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The Biology Of Aedes Albopictus
... In this study, we conducted an analysis to discern the far-reaching impacts of climate, specifically temperature, rainfall, and humidity, on the seasonal density of Ae. albopictus. The interplay of temperature and precipitation exhibits both direct and indirect effects on population dynamics and the complete life cycle of Ae. albopictus, spanning from egg hatching to the emergence of adult mosquitoes [8][9][10]. The development of Ae. albopictus is notably influenced by temperature, with a range of 15-35 • C, an optimal growth zone at approximately 29-30 • C, and a critical lower threshold at 9-10 • C [11,12]. ...
... In September, when the females start to lay their winter eggs, the population of the previous months (E MJJA = May + June + July + August) has a minor impact, while the temperature of August has a negative effect. The temperature recorded in September seemed to have a positive impact on the time of the development cycle and the flight capacity of gravid females (Equation (8) in Table 2 and Figure 4f). ...
... Using winter and spring data, we tested Equation (2) (frost days, temperature, and rain recorded in March and temperature and RH in May), Equation (3) (frost days, rain, and egg density recorded in May) in Table 2 to predict the seasonal population density over the years, from 2010 to 2023, displayed in Figure 5. the development cycle and the flight capacity of gravid females (Equation (8) in Table 2 and Figure 4f). ...
Background: Aedes albopictus, the Asian tiger mosquito, has become a prevalent pest in Italy, causing severe nuisance and posing a threat of transmission of arboviruses introduced by infected travelers. In this study, we investigated the influence of weather parameters on the seasonal population density of Aedes albopictus. Methods: A Bayesian approach was employed to identify the best meteorological predictors of species trend, using the eggs collected monthly from 2010 to 2022 by the Emilia-Romagna regional monitoring network. Results: The findings show that the winter-spring period (January to May) plays a crucial role in the size of the first generation and seasonal development of the species. Conclusions: A temperate winter and a dry and cold March, followed by a rainy and hot spring and a rainy July, seem to favor the seasonal development of Ae. albopictus.
... Such results have been observed both in native and non-native populations of Ae. albopictus, suggesting a relative conservation of feeding behaviors during the invasion process, however, anthropophily has been found to be highest in urban habitats. This highly invasive species is especially successful at colonizing artificial environments associated with urban areas (Hawley 1988;Dowling et al. 2013), such as container-style habitats, that are often small and inconspicuous (Dowling et al. 2013). ...
... In its native range, Ae. albopictus is described as a forest edge species and considered to be a rural vector, with larvae developing in various natural microhabitats such as tree holes, bamboo stumps, bromeliads and other leaf axils or coconut shells (Hawley 1988;Higa 2011;Li et al. 2014). In contrast, populations in recently colonized areas predominantly use a diversity of artificial and natural larval sites, with clear predominance for artificial containers (Hawley 1988;Simard et al. 2005;Delatte et al. 2008;Bagny et al. 2009). ...
... In its native range, Ae. albopictus is described as a forest edge species and considered to be a rural vector, with larvae developing in various natural microhabitats such as tree holes, bamboo stumps, bromeliads and other leaf axils or coconut shells (Hawley 1988;Higa 2011;Li et al. 2014). In contrast, populations in recently colonized areas predominantly use a diversity of artificial and natural larval sites, with clear predominance for artificial containers (Hawley 1988;Simard et al. 2005;Delatte et al. 2008;Bagny et al. 2009). ...
Invasive hematophagous arthropods threaten planetary health by vectoring a growing diversity of pathogens and parasites which cause diseases. Efforts to limit human and animal morbidity and mortality caused by these disease vectors are dependent on understandings of their biology and ecology-from cellular to ecosystem levels. Here, we review research into the biology and ecology of inva-sive hematophagous arthropods globally, with a particular emphasis on mosquitoes, culminating towards management recommendations. Evolutionary history , genetics, and environmental filtering contribute to invasion success of these taxa, with life history trait and ecological niche shifts between native and invaded regions regularly documented. Pertinent vector species spread readily through active and passive means, via anthropogenic and natural mechanisms as climate changes. The rate and means of spread differ among taxa according to their capacity for entrain-ment in human vectors and physiology. It is critical to understand the role of these invaders in novel ecosystems , as biotic interactions, principally with their resources, competitors, and natural enemies, mediate patterns of invasion success. We further highlight recent advances in understanding interactions among arthropod-associated microbiota, and identify future research directions integrating arthropod microbiota to explain invasion success under changing environments. These biological and ecological facets provide an integrative perspective on the invasion history and dynamics of invasive hematophagous arthropods, helping inform on their management strategies.
... reported in other parts of Albania or in any other European country until 1990, when it was detected in Italy [10]. Human activities, especially the used tires and the "lucky bamboo" trade [11][12][13][14], and the passive dispersal via public and private transportation have spread the species worldwide. This has resulted in a worldwide distribution of Ae. albopictus, and it is currently listed as one of the top 100 invasive species by the Invasive Species Specialist Group [15]. ...
... The successful invasion of Ae. albopictus is also the result of a combination of many abiotic and biotic factors, including ecological plasticity, strong competitiveness, globalization, inadequate mosquito surveillance, and inadequate mosquito control [12]. Climate change predictions suggest that Ae. albopictus will continue to successfully colonize areas beyond its current geographical range [3,13,14,16,17]. Strains of this species have adapted to temperate climates [3,[12][13][14][15][16][17][18], and this may lead to further expansion of this species and possible disease transmission in many European countries. ...
... Climate change predictions suggest that Ae. albopictus will continue to successfully colonize areas beyond its current geographical range [3,13,14,16,17]. Strains of this species have adapted to temperate climates [3,[12][13][14][15][16][17][18], and this may lead to further expansion of this species and possible disease transmission in many European countries. ...
Simple Summary
Today, we are faced with urbanization and growing urban environments. Therefore, the number of insect species in cities is decreasing. However, urban insect pests, particularly populations of invasive species, are not limited by the factors that limit native insect populations. This article aims to describe four scenarios of the successful spread of invasive species in urban areas. Two mosquitoes and two stink bug species were selected for this study: the Asian tiger mosquito, the Japanese bush mosquito, the brown marmorated stink bug, and the southern vegetable stink bug. Regardless, mosquito species are considered insects of medical importance and stink bugs cause significant damage to agricultural production. What these four species have in common is their role as nuisance pests in urban environments.
Abstract
Urban areas are often populated by specific species of insects, some colorful and appealing, such as ladybugs and butterflies, and others irritating as nuisance bitters or as vectors of pathogens of public health importance. Mosquitoes in urban areas often utilize habitats adjacent to human residences, while phytophagous insect species such as stink bugs often colonize ornamental plants and utilize human-made structures including houses as overwintering shelters. This article discusses the early detection and the current distribution of two invasive mosquito species, Aedes albopictus Skuse 1894 and Ae. japonicus (Theobald 1901), in Serbia, introduced in 2009 and 2018, respectively. From the first findings until today, regular monitoring has been carried out and the establishment of both species in the newly invaded areas has been confirmed. Both species can become nuisance species, especially at high population densities, but more importantly, they are capable of transmitting a wide variety of arboviruses of public health importance. This article also discusses two invasive stink bug species Halyomorpha halys Stål 1855 and Nezara viridula Linnaeus 1758, introduced in Serbia in 2015 and 2008, respectively. These two stink bug species have also been monitored, and the establishment of their populations in the country has been confirmed. Both species have caused damage to a wide range of crops and ornamental plants and sometimes become nuisance pests in urban areas.
... The presence of decaying leaves can cause conditions similar to those found in the crevices of tree trunks, creating an optimal place and climate for mosquito life and reproduction. A. albopictus can settle in non-urbanized areas [8]. A. albopictus breeding sites include natural sites like bamboo trunks, bromeliads, and wood crevices [9]. Large natural water reservoirs, such as canals, marshes, lakes and rivers, are not used by these mosquito species for breeding. ...
... Large natural water reservoirs, such as canals, marshes, lakes and rivers, are not used by these mosquito species for breeding. A. albopictus cannot lay eggs in brackish or salt waters [9]. Of the listed egg-laying sites, used tires are most often used by A. albopictus [11,12]. ...
... The ecological plasticity of A. albopictus may explain successful expansions towards northern cooler climates. In particular, A. albopictus is able to induce photoperiodic egg diapause, allowing overwintering survival in temperate regions (Hawley 1988) and population establishment at higher latitudes than other exotic mosquito species that do not produce diapausing eggs. As European winter temperatures still remain an ecological limiting factor for survival (Medlock et al. 2006;Caminade et al. 2012) and as spring and summer climate conditions play a key role on larval development (Komagata et al. 2017) and adult reproduction ), it is acknowledged that climate change is a key driver of expansion towards northern latitudes (Caminade et al. 2012). ...
... First adult emergence The date of first adult emergence depends on late winter and spring temperatures. Hawley (1988) observed that larval development ceases at temperatures below 11 • C. Based on this observation, several studies assumed that hatching starts when spring temperatures are above a threshold comprised between 10 and 11 • C, see Model 3 in Caminade et al. (2012), or the report of the European Centre for Disease Prevention and Control (2009). In other approaches, instead of a threshold value at current time, mean spring temperatures are used (Medlock et al. 2006). ...
