015 and distributed in many different geographic regions worldwide (Kraemer et al. 2015, Laporta et al. 2023. Both species are widespread in Florida with recorded presence of Ae. aegypti and/or Ae. albopictus in 56 out of 67 counties (Parker et al. 2019). ...
This is Volume 72, 2025 of the Journal of the Florida Mosquito Control Association (one volume a year). This volume contains two review articles, eight research articles, two scientific notes, and the abstracts submitted from the 96th annual meeting of the FMCA.
... Chen et al. 2020). Among them, pyrethroid insecticide is widely used on insect pests, including mosquitoes, during any vector control program or agriculture sectors worldwide because of its fast-acting nature and relatively lesser toxicity to vertebrates (Baldacchino et al. 2015). Various commercial products of pyrethroids in the form of aerosol sprays or coils are popularly used as adult mosquitocides (M. ...
Aedes aegypti ( Ae. aegypti )‐mediated transmission of arboviral diseases is posing a great concern globally. The challenge to traditional vector control methods is heightened by the increasing resistance of mosquitoes to chemical pesticides. In the present study, adulticide susceptibility tests against the pyrethroid insecticides—Permethrin and Deltamethrin were conducted using standard protocols, subsequently characterizing the partial segments of the voltage‐gated sodium channel (VGSC) gene for Ae. aegypti populations sampled across ten districts of West Bengal, India. The mean mortalities for Permethrin and Deltamethrin were found to be 86.87 ± 2.36 and 92.03 ± 1.54, respectively, with significant differences between the regional populations. The knockdown time, KDT90 (min.), ranges between 61.85–314.68 and 74.49–298.92, respectively. Analysis of segment 6 from the partial domains II, III, and IV of the VGSC gene indicated amino acid substitutions at specific positions: S to P at 989, V to G at 1016, A to T at 1022, T to I at 1520, and F to C at 1534. The F1534C is the most frequent mutation (0.41) observed amongst the resistant population. Analysis of Molecular Variance (AMOVA) revealed significant genetic variation within and among the regional populations ( F = 0.453 p < 0.001). Though the allele frequencies lied within the 95% confidence interval of the Hardy–Weinberg parabola, slight deviation of the allele frequencies from the equilibrium is indicative of operational selection pressure favouring the kdr mutants. Haplotype map shows the phylogeographical pattern with two distinct haplogroups diverging by 32 mutational steps. Thus, the study identified the resistance profile of Ae. aegypti mosquitoes across districts, aiding the selection of region‐specific pesticides.
... Aedes aegypti (Linnaeus) and Aedes albopictus (Skuse) are vectors of arboviruses such as dengue virus, yellow fever virus, chikungunya virus, and Zika virus (Jansen et al. 2010, Gubler 2011, Higgs and Vanlandingham 2015, Kauffman and Kramer 2017. These species are known to be invasive (Juliano et al. 2005, Baldacchino et al. 2015 and distributed in many different geographic regions worldwide (Kraemer et al. 2015, Laporta et al. 2023. Both species are widespread in Florida with recorded presence of Ae. aegypti and/or Ae. albopictus in 56 out of 67 counties (Parker et al. 2019). ...
Insecticide resistance is a global issue in effective mosquito control. Since only a limited number of insecticide classes are available to mosquito control programs, reliance on a few active ingredients has developed resistance in many mosquito species. Several studies have been published documenting the development of resistance to pyrethroid active ingredients in Florida populations of Aedes aegypti (Linnaeus). However, there are only a few published studies on resistance levels of Aedes species to formulated products used in mosquito control programs. This study was conducted to determine baseline laboratory resistance levels of different populations of Ae. aegypti and Aedes albopictus (Skuse) in St. Johns County (SJC), Florida to Aqualuer 20-20® and Duet®. Ae. aegypti and Ae. albopictus were collected separately from five mosquito control zones where they received different treatment pressures of insecticides. Topical application bioassays were conducted on those populations to determine the doses required to achieve 100% population mortalities and resistance ratios compared to a susceptible population of each species. Based on the availability of mosquitoes, the Centers for Disease Control and Prevention (CDC) bottle bioassays were conducted on the same populations. All three Ae. aegypti populations tested were detected as having high resistance to at least one formulation, irrespective of the insecticide treatment pressure. The only Ae. albopictus population to display resistance came from the highest insecticide-pressured mosquito control zone and this is the first quantification of high pyrethroid resistance (RR>10) in Ae. albopictus in Florida. The study established the baseline laboratory resistance levels of Ae. aegypti and Ae. albopictus in SJC to the two pyrethroid formulations. Results indicated the limited efficacy of the synergist piperonyl butoxide (PBO) in reversing high insecticide resistance and highlighted the need for routine monitoring in different populations in the target area.
... albopictus may also be under strong selective pressure to evolve insecticide resistance as management strategies to control arbovirus outbreaks in new areas intensify (Pichler, Malandruccolo, et al. 2019). Understanding the current population structure and past demographic history of Ae. albopictus has critical applications for assessing the potential risk this vector mosquito poses for human health and can offer insights into how to control these invasive populations (Unlu et al. 2013;Baldacchino et al. 2015;Caputo et al. 2016;Farajollahi et al. 2012) by enhancing efforts to determine the genetic bases of vector competence and insecticide resistance and predict invasion success in more temperate climates. ...
The Asian tiger mosquito, Aedes albopictus, is currently the most widespread invasive mosquito species in the world. It poses a significant threat to human health, as it is a vector for several arboviruses. We used a SNP chip to genotype 748 Ae. albopictus mosquitoes from 41 localities across Europe, 28 localities in the native range in Asia, and 4 in the Americas. Using multiple algorithms, we examined population genetic structure and differentiation within Europe and across our global dataset to gain insight into the origin of the invasive European populations. We also compared results from our SNP data to those obtained using genotypes from 11 microsatellite loci (N = 637 mosquitoes from 25 European localities) to explore how sampling effort and the type of genetic marker used may influence conclusions about Ae. albopictus population structure. While some analyses detected more than 20 clusters worldwide, we found mosquitoes could be grouped into 7 distinct genetic clusters, with most European populations originating in East Asia (Japan or China). Interestingly, some populations in Eastern Europe did not share genetic ancestry with any populations from the native range or Americas, indicating that these populations originated from areas not sampled in this study. The SNP and microsatellite datasets found similar patterns of genetic differentiation in Europe, but the microsatellite dataset could not detect the more subtle genetic structure revealed using SNPs. Overall, data from the SNP chip offered a higher resolution for detecting the genetic structure and the potential origins of invasions.
... Female mosquitoes ingest viruses during a blood meal from an infected host and then transfer viruses into a naïve host through biting 12,13 . Blocking virus transmission at the mosquito stage, rather than solely targeting the virus in human hosts, constitutes a promising, alternative approach to prevent arbovirus spread 14 . The development of such approaches requires in-depth knowledge of mosquito antiviral immunity. ...
Aedes mosquitoes transmit pathogenic arthropod-borne (arbo) viruses, putting nearly half the world’s population at risk. Blocking virus replication in mosquitoes is a promising approach to prevent arbovirus transmission, the development of which requires in-depth knowledge of virus-host interactions and mosquito immunity. By integrating multi-omics data, we find that heat shock factor 1 (Hsf1) regulates eight small heat shock protein (sHsp) genes within one topologically associated domain in the genome of the Aedes aegypti mosquito. This Hsf1-sHsp cascade acts as an early response against chikungunya virus infection and shows pan-antiviral activity against chikungunya, Sindbis, and dengue virus as well as the insect-specific Agua Salud alphavirus in Ae. aegypti cells and against chikungunya virus and O’nyong-nyong virus in Aedes albopictus and Anopheles gambiae cells, respectively. Our comprehensive in vitro data suggest that Hsf1 could serve as a promising target for the development of novel intervention strategies to limit arbovirus transmission by mosquitoes.
... So, vector control is considered the most effective way to minimize infestation of those diseases or prevent arbovirus outbreaks (Achee et al. 2015). In most cases preventive measures have been taken by applying chemical insecticides or biological control agents to eliminate adult mosquitoes or their immature stages (eggs, larvae and pupae) in breeding sites (Baldacchino et al. 2015). But in most cases, it is found that Aedes spp. ...
High-resolution microscopic images of the 8th abdominal segment, comb scales, pectin, tuft of hairs, saddle, head antenna, thoracic hooks and other morphological characteristics of Culex quinquefasciatus, Aedes aegypti and Aedes albopictus have been provided for the first time in Bangladesh. Mosquitoes spread deadly diseases (dengue, chikungunya, Japanese encephalitis, yellow fever, malaria, filariasis) that kill millions of people every year including Bangladesh. During dengue and dengue outbreak situations, it is very much necessary to identify the dengue-occurring mosquito vectors. Proper identification of the mosquito vectors of Bangladesh is the key factor for public health protection and disease prevention. Larval movement patterns and habitat characterization were also observed. Results obtained in this study revealed that dengue virus can also be carried by other Aedes species rather than A. aegypti. Results were discussed with previous study dealing with Aedes mosquito samples of Bangladesh. The findings will be very useful for the proper identification of dengue mosquito vectors in Bangladesh and the knowledge assists in the accuracy of mosquito control activities as well as prevention of mosquito-borne diseases.
... Moreover, there are no adulticidal products that are completely safe and produce a low environmental impact. Moreover, adulticide use can cause resistance in mosquitoes, decreasing their effectiveness in the event of an epidemic [54]. Appropriate thresholds can be defined as indications for adulticide treatments to avoid unnecessary treatments. ...
Background
Knowledge of the distribution and abundance of disease-causing mosquito vectors is fundamental for assessing the risk of disease circulation and introduction. Aedes caspius (Pallas, 1771) and Aedes vexans (Meigen, 1830) have been implicated, to different extents, in the circulation of several arthropod-borne viruses (arboviruses). These two mosquitoes are vectors of Tahyna virus in Europe and are considered potential vectors of Rift Valley fever virus, a virus not present but at risk of introduction on the continent.
Methods
In this work, we analysed abundance data collected during West Nile virus (WNV) surveillance in northern Italy (Po Plain) via 292 CO2-baited traps to evaluate the distribution and density of these two non-target mosquitoes. We modelled the distribution and abundance of these two mosquito species in the surveyed area using two distinct spatial analysis approaches (geostatistical and machine learning), which yielded congruent results.
Results
Both species are more abundant close to the Po River than elsewhere, but Ae. caspius is present in the eastern and western parts of the plain, linked with the occurrence of rice fields and wetlands, while Ae. vexans is observed in the middle area of the plain.
Conclusions
Presence and abundance data at the municipality level were obtained and made available through this work. This work demonstrates the importance of maintaining and improving entomological surveillance programs with an adequate sampling effort.
Graphical Abstract
... These insecticides can be used for indoor residual treatments [78]. Pyrethroids Togo 2020 [75] are used for the treatment of nets [76] as well as adult mosquito populations [79] [78]. ...
... quinquefasciatus are more abundant in urbanized areas and collected more frequently in the intradomestic environment of tropical regions. Aedes albopictus is more eclectic in biting behavior and habitat preferences, being found from suburban to peridomestic areas with high vegetation coverage [4][5][6][7][8][9][10][11]. ...
Background
The recent rise in the transmission of mosquito-borne diseases such as dengue virus (DENV), Zika (ZIKV), chikungunya (CHIKV), Oropouche (OROV), and West Nile (WNV) is a major concern for public health managers worldwide. Emerging technologies for automated remote mosquito classification can be supplemented to improve surveillance systems and provide valuable information regarding mosquito vector catches in real time.
Methods
We coupled an optical sensor to the entrance of a standard mosquito suction trap (BG-Mosquitaire) to record 9151 insect flights in two Brazilian cities: Rio de Janeiro and Brasilia. The traps and sensors remained in the field for approximately 1 year. A total of 1383 mosquito flights were recorded from the target species: Aedes aegypti and Culex quinquefasciatus. Mosquito classification was based on previous models developed and trained using European populations of Aedes albopictus and Culex pipiens.
Results
The VECTRACK sensor was able to discriminate the target mosquitoes (Aedes and Culex genera) from non-target insects with an accuracy of 99.8%. Considering only mosquito vectors, the classification between Aedes and Culex achieved an accuracy of 93.7%. The sex classification worked better for Cx. quinquefasciatus (accuracy: 95%; specificity: 95.3%) than for Ae. aegypti (accuracy: 92.1%; specificity: 88.4%).
Conclusions
The data reported herein show high accuracy, sensitivity, specificity and precision of an automated optical sensor in classifying target mosquito species, genus and sex. Similar results were obtained in two different Brazilian cities, suggesting high reliability of our findings. Surprisingly, the model developed for European populations of Ae. albopictus worked well for Brazilian Ae. aegypti populations, and the model developed and trained for Cx. pipiens was able to classify Brazilian Cx. quinquefasciatus populations. Our findings suggest this optical sensor can be integrated into mosquito surveillance methods and generate accurate automatic real-time monitoring of medically relevant mosquito species.
Graphical Abstract
... If the ovideterrent effect is confirmed, a mix of FP, N8H10 and N1H10 should be tested to evidence potential synergistic effects. Oviposition deterrents are great tools in vector control management programs, as they can be used both in push-pull methods by redirecting females towards an attractant, as well as used in sites where water cannot be removed [52][53][54] . To confirm the irritant and deterrent effect against host seeking and blood feeding females, the extracts should be tested together with host volatiles, such as in arm-in-cage assays and in tunnel tests following the WHO protocol 55 . ...
Influxes of sargassos are responsible for economic and environmental disasters in areas where they bloom, especially in regions whose main income relies on tourism and with limited capacity for sanitation and public health response. A promising way of valorization would be to convert this incredible biomass into tools to fight the deadly vector mosquito Aedes aegypti. In the present study, we generated hydrolates and aqueous extracts from three main Sargassum morphotypes identified in Guadeloupe (French West Indies): Sargassum natans VIII, Sargassum natans I and Sargassum fluitans. We conducted a chemical characterization and a holistic evaluation of their potential to induce toxic and behavioral effects in Ae. aegypti. Despite the low insecticidal potential observed for all the extracts, we found that S. natans VIII and S. fluitans hydrolates deterred oviposition, induced contact irritancy and stimulated blood feeding behavior in host seeking Ae. aegypti females, while aqueous extracts from S. natans I and S. fluitans deterred both blood feeding behavior and oviposition. Chemical characterization evidenced the presence of phenylpropanoid, polyphenols, amino acids and esters. Thus, Sargassum spp. aqueous extracts and hydrolates could be used to manipulate Ae. aegypti behavior and be valorized as control tools against this mosquito.
... In addition, the confirmation of the vector species through the detection of field-infected vectors guides public policies against vector-borne diseases. It can act as a powerful driver for community engagement and could be used as a lever towards better vector management [41]. ...
