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Repellency of Volatile Oils from Plants against Three Mosquito Vectors
Abstract
Volatile oils extracted by steam distillation from four plant species (turmeric (Curcuma longa), kaffir lime (Citrus hystrix), citronella grass (Cymbopogon winterianus) and hairy basil (Ocimum americanum)), were evaluated in mosquito cages and in a large room for their repellency effects against three mosquito vectors, Aedes aegypti, Anopheles dirus and Culex quinquefasciatus. The oils from turmeric, citronella grass and hairy basil, especially with the addition of 5% vanillin, repelled the three species under cage conditions for up to eight hours. The oil from kaffir lime alone, as well as with 5% vanillin added, was effective for up to three hours. With regard to the standard repellent, deet alone provided protection for at least eight hours against Ae. aegypti and Cx. quinquefasciatus, but for six hours against An. dirus. However, deet with the addition of 5% vanillin gave protection against the three mosquito species for at least eight hours. The results of large room evaluations confirmed the responses for each repellent treatment obtained under cage conditions. This study demonstrates the potential of volatile oils extracted from turmeric, citronella grass and hairy basil as topical repellents against both day- and night-biting mosquitoes. The three volatile oils can be formulated with vanillin as mosquito repellents in various forms to replace deet (N,N-diethyl-3-methylbenzamide), the most common chemical repellent currently available.
... The repellency of the emulgels was evaluated using the human-bait technique. [16] Ethic protocol number 12-33-007 was approved on 18 May 2012 by The Ethics Committee of the Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok, Thailand. ...
... Vanillin is a well-known fixative agent in mosquito repellent products. [16,[22][23][24] Vanillin (5%) in ethanol lacks repellent effect. The presence of 5% vanillin in preparations containing 10% essential oils obtained from Zanthoxylum piperitum or Kaempferia galanga enhances the repellent times up to 1.5 h. ...
... Nowadays, natural repellents are attracting increasing interest among people in developed countries who do not like synthetic repellents. Large numbers of plant-derived essential oils have recently been tested in studies for their repellent activities, with promising results in some cases (Tawatsin et al. 2001, Trongtokit et al. 2005, Amer and Mehlhorn 2006. However, in most cases their efficacy is much lower than that of synthetic repellents such as deet. ...
... Citronella oil is predominantly derived from Cymbagon nardus or C. citratus and, when used as a repellent, is generally diluted in ethanol. A laboratory study by Tawatsin et al. (2001) showed that volatile oils from C. winterianus with 5% vanillin could repel Ae. aegypti, An. dirus and Cx. quinquefasciatus for up to eight hours. ...
... Therefore, their effectiveness and protection time are time-limited [38,43]. Improved repellency of plant-derived topical repellents has been shown after formulation with some bases or fixative materials, such as liquid paraffin, vanillin, and salicyluric acid [44][45][46][47]. According to Chareonviriyaphap et al. [48], three laboratory strains utilized in this study had been continuously colonized for 15-20 years and appeared to have lost some of their natural behavioral avoidance response to deltamethrin. ...
... These have included Ocimum spp. [46,55], Nepeta cataria [14], Citrus hystrix [56], Melaleuca leucadendron, Litsea cubeba, and Litsea salicifolia [13], Citrus aurantium, Cinnamomum verum, Cymbopogon winterianus, Syzygium aromaticum [15], V. zizanioides [12,17], C. odorata [57,58], and A. paniculata [21]. Notably, several research studies have demonstrated that mixtures of essential oils provide a higher repellency against Ae. ...
Each binary mixture formulation of Vetiveria zizanioides (L.) Nash (VZ) with Andrographis paniculata (Burm.f.) Wall. ex Nees (AP) or Cananga odorata (Lam.) Hook.f. & Thomson (CO) and AP with CO at 1:1, 1:2, 1:3, and 1:4 ratios (v:v) was investigated for behavioral responses on laboratory and field strains of Aedes aegypti. Irritant and repellent activities of each formulation were compared with N,N-diethyl-3-methylbenzamide (DEET) using an excito-repellency test system. The result demonstrated that the mixture of VZ:AP in all combination ratios was the most effective in inducing an irritancy response against the laboratory strain (56.57–73.33%). The highest percentage of escaped mosquitoes exposed to the mixture at a 1:4 ratio (73.33%) was significantly different from DEET (26.67%) (p < 0.05). Against the field strain, the strongest escape response of AP:CO at a 1:1 ratio in the contact trial (70.18%) was significantly different compared with DEET (38.33%) (p < 0.05). There was a weak non-contact escape pattern in all combinations of VZ:CO against the laboratory strains (6.67–31.67%). These findings could lead to the further development of VZ and AP as active ingredients in a repellent that could advance to human use trials.
... Curcuma longa: Antihyperlipidemic (51,52), antidiabetic and hypoglycemic (53), antiobesity (54), antioxidant (55,56), neuroprotective (57), antiplatelet and antithrombotic (58,59), cytotoxicity (60), anti-inflammatory (61,62), antiarthritic and joint protective (63), antihepatotoxic (64), anticonvulsant (65), spasmolytic (66), hepatoprotective (67), antimutagenic (68), antidote (69), antibacterial (70), antifungal (71), antiaflatoxigenic (72), insecticidal (27), insect repellent (73), anticancer (74), antitubercular (75), and antiulcer (76). ...