France has a latitudinal range for the expansion of Aedes albopictus invasive populations that is not yet completely colonized providing a critical opportunity to address key invasion processes. We propose a spatio-temporal model (DISTIGRI) to describe and predict current and future expansions at intra- and inter-annual scales of A. albopictus. This process-based model integrates mechanistic descriptions of the developmental cycle and the dispersal process of A. albopictus within a reaction-diffusion framework, depending on climatic suitability and photoperiod with a high spatio-temporal resolution. Using this model coupled with a climatic database, we propose several maps describing the current intra-annual distribution of A. albopictus, including the date of first emergence and the length of the period with significant adult presence. We also compute its future distribution over the next 10 years under several climatic scenarios, which shows a range expansion with a strong dependence on the climatic scenario. The outputs of the model may constitute a valuable asset for designing control and avoidance strategies, and to anticipate the biting nuisance with a high spatio-temporal resolution. These outputs also emphasize the importance of taking dispersal and life cycle into account to obtain accurate descriptions of out-of-equilibrium processes such as ongoing invasions.
... The Asian tiger mosquito Aedes albopictus (Skuse, 1894) (Diptera: Culicidae) is a thermophilic invasive mosquito species originating from tropical regions of South-eastern Asia (Hawley 1988). It is a competitive vector able to transmit more than 20 viruses and filarial worms, which are pathogenic to animals and humans. ...
... We checked for larvae in ovitraps during the monitored season and we stimulated hatching in the lab but, in all cases, including Novi Sad, we did not succeed to hatch eggs or develop larvae before the beginning of the new season. The phenomenon of diapause is induced mainly by photoperiod and temperature (Hawley 1988); on this basis, Romi et al. (2006) made two hypotheses: (1) long-lived female Ae. albopictus belonging to the last seasonal generation could have continued their activity for three months and (2) one or more cycles of reproduction have occurred at breeding sites with a favourable microclimate. ...
We confirmed occasions of outdoor reproductive activity of Aedes albopictus during the winter period in three Balkan countries. The main question was how long females of Ae. albopictus can stay active deposing overwintering eggs? In Podgorica (Montenegro), eggs were collected until 20 th December; afterwards, no eggs were found until 28 th March when the new season started. In Skopje (North Macedonia), eggs were observed until 22 nd November; the activity in the new season started on 26 th April. In Novi Sad (Serbia), eggs were found until 6 th December; surprisingly, during wintertime, oviposition activity was observed at the end of December and during February. In the new season, the activity started on the 7 th of June. During the winter period, we did not find any larvae in the ovitraps, and we were not able to hatch them in the laboratory from collected eggs. We conclude that long-lived females (belonging to the last seasonal generation) continue their activity during wintertime when favourable microclimate is available. Considering results and climate change predictions, surveillance should be planned during the whole year, at least in South European countries.
... [12] . Aedes aegypti are adaptive towards human residential areas and they frequently prefer urban areas, on the other hand, Aedes albopictus frequently prefer vegetation areas [4,10,26] . According to Sharma and Chharang, (2016) people are not alert about the breeding of dengue vector and approaches for prevention against them in Alwar city of Rajasthan. ...
... It is both zoophilous and anthropophile, active during day and night, able to produce diapausing, cold-resistant eggs. 66 In recent years, its reach is constantly expanding, to the point that it is considered responsible for the first outbreak recorded in Europe (Italy -Emilia Romagna Region), in 2007. 67 CHIKV transmission is mainly horizontal and it occurs through the saliva of infected mosquitoes that is injected during a blood meal. ...
Chikungunya virus (CHIKV), an arthropod-borne virus, is the aetiological agent of a disease characterized by several aspecific symptoms including fever, myalgia and arthralgia. The virus is primarily transmitted to humans through the bite of an infected mosquito of Aedes genus. This virus was first isolated in Tanzania in 1953, from which it spread to other African countries, Asia, Northern and Southern America, Europe and Oceania. Today, many human cases of CHIKV infection have been identified. The diffusion of CHIKV across the world, including Italy, is due to multiple factors amongst which the wide distribution of its vectors and high transmission efficiency play a crucial role. Currently, there are no specific treatments and effective vaccines against CHIKV; indeed, available therapies allow symptoms mitigation and some promising vaccines are undergoing clinical trials. The purpose of this review is to offer an updated picture of CHIKV molecular biology, epidemiology and vector distribution, clinical features and strategies for infection prevention and treatment.
... aegypti include flower vases, tires, and flasks, among others (Christophers, 1960). As in most Aedes species, the female has a preference for laying its eggs on moist surfaces inside a container (Hawley, 1988), and in places with previously stagnant water that are floodable (Clements, 1963). In addition, previous studies have shown that female Aedes mosquitoes prefer dark containers to lay their eggs (Tsunoda et al., 2020). ...
... Gobbi et al. (2013) reported that females of Hermetia illucens (L.) reared on meat meal had the smallest ovaries, while maximum ovary size was observed in females reared on chicken feed and mixed diets. The number of ovarioles and size of the ovaries of Aedes albopictus Skuse are affected by the conditions in which the larvae develop (Hawley 1988, Clements 1992. ...
The effects of three larval diets (beef meat, chicken meat, and beef liver) on development of Lucilia cuprina (Wiedemann) were evaluated. Egg hatching rates were higher on chicken meat and beef meat (99.5%) than on beef liver (96.5%). Pupation success was higher on chicken meat (99.0%) and beef meat (98.0%) than on beef liver (87.1%). Adult emergence rates were higher in flies reared on chicken meat (99.0%) and beef meat (98.5%) than on beef liver (93.5%). Proportions of female flies were somewhat higher in flies reared on chicken meat or beef meat (54-56% female) than on beef liver (52.5%). Flies that were reared on chicken meat and beef meat had shorter egg-adult development times (16.3 days) than flies reared on beef liver (18.5 days), and the generation time of flies reared on chicken meat or beef meat (51-52 days) was several days shorter than flies reared on beef liver (54 days). Flies reared on chicken meat had larger ovaries and more ovarioles per ovary when larvae were reared on chicken than flies reared on beef meat or beef liver. The ovaries of flies reared on chicken meat had significantly higher amounts of protein (21 mg/g body weight) than flies reared on beef liver (12 mg). Analysis of the larval diets showed that beef liver had the lowest amounts of protein and carbohydrate of the three tested diets, whereas the amounts of lipids did not differ among the diets. Journal of Vector Ecology 48 (2): xxx-xxx. 2023.
... Dengue fever risk was seen to increase after extremely high temperatures due to accelerated incubation and increased mosquito population, although dengue lifespan and egg survival rate was decreased [48]. Hawley [49] observed that the optimal thermal conditions for A. albopictus survival is around 20 to 27 degrees Celsius. Another study by Servadio et. ...
Background
Temperature has a significant impact on dengue incidence, however, changes on the temperature-dengue relationship across axes of socio-economic vulnerability is not well described. This study sought to determine the association between dengue and temperature in multiple locations in the Philippines and explore the effect modification by socio-economic factors.
Method
Nationwide dengue cases per province from 2010 to 2019 and data on temperature were obtained from the Philippines’ Department of Health–Epidemiological Bureau and ERA5-land, respectively. A generalized additive mixed model (GAMM) with a distributed lag non-linear model was utilized to examine the association between temperature and dengue incidence. We further implemented an interaction analysis in determining how socio-economic factors modify the association. All analyses were implemented using R programming.
Results
Nationwide temperature-dengue risk function was noted to depict an inverted U-shaped pattern. Dengue risk increased linearly alongside increasing mean temperature from 15.8 degrees Celsius and peaking at 27.5 degrees Celsius before declining. However, province-specific analyses revealed significant heterogeneity. Socio-economic factors had varying impact on the temperature-dengue association. Provinces with high population density, less people in urban areas with larger household size, high poverty incidence, higher health spending per capita, and in lower latitudes were noted to exhibit statistically higher dengue risk compared to their counterparts at the upper temperature range.
Conclusions
This observational study found that temperature was associated with dengue incidence, and that this association is more apparent in locations with high population density, less people in urban areas with larger household size, high poverty incidence, higher health spending per capita, and in lower latitudes. Differences with socio-economic conditions is linked with dengue risk. This highlights the need to develop interventions tailor-fit to local conditions.
... This is a time-consuming task that requires expertise and training. The discriminative morphological identification of adult Ae. albopictus is readily amenable by looking at bold black shiny scales and distinct silver-white scales on the palpus and tarsi 4 . Additionally, the dorsal scutum is black, with a distinguishing white stripe in the center, beginning at the dorsal surface of the head and continuing along the thorax. ...
Hematophagous insects belonging to the Aedes genus are proven vectors of viral and filarial pathogens of medical interest. Aedes albopictus is an increasingly important vector because of its rapid worldwide expansion. In the context of global climate change and the emergence of zoonotic infectious diseases, identification tools with field application are required to strengthen efforts in the entomological survey of arthropods with medical interest. Large scales and proactive entomological surveys of Aedes mosquitoes need skilled technicians and/or costly technical equipment, further puzzled by the vast amount of named species. In this study, we developed an automatic classification system of Aedes species by taking advantage of the species-specific marker displayed by Wing Interferential Patterns. A database holding 494 photomicrographs of 24 Aedes spp. from which those documented with more than ten pictures have undergone a deep learning methodology to train a convolutional neural network and test its accuracy to classify samples at the genus, subgenus, and species taxonomic levels. We recorded an accuracy of 95% at the genus level and > 85% for two (Ochlerotatus and Stegomyia) out of three subgenera tested. Lastly, eight were accurately classified among the 10 Aedes sp. that have undergone a training process with an overall accuracy of > 70%. Altogether, these results demonstrate the potential of this methodology for Aedes species identification and will represent a tool for the future implementation of large-scale entomological surveys.