While locally-acquired dengue virus (DENV) human infections occur in mainland France since 2010, data to identify the mosquito species involved and to trace the virus are frequently lacking. Supported by a local network gathering public health agencies and research laboratories, we analysed, in late summer 2023, mosquitoes from privately-owned traps within a French urban neighbourhood affected by a dengue cluster. The cluster, in Auvergne-Rhône-Alpes, comprised three cases, including two autochthonous ones. Upon return from a recent visit to the French Caribbean Islands, the third case had consulted healthcare because of dengue-compatible symptoms, but dengue had not been recognised. For the two autochthonous cases, DENV-specific antibodies in serum or a positive quantitative PCR for DENV confirmed DENV infection. The third case had anti-flavivirus IgMs. No DENV genetic sequences were obtained from affected individuals but Aedes albopictus mosquitoes trapped less than 200 m from the autochthonous cases’ residence contained DENV. Genetic data from the mosquito-derived DENV linked the cluster to the 2023–2024 dengue outbreak in the French Caribbean Islands. This study highlights the importance of raising mosquito-borne disease awareness among healthcare professionals. It demonstrates Ae. albopictus as a DENV vector in mainland France and the value of private mosquito traps for entomo−virological surveillance.
... Comparison studies of vector competence with those viruses using populations from different places could help elucidate intrinsic differences between populations and prevent outbreaks if that species is competent for one or more viruses. Aedes japonicus japonicus (Theobald, 1901), known as the rock pool mosquito or the Asian bush mosquito, is a species common in Japan, Korea, and China; however, it is increasingly expanding around the world, invading countries in Europe and the Americas, including Canada and the US [59,[62][63][64][65][66][67][68]. In Europe, this mosquito was first detected in the 2000s in France, and since then, it has been found in West Germany, Luxembourg, French Alsace, and southwards to Switzerland, Liechtenstein, Austria, Spain, and Italy. ...
Simple Summary
The main mosquito species capable of transmitting arboviruses belong to the genera Aedes spp., Psorophora spp., Anopheles spp., Culex spp., Mansonia spp., Coquillettidia spp., Haemagogus spp., Sabethes spp., Culiseta spp., and Wyeomyia spp. Some neglected mosquito species have the potential to become significant disease vectors due to parameters such as global distribution, rapid adaptation to urban areas, and anthropophilic habits. This review discusses the epidemiological importance and biology of three neglected mosquitoes, Aedes scapularis, Aedes vittatus, and Aedes japonicus japonicus, in the context of vectorial capacity and how urbanization, climate change, and globalization alter disease transmission dynamics and may increase the participation of neglected species in propagating diseases.
Abstract
More than 3550 species of mosquitoes are known worldwide, and only a fraction is involved in the transmission of arboviruses. Mosquitoes in sylvatic and semi-sylvatic habitats may rapidly adapt to urban parks and metropolitan environments, increasing human contact. Many of these mosquitoes have been found naturally infected with arboviruses from the Alphaviridae, Flaviviridae, and Bunyaviridae families, with many being the cause of medically important diseases. However, there is a gap in knowledge about the vector status of newly invasive species and their potential threat to human and domestic animal populations. Due to their rapid distribution, adaptation to urban environments, and anthropophilic habits, some neglected mosquito species may deserve more attention regarding their role as secondary vectors. Taking these factors into account, we focus here on Aedes (Ochlerotatus) scapularis (Rondani), Aedes japonicus japonicus (Theobald), and Aedes (Fredwardsius) vittatus (Bigot) as species that have the potential to become important disease vectors. We further discuss the importance of these neglected mosquitoes and how factors such as urbanization, climate change, and globalization profoundly alter the dynamics of disease transmission and may increase the participation of neglected species in propagating diseases.
... Mosquitoes transmit a substantial share of arboviruses. In recent years, the relevant illnesses have risen and steadily expanded to places not afflicted by Baldacchino et al. (2015). Climate change, globalisation, lack of efficient vector management, pesticide resistance, and the migration of vector populations to the new geographic areas are among the reasons that have contributed to the development of such diseases (Cebrián-Camisón et al., 2020). ...
... Prior to field application of this larvicide, it is important to establish baseline information on the susceptibility of the target mosquitoes present in a given area. Bti doses for the control of Aedes albopictus have already been defined, and protocols and recommendations for practical use are available (Baldacchino et al., 2015). However, the efficacy of Bti against Ae. ...
Mosquito control, which is not always easily accomplished, is further complicated by the spread of invasive species. This is the case of Aedes koreicus, a mosquito native to East Asia, whose presence has been recorded in several European countries, including Italy. This mosquito found suitable ecological conditions in central Europe in general, and in northern Italy in particular, as shown by the ongoing expansion of its distribution. While basic knowledge on feeding habits of Ae. koreicus have already been acquired, information on its vectorial competence is scarce. Therefore, active monitoring on the presence of this mosquito, and the pre-planning of future control actions, are of paramount importance. Currently, there are no specific guidelines for controlling this mosquito, both in its native regions and in invaded countries. Here we present the first study on the efficacy of a bioinsecticide based on Bacillus thuringiensis on Ae. koreicus larvae, with a comparison with results obtained on the tiger mosquito Aedes albopictus. Our results proved that this bioinsecticide is effective on Ae. koreicus, both dissolved in water and incorporated into MosChito raft, a hydrogel-based matrix that has recently been developed for the delivery of insecticides to other mosquito species and suitable for safe and eco-compatible applications.
... Traditional mosquito vector control methods include the use of chemical products, primarily insecticides, and biological products (Baldacchino et al., 2015;Wilson et al., 2020). Biological methods now encompass releasing mosquito populations infected with Wolbachia sp. to render natural populations refractory to the arboviruses they transmit (Caputo et al., 2019;O'Neill, 2018), or using transgenic mosquitoes to suppress populations and interrupt the vector transmission cycles (Bellini et al., 2013;Carvalho et al., 2015). ...
Introduction:
The Aedes vittatus mosquito is an important vector of yellow fever in Africa, with vectorial competence for dengue, chikungunya and Zika. Its presence has been reported in some places in Africa, Asia, Europe, and -recently- America. However, information on its distribution is fragmented, with limited descriptions of the specific characteristics of its habitats.
Objective:
To compile records of its occurrence, describe the ecological characteristics of its habitat and estimate its current and future global potential invasion.
Methods:
We employed both first-record data and global occurrence records to describe its habitat. Additionally, we used an ecological niche model, specifically the MaxEnt algorithm, with bioclimatic variable layers to estimate potential invasion areas. Since the native range of A. vittatus is unknown, we calibrated accessible areas using two hypotheses, Africa and Asia, based on available genetic information.
Results:
Regardless of its native area, A. vittatus appears to be distributed in tropical and subtropical areas in all continents with potential to reach even currently colder climates as global climate change. It is found mainly in tropical and urban areas, likely through transcontinental and terrestrial passive transport.
Conclusions:
The mosquito can be found on all continents, ranging from sea level to 2 500 m.a.s.l., at temperatures between 15 and 30 °C, and has the potential for further expansion.
... 64,65 This encompasses the administration of Aedes mosquito populations using strategies such as the application of insecticides, the decrease of larval sources, and the utilization of mosquito nets and screens. 66,67 The active participation of the community is of utmost importance in identifying and eradicating breeding sites located within residential areas, educational institutions, and public areas. 68 The rapid identification of dengue cases is of utmost importance for prompt intervention. ...
Background
Dengue, the world's fastest‐growing vector‐borne disease, has skyrocketed in the 21st century. Dengue has harmed human health since its first known cases among Spanish soldiers in the Philippines to its 21st‐century outbreaks in Southeast Asia, the Pacific, and the Americas. In light of the current circumstances, it is imperative to investigate its origin and prevalence, enabling the implementation of effective interventions to curb the upsurge.
Methods
Our study examines the history of dengue outbreaks, and evolving impact on public health, aiming to offer valuable insights for a more resilient public health response worldwide. In this comprehensive review, we incorporated data from renowned databases such as PubMed, Google Scholar, and Scopus to provide a thorough analysis of dengue outbreaks.
Results
Recent dengue outbreaks are associated with rapid urbanization, international travel, climatic change, and socioeconomic factors. Rapid urbanization and poor urban design and sanitation have created mosquito breeding places for dengue vectors. Also, international travel and trade have spread the pathogen. Climate change in the past two decades has favored mosquito habitats and outbreaks. Socioeconomic differences have also amplified the impact of dengue outbreaks on vulnerable communities. Dengue mitigation requires vector control, community engagement, healthcare strengthening, and international cooperation.
Conclusion
Climate change adaptation and urban planning are crucial. Although problems remain, a comprehensive vector control and community involvement plan may reduce dengue epidemics and improve public health in our interconnected world.
... Regarding dengue transmission in endemic settings, attention has been placed on mapping the most productive breeding sites, key premises, and houses more likely to harbor high populations of Ae. aegypti, entomovirological surveillance, massive trapping, satellite images, and modeling 23,36,[48][49][50][51][52][53][54][55][56] . Using data from Foz do Iguaçu, Brazil, we are able to predict an increase in dengue cases with 4 weeks in advance but face no success in providing spatial prediction to local health managers 34,35 . ...
In the last decades, dengue has become one of the most widespread mosquito-borne arboviruses in the world, with an increasing incidence in tropical and temperate regions. The mosquito Aedes aegypti is the dengue primary vector and is more abundant in highly urbanized areas. Traditional vector control methods have showing limited efficacy in sustaining mosquito population at low levels to prevent dengue virus outbreaks. Considering disease transmission is not evenly distributed in the territory, one perspective to enhance vector control efficacy relies on identifying the areas that concentrate arbovirus transmission within an endemic city, i.e., the hotspots. Herein, we used a 13-month timescale during the SARS-Cov-2 pandemic and its forced reduction in human mobility and social isolation to investigate the spatiotemporal association between dengue transmission in children and entomological indexes based on adult Ae. aegypti trapping. Dengue cases and the indexes Trap Positive Index (TPI) and Adult Density Index (ADI) varied seasonally, as expected: more than 51% of cases were notified on the first 2 months of the study, and higher infestation was observed in warmer months. The Moran's Eigenvector Maps (MEM) and Generalized Linear Models (GLM) revealed a strong large-scale spatial structuring in the positive dengue cases, with an unexpected negative correlation between dengue transmission and ADI. Overall, the global model and the purely spatial model presented a better fit to data. Our results show high spatial structure and low correlation between entomological and epidemiological data in Foz do Iguaçu dengue transmission dynamics, suggesting the role of human mobility might be overestimated and that other factors not evaluated herein could be playing a significant role in governing dengue transmission.
... Consequently, there is an urgent need for low-toxicity and environmentally friendly tools to control parasite-transmitting snails. Biological control, which involves the use of specific gut microbiota or microorganisms, has emerged as a promising approach for the management of IAS and pathogens [5,84,[99][100][101]. This study revealed the modes of microbial transmission in the guts of gastropod mollusks and showed that core gut microbes Cloacibacterium and Aeromonas associated with different gastropod species could be persistently transmitted across multiple generations. ...
Background
Studies on the gut microbiota of animals have largely focused on vertebrates. The transmission modes of commensal intestinal bacteria in mammals have been well studied. However, in gastropods, the relationship between gut microbiota and hosts is still poorly understood. To gain a better understanding of the composition of gut microbes and their transmission routes in gastropods, a large-scale and long-term experiment on the dynamics and transmission modes of gut microbiota was conducted on freshwater snails.
Results
We analyzed 244 microbial samples from the digestive tracts of freshwater gastropods and identified Proteobacteria and Bacteroidetes as dominant gut microbes. Aeromonas, Cloacibacterium, and Cetobacterium were identified as core microbes in the guts, accounting for over 50% of the total sequences. Furthermore, both core bacteria Aeromonas and Cloacibacterium, were shared among 7 gastropod species and played an important role in determining the gut microbial community types of both wild and cultured gastropods. Analysis of the gut microbiota at the population level, including wild gastropods and their offspring, indicated that a proportion of gut microbes could be consistently vertically transmitted inheritance, while the majority of the gut microbes resulted from horizontal transmission. Comparing cultured snails to their wild counterparts, we observed an increasing trend in the proportion of shared microbes and a decreasing trend in the number of unique microbes among wild gastropods and their offspring reared in a cultured environment. Core gut microbes, Aeromonas and Cloacibacterium, remained persistent and dispersed from wild snails to their offspring across multiple generations. Interestingly, under cultured environments, the gut microbiota in wild gastropods could only be maintained for up to 2 generations before converging with that of cultured snails. The difference observed in gut bacterial metabolism functions was associated with this transition. Our study also demonstrated that the gut microbial compositions in gastropods are influenced by developmental stages and revealed the presence of Aeromonas and Cloacibacterium throughout the life cycle in gastropods. Based on the dynamics of core gut microbes, it may be possible to predict the health status of gastropods during their adaptation to new environments. Additionally, gut microbial metabolic functions were found to be associated with the adaptive evolution of gastropods from wild to cultured environments.
Conclusions
Our findings provide novel insights into the dynamic processes of gut microbiota colonization in gastropod mollusks and unveil the modes of microbial transmission within their guts.
1dB18pPYxP-ygVgUJj2q9BVideo Abstract
... Other ways to combat mosquitoes include the use of microbial insecticides containing the bacteria Bacillus thuringiensis israelensis (Bti), educational campaigns aimed at eliminating breeding sites, implementation of traps to capture eggs and adults, in addition to biological control using the bacteria Wolbachia spp., in addition to the use of A. aegypti predators (Baldacchino et al., 2015;Weeratunga et al., 2017;Ogunlade et al., 2021). ...
This study evaluated the insecticidal activity of crude extracts from Enterolobium contortisiliquum (Vell.) seeds on eggs and larvae of A. aegypti, and also verified the phytochemical profile and the presence of lectins in the extract. The 0.15 M NaCl saline solution was used as the extracting substance. For tests with eggs and larvae, the crude extract was used in its raw form (RCE) and boiled at 100º C for 5 min (BCE). Concentrations of 4.68; 9.37; 18.75; 28.13; 37.13 and 46.89 mg/mL, with distilled water as a negative control. Assays were performed in triplicate. The results were subjected to analysis of variance, Tukey's test and Log-Probit analysis to determine LC50 and LC90. BCE showed better results on eggs than RCE, managing to prevent the hatching of larvae in 81.66% ± 10.40 of treated eggs, at a concentration of 46.89 mg/mL. The LC50 and LC90 were set at 35.95 and 52.67 mg/mL, respectively. In tests with larvae, concentrations of 46.89 and 37.13 mg/mL, for RCE and BCE, caused 100% mortality in 24 hours of exposure. Larval mortality at the other concentrations increased with exposure time extending to 48 h. RCE, at 48 h exposure is the most promising extract on larvae (E = 72.77%, LC90 = 10.86 mg/mL). In RCE, the presence of lectins and secondary metabolites: flavonoids, xanthones and phenols, were detected. The results demonstrate the potential of E. contortisiliquum seed extracts with ovicidal and larvicidal action on A. aegypti.
... Moreover, the cold-tolerant biology of Ae. koreicus gives it an advantage in terms of spreading and establishing its population. Between 2007 and 2012, many autochthonous cases of dengue and chikungunya were reported in Europe [48]. CHIKV was first isolated in the 1950s from patients in Tanzania, and then the virus began to spread widely over the last decade [49]. ...