... On the contrary, abundance of Ae. albopictus is affected by urbanization. The main reason behind the fact is adoption of this species with dense vegetation (Chan et al., 1971;Hawley, 1988;Maciel-de-Freitas et al., 2006). For that reason, when a house is taken as a spatial unit, the density of Ae. aegypti is more in indoors (endo-phagy/phily) and Ae. ...
This is a well-known fact that, climate change (CC) is a major challenge for the human civilization. This has happened because CC affects the biological system in terms of physiology and phenology of the living creatures on the earth. One of the most damaging effects of CC is global expansion of vector borne diseases. Albeit, there are 150 arboviruses which affect the human but we have restricted our discussion on malaria, dengue virus (DENV), West Nile virus (WNV), Zika virus (ZIKV) and chikungunya virus due to their global concern. This lead paper has detailed how CC is responsible for propagation of vector, future research plan, control strategy, conclusive remark and brief methodology followed to build up the write up.
... Both Ae. albopictus and Ae. triseriatus will similarly breed in both natural and man-made habitats, but they are less associated with humans and prefer vegetated urban, suburban, and rural landscapes and forests (24,25). Due to their geographic and ecologic overlap, it is possible to have all three species co-exist in certain locales. ...
In this study, we describe the generation of two new species of axenic mosquito, Aedes albopictus and Aedes triseriatus . Along with Aedes aegypti , axenic larvae of these three species were exposed to an environmental water source to document the assembly of the microbiome in a common garden experiment. Additionally, the larvae were reared either individually or combinatorially with the other species to characterize the effects of co-rearing on the composition of the microbiome. We found that the microbiome of the larvae was composed of a relatively low-diversity collection of bacteria from the colonizing water. The abundance of bacteria in the water was a poor predictor of their abundance in the larvae, suggesting the larval microbiome is made up of a subset of relatively rare aquatic bacteria. We found 11 bacterial 16S rRNA gene amplicon sequence variants (ASVs) that were conserved among ≥90% of the mosquitoes sampled, including 2 found in 100% of the larvae, pointing to a conserved core of bacteria capable of colonizing all three species of mosquito. Yet, the abundance of these ASVs varied widely between larvae, suggesting individuals harbored largely unique microbiome structures, even if they overlapped in membership. Finally, larvae reared in a tripartite mix of the host-species consistently showed a convergence in the structure of their microbiome, indicating that multi-species interactions between hosts potentially lead to shifts in the composition of their respective microbiomes.
IMPORTANCE
This study is the first report of the axenic (free of external microbes) rearing of two species of mosquito, Aedes albopictus and Aedes triseriatus . Our previous report of axenic Aedes aegypti brings the number of axenic species to three. We designed a method to perform a common garden experiment to characterize the bacteria the three species of axenic larvae assemble from their surroundings. Furthermore, species could be reared in isolation or in multi-species combinations to assess how host-species interactions influence the composition of the microbiome. We found all three species recruited a common core of bacteria from their rearing water, with a large contingent of rare and sporadically detected bacteria. Finally, we also show that co-rearing of mosquito larvae leads to a coalescence in the composition of their microbiome, indicating that host-species interactions potentially influence the composition of the microbiome.
... The temperature and precipitation directly or indirectly affect the population dynamics and the life cycle from egg-hatching to adult mosquitoes [8][9][10] Ae. albopictus develop at a temperature of 15-35 °C, with an optimum of about 29-30 °C and a minimum threshold around 9-10 °C [11,12]. High temperatures result in a reduction in the cycle length and survival rate while low temperatures increase the cycle length and survival rate. ...
Background: Aedes albopictus, the Asian Tiger Mosquito, has become a prevalent pest in Italy, causing severe nuisance and posing a threat of transmission of arboviruses introduced by infected travellers. In this study, we investigated the influence of weather parameters on the seasonal population density of Aedes albopictus. Methods: A Bayesian approach was employed to identify the best meteorological predictors of species trend, using the eggs collected monthly from 2010 to 2022 by the Emilia-Romagna regional monitoring network. Results: The findings show that the winter-spring period (January to May) plays a crucial role in the size of the first generation and seasonal development of the species. Conclusions: A temperate winter and a dry and cold March, followed by a rainy and hot spring and a rainy July, seem to favour the seasonal development of Ae. albopictus.
... quinquefasciatus). Ae. albopictus, Ar. subalbatus, Ae. aegypti coexisting in numerous locations suggested by Hawley (1988) that they shared a common habitat. ...
Mosquito diversity, abundance, density, and habitats were studied at four selected breeding areas in Dhaka city from December 2015 to April 2016. A total of 3214 individuals of 10 mosquito species belonging to 3 genera namlely Culex (7spp.), Aedes (2spp.), and Anopheles (1sp.) were documented during the study period. The Cx. quinquefasciatus (37.83%) was found the highest in number followed by Cx. vishnui (16.74%), Cx. tritaeniorhynchus (16.21%), Cx. gelidus (9.40%), Cx. hutchinsoni (9.12%), Cx. fuscocephala (2.77%), Cx. vagans (2.21%), Ae. aegypti (3.17%), An. annularis (2.77%), and Ae. albopictus (1.15%). Maximum number of mosquitoes were found in Hazaribagh (1178 individuals), followed by Badda (1128 individuals), Demra (594 individuals), and Sutrapur (314 individuals). Mosquitoes were plentiful in March, regardless of species distribution which was influenced by rainfall and the lowest was in February. Eighteen different habitats of the mosquitoes were identified. The Simpson’s Index (λ= 0.18) and Shanon’s Diversity Index (H′= 1.93) indicated maximum mosquito diversity at Demra thana where species richness was 3.24. However, the Sutrapur thana (λ= 0.34, H′ =1.34) was minimum in which species richness had 2.40. The Species Evenness in the Demra thana (J′= 0.84) indicated that the species were evenly distributed whereas the Sutrapur thana (J′= 0.69) was comparatively less evenly distributed. The highest Community Dominance was 76.11% for the Sutrapur and the lowest was 49.66% for the Demra. Sorenson's Coefficient (CC) was 0.76 indicating that there was considerable overlap or similarity across the four communities. Bangladesh J. Zool. 50(3): 337-352, 2022
... Regarding the blood meal for oviposition activity, some authors proved that one blood meal is sufficient for Aedes albopictus to lay eggs. [20][21][22][23] In addition, Delatte et al. 8 reported that at higher temperatures, Aedes albopictus can have the shortest but largest number of cycles. ...
Environmental temperature is an important abiotic element that plays a significant role in various aspects of the insect life cycle. Insects have evolved different mechanisms to adjust to temperature variations in order to avoid thermal stress over evolutionary time. They have been able to invade practically every type of habitat due to these adaptations. Aedes albopictus, the Asian tiger mosquito, is a Southeast Asian forest-dwelling mosquito species that has spread throughout the world in the last forty years. Since it can effectively transmit a variety of viruses, Aedes albopictus is a significant public health issue in all areas where it has already been entrenched. The current article shows the existing understanding of the impact of environmental temperature on the dispersion and ecology of Aedes albopictus.
... Some mosquito species prefer artificial containers whereas other species prefer to breed in temporary places and some species breed preferably in water rich in Ammonia content (Reisen et al., 1977) like Anopheles stephensi, a chief vector of urban malaria (Ramachandra Rao, 1989) while others are adapted to clean and clear water like Aedes mosquitoes. Entomological studies prove that Aedes albopictus, a rural vector (Hawley, 1988) was responsible for dengue transmission (Gubler and Kuno, 1997) in some countries of S.E Asia (Smith, 1956;Hammon, 1966;Rudnick, 1967;Stephenson et al., 2003;Gratz, 2004) and thought to be a possible vector of encephalitis (Beaman and Turell, 1991), Rift Valley Fever (Turell et al., 1988) and Chikungunya virus (Turell et al., 1992). ...
To determine the species composition, relative abundance and seasonal variation of different mosquitoes Genera (Aedes, Anopheles, Armigeres, Culex, and Culiseta) in different habitats the present research work was carried out in Entomology Research Laboratory of The University of Peshawar. Sampling performed from variety of permanent and temporary breeding habitats was carried out on monthly basis from targeted breeding sites for two consecutive years through dipping method. Species diversity in the survey sites was noted. Collection from these seventeen various types of potential larval habitats, yielded a total of 42,430 immature constituting 41,556 larvae and 874 pupae. Among these only 19,651 adult mosquitoes emerged comprising 11,512 female and 8,139 male mosquitoes. 78% (n= 15333) of mosquito larvae were from permanent and 22% (n=4318) were from temporary breeding sites. This study showed that Peshawar valley harbours 15 species from the genera Aedes, Anopheles, Armigeres, Culex and Culiseta. When the density of each species was examined, Culex quinquifasciatus was found to be dominant (79%) and constant in distribution. Among the temporary habitats Aedes albopictus was found as the most prevalent species particularly from tree holes and water cisterns. The highest intensity of mosquitoes was in June (2243 emerged adults) and November (2667 emerged adults) while the lowest was in January (203 emerged adults). A perfect positive correlation (r = +0.8) was found between temperature and population of mosquitoes (df 10 and α 0.05). The species diversity index for mosquitoes remained between 0.12 and 1.76. The Margalef’s richness components was noticeably low for bamboo traps (0.2) and fairly high for rice fields, Percolating water and Animal tracks (1.3) which shows the abundance of mosquito species in these habitats. Similarly Pielou’s Evenness was highest for bamboo traps (E=1) showing species uniform distribution. Animal tracks were presumed not only the diverse habitat rather also possessed high value for species richness and species evenness. Temperature, rainfall, humidity and other related attributes responsible for species variation and abundance need to be analysed further to pave way for controlling vector species in their oviposition targeted sites.