Invasive alien species are a growing threat to natural systems, the economy, and human health. Active surveillance and responses that readily suppress newly established colonies are effective actions to mitigate the noxious consequences of biological invasions. Aedes (Hulecoeteomyia) koreicus (Edwards), a mosquito species native to East Asia, has spread to parts of Europe and Central Asia since 2008. In the last decade, Ae. koreicus has been shown to be a competent vector for chikungunya virus and Dirofilaria immitis. However, information about the current and potential distribution of Ae. koreicus is limited. Therefore, to understand the changes in their global distribution and to contribute to the monitoring and control of Ae. koreicus, in this study, the MaxEnt model was used to predict and analyze the current suitable distribution area of Ae. koreicus in the world to provide effective information.
... Their lipophilic nature facilitates their interference in the basic metabolic, biochemical, physiological and behavioral functions of insects [43]. Essential oils can interfere with the feeding behavior of arthropods, act as a growth regulator or act as a neurotoxin, among the toxicity mechanisms; they can also act as protein denaturants and enzyme inhibitors, in addition to promoting the disintegration of the plasma membrane [44,45]. These diverse mechanisms of action contribute to preventing the emergence of resistant vectors. ...
Dengue, Chikungunya and Zika are arboviruses, transmitted by the mosquito Aedes aegypti, that cause high mortality and serious health consequences in human populations. Efforts to control Ae. aegypti are important for preventing outbreaks of these diseases. Essential oil constituents are known to exhibit many activities, such as their use as larvicides. Given their potential, the present study aimed to characterize the larvicidal effect of dihydrojasmone, p-cymene, carvacrol, thymol, farnesol and nerolidol on the larvae of Ae. aegypti and their interference over the morphology of the mosquitos. The essential oil constituents were dissolved in dimethylsulfoxide at concentrations of 1–100 μg/mL and were applied in the breeding environment of third-stage larvae. The larvae from bioassays were fixed, dehydrated and embedded. Ultrathin sections were contrasted using 5% uranyl acetate and 1% lead citrate for observation through transmission electron microscopy. The oil with the highest larvicidal efficiency was found to be nerolidol, followed by farnesol, p-cymene, carvacrol, thymol and dihydrojasmone, with an LC50 of 11, 21, 23, 40, 45 and 66 µg/mL, respectively. The treated Ae. aegypti larvae caused alteration to the tegument or internal portions of larvae. The present study demonstrated which of these oils—dihydrojasmone, farnesol, thymol, p-cymene, carvacrol and nerolidol—have effective larvicidal activity.
... In North America, Ae. albopictus is expanding its range into Canada, where it is considered established in Windsor, Ontario (Giordano et al., 2020). Predation by cyclopoid copepods has previously been identified as a method for controlling Ae. albopictus populations in Europe (Baldacchino et al., 2015), but more research is needed to assess the efficacy of copepod biocontrol agents against Ae. albopictus in the presence of native mosquito prey species. ...
As the global temperature rises in the coming decades, Aedes albopictus is expected to invade and establish in South East England, where Culex pipiens is currently the most common native mosquito species. Biocontrol measures that use local cyclopoid copepods against Ae. albopictus may be compromised if the copepods prefer alternate Cx. pipiens prey. In this study, I assessed the predation efficiency of Megacyclops viridis copepods against Ae. albopictus larvae from France and larvae that hatched from egg rafts of Cx. pipiens collected in South East England. The experiments were conducted at 15 and 25°C, which are representative of present and future summer temperatures in South East England. Ae. albopictus larvae that survived the course of the experiment in the predator-absent controls were significantly smaller than Cx. pipiens larvae that survived in the absence of predation. The background mortality of Cx. pipiens larvae increased with the 10-degree increase in temperature, and the smaller size of surviving Cx. pipiens larvae at 25°C, relative to survivors at 15°C, suggests that larger Cx. pipiens larvae were more likely to die at the higher temperature setting. Across all experimental treatments, the ratio of copepod body length to mean prey length, based on larval lengths of survivors from the corresponding predator-absent controls, was a significant predictor of the copepod's predation efficiency. Adding temperature setting to the predation efficiency model as a predictor did not improve model fit. Within the mixed prey treatments, the predation efficiency of M. viridis was 34.5 percentage points higher against Ae. albopictus prey than against Cx. pipiens prey. The higher predation efficiency that M. viridis exhibited against invasive Ae. albopictus prey, likely due to the smaller size of these larvae, supports the future use of M. viridis as a biocontrol agent in the United Kingdom.
... Vector control measures include indoor and outdoor residual spraying, insecticide-treated bed nets and mosquito traps (Greisman et al., 2019). However, long-term use of such chemical applications can be harmful to the natural environment and other nontarget organisms (Baldacchino et al., 2015;Lee et al., 2020;Pereira et al., 2009). Moreover, many of these methods have lost, or are gradually losing, their effectiveness as mosquitoes evolve resistance to the insecticides (Dambach, 2020;Hemingway & Ranson, 2000). ...
Dragonfly/damselfly naiads have the potential to control mosquitoes, and indirectly the diseases they carry, due to their extensive predation on mosquito larvae. Experimental studies have measured the effectiveness of individual dragonfly/damselfly naiads in controlling mosquitoes by introducing them to mosquito larvae and counting the number of larvae eaten in a given time period (i.e. predation success).
Without a quantitative synthesis, however, such individual measures are unable to provide a generalized estimation about the effectiveness of dragonflies/damselflies as biological mosquito control agents. To achieve this, we assembled a database containing 485 effect sizes across 31 studies on predation successes of 47 species of commonly found dragonfly/damselfly naiads on nine species of mosquito larvae belonging to Aedes, Anopheles and Culex. These studies covered 14 countries across Asia, Africa and South and North America, where mosquitoes are the vectors of Chikungunya, Dengue, Japanese encephalitis, Lymphatic filariasis, Malaria, Rift Valley fever, West Nile fever, Yellow fever and Zika.
Using this database, we conducted a meta‐analysis to estimate the average predation success per day by a single individual dragonfly/damselfly naiad on these mosquito larvae as a generalized measure of the effectiveness of dragonflies/damselflies for mosquito control. We also built an interaction network for predator‐dragonflies/damselflies and prey‐mosquitoes and the diseases they vector to understand the functioning of this important predator‐prey network.
Our results showed that mosquito larvae were significantly reduced through predation by dragonfly/damselfly naiads. Within experimental containers, a single individual dragonfly/damselfly naiad can eat on average 40 (95% confidence intervals [CIs] = 20, 60) mosquito larvae per day, equivalent to a reduction of the mosquito larval population by 45% (95% CIs = 30%, 59%) per day. The average predation success did not significantly vary among Aedes, Anopheles and Culex mosquitoes or among the four (I–IV) mosquito larval stages.
These results provide strong evidence that dragonflies/damselflies can be effective biological control agents of mosquitoes, and environmental planning to promote them could lower the risk of spreading mosquito‐borne diseases in an environmentally friendly and cost‐effective manner.
The increasing number of imported and locally transmitted cases of dengue and chikungunya in Europe is raising concerns, prompting local authorities to regulate Aedesalbopictus populations. The development and commercialization of olfactory traps are contributing to the reduction of mosquito populations and biting nuisances. These traps mimic human host by emitting only two to three bacterial-derived volatiles organic compounds. However, they are less attractive to Aedes species than live human hosts or natural odor blends collected directly from humans. Using seven representative microbial species isolated from the skin microbiota of human volunteers, we successfully created an attractive microbial blend that enhanced the effectiveness of commercial olfactory traps in attracting field Ae.albopictus mosquitoes. This effect is likely due to a synergistic interaction between attractive compounds emitted by the microbial blend and commonly used attractants in commercial lures. Our results highlight the importance of considering the complexity of the human skin microbiota, including yeasts, to identify new volatile organic compounds that could enhance the capture efficacy of olfactory traps. Incorporating these compounds into traps could improve the capture of Ae.albopictus females in field settings, though further investigation is needed to ensure their stable and effective release.
A promising avenue to control mosquito-borne diseases such as dengue, malaria, and Zika involves releasing male mosquitoes carrying the bacterium Wolbachia in wild areas to drive female sterility by a mechanism called cytoplasmic incompatibility (CI). In this work, we initiate a preliminary assessment of how the combined impact of dispersal, incomplete CI and mating competitiveness on mosquito population suppression by a delay differential equation model. Our theoretical analyses indicate that the immigration of eggs plays a significant role in the suppression dynamics. For the case without egg immigration, we identify a threshold dispersal rate v* of adult mosquitoes, threshold CI density ξ*, and threshold release ratio r*. A successful mosquito suppression would be established only when v < v*, ξ > ξ*, and r(t) ≥ r* uniformly. The immigration of eggs causes the threshold dynamics to be invalid, and warns an absolute failure of population suppression. The monotonicity of the adult steady-state in the dispersal rate and CI intensity indicates that choosing a suitable Wolbachia strain with strong CI intensity, or bringing down the dispersal rate of mosquitoes by blocking the suppression zones is a feasible strategy to obtain a better suppression level.
Despite the application of control measures, mosquito-borne diseases continue to pose a serious threat to human health. In this context, exploiting Wolbachia, a common symbiotic bacterium in insects, may offer effective solutions to suppress vectors or reduce their competence in transmitting several arboviruses. Many Wolbachia strains can induce conditional egg sterility, known as cytoplasmic incompatibility (CI), when infected males mate with females that do not harbor the same Wolbachia infection. Infected males can be mass-reared and then released to compete with wild males, reducing the likelihood of wild females encountering a fertile mate. Furthermore, certain Wolbachia strains can reduce the competence of mosquitoes to transmit several RNA viruses. Through CI, Wolbachia-infected individuals can spread within the population, leading to an increased frequency of mosquitoes with a reduced ability to transmit pathogens. Using artificial methods, Wolbachia can be horizontally transferred between species, allowing the establishment of various laboratory lines of mosquito vector species that, without any additional treatment, can produce sterilizing males or females with reduced vector competence, which can be used subsequently to replace wild populations. This manuscript reviews the current knowledge in this field, describing the different approaches and evaluating their efficacy, safety, and sustainability. Successes, challenges, and future perspectives are discussed in the context of the current spread of several arboviral diseases, the rise of insecticide resistance in mosquito populations, and the impact of climate change. In this context, we explore the necessity of coordinating efforts among all stakeholders to maximize disease control. We discuss how the involvement of diverse expertise—ranging from new biotechnologies to mechanistic modeling of eco-epidemiological interactions between hosts, vectors, Wolbachia, and pathogens—becomes increasingly crucial. This coordination is especially important in light of the added complexity introduced by Wolbachia and the ongoing challenges posed by global change.
Aedes albopictus, known as the Asian tiger mosquito, is a significant vector for dengue fever, chikungunya, zika virus, yellow fever. Current control methods rely on chemical insecticides, which face challenges such as resistance, environmental harm, and impact on non-target species Eudrilus eugeniae and Artemia salina. This study evaluates the toxic effects of biogenic copper nanoparticles (CuNPs) synthesized using Metarhizium robertsii intracellular extract obtained from our previous research. The CuNPs were tested against A. albopictus and non-target species at 24 and 48 hours post-treatment. Results demonstrated that entomopathogenic fungi-derived CuNPs exhibited potent mosquitocidal activity, resulting in 97.33% mortality in larvae, 93.33% in pupae, and 74.66% in adults at 48 hours post-treatment. The CuNPs derived from M. robertsii showed lower LC50 values of 74.873 mg/L in larvae, 76.101 mg/L in pupae, and 136.645 mg/L in adults at 48 hours post-treatment. Additionally, 12 hours post-treatment, catalase (an antioxidant enzyme) activity decreased 1.5-fold in a dose-dependent manner, while glutathione S-transferase (a detoxification enzyme) activity increased 7.8-fold. CuNPs demonstrated lower toxicity to non-target species, with 24% mortality in A. salina and 24.44% mortality in E. eugeniae at 24 hours post-treatment. The LC50 values were 634.747 mg/L for A. salina and 602.494 mg/L for E. eugeniae at 24 hours post-treatment. These findings indicate that entomopathogenic fungi-derived CuNPs are a promising, target-specific candidate for controlling A. albopictus at various life stages (larvae, pupae, and adults).
Releasing Wolbachia-infected male mosquitoes to suppress wild females through cytoplasmic incompatibility (CI) has proven to be a safe and effective method for mosquito control. We study a release strategy that males are released with a constant amount c at time , . The determination of T is related to the sexually active lifespan of released males . By introducing the early lethal effect of CI, we formulate a delay differential equation model for mosquito suppression based on Beverton-Holt-type of birth. After explicitly expressing two thresholds and , we prove that when and , the model displays the bistable dynamics, where mosquito population either declines to zero, or approaches a positive periodic state. The rigorous mathematical proof of the exact number of periodic solutions and their stability analyses is obtained by proving that every solution is sandwiched between two “good” solutions, whose initial functions are chosen to be the solutions of the model without delay.
Due to their potential role in pathogen transmission, invasive mosquitoes pose considerable threats to human and animal health. Several studies have identified the most important ecological drivers mediating the establishment and spread of key mosquito species (e.g., Aedes aegypti, and Ae. albopictus), and made predictions for future distribution. We evaluated the effect of an exhaustive list of environmental predictors on the distribution of three invasive species in Hungary (Ae. albopictus, Ae. japonicus, and Ae. koreicus) by using the same standards for data collection based on citizen science observations. Current distribution maps of these species were generated from a 5-year survey, then were compared with various predictor maps reflecting climate, habitat type, food supply, traffic, and interspecific competition by using a boosted regression trees approach that resulted in a subset of variables with the strongest impact. The best predictor sets were used to predict the probability of occurrence of the focal species for the whole country, and these predictions based on citizen science were evaluated against the results of an independent recent field surveillance. We uncovered species-specific patterns and found that different predictor sets were selected for the three different species, and only predictions for Ae. albopictus could be validated with direct trapping data. Therefore, citizen science informed distribution maps can be used to identify ecological predictors that determine the spread of invasive mosquitoes, and to estimate risk based on the predicted distribution in the case of Ae. albopictus.
BACKGROUND
Within the framework of sustainable and effective control methods for Aedes albopictus, two different conidial suspensions, BbCS‐1 and BbCS‐2 (respectively without and with nutrients), were used as solvents for the biopolymers water‐soluble 2‐hydroxyethylcellulose (HEC) and sodium alginate (SA). In this way, two different classes of hydrogels were prepared for each polymer (previously shown to attract tiger mosquito oviposition) to produce HEC‐based and SA‐based Bb/Gel systems with and without nutrients. The aim was to achieve a long‐lasting and cost‐effective lure‐and‐kill oviposition substrate useful for lethal ovitraps. Beauveria bassiana (Bb) survival and growth in the different Bb/Gel systems were monitored for 24 days. Following the growth assay, 24‐day‐old Bb/Gel systems were tested against Ae. albopictus eggs through a hatching test to evaluate their lethal effect.