... Ae. albopictus, a major rural vector responsible for the transmission of dengue, zika, west nile fevers, chikungunya, etc., and found in the tropical countries of the world. The adults breed in different types of rainwater-filled natural and artificial containers, tires and tubes, and micro water bodies like tree holes, bamboo holes, earthen pots, etc 27 . The similarity in the selection of habitats for oviposition of Toxorhynchites and Ae. ...
Larvae of the elephant mosquitoes, Toxorhynchites spp. (Diptera: Culicidae) are predacious on larvae of other mosquito species and some small aquatic organisms; this predatory behavior can be applied in (mosquito) vector control. The present study examined the feeding behavior of Toxorhynchites splendens on Aedes albopictus in relation to search area [volume of water (X1)] and prey density (X2), prey instars, predatory preference and larvae's functional response on variable prey densities. Experiments were conducted to determine changes in the feeding activity of T. splendens with different search areas and showed that rate of prey consumption was inversely proportional to the search area as evidenced by a negative value of X1 in the regression equation and positively related to prey density. The non-linear polynomial logistic regression estimated a significant linear parameter (P1 < 0) for the functional response analysis suggesting a Type II functional response. Differences in feeding response related to the different combinations of prey instars were statistically not significant (p > 0.05), expressing that all the instars of prey were equally susceptible to the predator. Toxorhynchites splendens preferred to consume Ae. albopictus larvae rather than Tubifex when supplied together as a food source.
... La compétition peut également aboutir à l'exclusion de la population de l'espèce la moins apte à l'utilisation d'une ressource limitée du milieu par une autre espèce plus efficace dans son utilisation (Schoener, 1974 ;Connell, 1980). Des exemples de déplacements niche ont été étudiés par plusieurs auteurs (Hawley, 1988 ;Christenson et Foote, 1960 ;Duyck et al., 2004) ...
... In the present study, none of the samples taken from the rural or urban environments contained phosphates within a specific range, as reported in earlier studies by Sehagl and Pillai (1970) [48] . Similarly, the levels of nitrogen and phosphorus in the breeding habitats were not significantly affected the emergence of adult mosquitoes [23] . A study on the correlation of larval productivity with adult emergence revealed a resultant coefficient of 0.036 ( Figure 2) and was positive. ...
The range and spread of dengue cases can be ascribed to the breeding habitat of Aedes albopictus. There is a paucity of scientific information on the influence of the water quality of breeding habitats on adult emergence in Aedes albopictus. The objective of the present study was to evaluate the water quality characteristics responsible for the adult emergence of Aedes albopictus confining to selected urban and rural habitats of northern Kerala, India. Larvae of Aedes albopictus were collected using the dipping method, along with the collection and analysis of water samples following APHA (2017). The larvae were retained in controlled environmental conditions to assess the magnitude of adult emergence. The average larval productivity in both rural and urban areas was almost the same and exhibits a particular seasonal pattern. Both the rural and urban sectors showed substantial variations in the magnitude of adult emergence. The percentage of adult emergence followed a pattern of pre-monsoon > post-monsoon> monsoon season. With a correlation coefficient of 0.036, larval productivity and adult emergence were shown to be positively correlated. EC, TDS, salinity, Na, K, and NO3 showed a positive correlation while temperature, pH, turbidity, chloride, and DO showed a negative correlation with the adult emergence. Multiple regression models revealed temperature (p=0.00), DO (p= 0.007), NO3 (p=0.007), and chloride (p=0.030) as the distinguishing elements in the adult emergence of Aedes albopictus.
... It is a daytime feeder, with feeding peaks in the early morning and late afternoon. It is an opportunistic and belligerent species with an extensive host variety of wild animal fauna including man (Hawley, 1988). ...
Understanding the seasonal prevalence and biological parameters of mosquito Aedes albopictus (Skuse) are indispensable for population estimates, efficient vector control and dengue prevention tactics. The sampling of Ae. albopictus was completed through the collection of eggs, larvae, pupae and adults throughout the study seasons by use of nets and ovitraps at least once a week. Occurrence of Ae. albopictus was distinguished heterogeneously and populations were observed maximum in October post-monsoon season. The populations increased progressively from January-May and sharply deteriorated in June-July and September-November months revealing the highest breeding. However, the lowest density was observed during December-February. Growth of Ae. albopictus evaluated under standardized laboratory conditions with the provision of Balb/C mice as blood meal to adult mosquitoes, exhibited eggs hatching, and first, second, third and fourth instar larvae development in 3, 1.3, 1.2, 1.7 and 2.8 days, respectively. Nevertheless, pupation development, adult emergence, total life duration from egg hatching to adult emergence, male and female life spans persisted for 7, 3, 20, 25 and 30 days, respectively. Aedes albopictus accounted for 1% density of other mosquito genera collected (Culex and Anopheles), while, Aedes aegypti (L) was 3% abundant and indicated that both Aedes species had coexistence.
... tree holes and bromeliads) to artificial (e.g. discarded tires, plant pot receptacles, and bird baths) containers (Hawley 1988) . Source reduction of oviposition sites can help reduce container-ovipositing mosquitoes such as Ae. ...
Pyrethroids are commonly used in barrier treatments but less is known about how mosquitoes are affected by the simultaneous application of an insect growth regulator (i.e., pyriproxyfen) used in barrier treatments. This field study, conducted from May 14 - October 16, 2018, evaluated the effect of lambda-cyhalothrin (pyrethroid adulticide) and pyriproxyfen on the reproduction (measured by fecundity and adult emergence) and abundance of Aedes albopictus. Nine properties were treated with Demand®CS 0.06% + Archer® 0.010% (every 60 days) and three control properties received no treatment (N=12 total properties). No significant (P>0.05) differences were observed between abundance of Ae. albopictus in treatment compared to control groups. However, significant differences were observed in abundance of Ae. albopictus adults between weeks at both control (P = 0.003) and treatment (P < 0.0001) properties. Results from our research show that continued studies are needed to determine the efficacy of barrier treatments for this species. .
... Despite this, A. albopictus has rarely been used as a model organism for these kind of studies. The reason for this may be the fact that it was traditionally associated with wild animals and territories, and hence, it was a less dangerous species for humans [59]. A. aegypti, on the contrary, has often been regarded as the primary vector of arborviruses in human health, becoming the most studied mosquito within its genus. ...
Aedes albopictus is a species of mosquito, originally from Southeast Asia, that belongs to the Culicidae family and the Dipteran insect order. The distribution of this vector has rapidly changed over the past decade, making most of the temperate territories in the world vulnerable to important human vector-borne diseases such as dengue, yellow fever, zika or chikungunya. Bacillus thuringiensis var. israeliensis (Bti)-based insecticides represent a realistic alternative to the most common synthetic insecticides for the control of mosquito larvae. However, several studies have revealed emerging resistances to the major Bti Crystal proteins such as Cry4Aa, Cry4Ba and Cry11Aa, making the finding of new toxins necessary to diminish the exposure to the same toxicity factors overtime. Here, we characterized the individual activity of Cyt1Aa, Cry4Aa, Cry4Ba and Cry11Aa against A. albopictus and found a new protein, Cyt1A-like, that increases the activity of Cry11Aa more than 20-fold. Additionally, we demonstrated that Cyt1A-like facilitates the activity three new Bti toxins: Cry53-like, Cry56A-like and Tpp36-like. All in all, these results provide alternatives to the currently available Bti products for the control of mosquito populations and position Cyt proteins as enablers of activity for otherwise non-active crystal proteins.
... V. Lencioni et al. albopictus has the ability to breed in natural and artificial habitats, some of which include tyres, barrels, rainwater gulley, catch basins and watering troughs (Hawley 1988). Monitoring sites were classified according to the presence of anthropogenic or natural factors. ...
The invasive tiger mosquito Aedes albopictus is a serious nuisance for people due to its biting and potential for disease transmission, even in Italian mountain regions. In this work, we examined its occurrence dynamic from the first invasion in two Alpine cities, Rovereto and Trento, only 25 km apart. Mosquito’s distribution was assessed using ovitraps, from mid-May to end-October, from its first reported occurrence, i.e. 2001 in Rovereto and 2010 in Trento. In both cities, ovitraps were located in seven habitat types: gathering places, residential areas, urban parks, car parks, near watercourses, industrial areas and croplands. The annual average temperature and precipitation were similar in the two cities from 2001 to 2020. We had hypothesized that the seasonal and annual differences in egg number between both cities would be limited. Significant linear and positive relationship was found between the average number of eggs and air temperature in both the cities, but with a steeper slope in Trento. In addition, the average number of eggs per ovitrap was higher in Trento than in Rovereto (average 50.3 vs 14.2). None of the considered risk factors (climate, habitat type) explained such difference in abundance between cities. Indeed, based on the temperature, the expectation was to find fewer eggs in Trento being cooler than Rovereto during 2010–2020 (the average in the period of activated traps was, respectively, 19.2 vs 19.7°C). Thus, we argue that other anthropogenic factors, such as different control activities (adulticide treatments were carried out solely in Rovereto), might explain the difference in egg abundance found between cities. A specific experimental design to evaluate treatment effect might validate our hypothesis (e.g. apply adulticides during the surveillance period, with treatments applied at regular distances from the ovitraps and with a specific periodicity to compare adult and egg abundance).