RESULTS
Gel systems enhance Bb's longevity (up to 24 days) more effectively than standard liquid conidial suspensions, proving that tested HEC‐ and SA‐based hydrogels are not toxic for Bb (biocompatibility) and create a microenvironment suitable to sustain prolonged fungal growth. In particular, the results indicate that gel system based on hydroxyethylcellulose is a suitable delivery substrate for supporting the activity of Bb and is simultaneously effective against Ae. albopictus eggs through a combined mechanism of mechanical effect and fungal action (CM > 90%).
CONCLUSION
The efficacy of Bb gel systems was assessed according to its properties in favouring the growth and vitality of Bb as well as in reducing the Ae. albopictus hatching eggs rate. Further studies, in semi‐field and field conditions, will be useful to evaluate the efficacy of Bb/Gel systems on adults in terms of attraction, oviposition, mortality, and potential autodissemination to propose a new tool in precision pest management. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
Dengue fever is a mosquito-transmitted disease of great public health importance. Dengue lacks adequate vaccine protection and insecticide-based methods of mosquito control are proving increasingly ineffective. Here we review the emerging use of mosquitoes transinfected with the obligate intracellular bacterium Wolbachia pipientis for vector control. Wolbachia often induces cytoplasmic incompatibility in its mosquito hosts, resulting in infertile progeny between an infected male and an uninfected female. Wolbachia infection also suppresses the replication of pathogens in the mosquito, a process known as "pathogen blocking". Two strategies have emerged. The first one releases Wolbachia carriers (both male and female) to replace the wild mosquito population, a process driven by cytoplasmic incompatibility and that becomes irreversible once a threshold is reached. This suppresses disease transmission mainly by pathogen blocking and frequently requires a single intervention. The second strategy floods the field population with an exclusively male population of Wolbachia-carrying mosquitoes to generate infertile hybrid progeny. In this case, transmission suppression depends largely on decreasing the population density of mosquitoes driven by infertility and requires continued mosquito release. The efficacy of both Wolbachia-based approaches has been conclusively demonstrated by randomized and non-randomized studies of deployments across the world. However, results conducted in one setting cannot be directly or easily extrapolated to other settings because dengue incidence is highly affected by the conditions into which the mosquitoes are released. Compared to traditional vector control methods, Wolbachia-based approaches are much more environmentally friendly and can be effective in the medium/long term. On the flip side, they are much more complex and cost-intensive operations, requiring a substantial investment, infrastructure, trained personnel, coordination between agencies, and community engagement. Finally, we discuss recent evidence suggesting that the release of Wolbachia-transinfected mosquitoes has a moderate potential risk of spreading potentially dangerous genes in the environment.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11637914
The recent reemergence of Oropouche virus (OROV) highlights the need to better understand insecticide susceptibility in Culicoides (Diptera: Ceratopogonidae), which contains the vector of OROV and many other species that are biting nuisances and vectors of pathogens that affect humans, livestock, and wildlife. With adulticides as the primary method of Culicoides control, there is growing concern about insecticide resistance, compounded by the lack of tools to monitor Culicoides susceptibility. We adapted the CDC bottle bioassay and field cage trial methods, typically used to monitor insecticide susceptibility in mosquitoes and formulated adulticide efficacy, to evaluate permethrin susceptibility in the widely distributed coastal nuisance species, Culicoides furens . Permethrin caused complete mortality in C. furens in field and laboratory assays. We identified a diagnostic dose (10.75 µg) and time (30 minutes) that resulted in complete mortality in CDC bottle bioassays. Additionally, we determined that no-see-um netting is an effective mesh for field cage trials, allowing for accurate assessment of Culicoides susceptibility to ultra-low volume applications of formulated adulticides like Permanone 30–30, a widely utilized adulticide. These methodologies offer essential tools for assessing Culicoides susceptibility, which is crucial for managing populations of Culicoides and preventing the spread of OROV and other pathogens.
It takes into account that conscious, susceptible individuals with self‐protection cannot be infected by mosquito bites, a seven‐dimensional dengue transmission model with self‐protection, and two different standard incidence rates are proposed. Our focus is on discussing the global behavior and the optimal control of the model. We first calculate the control reproduction number Rc and determine that if Rc>1, the model has a unique dengue equilibrium E∗. Furthermore, we obtain the local stability of dengue‐free equilibrium E0 and the dengue equilibrium E∗ by using the method of proof by contradiction. By utilizing the limit system of the model and the Lyapunov direct method, we acquire that E0 is globally stable if Rc<1; E0 is globally attractive if Rc=1, and if Rc>1, the model is weakly persistent with a thorough analysis, and then E∗ is globally stable. Finally, in order to minimize investment in dengue transmission, an optimal control strategy with four control variables is presented using Pontryagin's minimum principle.
Aedes aegypti spreads many dangerous and fatal illnesses like yellow fever, chikungunya and dengue fever. Several tropical plants contain eco-friendly, bioactive molecules act as a valuable supply of alternative mosquito control treatment including specific target insects. Therefore, the larvicidal effectiveness of three tropical plants-pignut (Hyptis suaveolens), carrot grass (Parthenium hysterophorus), and corn mint (Mentha arvensis) against mosquito larvae particularly second and third instars has been evaluated in the current study using aqueous leaf extracts. The fresh plant leave of the above plants were collected locally and identified by Plant taxonomist. Stock solution was prepared 20% of each extract in deionised water. Fully fed larvae were collected from the stagnant water at diverse residential areas of Gorakhpur city. The larvae were exposed to a wide range of test concentrations as mortality in 24, 48, 72 and 96 hours were used to determine LC 50 and LC 90 values. The sub-lethal doses 5.88 gm/l of P. hysterophorus showed significant larvicidal effect against the mosquito's larva. However, M. arvensis and H. suaveolens showed comparatively higher sub-lethal concentrations 27.97 gm/l and 29.53 gm/l; respectively against larvae. Our study suggests that P. Hysterophorus leave extracts to have promising phytochemicals for larvicidal potential of Ae. aegypti mosquitoes.
Background
Mosquito research in Europe has a long history, primarily focused on malaria vectors. In recent years, invasive mosquito species like the Asian tiger mosquito ( Aedes albopictus ) and the spread of arboviruses like dengue virus, chikungunya virus or bluetongue virus have led to an intensification of research and monitoring in Europe. The risk of further dissemination of exotic species and mosquito-borne pathogens is expected to increase with ongoing globalization, human mobility, transport geography, and climate warming. Researchers have conducted various studies to understand the ecology, biology, and effective control strategies of mosquitoes and associated pathogens.
Main body
Three invasive mosquito species are established in Europe: Asian tiger mosquito ( Aedes albopictus ), Japanese bush mosquito ( Ae. japonicus ), and Korean bush mosquito ( Aedes koreicus ). Ae. albopictus is the most invasive species and has been established in Europe since 1990. Over the past two decades, there has been an increasing number of outbreaks of infections by mosquito-borne viruses in particular chikungunya virus, dengue virus or Zika virus in Europe primary driven by Ae. albopictus . At the same time, climate change with rising temperatures results in increasing threat of invasive mosquito-borne viruses, in particular Usutu virus and West Nile virus transmitted by native Culex mosquito species. Effective mosquito control programs require a high level of community participation, going along with comprehensive information campaigns, to ensure source reduction and successful control. Control strategies for container breeding mosquitoes like Ae. albopictus or Culex species involve community participation, door-to-door control activities in private areas. Further measures can involve integration of sterile insect techniques, applying indigenous copepods, Wolbachia sp. bacteria, or genetically modified mosquitoes, which is very unlike to be practiced as standard method in the near future.
Conclusions
Climate change and globalization resulting in the increased establishment of invasive mosquitoes in particular of the Asian tiger mosquito Ae. albopictus in Europe within the last 30 years and increasing outbreaks of infections by mosquito-borne viruses warrants intensification of research and monitoring. Further, effective future mosquito control programs require increase in intense community and private participation, applying physical, chemical, biological, and genetical control activities.
Zika virus (ZIKV) poses a serious threat to the entire world. The rapid spread of ZIKV and recent outbreaks since 2007 have caused worldwide concern about the virus. Diagnosis is complicated because of the cross-reactivity of the virus with other viral antibodies. Currently, the virus is diagnosed by molecular techniques such as RT-PCR and IgM-linked enzyme immunoassays (MAC-ELISA). Recently, outbreaks and epidemics have been caused by ZIKV, and severe clinical symptoms and congenital malformations have also been associated with the virus. Although most ZIKV infections present with a subclinical or moderate flu-like course of illness, severe symptoms such as Guillain-Barre syndrome in adults and microcephaly in children of infected mothers have also been reported. Because there is no reliable cure for ZIKV and no vaccine is available, the public health response has focused primarily on preventing infection, particularly in pregnant women. A comprehensive approach is urgently needed to combat this infection and stop its spread and imminent threat. In view of this, this review aims to present the current structural and functional viewpoints, structure, etiology, clinical prognosis, and measures to prevent this transmission based on the literature and current knowledge. Moreover, we provide thorough description of the current understanding about ZIKV interaction with receptors, and a comparative examination of its similarities and differences with other viruses.
The Wolbachia-induced incompatible insect technique is a promising strategy for controlling wild mosquito populations. However, recent experimental studies have shown that mosquito migration into target areas dilutes the strategy’s effectiveness. In this work, we formulate a delay differential equation model to assess the impact of migration on mosquito population suppression. We identify that mosquito migration into an idealized target area makes it impossible to eliminate the target population completely. Our analysis identifies a lower bound of the suppression rate for a given migration number, which reveals the possible maximum reduction of wild population size in the peak season. For a given suppression rate target , we identify the permitted maximum migration number , above which is impossible to reduce the field mosquito density up to in peak season. To reduce more than of Aedes albopictus population during its peak season in Guangzhou within six weeks, the required minimum release number of Wolbachia-infected males climbs steeply as the migration number increases to D(0.05).
Background: Measurement of antibody titers directed against mosquito salivary antigens in blood samples has been proposed as an outcome measure to assess human exposure to vector bites. However, only a handful of antigens have been identified and the specificity and longitudinal dynamics of antibody responses are not well known. We report the protocol of a clinical trial of controlled exposure to mosquito bites that aims to identify and validate biomarkers of exposure to bites of mosquito vector species that transmit malaria and dengue in Southeast Asia and some other parts of the world. Methods: This study is an exploratory factorial randomized control trial of controlled exposure to mosquito bites with 10 arms corresponding to different species (Aedes aegypti, Ae. albopictus, Anopheles dirus, An. maculatus and An. minimus) and numbers of bites (35 or 305 bites in total over 6 weeks). Blood samples will be collected from study participants before, during and after mosquito biting challenges. Candidate peptides will be identified from published literature with antigen prediction algorithms using mosquito DNA sequence data and with immunoblotting assays carried out using protein extracts of dissected mosquito salivary glands and participants samples. Antibody titers against candidate peptides will be determined in participants samples with high-throughput cutting-edge immuno-assays. Quantification of the antibody response profile over time (including an estimate of the decay rate) and the effect of the number of bites on the antibody response will be determined using linear and logistic mixed-effects models for the continuous and the binary response, respectively. Conclusion: This research is expected to generate important knowledge for vector sero-surveillance and evaluation of vector-control interventions against malaria and dengue in the Greater Mekong Subregion. Registration: This study is registered with clinicaltrials.gov (NCT04478370) on July 20th, 2020.
Mosquitoes are very serious household and medically important pests transmitting many diseases of humans and animals. Among mosquitoes, Aedes aegypti L., is an active transmitter of dengue and lumpy skin disease virus, horrible and terrifying diseases, causing human and animal death throughout the world. Fipronil is a new chemistry insecticide used to control agriculture and medically important insect pests. It affects the GABA receptors in the nervous system and consequently causes the death of the pests. A laboratory experiment was conducted to investigate the onset of fipronil resistance and associated fitness costs in Ae. Aegypti. Moreover, the stability of fipronil resistance was evaluated after five generations of rearing without selection pressure. The population of Ae. Aegypti was exposed continuously for 12 generations to fipronil under controlled conditions. The fipronil selected population (Fipro-Sel Pop) had a 317 and 115.7-fold level of resistance compared to a susceptible and field population, respectively. Relative fitness for Fipro-Sel Pop was 0.57, with a significant disadvantage in larval duration, developmental time, percent hatchability, intrinsic rate of natural increase (rm), net reproductive rate (Ro), number of larvae in the next generation, and mean relative growth rate (MRGR) when compared to the Unselected population (Un-Sel Pop). However, the relative fitness value of Cross1 (Un-Sel Pop ♂ × Fipro-Sel Pop ♀) and Cross2 (Fipro-Sel Pop ♂ × Un-Sel Pop ♀) was 1.69 and 1.12, respectively. It is evident from the results that fipronil resistance comes with a fitness disadvantage, and it is unstable in the Fipro-Sel Pop of Ae. Aegypti. Therefore, the alternation of fipronil with other chemicals or suspension of fipronil usage for some time could improve its efficacy by delaying resistance development in Ae. Aegypti. Further research should be performed to investigate the field applicability of our findings.
In July 2010, during routine mosquito surveillance inspections at companies that import used tires, three invasive species were found at five locations in the Netherlands: the yellow fever mosquito (Aedes aegypti), the Asian tiger mosquito (Ae. albopictus), and the American rock-pool mosquito (Ae. atropalpus). This is the first time that Ae. aegypti is reported from the Netherlands. Mosquito control was initiated one week after the first invasive mosquito was found, using adulticides and larvicides. The available data suggest that the implemented control measures have been effective for this season.
The aim of our study was to assess the potential of Macrocyclops albidus as a biological control agent against the 1st and 2nd instars of Culex pipiens and Aedes albopictus. Under laboratory conditions of prey saturation (50 1st instars/copepod), an average of 58.98% of Cx. pipiens and 54.99% of Ae. albopictus larvae were killed by 1 copepod in 24 h. Trials run in big drums containing 200 liters of water showed that the M. albidus population, inoculated in April, efficiently controlled the mosquito population for the entire season. The predator was particularly effective against Ae. albopictus, as only 2 larvae of this species were found in the treated drums, compared to 814 larvae in untreated control drums throughout the study period. No difference was observed in the control efficacy between the 2 initial densities of copepods used. The reduction in Ae. albopictus density in the drums with 100 and 500 M. albidus with respect to the control drums was 99.90 ± 0.35% and 100.0 ± 0.0%, respectively. For Cx. pipiens, the reduction in density was 88.69 ± 13.51% and 84.65% in drums inoculated with 100 and 500 copepods, respectively. Macrocyclops albidus populations survived through the winter and continued to keep the mosquito population under control during the 2008 season. The M. albidus population developed very well both in drums placed in sunny and shaded areas and proved to be tolerant to both high (summer) and low (winter) temperatures. Trials performed on M. albidus survival in catch basins showed that after a few weeks, the copepod population dramatically decreased and subsequently disappeared. The main problem for copepod survival in catch basins seemed to be the low oxygen tension and accumulation of toxic substances, rather than copepods being flushed out in heavy rainfall episodes. During the period when copepods were present, they maintained the mosquito population under control; their partial disappearance from the catch basins, however, would require more recolonization intervention to maintain mosquito control during the season.