... In this scenario, many studies focused on the possible geographical spread of A. albopictus in temperate regions due to climate change and on the concomitant expansion of the risk of occurrence of A. albopictus-borne diseases [10,25]. Cold winter temperatures have been identified as the most limiting factor for A. albopictus range expansion in Europe [26,27] and January's minimum temperatures play a crucial role in A. albopictus survival [28]. Surprisingly enough, few studies took into consideration another important factor dealing with human health threats posed by A. albopictus, i.e. the risk that, due to global warming, this species could in the future become homodynamic in some temperate regions. ...
The Asian tiger mosquito, Aedes albopictus, competent vector of several arboviruses, poses significant impact on human health worldwide. Although global warming is a driver of A. albopictus range expansion, few studies focused on its effects on homodynamicity (i.e. the ability to breed all-year-round), a key factor of vectorial capacity and a primary condition for an Aedes-borne disease to become endemic in temperate areas. Data from a 4-year monitoring network set in Central Italy and records from weather stations were used to assess winter adult activity and weekly minimum temperatures. Winter oviposition occurred in 38 localities with a seasonal mean photoperiod of 9.7 : 14.3 (L : D) h. Positive collections (87) occurred with an average minimum temperature of the two and three weeks before sampling of approximately 4°C. According to these evidences and considering the climate projections of three global climate models and three shared socio-economic pathways for the next three 20-year periods (from 2021 to 2080), the minimum temperature of January will increase enough to allow an all-year-round oviposition of A. albopictus in several areas of the Mediterranean Basin. Due to vector homodynamicity, Aedes-borne diseases could become endemic in Southern Europe by the end of the twenty-first century, worsening the burden on human health.
... Globally, dengue virus is the most wide spread arbovirus, causing an estimated 390 million infections per year [4]. Global number of deaths reported only in 2013 for males and females are 4238 and 4324 respectively, with a mortality rate of 0.12 per 100,000 infected cases [5]. ...
Objective: Seasonal prevalence of female Aedes aegypti was studied to determine its habits and its transmission season in Lahore, Pakistan. Methods: The study was carried out by placing black modified ovitraps indoor & outdoor in 25 different households per town in ten administrative areas of the city. The placement of ovitraps was done by a stratified random sampling method. Data was collected on a weekly basis and monthly indices of adult and larvae were calculated. High (>9 Breteau Index) indoor prevalence of adult was found in Data Gunj Bakhsh and Iqbal Town, moderate (5 to 9 Breteau Index) was observed in Aziz Bhatti town only. Results: In all other seven study areas, the indoor prevalence of adult was found low (<5 Breteau Index). Regarding the outdoor prevalence of adults, high (>9 Breteau Index) was not detected from any area, moderate (5 to 9 Breteau Index) was observed in Aziz Bhatti, Gulberg, Shalimar and Nishtar towns. In all other six study areas, the outdoor prevalence of adult was found low (<5 Breteau Index).
During the months September, October, November, March and April Aedes aegypti density was
found high and no adult or larva were found during the months of December, January, February,
June and July. Prevalence of Aedes aegypti in various seasons was detected significantly (p< 0.05) different.
Conclusion: It is concluded that A. aegypti is widely distributed in all the towns of Lahore but some areas like Iqbal town and the Data Gunj Baksh town had a high indoor prevalence.
... From the point of introduction, it expanded its range to the north and east and became an important pest mosquito in much of its new habitat. 13 The introduction of the West Nile virus (WNV1) into North America in 1999 may have elevated Ae. albopictus from a pest to a public health threat. 14 In 1980, a set of guidelines were published by the subcommittee on Arboviral Laboratory Safety (SALS1). ...
Vectors of malaria, filaria, dengue, chikungunya, zika, japanese encephalitis, and kala-azar play an important role in the disease transmission in different eco-settings with variable climatic conditions. Ticks, mites, and fleas also pose a threat to new emerging and re-emerging vector-borne diseases, i.e. Kyasanur Forest Disease (KFD), Crimean Congo Hemorrhagic Fever (CCHF), scrub typhus, and other rickettsioses. Now, the time has come that field oriented entomological work has to shift from open, field based towards closed medical entomological laboratories for undertaking molecular research and pathogen/ virus detection among vector species handling them by minimising human risks. It is imperative to note that there is a strong need for a standard protocol for effective medical entomological laboratory practices while handling the pathogen carrying vector species under laboratory conditions. This may help to prevent the transmission of pathogens/ viruses in case of accidental release of vectors carrying pathogens/ viruses from the entomology laboratories. Such protocols would always help the scientists to minimise risks working in closed conditions. Though, there are guidelines/ procedures available for developing medical entomology laboratory, having facilities for insect rearing, its handling and equipment, however, no specific published protocol or guidelines exist presently in the Indian context. In the present manuscript, the need for a standard protocol for arthropod containment levels (ACLs 1- 4) along with the appropriate bio-safety levels based on the risk potential of pathogen carried by the vector species has been discussed for its application at the ground by the respective health authorities/ institutions.The presence of Standard Operating Procedures (SoPs) and guidelines on Good Medical Entomology Laboratory Practices (GMELP) would help the professionals working in a medical entomology laboratory to minimise risks. There is a need to develop and follow Good Medical Entomology Laboratory Practices (GMELP) for handling the vectors (Arthropods) carrying the pathogens/ viruses at the national/ state/ district level as well as by the research institutes, medical colleges, and universities. The present concept note shall help to provide a guiding principle to develop standard operating procedure (SoP)/ Guidelines for GMELP.
... The same applies to use tires found in large numbers in the urban sites of Douala and Kribi. The presence of such sites is a permanent risk of Ae. albopictus proliferation [35]. ...
Background: A good knowledge of Aedes diversity and their biting cycle is necessary for better planning of vector control interventions against arboviruses diseases. This study aims to determine the diversity of Aedes and the biting cycle of Aedes albopictus in suburban as well as urban areas of Douala, Kribi, and Ayos to propose a method for vector control based on Ageratum conyzoides L., 1753 and Chromolaena odorata L., 1970 (Asteraceae) essential oil. Methods: Larvae were sampled by dipping method and reared by Desfontaine method. The aggressiveness of Aedes was determined by the outdoors Human Landing Catches method from 6 am to 6 pm. Captured mosquitoes were morphologically identified using identification keys. Essential oils from fresh leaves of A. conyzoides and C. odorata were extracted by hydrodistillation using Clevenger while the chemical composition was determined by GC-MS. Insecticide tests were carried out according to WHO protocol on matures Ae. albopictus larvae. Results: Ae. albopictus (n=3499; 80.5%) was the most aggressive species in urban and suburban areas followed by Ae. unilineatus (n=392; 9.02%) and Ae. aegypti (n=210; 4.83%). The mean biting rate of Aedes was 21.52 bites/person/day (b/p/d). In urban and suburban areas Ae. albopictus (18.22 b/p/d) was the most aggressive species followed by Ae. unilineatus (2.04 b/p/d) and Ae. aegypti (1.09 b/p/d). Precocene I (54.4%) and Androencecalinol (24.69%) were the major compounds of A. conyzoides fresh leaves essential oil. Geijerene (20.02%) and trans-Muurola-4(14), 5-diene (19.15%) were the major compounds of C. odorata fresh leaves essential oil. A. conyzoides fresh leaves essential oil was the most effective with 100% mortality after 10 hours of exposure at 75 ppm concentration. Conclusion: This study reveals that Aedes was more aggressive in urban areas than in suburban areas. Aedes albopictus was the most aggressive species. A. conyzoides fresh leaves essential oil should be taken into account in the implementation of control strategies against Aedes. Keywords: Aedes diversity; biting cycle; fresh leaves; urban; suburban.
Hematophagous insects belonging to the Aedes genus are proven vectors of viral and filarial pathogens of medical interest. Aedes albopictus is an increasingly important vector because of its rapid worldwide expansion. In the context of global climate change and the emergence of zoonotic infectious diseases, identification tools with field application are required to strengthen efforts in the entomological survey of arthropods with medical interest. Large scales and proactive entomological surveys of Aedes mosquitoes need skilled technicians and/or costly technical equipment, further puzzled by the vast amount of named species. In this study, we developed an automatic classification system of Aedes species by taking advantage of the species-specific fingerprinting displayed by Wing Interferential Patterns. A database containing 494 photomicrographs of 24 Aedes spp. from which those documented with more than ten pictures have undergone a deep learning methodology to train a convolutional neural network and test its accuracy to classify samples at the genus, subgenus, and species taxonomic levels. We recorded an accuracy of 95% at the genus level and >85% for two (Ochlerotatus and Stegomyia) out of three subgenera tested. Lastly, eight were accurately classified among the 10 Aedes sp. that have undergone a training process with an overall accuracy of>70%. Altogether these results demonstrate the potential of this methodology for Aedes species identification and will represent a tool for the future implementation of large-scale entomological surveys.
Background:
Aedes albopictus is an important vector of many mosquito-borne viral diseases, including dengue fever and Zika. In recent years, it has spread and colonized tropical, subtropical and temperate regions worldwide. Monitoring of Ae. albopictus population dynamics is an important tool for early warning of mosquito-borne infections. Because the genetic diversity and genetic structure of natural populations are the genetic bases of population dynamics, studies of population genetics can reveal the origin, differentiation and dispersal characteristics of Ae. albopictus populations. Then, their evolutionary potential and environmental adaptability can be analyzed, providing a theoretical basis for the formulation of accurate Ae. albopictus surveillance and integrated control programs.
Methods:
In 2018, 552 Ae. albopictus larvae were collected during an invasive mosquito species surveillance project in China's Yangtze River Basin. Morphological analysis was performed to assign the adult mosquitoes to species, and then the genetic marker ITS2 was amplified and sequenced.
Results:
There were 179 haplotypes among 552 ITS2 sequences with a length of 378 bp. In total, 155/179 (86.59%) haplotypes were specific to individual populations, and 24/179 (13.41%) haplotypes were shared by populations. Hap4 (126), Hap7 (43), and Hap16 (34) were the most numerous haplotypes and the most widely distributed. The overall Hd was 0.928, π was 0.031, the mean nucleotide difference number (K) was 7.255, and the number of segregating sites was 169. TCS network maps mainly showed a single star-like scattered distribution. According to geographical location, there were no obvious haplotype groups, and the haplotypes were intricately connected. The genetic diversity of Ae. albopictus populations in the Yangtze River Basin was high. The molecular variance observed in the populations of Ae. albopictus mainly occurred among individuals within populations, accounting for 98.79% of the total, while that among populations accounted for only 1.21% of the total. Only the populations of Ae. albopictus in the Chongqing and Sichuan regions showed a moderate degree of population genetic differentiation, while genetic differentiation between the other regions were small, gene exchange was very common, and genetic differentiation within populations was minimal.
Conclusions:
According to this study, the genetic diversity of Ae. albopictus populations in the Yangtze River Basin is high, the genetic differentiation among populations is small, and gene exchange is common. In addition, frequent interregional exchange exacerbates the abnormal spread of vectors. This study highlighted the potential spread route of the vector Ae. albopictus in the Yangtze River Basin. There are three potential dispersal routes for Ae. albopictus populations in the Yangtze River Basin. The findings could be helpful for effective surveillance and early warning of Ae. albopictus vectors.
The present study identifies species composition and breeding preferences of Aedes mosquitoes in container habitats of selected urban localities in Peshawar, Khyber Pakhtunkhwa, Pakistan. Sampling was carried out from 6 sites including Shoba Bazar, Railway Road, Charsadda Road, Kohat Road, Tehkal Payan and Peshawar University Campus. Monthly sampling of mosquito immature was conducted from October 2011 to September 2012. Total of 2852 adult mosquitoes emerged after rearing, consisting of three genera and five species; Aedes aegypti, Aedes albopictus, Culex quinquefasciatus, Culex tritaeniorhynchus and Anopheles stephensi. Aedes was the dominant genus followed by Culex and Anopheles. University campus and Tehkal showed the highest species diversity; the former had the highest species richness while later presented the highest species evenness compared to other localities. Ae. aegypti was not demonstrated in the collection from December to March and in May. Ae. albopictus was recorded in October, April, August and September. Highest abundance of Ae. aegypti was recorded in October corresponding to the lowest average humidity levels whereas Ae. albopictus peaked on September parallel to increased humidity. Aedes aegypti and Aedes albopictus populations showed no significant associations with environmental variables during the study. Immatures of Aedes were recovered from tyres, mud pots, plastic cans, metallic drums and ceramic pots. Tyres were the most productive habitat for Aedes breeding preference ratio (BPR = 1.31) followed by plastic cans (BPR = 1.23). Findings from study pave means for the development and implementation of sustainable dengue control measures through vector management.
Great advances in automated identification systems, or ‘smart traps’, that differentiate insect species have been made in recent years, yet demonstrations of field-ready devices under free-flight conditions remain rare. Here, we describe the results of mixed-species identification using an advanced optoacoustic smart trap design under free-flying conditions. Point-of-capture classification was assessed using mixed populations of congeneric ( Aedes albopictus and Aedes aegypti ) and non-congeneric ( Ae. aegypti and Anopheles stephensi ) container-inhabiting species of medical importance. Culex quinquefasciatus , also common in container habitats, was included as a third species in all assessments. At the aggregate level, mixed collections of non-congeneric species ( Ae. aegypti , Cx. quinquefasciatus , and An. stephensi ) could be classified at accuracies exceeding 95% (% error = 2.08–3.29%). Conversely, error rates increased when analysing individual replicates (mean % error = 48.6; 95% CI 8.1–68.6) representative of daily trap captures and at the aggregate level when Ae. albopictus was released in the presence of Ae. aegypti and Cx. quinquefasciatus (% error = 4.7–42.5%). These findings highlight the many challenges yet to be overcome but also the potential operational utility of optoacoustic surveillance in low diversity settings typical of urban environments.
The present study was carried out to understand the impact of climatic conditions on adult life table parameters of Aedes albopictus (Skuse) (Diptera: Culicidae). Thus, strains of Aedes albopictus were collected from two different ecological regions of Rajasthan, India i.e., Kota (semi-arid) and Barmer (arid), and compared under insectary conditions. The result showed that male life expectancy was greater in the Kota strain (8.19 days) than in the Barmer strain (5.91 days) with significant differences whereas no significant differences were found for female life expectancy (Kota: 13.75 days; Barmer: 12.24 days). Barmer strain showed a higher intrinsic rate of increase (rm) (0.25), finite rate of increase (λ) (1.29), and lower doubling time (DT) (2.66 days) than the Kota strain (rm: 0.22; λ: 1.24; DT: 3.12 days) with significant differences which shows more r-strategic pattern in Barmer strain. However, the slobodkin curve for males and females of both strains showed a type II survivorship curve. No significant differences were found for net reproductive rate (R0), mean generation time (T), oviposition schedule, and fecundity parameters. Conclusively, the present study may help in the better prediction of Ae. albopictus population dynamics prevalent in these geographical areas and for implementing the efficient vector management practices.
RESUMEN DEL PROYECTO
Una de las enfermedades con mayor extensión en cuanto al número de casos en los últimos años el mundo es el dengue, siendo catalogada como una de las patologías transmisibles con mayor magnitud e importancia a nivel mundial tanto por la carga en salud como por su impacto económico (1). Esta enfermedad presenta un estimado de infecciones de aproximadamente 390 millones de personas al año; de los 194 países que hay actualmente en el mundo, 128 son catalogados como lugares endémicos de la enfermedad (2). La literatura actual habla del efecto de diversas vulnerabilidades sociales, climáticas y gubernamentales en la dinámica del dengue, exacerbando la presencia de la enfermedad en muchos territorios a nivel mundial (3–6).
El presente estudio tiene como objetivo evaluar el posible impacto de estos factores en el territorio colombiano en la frecuencia de esta enfermedad, todo desde un marco de vulnerabilidades presentes en la población colombiana, con fines de exponer el comportamiento complejo del dengue y proponer herramientas que permitan un manejo del dengue más particularizado, especifico y efectivo.
Diseño y objetivo
El siguiente estudio tiene como objetivo principal establecer la influencia de las vulnerabilidades sociales, climáticas, gubernamentales y de equidad a nivel departamental y municipal la evolución del dengue en el periodo de enero de 2015 a diciembre de 2020. Con esto se busca exponer la influencia de estas vulnerabilidades y establecer cuáles de estas son modificables con fines de reducir la frecuencia de dengue en el país.
Metodología
Estudio observacional, de medidas repetidas basado en los datos recolectados de manera mensual en todo el territorio a lo largo del periodo de análisis establecido, analítico, de tipo multinivel basado en la recolección de información de distintas fuentes nacionales.
El análisis principal se centrará en el número de casos de dengue presentados en el país en el periodo de enero de 2015 a diciembre de 2020. Se estimará la correlación espacial del número de casos de dengue presentados. Por otro lado se realizará un Gráfico Acíclico Dirigido (DAG por sus siglas en inglés) con fines de estudiar las interrelaciones de las distintas vulnerabilidades estudiadas con la presencia de dengue en el país y se estimará el posible impacto de dichos factores de vulnerabilidad con el número de casos de dengue por medio de un Modelo Aditivo Generalizado de tipo Poisson multinivel.
Por otro lado, se tiene presupuestado realiza un Análisis de Componentes Principales con fines de construir un índice multidimensional de vulnerabilidad que permita cuantificar el nivel de propensión a nivel municipal en cuanto al número de casos de dengue en el país.
Resultados esperados
De acuerdo con la información que se obtenga de los análisis propuestos, se espera describir el impacto de distintas vulnerabilidades objeto del estudio, así como las tendencias tanto temporales como espaciales del fenómeno del dengue, con el propósito de conocer más sobre la afectación de estas vulnerabilidades en la frecuencia de dengue en el periodo establecido con fines de ofrecer mejor información sobre los probables resultados obtenidos con este tratamiento.