Since its introduction and establishment in Italy during the early 1990s, the Asian tiger
mosquito, Aedes albopictus, has spread over large parts of Italy and other Mediterranean countries. Aedes
albopictus is both a nuisance and a competent vector for various arthropod-borne pathogens. Although
efficient traps for Ae. albopictus exist and are used for population monitoring, their use as a control tool has
not yet been studied. We evaluated Biogents BG-Sentinel mosquito traps, used with the BG Lure, as control
tools in northern Italy. The trial was performed as a controlled experiment in which 3 intervention sites,
equipped with 7 or 8 BG-Sentinel traps each, were matched with 3 comparable control sites. Trap density
ranged from 1 trap per 150 m2 to 1 per 350 m2. Mosquito populations were monitored at both the
intervention and control sites with weekly human landing collections (HLC) and ovitraps. Between 64% and
87% fewer Ae. albopictus individuals were collected by HLC at the intervention sites with the BG-Sentinel
mosquito traps, as compared to the untreated control sites. These results indicate that the sustained use and
proper placement of efficient mosquito traps can significantly reduce Ae. albopictus biting pressure.
Introducción. Los virus del dengue transmitidos principalmente por el mosquito urbano Aedes aegypti, causan uno de los mayores problemas de salud pública que confrontan las ciudades tropicales. La aplicación de insecticidas ha sido la base para el control de mosquitos; sin embargo, su continuo uso ha servido para seleccionar individuos resistentes en las poblaciones de mosquitos. Otro método importante para el control involucra la participación comunitaria.
Objetivo. Este estudio evaluó dos métodos de control para Ae. aegypti que podrían ser usados por la comunidad: las ovitrampas letales (OL) y las briquetas de Bacillus thuringiensis var israeliensis (Bti).
Materiales y métodos. El estudio se llevó a cabo en cuatro barrios similares de la Comuna 16 de Cali, Colombia. Se evaluaron tres intervenciones (OL, Bti, OL y Bti) más educación y un área control (sólo educación) para medir la eficacia de la vigilancia entomológica posterior a la intervención. Además, los índices entomológicos se compararon con los resultados de una vigilancia antes de la intervención llevada a cabo en bloques de casas seleccionadas aleatoriamente en los mismos barrios. La abundancia relativa del vector en relación con las condiciones climáticas se comparó usando los mismos métodos del muestreo entomológico.
Resultados. Las intervenciones no produjeron diferencias significativas entre los tratamientos en la abundancia del vector. Sin embargo, las intervenciones lograron una reducción significativa de los índices entomológicos comparados con los observados en la vigilancia antes de la intervención: índice de casa, de 15,1% a 8,5%; promedio de pupas por casa, de 1,15 a 0,073, e índice de adultos, de 56,3% a 34,8% (p
Urban mosquitoes in temperate regions may represent a high nuisance and are associated with the risk of arbovirus transmission. Common practices to reduce this burden, at least in Italian highly infested urban areas, imply calendar-based larvicide treatments of street catch basins - which represent the main non-removable urban breeding site - and/or insecticide ground spraying. The planning of these interventions, as well as the evaluation of their effectiveness, rarely benefit of adequate monitoring of the mosquito abundance and dynamics. We propose the use of adhesive traps to monitor Aedes albopictus and Culex pipiens adults and to evaluate the efficacy of insecticide-based control strategies.
We designed two novel types of adhesive traps to collect adult mosquitoes visiting and/or emerging from catch basins. The Mosquito Emerging Trap (MET) was exploited to assess the efficacy of larvicide treatments. The Catch Basin Trap (CBT) was exploited together with the Sticky Trap (ST, commonly used to collect ovipositing/resting females) to monitor adults abundance in the campus of the University of Rome "Sapienza" - where catch basins were treated with Insect Growth Regulators (IGR) bi-monthly and Low-Volume insecticide spraying were carried out before sunset - and in a nearby control area.
Results obtained by MET showed that, although all monitored diflubenzuron-treated catch basins were repeatedly visited by Ae. albopictus and Cx. pipiens, adult emergence was inhibited in most basins. Results obtained by ST and CBT showed a significant lower adult abundance in the treated area than in the untreated one after the second adulticide spraying, which was carried out during the major phase of Ae. albopictus population expansion in Rome. Spatial heterogeneities in the effect of the treatments were also revealed.
The results support the potential of the three adhesive traps tested in passively monitoring urban mosquito adult abundance and seasonal dynamics and in assessing the efficacy of control measures. ST showed higher specificity for Ae. albopictus and CBT for Cx. pipiens. The results also provide a preliminary indication on the effectiveness of common mosquito control strategies carried out against urban mosquito in European urban areas.
Les virus du chikungunya (CHIKV) et de la dengue (DENV) sont transmis par des moustiques du genre Aedes. La dengue est considérée comme l’arbovirose la plus importante dans le monde. Le chikungunya, connu d’Afrique continentale et d’Asie, et jusqu’à présent peu étudié, a été de 2004 à 2007 à l’origine de graves épidémies dans l’Océan Indien (OI), en Inde et en Afrique centrale, générant d’importants problèmes de santé publique et économiques. La récente épidémie dans le sud-ouest de l’Océan Indien (SOOI) a mis en exergue le caractère explosif de son émergence ainsi que la morbidité et la mortalité qui lui ont été associées, jusque-là sans précédent. Les deux vecteurs majeurs impliqués dans la transmission de ces arbovirus dans la zone OI sont Aedes aegypti et Aedes albopictus, ce dernier étant considéré comme le vecteur principal dans la majorité des îles de la zone. Dans l’île de la Réunion, où Ae. albopictus est le vecteur du CHIKV, la lutte anti-larvaire (téméphos puis Bacillus thuringiensis), anti-adulte (fénitrothion, puis deltaméthrine), ainsi qu’une protection individuelle et communautaire (utilisation de répulsifs, destruction des gîtes larvaires autour des habitations) ont été réalisées depuis 2006 et tout au long de la crise sanitaire. Afin de prévenir de telles épidémies, un plan de prévention des arboviroses est en cours de réalisation. Il devra permettre d’intervenir plus rapidement dès la réception des premiers signaux d’alerte, et d’adapter la réponse en fonction du virus et de son vecteur.
RNA interference (RNAi) was shown over 18 years ago to be a mechanism by which arbovirus replication and transmission could be controlled in arthropod vectors. During the intervening period, research on RNAi has defined many of the components and mechanisms of this antiviral pathway in arthropods, yet a number of unexplored questions remain. RNAi refers to RNA-mediated regulation of gene expression. Originally, the term described silencing of endogenous genes by introduction of exogenous double-stranded (ds)RNA with the same sequence as the gene to be silenced. Further research has shown that RNAi comprises three gene regulation pathways that are mediated by small RNAs: the small interfering (si)RNA, micro (mi)RNA, and Piwi-interacting (pi)RNA pathways. The exogenous (exo-)siRNA pathway is now recognized as a major antiviral innate immune response of arthropods. More recent studies suggest that the piRNA and miRNA pathways might also have important roles in arbovirus-vector interactions. This review will focus on current knowledge of the role of the exo-siRNA pathway as an arthropod vector antiviral response and on emerging research into vector piRNA and miRNA pathway modulation of arbovirus-vector interactions. Although it is assumed that arboviruses must evade the vector's antiviral RNAi response in order to maintain their natural transmission cycles, the strategies by which this is accomplished are not well defined. RNAi is also an important tool for arthropod gene knock-down in functional genomics studies and in development of arbovirus-resistant mosquito populations. Possible arbovirus strategies for evasion of RNAi and applications of RNAi in functional genomics analysis and arbovirus transmission control will also be reviewed.
Mosquito-borne diseases threaten over half the world's human population, making the need for environmentally-safe mosquito population control tools critical. The sterile insect technique (SIT) is a biological control method that can reduce pest insect populations by releasing a large number of sterile males to compete with wild males for female mates to reduce the number of progeny produced. Typically, males are sterilized using radiation, but such methods can reduce their mating competitiveness. The method is also most effective if only males are produced, but this requires the development of effective sex-sorting methods. Recent efforts to use transgenic methods to produce sterile male mosquitoes have increased interest in using SIT to control some of our most serious disease vectors, but the release of genetically modified mosquitoes will undoubtedly encounter considerable delays as regulatory agencies deal with safety issues and public concerns.
Testis genes in the dengue vector Aedes aegypti were identified using a suppression subtractive hybridization technique. Mosquito larvae were fed double-stranded RNAs (dsRNAs) that targeted both the testis genes and a female sex determination gene (doublesex) to induce RNA interference (RNAi) -mediated sterility and inhibition of female development. Fertility and mating competiveness of the treated males were assessed in small-scale mating competition experiments.
Feeding mosquito larvae dsRNAs targeting testis genes produced adult males with greatly reduced fertility; several dsRNAs produced males that were highly effective in competing for mates. RNAi-mediated knockdown of the female-specific isoform of doublesex was also effective in producing a highly male-biased population of mosquitoes, thereby overcoming the need to sex-sort insects before release.
The sequence-specific gene-silencing mechanism of this RNAi technology renders it adaptable for species-specific application across numerous insect species. We envisage its use for traditional large-scale reared releases of mosquitoes and other pest insects, although the technology might also have potential for field-based control of mosquitoes where eggs deposited into a spiked larval site lead to the release of new sterile males.
IGRs (Insect Growth Regulators) are chemical insecticide compounds that cause physiological alteration during the development of the insects. Within the IGRs, pyriproxyfen and diflubenzuron are characterized by a low acute toxicity towards mammals and a good safety level for non-target organisms. Both active ingredients are in use as larvicides in mosquito control programmes and in Italy they are registered as liquid, granular and tablet formulations. These products are good candidates for larval control in catch basins where conditions are suitable for the development of Culex pipiens and Aedes albopictus. The trials conducted in four localities of the Emilia-Romagna Region during 2006-2007 were planned to estimate the efficacy and the lasting action of different formulations under conditions in Northern Italy. Three diflubenzuron formulations (DEVICE ® GR-2, DEVICE ® TB-2 and DEVICE ® SC-15) and one pyriproxyfen formulation (SUMILARV ® 0.5G) were tested and compared.
Mosquito species that utilize peridomestic containers for immature development are commonly aggressive human biters, and because they often reach high abundance, create significant nuisance. One of these species, the Asian tiger mosquito Aedes albopictus, is an important vector of emerging infectious diseases, such as dengue, chikungunya, and Zika fevers. Integrated mosquito management (IMM) of Ae. albopictus is particularly difficult because it requires access to private yards in urban and suburban residences. It has become apparent that in the event of a public health concern due to this species, homeowners will have to be active participants in the control process by reducing mosquito habitats in their properties, an activity known as source reduction. However, limited attempts at quantifying the effect of source reduction by homeowners have had mixed results. Of note, many mosquito control programs in the US have some form of education outreach, however the primary approach is often passive focusing on the distribution of education materials as flyers. In 2010, we evaluated the use of active community peer education in a source reduction program, using AmeriCorps volunteers. The volunteers were mobilized over a 4-week period, in two areas with approximately 1,000 residences each in urban Mercer and suburban Monmouth counties in New Jersey, USA. The volunteers were first provided training on peridomestic mosquitoes and on basic approaches to reducing the number of container habitats for mosquito larvae in backyards. Within the two treatment areas the volunteers successfully engaged 758 separate homes. Repeated measures analysis of variance showed a significant reduction in container habitats in the sites where the volunteers actively engaged the community compared to untreated control areas in both counties. Our results suggest that active education using community peer educators can be an effective means of source reduction, and a critical tool in the arsenal against peridomestic mosquitoes.
Background:
The primary sources of Aedes albopictus (Skuse) in its exotic range in North America are artificial containers in backyards, which vary widely in accessibility. In this study we examined their prevalence in two container types that are difficult to inspect: catch basins and corrugated extension spouts (CES), the latter used to divert rainwater in downspouts away from house foundations.
Methods:
We conducted larval and pupal surveys in catch basins, CES and open containers such as buckets and plant saucers in three urban locations in Mercer County, New Jersey, USA.
Results:
We found that Ae. albopictus were rare in catch basins but prevalent in CES, and were often the only species collected in CES. Specific characteristics of the CES were not significantly associated with the presence or number of Ae. albopictus in them, but those longer and closer to the ground were significantly more likely to contain water, and therefore mosquitoes. During peak season (July-August), the abundance of immature Ae. albopictus was significantly higher in CES than open containers.
Conclusions:
We found that CES are an important source of Ae. albopictus in our region and propose that effective control strategies should be implemented to minimize mosquito populations from these cryptic habitats.
The symbiotic bacterium Wolbachia is an attractive agent for vector-borne pathogen control. It has long been studied for its ability to manipulate host reproduction and spread into arthropod populations [1]. These properties, coupled with the recently identified ability to inhibit diverse pathogens [2]–[6], open avenues for its use in controlling vector-borne disease. Numerous Wolbachia-based control strategies are being investigated (reviewed in [7]–[9]), with some studies having progressed to field trials [10], [11]. However, a worrying trend is emerging whereby Wolbachia infections have been demonstrated to enhance rather than suppress pathogens in some systems [12]–[18]. Plasmodium parasites, which are the causal agent of malaria, seem particularly prone to Wolbachia-mediated pathogen enhancement [13]–[16].
West Nile virus infection is a growing concern in Europe. Vector management is often the primary option to prevent and control outbreaks of the disease. Its implementation is, however, complex and needs to be supported by integrated multidisciplinary surveillance systems and to be organized within the framework of predefined response plans. The impact of the vector control measures depends on multiple factors and the identification of the best combination of vector control methods is therefore not always straightforward. Therefore, this contribution aims at critically reviewing the existing vector control methods to prevent and control outbreaks of West Nile virus infection and to present the challenges for Europe.
Most West Nile virus vector control experiences have been recently developed in the US, where ecological conditions are different from the EU and vector control is organized under a different regulatory frame. The extrapolation of information produced in North America to Europe might be limited because of the seemingly different epidemiology in the European region. Therefore, there is an urgent need to analyse the European experiences of the prevention and control of outbreaks of West Nile virus infection and to perform robust cost-benefit analysis that can guide the implementation of the appropriate control measures. Furthermore, to be effective, vector control programs require a strong organisational backbone relying on a previously defined plan, skilled technicians and operators, appropriate equipment, and sufficient financial resources. A decision making guide scheme is proposed which may assist in the process of implementation of vector control measures tailored on specific areas and considering the available information and possible scenarios.