Os insetos são indicadores dos níveis de impacto ambiental devido sua grande diversidade de espécies e habitat, além do papel nos processos biológicos dos ecossistemas naturais. Por isso, o objetivo deste trabalho foi realizar o levantamento da entomofauna terrestre e vetora no período de chuva e seca em uma área de exploração florestal no norte de Mato Grosso. O levantamento da entomofauna do local foi realizado em 14 pontos de coleta, distribuídos nos diversos ambientes para uma maior abrangência no diagnóstico das áreas de exploração florestal de uma fazenda madeireira localizada em Colniza, Mato Grosso, Brasil. A plasticidade dos insetos permite que sejam utilizados como bioindicadores de alterações ambientais, sendo as formigas e os besouros os mais utilizados neste trabalho, por terem uma taxonomia definida, e resposta correlacionada a qualidade ambiental. Nesta área de floresta ombrófila densa, a entomofauna apresentou distinção significativamente maior entre os pontos amostrais devido a especificidade dos organismos quanto a estrutura do habitat em relação às variações sazonais.
Since the first detection of the Asian tiger mosquito Aedes albopictus (Diptera: Culicidae) eggs in Germany in 2007, several populations of this species have established in Germany. Although colloquially Ae. albopictus is called an 'invasive species', it is not considered 'invasive' and therefore to be controlled according to the European Union (EU) Environmental and Nature Protection Act since evidence of displacement of native species is missing. To test the competitive potential of Ae. albopictus towards mosquito species native to Germany, laboratory experiments were conducted with larvae of this species and indigenous Cx. pipiens complex species/biotypes. First instar larvae of Ae. albopictus and of one of the native taxa were exposed to different temperatures and fed with different food sources. The ratio of individuals developing into adults as well as the time the larvae needed for development were taken as a measure of competitive outcome. In addition, the size of emerging adults was compared between control and experimental groups. Regarding developmental time, no significant differences were found between treatments and controls while significant differences were found regarding developmental rate and average wing size of individuals. Because no evidence of competitive repression of the native species was found, Ae. albopictus cannot be included in the EU list of invasive species.
Due to changes in climate, numerous mosquito species are continuously extending their geographical distributions, posing potential new public health threats as arbovirus infections emerge in these new areas. During probing and feeding on the vertebrate host, a mosquito can inject both arbovirus and saliva into the skin of the host. The presence of mosquito saliva in the host skin during arbovirus transmission contributes to high viral titers in the skin, enhanced viremia, and rapid dissemination of the virus to target organs. This enhanced phenotype effectuated by the presence of mosquito saliva in the skin can be partly ascribed to a polarization of the local immune balance towards a Th2 response, an increased permeability of the dermal endothelium, and the influx of virus-susceptible immune cells to the bite site. However, the complete identification and characterization of immunomodulatory salivary proteins from different mosquito species and the mechanisms by which these salivary proteins exert their effects synergistically or antagonistically remains to be further explored. Moreover, the effect of new virus-vector combinations on the outcome of arbovirus infection in a new host is limited. Here, we review the immunomodulatory effects of mosquito saliva in the skin and the proposed mechanisms by which mosquito saliva enhances arbovirus pathogenesis in the vertebrate host, and discuss potential differences between Aedes and Culex mosquito species, the main vectors for medically important arboviruses. Gaining more insight into the effect of mosquito saliva in the vector-virus-host triad aids in predicting the potential transmission risk and disease severity of emerging vector-borne diseases.
Various arboviruses are transmitted to humans by mosquitoes, particularly Aedes aegypti and Aedes albopictus, two invasive and frequently sympatric species. The objective of this study was to evaluate the dispersion and the behavior of Ae. albopictus in relation to houses and its association with other mosquitoes in the province of Havana, Cuba. All water-containing deposits in the houses or vacant lots in urban and peri‑urban municipalities of the province of Havana were sampled during the two study periods: 1995-1999 and 2010-2018. The following patterns in the presence of Ae. albopictus in the study area were observed: a persistent absence of Ae. albopictus in one of the municipalities; a rapid dispersion in the second period, staring from the absence of vector in the first period, in tow other municipalities; and a sustained decrease in the dispersion of Ae.albopictus in two other municipalities. The peripheral municipalities noted the highest presence of Ae. albopictus, but few associations with other mosquitoes. However, overall, we found an increase in this association when comparing the period 2010-2018 with the first period. Ae. albopictus was present in 8% (2016) to 21.5% (2013) inside the houses with an average of 15%, which evidences an initial domiciliation of the species. The results obtained in this work show an initiation of domiciliation of Ae. albopictus in the urban area of the province of Havana. This is important to alert the National Control Program to strengthen the entomological monitoring of Ae. albopictus, and not only Ae. aegypti. The follow-up of this domiciliation is important to guide control efforts, knowing its role as a vector of different arboviruses.
The Asian tiger mosquito, Aedes albopictus, is one of the most invasive species in the world. Native to the tropical forests of Southeast Asia, over the past 30 years it has rapidly spread throughout tropical and temperate regions of the world. Its dramatic expansion has resulted in public health concerns as a consequence of its vector competence for at least 16 viruses. Previous studies showed that Ae. albopictus spread has been facilitated by human-mediated transportation, but much remains unknown about how this has affected its genetic attributes. Here we examined the factors that contributed to shaping the current genetic constitution of Ae. albopictus in the Iberian Peninsula, where the species was first found in 2004, by combining population genetics and Bayesian modelling. We found that both mitochondrial and nuclear DNA markers showed a lack of genetic structure and the presence of worldwide dominant haplotypes, suggesting regular introductions from abroad. Mitochondrial DNA showed little genetic diversity compared to nuclear DNA, likely explained by infection with maternally transmitted bacteria of the genus Wolbachia. Multilevel models revealed that greater mosquito fluxes (estimated from commuting patterns and tiger mosquito population distribution) and spatial proximity between sampling sites were associated with lower nuclear genetic distance, suggesting that rapid short- and medium-distance dispersal is facilitated by humans through vehicular traffic. This study highlights the significant role of human transportation in shaping the genetic attributes of Ae. albopictus and promoting regional gene flow, and underscores the need for a territorially integrated surveillance across scales of this disease-carrying mosquito.
Background and objective
Dengue is a vector-borne viral disease usually transmitted by Aedes mosquitoes. Around the world, the relationship between local vector density and frequency of dengue cases is being explored and needs further evidence. This study aimed to analyze the potential spatial relationships between the dengue vector (Aedes aegypti) and dengue cases in the megacity of Bangladesh during the 2019 dengue outbreak.
Methods
Vector density measures were used to estimate spatial associations with dengue case distribution. Location was determined for 364 dengue cases who were admitted to Dhaka Medical College Hospital over a period of 4 months. Data were collected using a semi-structured questionnaire, and prior consent was ensured before participation. The Moran global index, Getis-Ord Gi*, ordinary least squares regression, geographically weighted regression and count data regression methods were used for spatial analysis.
Results
We found that dengue case distribution was not associated with immature Aedes aegypti mosquito (larvae) density across the city. The relationship between larval density measured by the Breteau Index (BI) and House Index (HI) with dengue cases was nonstationary and not statistically significant.
Conclusion
The location of dengue cases appears to be unrelated to vector distribution and vector density. These findings should prompt the search for other transmission risk factors.
Mosquito species belonging to the genus Aedes have attracted the interest of scientists and public health officers because of their capacity to transmit viruses that affect humans. Some of these species were brought outside their native range by means of trade and tourism and then colonised new regions thanks to a unique combination of eco-physiological traits. Considering mosquito physiological and behavioural traits to understand and predict their population dynamics is thus a crucial step in developing strategies to mitigate the local densities of invasive Aedes populations. Here, we synthesised the life cycle of four invasive Aedes species (Ae. aegypti, Ae. albopictus, Ae. japonicus and Ae. koreicus) in a single multi-scale stochastic modelling framework which we coded in the R package dynamAedes. We designed a stage-based and time-discrete stochastic model driven by temperature, photo-period and inter-specific larval competition that can be applied to three different spatial scales: punctual, local and regional. These spatial scales consider different degrees of spatial complexity and data availability by accounting for both active and passive dispersal of mosquito species as well as for the heterogeneity of the input temperature data. Our overarching aim was to provide a flexible, open-source and user-friendly tool rooted in the most updated knowledge on the species’ biology which could be applied to the management of invasive Aedes populations as well as to more theoretical ecological inquiries.
Graphical Abstract
As a widespread vector of disease with an expanding range, the mosquito Aedes albopictus Skuse (Diptera: Culicidae) is a high priority for research and management. A. albopictus has a complex life history with aquatic egg, larval and pupal stages, and a terrestrial adult stage. This requires targeted management strategies for each life stage, coordinated across time and space. Population genetics can aid in A. albopictus control by evaluating patterns of genetic diversity and dispersal. However, how life stage impacts population genetic characteristics is unknown. We examined whether patterns of A. albopictus genetic diversity and differentiation changed with life stage at a spatial scale relevant to management efforts. We first conducted a literature review of field‐caught A. albopictus population genetic papers and identified 101 peer‐reviewed publications, none of which compared results between life stages. Our study uniquely examines population genomic patterns of egg and adult A. albopictus at five sites in Wake County, North Carolina, USA, using 8425 single nucleotide polymorphisms. We found that the level of genetic diversity and connectivity between sites varied between adults and eggs. This warrants further study and is critical for research aimed at informing local management. Population genetics studies of the invasive mosquito Aedes albopictus commonly sample multiple life stages. However, the congruence between genetic patterns of different life stages has not been evaluated. We found contrasting patterns in genetic variation, diversity and connectivity between Aedes albopictus adults and eggs within and among five sites at a fine spatial scale. Research on population genetic differences between life stages offers new opportunities for the field of vector ecology and to inform adaptive management strategies.