Aedes albopictus (Skuse) is an invasive mosquito that has become an important vector of chikungunya and dengue viruses. Immature Ae. albopictus thrive in backyard household containers that require treatment with larvicides and when adult populations reach pest levels or disease transmission is ongoing, adulticiding is often required. To assess the feasibility of control of USA populations, we tested the susceptibility of Ae. albopictus to chemicals representing the main insecticide classes with different modes of action: organochlorines, organophosphates, carbamates, pyrethroids, insect growth regulators (IGR), naturalytes, and biolarvicides. We characterized a susceptible reference strain of Ae. albopictus, ATM95, and tested the susceptibility of eight USA populations to five adulticides and six larvicides. We found that USA populations are broadly susceptible to currently available larvicides and adulticides. Unexpectedly, however, we found significant resistance to dichlorodiphenyltrichloroethane (DDT) in two Florida populations and in a New Jersey population. We also found resistance to malathion, an organophosphate, in Florida and New Jersey and reduced susceptibility to the IGRs pyriproxyfen and methoprene. All populations tested were fully susceptible to pyrethroids. Biochemical assays revealed a significant up-regulation of GSTs in DDT-resistant populations in both larval and adult stages. Also, β-esterases were up-regulated in the populations with suspected resistance to malathion. Of note, we identified a previously unknown amino acid polymorphism (Phe → Leu) in domain III of the VGSC, in a location known to be associated with pyrethroid resistance in another container-inhabiting mosquito, Aedes aegypti L. The observed DDT resistance in populations from Florida may indicate multiple introductions of this species into the USA, possibly from tropical populations. In addition, the mechanisms underlying DDT resistance often result in pyrethroid resistance, which would undermine a remaining tool for the control of Ae. albopictus. Continued monitoring of the insecticide resistance status of this species is imperative.
Author Summary
Current methods to control mosquitoes and the pathogens they transmit are ineffective, partly due to insecticide and drug resistance. One novel control method involves exploiting naturally occurring Wolbachia bacteria in insects. Wolbachia are bacterial symbionts that are attractive candidates for mosquito-borne disease control due to their ability to inhibit pathogens infecting humans. Additionally, Wolbachia affects insect reproduction to facilitate its own transmission to offspring, which has been exploited to establish the bacterium in naturally uninfected field populations. Most Wolbachia pathogen control research has focused on Aedes and Anopheles mosquitoes, but Culex mosquitoes also transmit pathogens that affect human health. We evaluated impacts of Wolbachia infection on West Nile virus (WNV) in the naturally uninfected mosquito Culex tarsalis. Wolbachia was able to efficiently establish infection in Cx. tarsalis but contrary to other studies, Wolbachia enhanced rather than inhibited WNV infection. Enhancement occurred in conjunction with suppression of mosquito anti-viral immune gene expression. This study indicates that Wolbachia control strategies to disrupt WNV via pathogen interference may not be feasible in Cx. tarsalis, and that caution should be used when releasing Wolbachia infected mosquitoes to control human vector-borne diseases.
The effect of spraying a mixture of the insect growth regulator (IGR) pyriproxyfen (1 mg/liter) and either 1% boric acid sugar bait or eugenol sugar bait on croton petra plants (Codiaeum variegatum L.) was evaluated against the container-inhabiting mosquito, Aedes albopictus (Skuse). Treatments were applied to plants and evaluated against adult and larval Ae. albopictus in the laboratory through contact and wash off experiments, respectively. The control treatment lacked an active ingredient and were treated with an attractive sugar bait. The plants treated with attractive toxic sugar baits plus the IGR resulted in 60‐100% mortality of laboratory-reared adult Ae. albopictus. The pyriproxyfen solutions collected from the plant wash experiment resulted in 80‐100% emergence inhibition to the exposed third- and fourth-instar larvae, compared with the untreated control. Attractive toxic sugar baits mixed with the IGR not only provide effective control of adult mosquitoes, but also provide additional control of larval mosquitoes after being washed off from the treated plants.
An assessment was made of the toxicity of 12 insecticides and three essential oils as well as Bacillus thuringiensis subsp. israelensis (Bti) alone or in combination with the oil major constituents (E)-anethole (AN), (E)-cinnamaldehyde (CA), and eugenol (EU; 1:1 ratio) to third instars of bamboo forest-collected Aedes albopictus (Skuse) and rice paddy field-collected Anopheles sinensis Wiedemann. An. sinensis larvae were resistant to various groups of the tested insecticides. Based on 24-h LC50 values, binary mixtures of Bti and CA, AN, or EU were significantly more toxic against Ae. albopictus larvae (0.0084, 0.0134, and 0.0237 mg/liter) and An. sinensis larvae (0.0159, 0.0388, and 0.0541 mg/liter) than either Bti (1.7884 and 2.1681 mg/liter) or CA (11.46 and 18.56 mg/liter), AN (16.66 and 25.11 mg/liter), or EU (24.60 and 31.09 mg/liter) alone. As judged by cotoxicity coefficient (CC) and synergistic factor (SF), the three binary mixtures operated in a synergy pattern (CC, 140.7‐368.3 and SF, 0.0007‐0.0010 for Ae. albopictus; CC, 75.1‐245.3 and SF, 0.0008‐0.0017 for An. sinensis). Global efforts to reduce the level of highly toxic synthetic insecticides in the aquatic environment justify further studies on the binary mixtures of Bti and essential oil constituents described, in particular CA, as potential larvicides for the control of malaria vector mosquito populations.
In 2008, specimens resembling Aedes (Finlaya) koreicus (Edwards) (also Ochlerotatus koreicus or Hulecoeteomyia kore-ica) were found in Belgium during a national mosquito survey (MODIRISK). Small but consistent differences were, how-ever, observed between the specimens described from Peninsula Korea and those found in Belgian. To achieve the correct identification a detailed morphological comparison was made between the Belgian specimens and reference material from Korean mainland and island populations housed at the Smithsonian Institution (Walter Reed Biosystematics Unit (WR-BU), Washington, USA). The identification was furthermore supported by molecular evidence based on the ND4 region (mtDNA) of available Korean and Belgian mosquito specimens. Morphological and molecular comparison confirmed the initial identification of Aedes koreicus. Based on morphological characteristics, the species collected in Belgium most likely originated from Jeju-do, an island south of the Korean Peninsula. The observed dissimilarities between Korean and Belgian specimens resembled a number of morphological differences mentioned previously between female adults col-lected on the Korean Peninsula and Jeju-do. This is the first report of Aedes koreicus outside its natural distribution range. A correct and rapid identification of new invading and spreading vector species is crucial for the implementation of effec-tive control measurements. Hence a correct and easy accessible description of all possible variations of species arriving in new areas is highly recommended. Therefore, a comparative morphological study on the Smithsonian material of the species from Korean mainland, island population and from Belgium is given, pictures of the main aberrant characteristics and scanning electron microscope images of all stages of the species are included and molecular confirmation of the iden-tification based on the mtDNA ND4 region is provided.
Vector control interventions have resulted in considerable reductions in malaria morbidity and mortality. When universal coverage cannot be achieved for financial or logistical reasons, the spatial arrangement of vector control is potentially important for optimizing benefits. This study investigated the effect of spatial clustering of vector control interventions on reducing the population of biting mosquitoes. A discrete-space continuous-time mathematical model of mosquito population dynamics and dispersal was extended to incorporate vector control interventions of insecticide treated bednets (ITNs), Indoor residual Spraying (IRS), and larviciding. Simulations were run at varying levels of coverage and degree of spatial clustering. At medium to high coverage levels of each of the interventions or in combination was more effective to spatially spread these interventions than to cluster them. Suggesting that when financial resources are limited, unclustered distribution of these interventions is more effective. Although it is often stated that locally high coverage is needed to achieve a community effect of ITNs or IRS, our results suggest that if the coverage of ITNs or IRS are insufficient to achieve universal coverage, and there is no targeting of high risk areas, the overall effects on mosquito densities are much greater if they are distributed in an unclustered way, rather than clustered in specific localities. Also, given that interventions are often delivered preferentially to accessible areas, and are therefore clustered, our model results show this may be inefficient. This study provides evidence that the effectiveness of an intervention can be highly dependent on its spatial distribution. Vector control plans should consider the spatial arrangement of any intervention package to ensure effectiveness is maximized.
In 2012, the new guidelines for the surveillance of IMS in Europe, produced by the European Centre for Disease Prevention and Control (ECDC), were tested in Belgium. This study aimed at (1) testing the usefulness and applicability in the field of the ECDC guidelines for the surveillance of IMS in Europe and (2) surveying IMS throughout Belgium.
First, the scenarios, which Belgium is facing, were identified according to the ECDC guidelines. Second, the surveillance strategy and the methods were identified based on the guidelines and adjusted to the Belgium context. Two areas colonised by IMS and 20 potential points of entry (PoE) were selected. Mosquito Magnet Liberty Plus (CO2-baited) traps (23) and oviposition traps (147) were set-up, and larval sampling was performed monthly or bi-monthly from July till October 2012. Finally, the costs and workload of the surveillance activities were compared to the estimates provided by the ECDC guidelines.
Surveillance at 20 potential PoE (complying with scenario 1) revealed that no new IMS were established in Belgium. Surveillance at two sites colonised by IMS (scenario 2) indicated that although control measures have drastically reduced the Ae. j. japonicus population this species is still present. Furthermore, Ae. koreicus is permanently established. For both scenarios, the problems encountered are discussed and recommendations are given. In addition, the actual workload was lower than the estimated workload, while the actual costs were higher than the estimated ones.
The ECDC guidelines are helpful, applicable and efficient to implement surveillance of IMS in Belgium. Recommendations were customised to the local context (political demands, salary and investment costs, and existing expertise). The workload and costs related to the preparatory phase (i.e., planning, contacts with the PoE, writing a protocol) were found to be missing in the cost evaluation suggested in the guidelines. Updates on the occurrence of IMS in Belgium and the related risk for disease agents they can transmit will only be available once a structured and permanent surveillance system is implemented.
The increasing global threat of Dengue demands new and easily applicable vector control methods. Ovitraps provide a low-tech and inexpensive means to combat Dengue vectors. Here we describe the development and optimization process of a novel contamination device that targets multiple life-stages of the Aedes aegypti mosquito. Special focus is directed to the diverse array of control agents deployed in this trap, covering adulticidal, larvicidal and autodissemination impacts.
Different trap prototypes and their parts are described, including a floater to contaminate alighting gravid mosquitoes. The attractiveness of the trap, different odor lures and floater design were studied using fluorescent powder adhering to mosquito legs and via choice tests. We demonstrate the mosquitocidal impacts of the control agents: a combination of the larvicide pyriproxyfen and the adulticidal fungus Beauveria bassiana. The impact of pyriproxyfen was determined in free-flight dissemination experiments. The effect on larval development inside the trap and in surrounding breeding sites was measured, as well as survival impacts on recaptured adults.
The developmental process resulted in a design that consists of a black 3 Liter water-filled container with a ring-shaped floater supporting vertically placed gauze dusted with the control agents. On average, 90% of the mosquitoes in the fluorescence experiments made contact with the gauze on the floater. Studies on attractants indicated that a yeast-containing tablet was the most attractive odor lure. Furthermore, the fungus Beauveria bassiana was able to significantly increase mortality of the free-flying adults compared to controls. Dissemination of pyriproxyfen led to >90% larval mortality in alternative breeding sites and 100% larval mortality in the trap itself, against a control mortality of around 5%.
This ovitrap is a promising new tool in the battle against Dengue. It has proven to be attractive to Aedes aegypti mosquitoes and effective in contaminating these with Beauveria bassiana. Furthermore, we show that the larvicide pyriproxyfen is successfully disseminated to breeding sites close to the trap. Its low production and operating costs enable large scale deployment in Dengue-affected locations.
Mosquitoes are vectors of major diseases. Auto-dissemination recently proved very efficient to control Aedes species, using adult females contaminated with dissemination stations of juvenile hormone to treat breeding habitats, but cannot be used at large scales. Here we propose to combine it to the Sterile Insect Technique (SIT) to create a new control concept, named 'boosted SIT' that might enable the area-wide eradication of mosquitoes and many other vectors and insect pests.
To enable a better understanding of the overwhelming alterations in the invasive mosquito species (IMS), methodical insight into the population and environmental factors that govern the IMS and pathogen adaptations are essential. There are numerous ways of estimating mosquito populations, and usually these describe developmental and life-history parameters. The key population parameters that should be considered during the surveillance of invasive mosquito species are: (1) population size and dynamics during the season, (2) longevity, (3) biting behaviour, and (4) dispersal capacity. Knowledge of these parameters coupled with vector competence may help to determine the vectorial capacity of IMS and basic disease reproduction number (R0) to support mosquito borne disease (MBD) risk assessment. Similarly, environmental factors include availability and type of larval breeding containers, climate change, environmental change, human population density, increased human travel and goods transport, changes in living, agricultural and farming habits (e.g. land use), and reduction of resources in the life cycle of mosquitoes by interventions (e.g. source reduction of aquatic habitats). Human population distributions, urbanisation, and human population movement are the key behavioural factors in most IMS-transmitted diseases. Anthropogenic issues are related to the global spread of MBD such as the introduction, reintroduction, circulation of IMS and increased exposure to humans from infected mosquito bites. This review addresses the population and environmental factors underlying the growing changes in IMS populations in Europe and confers the parameters selected by criteria of their applicability. In addition, overview of the commonly used and newly developed tools for their monitoring is provided.
The objective of this study was to assess the effectiveness of BG-Sentinel (BGS) traps for mass trapping at the household level to control the dengue vector, Aedes aegypti (L.), in Manaus (Brazil) by performing a cluster randomized controlled trial. After an initial questionnaire and baseline monitoring, 6 out of 12 clusters were randomly allocated to the intervention arm, where participating premises received one BGS trap for mass trapping. The other six clusters did not receive traps and were considered as the control arm. Biweekly monitoring with BGS in both arms assessed the impact of mass trapping. At the end of the study, a serological survey was conducted and a second questionnaire was conducted in the intervention arm. Entomological monitoring indicated that mass trapping with BGS traps significantly reduced the abundance of adult female Ae. aegypti during the first five rainy months. In the subsequent dry season when the mosquito population was lower, no effect of mass trapping was observed. Fewer Ae. aegypti females were measured in the intervention arm during the next rainy period, but no significant difference between arms was observed. The serological survey revealed that in participating houses of mass trapping areas recent dengue infections were less common than in control areas, although this effect was not statistically significant. The majority of participants responded positively to questions concerning user satisfaction. Our results suggest that BGS traps are a promising tool which might be deployed as part of dengue control programs; however, further investigations and larger scale studies are necessary.
Autodissemination of insecticides is a novel strategy for mosquito management. We tested if contaminated Aedes albopictus (Skuse) mosquitoes from a small area treated with commercial formulations (79 gm a.i. pyriproxyfen/ha) using conventional techniques, would disseminate pyriproxyfen over a wider area. Pyriproxyfen showed LC50=0.012 ppb for Ae. albopictus. Direct treatment and autodissemination efficacy was measured as a pupal mortality by conducting Ae. albopictus larval bioassay. A tire pile (n=100 tires) treated by backpack sprayer as a point-source treatment showed higher pupal mortality in 2010 (60.8% for week 0-6) than in 2011 (38.3% for week 0-6). The sentinel containers placed for autodissemination in four compass directions out to 200-400m from the tire pile showed 15.8% pupal mortality (week 1-6) in the first year, and 1.4% pupal mortality in the second year. No significant difference was detected among the distances and direction for pupal mortality. In area-wide treatments, vegetation was sprayed in checkerboard' pattern (3.7% of 105ha) using backpack sprayer in 2010 and in strips (24.8% of 94ha) using truck-mounted ultra-low volume (ULV) sprayer in 2011. In both years, the area-wide direct treatment efficacy was lower (30.3% during 2010 and 5.3% in 2011) than point-source treatments. Autodissemination in area-wide plots was higher in 2010 (10.3%) than 2011 (2.9%). However, area-wide treatments were ineffective on field populations of Ae. albopictus as monitored by using BGS traps. We found accumulation of pyriproxyfen in the week 6 autodissemination containers in both experiments. The differences in autodissemination in 2010 and 2011 can be attributed to higher rainfall in the second year that may have eroded the pyriproxyfen from treatment surfaces and sentinel containers. Our study shows that ULV surface treatments of conventional formulation does not work for autodissemination. The effectiveness of pyriproxyfen in autodissemination may be improved by developing specific formulations to treat vegetation and tires that can load high doses on mosquitoes.
Invasive aedine mosquito species have become a major issue in many parts of the world as most of them are recognised vectors or potentially involved in transmission of pathogens. Surveillance of these mosquitoes (e.g. Ae. aegypti, Yellow fever mosquito, Aedes albopictus, Asian tiger mosquito) is mainly done by collecting eggs using ovitraps and by identification of the larvae hatched in the laboratory. In order to replace this challenging and laborious procedure, we have evaluated matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) for easy and rapid species identification.
Individual protein profiles were generated using five eggs each of nine aedine species (Ae. aegypti, Ae. albopictus, Ae. atropalpus, Ae. cretinus, Ae. geniculatus, Ae. japonicus, Ae. koreicus, Ae. phoeniciae, Ae. triseriatus) from various geographical origins, and species-specific biomarker mass sets could be generated. A blinded validation using our reference data base for automated egg identification was performed. In addition, pools of 10 aedine eggs (132 two-species and 18 three-species pools) in different ratios were evaluated.
Specific biomarker mass sets comprising 18 marker masses could be generated for eggs of nine container-inhabiting aedine species, including all the major invasive and indigenous species of Europe and North America. Two additional masses shared by all investigated aedine species are used as internal calibrators. Identification of single eggs was highly accurate (100% specificity, 98.75% sensitivity), and this method is also of value for the identification of species in pools of ten eggs. When mixing two or three species, all were identified in all pools in at least 2 or 1 of the 4 loaded replicates, respectively, if the "lesser abundant" species in the pool accounted for three or more eggs.
MALDI-TOF MS, which is widely applied for routine identification of microorganisms in clinical microbiology laboratories, is also suited for robust, low-cost and high throughput identification of mosquito vectors in surveillance programmes. This tool can further be developed to include a wide spectrum of arthropods but also other Metazoa for which surveillance is required, and might become the method of choice for their centralised identification via online platforms.
During a dengue outbreak with co-circulation of DENV-1 and -2 in the city of Boa Vista, one patient was diagnosed with DENV-4, a serotype supposed absent from Brazil for almost 30 years. The re-emergence of DENV-4 triggered the intensification of mechanical and chemical Aedes aegypti control activities in order to reduce vector density and avoid DENV-4 dissemination throughout the country.
Vector control activities consisted of (a) source reduction, (b) application of diflubenzuron against larvae and (c) vehicle-mounted space spraying of 2% deltamethrin to eliminate adults. Control activity efficacy was monitored by comparing the infestation levels and the number of eggs collected in ovitraps before and after interventions, performed in 22 Boa Vista districts, covering an area of ∼80% of the city and encompassing 56,837 dwellings. A total of 94,325 containers were eliminated or treated with diflubenzuron. The most frequently positive containers were small miscellaneous receptacles, which corresponded to 59% of all positive breeding sites. Insecticide resistance to deltamethrin was assessed before, during and after interventions by dose-response bioassays adopting WHO-based protocols. The intense use of the pyrethroid increased fourfold the resistance ratio of the local Ae. aegypti population only six months after the beginning of vector control. Curiously, this trend was also observed in the districts in which no deltamethrin was applied by the public health services. On the other hand, changes in the resistance ratio to the organophosphate temephos seemed less influenced by insecticide in Boa Vista.
Despite the intense effort, mosquito infestation levels were only slightly reduced. Besides, the median number of eggs in ovitraps remained unaltered after control activity intensification. The great and rapid increase in pyrethroid resistance levels of natural Ae. aegypti populations is discussed in the context of both public and domestic intensification of chemical control due to a dengue outbreak.
The mosquito larval rearing unit developed at the Insect Pest Control Laboratory (IPCL) of the FAO/IAEA Joint Division was evaluated for its potential use for Aedes albopictus (Skuse, 1895) mass rearing in support of the development of a sterile insect technique (SIT) package for this species. The use of the mass rearing trays and rack did not adversely affect larval development, pupation and survival rates and allowed the management of large larval rearing colonies with reduced space requirements in comparison with classical individual trays. The effects of larval density, water temperature and diet composition on pupal production and size differentiation for sex separation efficacy were analyzed for individual mass rearing trays as well as multiple trays stacked within the dedicated rack unit. Best results were obtained using eighteen thousand larvae per tray at a density of 3 larvae per ml of deionized water at a temperature of 28°C on a diet consisting of 50% tuna meal, 36% bovine liver powder, 14% brewer's yeast and, as an additive, 0.2 gr of Vitamin Mix per 100 ml of diet solution. Pupae were harvested on the sixth day from larval introduction at L1 stage and males were separated out by the use of a 1400 µm sieve with 99.0% accuracy with a recovery rate of ca. 25% of the total available males. With the use of this larval rearing unit, an average production of 100,000 male pupae per week can be achieved in just 2 square meter of laboratory space. Compared to previous laboratory rearing method, the same pupal production and sex separation efficacy could only be achieved by use of ca. 200 plastic trays which required the space of two 5 square meter climatic-controlled rooms.
Following the 2006 Chikungunya disease in La Reunion, questions were raised concerning the monitoring survey of Aedes albopictus populations and the entomological indexes used to evaluate population abundance. The objectives of the present study were to determine reliable productivity indexes using a quantitative method to improve entomological surveys and mosquito control measures on Aedes albopictus. Between 2007 and 2011, 4 intervention districts, 24 cities, 990 areas and over 850,000 houses were used to fulfil those objectives. Four indexes including the classical Stegomyia index (House Index, Container Index, Breteau Index) plus an Infested Receptacle Index were studied in order to determine whether temporal (year, month, week) and/or spatial (districts, cities, areas) heterogeneities existed. Temporal variations have been observed with an increase of Ae. albopictus population density over the years, and a seasonality effect with a highest population during the hot and wet season. Spatial clustering was observed at several scales with an important autocorrelation at the area scale. Moreover, the combination among these results and the breeding site productivity obtained during these 5 years allowed us to propose recommendations to monitor Aedes albopictus by eliminating not the most finding sites but the most productive ones. As the other strategies failed in La Reunion, this new approach should should work better.
Monitoring dengue vector control by sampling adult Aedes aegypti (L.) recently has been used to replace both larval and pupal surveys. We have developed and evaluated the Gravid Aedes Trap (GAT) through a sequential behavioral study. The GAT does not require electricity to function, and trapped mosquitoes are identified easily during trap inspections. The GAT concept relies on visual and olfactory cues to lure gravid Ae. aegypti and an insecticide to kill trapped mosquitoes. Gravid mosquitoes are lured to a black bucket base containing oviposition attractant (infusion) and are trapped in a translucent chamber impregnated with a pyrethroid insecticide where they are killed within 3-15 min. In semifield observations, the GAT captured a significantly higher proportion of gravid mosquitoes than the double sticky ovitrap. We also demonstrated that the visual cues of the prototype GAT-LgBF (large black base bucket with a black funnel at the top of the translucent chamber) captured a significantly higher proportion of gravid mosquitoes than the other prototypes. The visual contrast created by the addition of a white lid to the top of the black funnel significantly increased the number of captured gravid mosquitoes when compared with the GAT-LgBF in semifield trials. We conclude that the GAT is more efficient in recapturing gravid Ae. aegypti when compared with sticky ovitraps. The GAT is an effective, practical, low cost, and easily transportable trap, features that are essential in large-scale monitoring programs, particularly in areas where funding is limited.
In July 2011, during routine invasive exotic mosquito surveillance inspections at companies that
import used tyres, two invasive exotic mosquito species were found at three locations in the
Netherlands: the Asian tiger mosquito (Ae. albopictus) [Stegomyia albopicta sensu Reinert et al.,
2004] and the American rock-pool mosquito (Ae. atropalpus) [Georgecraigius atropalpus sensu
Reinert et al., 2006]. Mosquito control was initiated one week after the first invasive mosquito
was found, using adulticides and larvicides, and continued until the second week of November.
Despite control, findings of these species continued in August and September, with the last
finding in the first week of October. The same species were also found at these sites in 2010,
followed by control until the end of the season. The available surveillance data suggest, although
not conclusive, that the findings of 2011 are the result of unrestricted import of used tyres from
Ae.albopictus- and Ae. atropalpus-endemic areas in 2011, rather than from surviving specimens
found in 2010.
Control of the world's most important vector-borne viral disease, dengue, is a high priority. A lack of vaccines or effective vector control methods means that novel solutions to disease control are essential. The release of male insects carrying a dominant lethal (RIDL) is one such approach that could be employed to control Aedes aegypti. To maximise the potential of RIDL control, optimum release strategies for transgenic mosquitoes are needed. The use of field data to parameterise models allowing comparisons of the release of different life-stages is presented together with recommendations for effective long-term suppression of a wild Ae. aegypti population.
A compartmental, deterministic model was designed and fitted to data from large-scale pupal mark release recapture (MRR) field experiments to determine the dynamics of a pupal release. Pulsed releases of adults, pupae or a combination of the two were simulated. The relative ability of different release methods to suppress a simulated wild population was examined and methods to maintain long-term suppression of a population explored.
The pupal model produced a good fit to field data from pupal MRR experiments. Simulations using this model indicated that adult-only releases outperform pupal-only or combined releases when releases are frequent. When releases were less frequent pupal-only or combined releases were a more effective method of distributing the insects. The rate at which pupae eclose and emerge from release devices had a large influence on the relative efficacy of pupal releases. The combined release approach allows long-term suppression to be maintained with smaller low-frequency releases than adult- or pupal-only release methods.
Maximising the public health benefits of RIDL-based vector control will involve optimising all stages of the control programme. The release strategy can profoundly affect the outcome of a control effort. Adult-only, pupal-only and combined releases all have relative advantages in certain situations. This study successfully integrates field data with mathematical models to provide insight into which release strategies are best suited to different scenarios. Recommendations on effective approaches to achieve long-term suppression of a wild population using combined releases of adults and pupae are provided.
Some proposed genetics-based vector control methods aim to suppress or eliminate a mosquito population in a similar manner to the sterile insect technique. One approach under development in Anopheles mosquitoes uses homing endonuclease genes (HEGs)-selfish genetic elements (inherited at greater than Mendelian rate) that can spread rapidly through a population even if they reduce fitness. HEGs have potential to drive introduced traits through a population without large-scale sustained releases. The population genetics of HEG-based systems has been established using discrete-time mathematical models. However, several ecologically important aspects remain unexplored. We formulate a new continuous-time (overlapping generations) combined population dynamic and genetic model and apply it to a HEG that targets and knocks out a gene that is important for survival. We explore the effects of density dependence ranging from undercompensating to overcompensating larval competition, occurring before or after HEG fitness effects, and consider differences in competitive effect between genotypes (wild-type, heterozygotes and HEG homozygotes). We show that population outcomes-elimination, suppression or loss of the HEG-depend crucially on the interaction between these ecological aspects and genetics, and explain how the HEG fitness properties, the homing rate (drive) and the insect's life-history parameters influence those outcomes.
The Asian bush or rock pool mosquito Aedes japonicus japonicus is one of the most expansive culicid species of the world. Being native to East Asia, this species was detected out of its original distribution range for the first time in the early 1990s in New Zealand where it could not establish, though. In 1998, established populations were reported from the eastern US, most likely as a result of introductions several years earlier. After a massive spread the mosquito is now widely distributed in eastern North America including Canada and two US states on the western coast. In the year 2000, it was demonstrated for the first time in Europe, continental France, but could be eliminated. A population that had appeared in Belgium in 2002 was not controlled until 2012 as it did not propagate. In 2008, immature developmental stages were discovered in a large area in northern Switzerland and bordering parts of Germany. Subsequent studies in Germany showed a wide distribution and several populations of the mosquito in various federal states. Also in 2011, the species was found in southeastern Austria (Styria) and neighbouring Slovenia. In 2013, a population was detected in the Central Netherlands, specimens were collected in southern Alsace, France, and the complete northeastern part of Slovenia was found colonized, with specimens also present across borders in adjacent Croatia. Apparently, at the end of 2013 a total of six populations occurred in Europe although it is not clear whether all of them are completely isolated. Similarly, it is not known whether these populations go back to the same number of introductions. While entry ports and long-distance continental migration routes are also obscure, it is likely that the international used tyre trade is the most important mode of intercontinental transportation of the mosquito. Aedes j. japonicus does not only display an aggressive biting behaviour but is suspected to be a vector of various disease agents and to displace indigenous culicid species. Therefore, Aedes j. japonicus might both cause public health problems in the future and have a significant impact on the biodiversity of the invaded territories.
The larvicidal efficacy of the naturally derived insecticide spinosad, for control of immature stages of Anopheles albimanus and associated culicids, was compared to that of synthetic and biological larvicides. Effects on non-target insects were also determined.
A field trial was performed in replicated temporary pools during the rainy season, in southern Mexico. Pools were treated with 10 ppm a.i. spinosad (Tracer 480SC), Bti granules applied at 2 kg/ha (VectoBac WDG, ABG-6511), and 100 ml/ha temephos (50 EC), or an untreated control. Numbers of immature mosquitoes, and aquatic insects in pools were monitored for 20 weeks.
Samples of immature mosquitoes comprised approximately 10% An. albimanus, 70% Culex spp. (mostly Cx. melanoconion and Cx. coronator) and 20% Uranotaenia lowii. The most effective larvicides were spinosad and temephos that eliminated An. albimanus in 16 out of 20 post-treatment samples, or 9 weeks of continuous control of immature stages, respectively. These larvicides resulted in 15 and 5 weeks of elimination of Culex spp., respectively, or 20 and 4 weeks of continuous elimination of U. lowii, respectively. Bti treatment provided little consistent control. Aquatic insects were recorded comprising 3 orders, 20 families, 40 genera and 44 species. Shannon diversity index values (H') for aquatic insects were highest in the control (0.997) and Bti (0.974) treatments, intermediate in the spinosad treatment (0.638) and lowest in the temephos treatment (0.520). Severely affected non-target insects in the spinosad and temephos treated pools were predatory Coleoptera, Hemiptera and Odonata, which in the case of spinosad was likely due to the high concentration applied. Bti had little effect on aquatic insects.