Background. The effectiveness of Long-Lasting Insecticidal Nets (LLINs) and indoor residual spraying (IRS) in controlling malaria vectors is hampered by the resistance of anopheles to insecticides. A good knowledge of the breeding sites and of the resistance profile of the vectors could facilitate the development of an appropriate control strategy. This study looks at the larval ecology and the susceptibility profile of An. gambiae s.l. to insecticides in urban and rural areas in Kribi, South Region of Cameroon. Methods. Mosquito breeding sites were categorized and geo-referenced. For each site, larvae were collected and reared and physicochemical parameters were measured in situ. T he susceptibility of anopheles to dichlorodiphenyltrichloroethane (DDT), deltamethrin and permethrin, after pre-exposure to piperonyl butoxide (PBO) or not, was evaluated on the reared larvae. The Kdr mutation was detected using the Hot Oligonucleotide Ligation Assay (HOLA). Results. Natural breeding sites of An. gambiae s.l. were tyre tracks (12%, n=10), unbuilt wells (5%, n=4), pools of residual water (57%, n=48), foot and hoof prints, gullies, streams and the banks of the Kienké River (15%, n=13). Artificial breeding sites were abandoned dugouts (11%, n=9). Breeding sites in urban areas were characterized by higher mean values of temperature, conductivity, salinity and turbidity compared to the breeding sites in the rural area. The breeding sites of An. gambiae s.l. in urban Kribi were found to be sunnier than those in rural Kribi. A total of 4320 adults were used for testing, 1 440 mosquitoes from rural Kribi, 1 440 from urban Kribi and 1 440 specimens from the laboratory Kisumu strain. For DDT and deltamethrin, susceptibility tests showed that mortality was lower in a situation of no pre-exposure to PBO than in a situation of pre-exposure to PBO in the two study areas. The frequency of the resistant allele (R) was high for the Kdr West mutation in both urban (0.94) and rural areas in Kribi (0.93). Conclusion. An. gambiae s.l. colonizes a wide range of breeding sites and develops metabolic and mutation resistance to recommended insecticides. The search of alternative molecules for vector control is a necessity. Keywords: Anopheles gambiae s.l., Ecology, Breeding sites, Resistance to insecticides, Kdr mutation, Metabolic resistance, Kribi, Cameroon, Sub-Saharan Africa
Aedes albopictus and Ae. flavopictus differ in habitat use and seasonality; the former inhabits residential areas and is more frequent in summer, whereas the latter does forest areas and is more abundant in cooler seasons (early summer and autumn). To understand factors underlying their differential habitat use and seasonality, we examined whether Ae. flavopictus females survive longer and are more likely to cease reproduction than Ae. albopictus females under unfavorable conditions. We reared these two species at 25 and 28°C under high and low diet and examined wing length, longevity and a number of reproductive parameters. In both species, females with larger wings survived longer. In interspecific comparison, Ae. flavopictus survived longer than Ae. albopictus when raised at 25°C under high diet but Ae. albopictus survived longer when raised at 28°C under low diet. There was no difference in longevity between them when raised at 25°C under low diet and 28°C under high diet. In addition, the proportion of mature eggs to follicle cells was high in Ae. albopictus females raised at 28°C under high diet. These results suggest that Ae. albopictus is more adapted to 28°C while Ae. flavopictus to 25°C. This agrees with their seasonality that the former is more frequent in hot seasons whereas the latter in cooler seasons. In addition, this difference in their temperature adaptations would explain the difference in their habitat use.
Dengue fever, which is spread by Aedes mosquitoes, has claimed many lives in Kerala, with the Thiruvananthapuram district bearing the brunt of the toll. This study aims to demarcate the dengue risk zones in Thiruvananthapuram district using the analytical hierarchy process (AHP) and the fuzzy-AHP (F-AHP) methods. For the risk modelling, geo-environmental factors (normalized difference vegetation index, land surface temperature, topographic wetness index, land use/land cover types, elevation, normalized difference built-up index) and demographic factors (household density, population density) have been utilized. The ArcGIS 10.8 and ERDAS Imagine 8.4 software tools have been used to derive the risk zone maps. The area of the risk maps is classified into five zones. The dengue risk zone maps were validated using dengue case data collected from the Integrated Disease Surveillance Programme portal. From the receiver operating characteristic (ROC) curve analysis and the area under the ROC curve (AUC) values, it is proved that the F-AHP method (AUC value of 0.971) has comparatively more prediction capability than the AHP method (AUC value of 0.954) in demarcating the dengue risk zones. Also, based on the comparison of the risk zone map with actual case data, it was confirmed that around 82.87% of the dengue cases occurred in the very high and high-risk zones, thus proving the efficacy of the model. According to the dengue risk map prepared using the F-AHP model, 9.09% of the area of Thiruvananthapuram district is categorized as very high risk. The prepared dengue risk maps will be helpful for decision-makers, staff with the health, and disaster management departments in adopting effective measures to prevent the risks of dengue spread and thereby minimize loss of life.
Earth observation environmental features measured through remote sensing and models of vector mosquitoes species Aedes aegypti and Ae. albopictus provide an advancement with regards to dengue risk in urban environments of subtropical areas of Argentina. The authors aim to estimate the effect of landscape coverage and spectral indices (Normalized Difference Vegetation Index [NDVI], Normalized Difference Water Index [NDWI] and Normalized Difference Built-up Index [NDBI]) on the larvae abundance of Ae. aegypti and Ae. albopictus in Eldorado, Misiones, Argentina using remote satellite sensors. Larvae of these species were collected monthly (June 2016 to April 2018), in four environments: tire repair shops, cemeteries, dwellings and an urban natural park. The proportion of landscape coverage (water, urban areas, bare soil, low vegetation and high vegetation) was determined from the supervised classification of Sentinel-2 images and spectral indices, calculated. The authors developed spatial models of both vector species by generalized linear mixed models. The model's results showed that Ae. aegypti larvae abundance was better modelled by NDVI minimum values, NDBI maximum values and the interaction between them. For Ae. albopictus proportion of bare soil, low vegetation and the interaction between both variables explained better the abundance.
The risks of Aedes aegypti and Aedes albopictus nuisance and vector‐borne diseases are rising and the adverse effects of broad‐spectrum insecticide application has promoted species‐specific techniques, such as sterile insect technique (SIT) and other genetic strategies, as contenders in their control operations. When specific vector suppression is proposed, potential effects on predators and wider ecosystem are some of the first stakeholder questions. These are not the only Aedes vectors of human diseases, but are those for which SIT and genetic strategies are of most interest. They vary ecologically and in habitat origin, but both have behaviourally human‐adapted forms with expanding ranges. The aquatic life stages are where predation is strongest due to greater resource predictability and limited escape opportunity. These vectors' anthropic forms usually use ephemeral water bodies and man‐made containers as larval habitats; predators that occur in these are mobile, opportunistic and generalist. No literature indicates that any predator depends on larvae of either species. As adults, foraging theory predicts these mosquitoes are of low profitability to predators. Energy expended hunting and consuming will mostly outweigh their energetic benefit. Moreover, as adult biomass is mobile and largely disaggregated, any predator is likely to be a generalist and opportunist. This work, which summarises much of the literature currently available on the predators of Ae. aegypti and Ae. albopictus, indicates it is highly unlikely that any predator species depends on them. Species‐specific vector control to reduce nuisance and disease is thus likely to be of negligible or limited impact on non‐target predators.
Background
Aedes albopictus is a highly invasive species and an important vector of dengue and chikungunya viruses. Indigenous to Southeast Asia, Ae. albopictus has successfully invaded every inhabited continent, except Antarctica, in the past 80 years. Vector surveillance and control at points of entry (PoE) is the most critical front line of defence against the introduction of Ae. albopictus to new areas. Identifying the pathways by which Ae. albopictus are introduced is the key to implementing effective vector surveillance to rapidly detect introductions and to eliminate them.
Methods
A literature review was conducted to identify studies and data sources reporting the known and suspected dispersal pathways of human-mediated Ae. albopictus dispersal between 1940–2020. Studies and data sources reporting the first introduction of Ae. albopictus in a new country were selected for data extraction and analyses.
Results
Between 1940–2020, Ae. albopictus was reported via various dispersal pathways into 86 new countries. Two main dispersal pathways were identified: (1) at global and continental spatial scales, maritime sea transport was the main dispersal pathway for Ae. albopictus into new countries in the middle to late 20th Century, with ships carrying used tyres of particular importance during the 1980s and 1990s, and (2) at continental and national spatial scales, the passive transportation of Ae. albopictus in ground vehicles and to a lesser extent the trade of used tyres and maritime sea transport appear to be the major drivers of Ae. albopictus dispersal into new countries, especially in Europe. Finally, the dispersal pathways for the introduction and spread of Ae. albopictus in numerous countries remains unknown, especially from the 1990s onwards.
Conclusions
This review identified the main known and suspected dispersal pathways of human-mediated Ae. albopictus dispersal leading to the first introduction of Ae. albopictus into new countries and highlighted gaps in our understanding of Ae. albopictus dispersal pathways. Relevant advances in vector surveillance and genomic tracking techniques are presented and discussed in the context of improving vector surveillance.
Graphical Abstract
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