The spinosad treatment retained larvicidal activity for markedly longer than expected. Spinosad is likely to be an effective tool for control of anopheline and other pool-breeding mosquitoes in tropical regions. Non-target effects of spinosad on aquatic insects merit further study, but were likely related to the concentration of the product used.
Community participation is mandatory in the prevention of Dengue outbreaks. Taking public views into account is crucial to guide more effective planning and quicker community participation in preventing campaigns. This study aims to assess community perceptions of Madeira population in order to explore their involvement in the A. aegypti's control and reinforce health-educational planning. Due to the lack of accurate methodologies for measuring perception, a new tool to assess the community's perceptions was built.
A cross-sectional survey was performed in the Island's aegypti-infested area, exploring residents' perceptions regarding most critical community behaviour: aegypti-source reduction and their domestic aegypti-breeding sites. A novel tool defining five essential topics which underlie the source reduction's awareness and accession was built, herein called Essential-Perception (EP) analysis.
Of 1276 individuals, 1182 completed the questionnaire (92 . 6%). EP-Score analysis revealed that community's perceptions were scarce, inconsistent and possibly incorrect. Most of the population (99 . 6%) did not completely understood the five essential topics explored. An average of 54 . 2% of residents only partially understood each essential topic, revealing inconsistencies in their understanding. Each resident apparently believed in an average of four false assumptions/myths. Significant association (p[modifier letter left arrowhead]0.001) was found between both the EP-Score level and the domestic presence of breeding sites, supporting the validity of this EP-analysis. Aedes aegypti's breeding sites, consisting of decor/leisure containers, presented an atypical pattern of infestation comparing with dengue prone regions.
The studied population was not prepared for being fully engaged in dengue prevention. Evidences suggest that EP-methodology was efficient and accurate in assessing the community perception and its compliance to practices. Moreover, it suggested a list of myths that could persist in the community. This is the first study reporting an aegypti-entomological pattern and community's perception in a developed dengue-prone region. Tailored messages considering findings of this study are recommended to be used in future campaigns in order to more effectively impact the community perception and behaviour.
Inhibitory effects of a neem formulation on emergence of two common species of mosquitoes were evaluated. When fourth-instar larvae of Ochlero-tatus japonicus and Culex pipiens pallens were exposed to 1.9 ppm and 0.6 ppm solution of azadirachtin, 99% and 75% inhibition of the adult emergence was observed, respectively. The 1.9 ppm solution showed mainly larvicidal effects on these mosquitoes, but the 0.6 ppm solution mainly inhibited the emergence.
Hennig’s (1966) concept of hierarchies of monophyletic taxons based on common ancestors (with plesiomorphies or retained primitive, ancestral characters) and shared synapomorphies (homologous shared characters inferred to have been present in the nearest common ancestor but not in earlier ancestors nor in the taxa outside this group), has provided the theoretical basis for taxa formation. During the first decades following its proposal, it resulted in the establishment of cladistic trees where recency of common ancestry is the sole criterion for grouping of the taxa. The problem of ranking taxa and tree formation in a Darwinian evolutionary context was the next scientific step (Eldridge and Cracraft 1980). Opinions about what different nodes represent, how to deal with branch lengths, and how to rank monophyletic entities, have become part of a scientific field of its own (Britton et al. 2007). Applying both morphologic and genetic taxonomic methods, and working with different groups of characters to reveal evolutionary relationships between insect orders or families as monophyletic groups, is now becoming standard. In the new millennium this work has resulted in several new hypotheses of phylogenetic trees of Insecta. Wheeler et al. (2001) established the relationship between Diptera and Strepsiptera. Grimaldi and Engel (2005) in their comprehensive work on extinct and extant Insecta, summarized different hypotheses for Diptera. They accepted five suborders of Lower Diptera (Nematocera): Tipulomorpha, Psychodomorpha, Culicomorpha, Blephariceromorpha and Bibionomorpha. They placed Anisopodidae as a sistergroup to Brachycera (all higher Diptera) and discarded Nematocera as a paraphyletic group (including a most recent common ancestor and some, but not all, of it descendants). This view has been strongly advocated by Amorim et al. (2006). They recognised seven suborders/infraorders instead of Nematocera and added Brachycera as the eighth suborder/infraorder for the rest of the Diptera.
Mosquitoes are responsible for the transmission of many medically important pathogens and parasites such as viruses, bacteria, protozoans, and nematodes, which cause serious diseases such as malaria, dengue, yellow and Chikungunya fever, encephalitis or filariasis (Kettle 1995; Beaty and Marquardt 1996; Lehane 1991; Eldridge and Edman 2000). Transmission can be mechanical (e.g. Myxoma virus causing myxomatosis in rabbits) or biological. The latter is more complex because it involves an obligatory period of replication and/or development of the pathogen or parasite in the vector insect. Due to their blood-sucking behaviour, mosquitoes are able to acquire the pathogens or parasites from one vertebrate host and pass them to another, if the mosquito’s ecology and physiology is appropriate for transmission. Highly efficient vectors have to be closely associated with the hosts and their longevity has to be sufficient enough to enable the pathogens/parasites to proliferate and/or to develop to the infective stages in the vector. For successful transmission, multiple blood-meals are necessary.
As human populations continue to grow around the world, demand for food and the number of people at threat from vector-borne diseases increases. Insecticides have long been seen as the mainstay of control of insects important for agriculture and human health, but are becoming compromised by difficulties with discovery and development of novel chemistry, the loss of and restrictions on the use of existing products, and development of resistance in target pests. Growers and public health authorities are increasingly looking for other options to replace or supplement synthetic insecticides, or to prolong their useful life. Alternative control methods, which are diverse in action and environmentally sustainable, include beneficial organisms (predators and parasitoids), plant extracts, biopesticides, the sterile insect technique (SIT, mass-release of radiation-sterilised pest insects) and transgenic crops. The past decade has seen a massive increase in their uptake, and there is increasing demand for these and similar techniques as integrated pest management (IPM) practices become more prevalent. One new control method showing promise is based on the release of transgenic insect strains to control the target pest. First proposed over a decade ago, Release of Insects Carrying a Dominant Lethal (RIDL®) is similar in principle to the SIT: by releasing large numbers of a sterile pest insect species – one that produces non-viable offspring – over a sufficient period of time, the wild population's reproductive potential will be hampered and eventually it crashes. SIT is not new and has provided decades of successful pest control, but transgenic methods (i.e. RIDL) offer substantial improvements to existing programmes, and are likely to widen the application of the SIT to a broader range of pests and a wider scale of use.
Insecticide-treated clothing has been used for many years by the military and in recreational activities as personal protection against bites from a variety of arthropods including ticks, chigger mites, sandflies and mosquitoes. Permethrin is the most commonly used active ingredient, but others, including bifenthrin, deltamethrin, cyfluthrin, DEET (N,N-diethyl-3-methylbenz-amide) and KBR3023, have also been trialled. Treatment is usually carried out by home or factory dipping. However, new microencapsulation technologies which may prolong the activity of insecticides on clothing are now available and may help to overcome the inevitable reduction in efficacy over time that occurs as a result of washing, ultraviolet light exposure, and the normal wear and tear of the fabric. The aim of this article is to review the evidence base for the use of insecticide-treated clothing for protection against bites from arthropods and its effect on arthropod-borne pathogen transmission. Although some studies do demonstrate protection against pathogen transmission, there are surprisingly few, and the level of protection provided varies according to the disease and the type of study conducted. For example, insecticide-treated clothing has been reported to give between 0% and 75% protection against malaria and between 0% and 79% protection against leishmaniasis. Studies vary in the type of treatment used, the age group of participants, the geographical location of the study, and the pathogen transmission potential. This makes it difficult to compare and assess intervention trials. Overall, there is substantial evidence that insecticide-treated clothing can provide protection against arthropod bites. Bite protection evidence suggests that insecticide-treated clothing may be useful in the prevention of pathogen transmission, but further investigations are required to accurately demonstrate transmission reduction.
Mosquitoes and Their Control presents a wealth of information on the bionomics, systematics, ecology, research techniques and control of both nuisance and disease vector mosquitoes in an easily readable style, providing practical guidelines and important information for professionals and laymen alike. Ninety-two European species and more than 100 globally important vector and nuisance species are included in the book. Most of them, including all European species, are described in the fully illustrated identification keys, followed by a detailed description of the morphology, biology, distribution and medical importance of each species, including over 700 detailed drawings. Mosquitoes and Their Control includes: Systematics and biology medical significance research techniques illustrated identification keys for larval and adult mosquito genera morphology, ecology, and distribution of the species identified in the keys biological, chemical, physical and genetic control of mosquitoes Mosquitoes and Their Control is a valuable tool for vector ecologists, entomologists, and all those involved with mosquito control, biology, ecology, and systematics world-wide. It will especially benefit those professionals, scientists and students dealing with mosquitoes and their control on a day-to-day basis. Society as a whole stands to gain from improved, environmentally responsible mosquito management programs designed on the basis of a broader understanding of mosquitoes and their control, as provided in this enlightening book. © Springer-Verlag Berlin Heidelberg 2003, 2010. All rights reserved.
Ground ultra-low volume (ULV) application against Aedes albopictus is a challenging methodology as its efficacy is strongly related to environmental conditions, insect behavior, and the pesticide formulation. Such operations are very relevant in many control programs, although their real efficacy is often unknown. Trials were carried out as part of real-world applications in urban scenarios in the Baix Llobregat region to evaluate the efficacy of 2 active ingredients, delatamethrin and alpha-cypermethrin. Both pyrethroids were tested against caged mosquitoes placed at a range of distances and under varying environmental conditions. Additionally, persistence on plants placed at the same distances was evaluated after 5 h, as well as droplet distribution using water-sensitive papers. The deltamethrin formulation used yielded significantly higher 24-h mortality than alpha-cypermethrin (100% direct mortality up to 25 m versus 10 m; and 73.9% residual 5-h mortality at 20 m compared to <50% at 5 m). The influence of environmental factors, a comparison with other field tests, and the real effect on uncaged mosquitoes is discussed.
Abstract Recent laboratory successes in the development of genetically engineered mosquitoes for controlling pathogen transmission have fostered the need for standardized procedures for advancing the technical achievements to practical tools. It is incumbent in many cases for the same scientists doing the in-laboratory discovery research to also take on the initial challenges of developing the pathway that will move the technologies to the field. One of these challenges is having a set of criteria for selecting collaborators and sites for efficacy and safety field trials that combine rigorous science with good ethical and legal practices. Specific site-selection criteria were developed in four categories-Scientific, Regulatory, Community Engagement, and Resources-in anticipation of open-field releases of a transgenic mosquito strain designed to suppress populations of the dengue vector mosquito, Aedes aegypti. The criteria are derived from previous published material, discussions, and personal experiences with the expectation of providing guidance to laboratory scientists for addressing the conceptual and operational considerations for identifying partner researchers and countries with whom to collaborate. These criteria are not intended to be prescriptive nor can they be applied to every circumstance where genetic approaches are proposed for deployment. However, we encourage those involved in the discovery phase of research to consider each criterion during project planning activities, and where appropriate, incorporate them into a "go/no-go" decision-making process for further development and testing of the technologies.
Dengue incidence continues to increase globally and, in the absence of an efficacious vaccine, prevention strategies are limited to vector control. It has been suggested that targeting the most productive breeding sites instead of all water-holding containers could be a cost-effective vector control strategy. We sought to identify and continuously control the most productive Aedes (Stegomyia) breeding site in an endemic urban area in Colombia and followed the subsequent incidence of dengue. In the urban area of Guadalajara de Buga, southwestern Colombia, potential breeding sites inside and outside houses were first characterized, and local personnel trained to assess their productivity based on the pupae/person index. Simultaneously, training and monitoring were implemented to improve the dengue case surveillance system. Entomological data and insecticide resistance studies were used to define the targeted intervention. Then, a quasi-experimental design was used to assess the efficacy of the intervention in terms of the positivity index of the targeted and non- targeted breeding sites, and the impact on dengue cases. Street catch basins (storm drains) were the potential breeding site most frequently found containing Aedes immature stages in the baseline (58.3% of 108). Due to the high resistance to temephos (0% mortality after 24h), the intervention consisted of monthly application of pyriproxyfen in all the street catch basins (n=4,800). A significant decrease in catch basins positivity for Aedes larvae was observed after each monthly treatment (p <0.001). Over the intervention period, a reduction in the dengue incidence in Buga was observed (rate ratio 0.19, 95% CI 0.12-0.30, p<0.0001) after adjusting for autocorrelation and controlling with a neighboring town, Palmira, This study highlights the importance of street catch basins as Aedes breeding sites and suggests that their targeted control could help to decrease dengue transmission in such areas.
Both the increase in human mobility and climate change contribute to the globalization of vector‐borne diseases. Some mosquito species are efficient disease vectors in Europe, thus increasing the risk of epidemic (re)emergence.
Bacillus thuringiensis var. israelensis ( Bti ) is considered as the most efficient larvicide to control mosquito populations with negligible environmental impacts. However, repeated field applications of Bti over many years raise the question of possible long‐term effects on non‐target invertebrates with putative subsequent alterations of food webs.
Environmental effects of Bti have mainly been studied in continental freshwater wetlands. Much less is known for brackish water coastal wetlands. We investigated whether repeated treatments with Bti , applied as VectoBac ® WG over seven consecutive years, may affect non‐target invertebrate communities in wetlands of the French Atlantic coast. Particular attention was devoted to invertebrates potentially used as food sources by shorebirds and wading birds.
Invertebrates were sampled in the water and sediment of control and VectoBac ® ‐treated saltmarsh pools between 2006 and 2012. Taxa abundance data were used to calculate community descriptors and to analyse the potential structural changes due to VectoBac ® using the principal response curve method and similarity analysis. Physicochemical parameters were measured in the same pools so that homogeneity of the environmental conditions between the control and treated areas could be tested.
We demonstrated that long‐term use of VectoBac ® WG in French Atlantic coastal wetlands had no influence on the temporal evolution of the taxonomic structure and taxa abundance of non‐target aquatic invertebrate communities, which is highly driven by abiotic factors. In addition, over the long term, the amount of invertebrates that could be used as food resources by birds is maintained in VectoBac ® ‐treated areas.
Synthesis and applications . Reduced application rate and targeted spraying of VectoBac ® WG in mosquito breeding sites minimize potential environmental impacts of Bacillus thuringiensis var. israelensis ( Bti ). Even so, surveillance of its possible primary side effects is needed, which requires comparable control and treated areas. Indeed, systematic temporal trends and subtle differences in the range of variation of abiotic factors result in discrepancies between control and treated area in terms of invertebrate abundance, which could be wrongly attributed to VectoBac ® . Management decisions and mitigation measures may therefore benefit from (i) extending surveillance to a time frame that allows for coverage of the immense temporal variation in taxa abundance and diversity and (ii) the inclusion of environmental variables in the monitoring of non‐target animal communities potentially exposed to Bti .