Translating the conventional methods to produce novel materials with intriguing properties is much needed in the current scenario. It was well established that particles in the nanoscale exhibit superior activity than their bulk counterpart. Recently, biogenic synthesis has gained extensive attention for synthesizing a wide range of nanomaterials including metal/metal oxides, hybrid, and bioinspired nano-materials, respectively. In this context, we have summarized and reviewed the fundamental and mechanisms of biogenic synthesis strategies, especially for non-metal, metal, and metal oxide nanoparticles using four different natural sources of Curcuma viz. Curcuma amada, Curcuma caesia, Curcuma longa, and Curcuma zedoaria, respectively. In conclusion, the content reviewed and presented in current article will provide ready-to-use information for future improvements and value addition related to nanoparticle production through a green synthesis approach using Curcuma species as discussed. Finally, these methods were also found to be more reliable, sustainable, and eco-friendly as per protocols.
... There are some limitations associated with the field use of the compounds as discussed in this review, one of which is the short period of protection provided by the molecule, especially when its volatility is high and the application is directly on the fruit (Thireou et al. 2018). To overcome this issue, it is important to develop slow release formulations (Ghayempour and Montazer 2016), add fixatives to extend the protection time (Tawatsin et al. 2001) and create devices for continuous spatial release (Dame et al. 2014), which represent potential modifications to extend the effectiveness of these molecules. A strategy proposed by Drapeau et al. (2009) to increase repellent activity over time involves the use of microemulsions with surfactants associated with highly volatile compounds against A. aegypti. ...
Ceratitis capitata, known as Mediterranean fruit fly, represents one of the main problems to the agricultural production, due the ability to infest a wide variety of fruits, which makes it one of the most worrying pests globally. The infestation of host fruits by the insect compromises their quality and appearance, causing losses to their commercialization and consumption. In order to minimize this problem, fruit growers have adopted the indiscriminate use of conventional insecticides that raise environmental and public health concerns, in addition to promoting resistance in insects. Alternatively, semiochemicals have been explored as a management tool, attracting males and females into traps or promoting repellency in exposed fruits. In this context, in silico approaches, as Molecular Docking, Molecular Dynamics and the Virtual Screening procedures, offer opportunities to identify new molecular entities as potential ligands to Odorant Binding Proteins (OBP), that are involved in olfactory communication of C. capitata. In this review, we present a collection of data including the chemistry of olfactory communication of C. capitata and some computational tools that can be used in these studies, emphasizing their impact on the behavior of this and other associated insects. We also address theoretical ADME-Tox parameters as initial evaluation criteria to ensure human safety in the environmental applications, as well as the importance of molecular synergism for the effective management of the medfly.
... There are numerous ways to assess the efficacy of treated textiles for impregnated textiles. The methods are cone test, cage test, field test and excito chamber (Sritabutra et al. 2011;Standards 2006;Tawatsin et al. 2001;WHO 1996). Textiles impregnated with repellents like LLINs drive the vector away from the treated surface, or depending on the concentration may cause knock down or mortality. ...
Overview of Personal Protection Measures Through the
Innovative Use of Repellent-Textiles
... There are numerous ways to assess the efficacy of treated textiles for impregnated textiles. The methods are cone test, cage test, field test and excito chamber (Sritabutra et al. 2011;Standards 2006;Tawatsin et al. 2001;WHO 1996). Textiles impregnated with repellents like LLINs drive the vector away from the treated surface, or depending on the concentration may cause knock down or mortality. ...
Background
Arboviruses are one of the greatest threats to animal and public health. Culicidae family is one of the most important vectors for the transmission of arboviruses in the world. According to the geographical, demographic, and climatic features of Qom city in Iran, it can be a suitable region for vectors and therefore transmission of arboviruses.
Methods
In this study, which was conducted between 2019 and 2020 in different parts of Qom city, 83 414 mosquitoes were collected, and after evaluating the species of mosquitoes based on morphological and molecular detection, the presence of alphaviruses, flaviviruses, and phleboviruses were evaluated using genus-specific RT-PCR assays.
Results
In this study, Culex tarsalis, Culex theilerivoucher, Culex quinquefasciatus and most importantly for the first time in Iran C. tarsalis were detected. No alphavirus, flavivirus, and phlebovirus infection were identified in collected mosquitoes.
Conclusion
Climatic and weather changes are the basis for the growth and spread of vectors and, consequently, the spread of arboviral diseases, and this issue seems to be very important to the necessity of increasing and continuing entomological and virological studies.
... This finding aligns with previous research, where A. paniculata extracts demonstrated repellent activity against Ae. aegypti [55,56]. Sukkanon et al. [57] evaluated the efficacy of A. paniculata for its noncontact repellency, contact ex-citation (irritancy + repellency), and knockdown/toxicity response against five species of mosquitoes by using an excito-repellency assay system under laboratory-controlled conditions. ...
Infectious diseases that cause illness and/or death in humans can be contracted from mosquito bites. A viable and alternate method of personal protection that can lower the danger of human exposure to mosquito-borne diseases is the use of plant-based repellents. Using a high-throughput screening system, the current work examined the toxicity, contact irritancy, and spatial repellency of Andrographis paniculata crude extract and its fractions against Aedes aegypti, Anopheles minimus, and An. dirus. Five fractions (i.e., F1, F2, F3, F4, and F5) were separated from the crude extract by column and thin layer chromatography and analyzed using high-performance liquid chromatography and mass spectrometry. The major active compounds identified from F3 and F5 were 4-deoxy-11,12-didehydroandrographolide and andrographolide. Three concentrations (1.0, 2.5, and 5.0%) for each of the crude extracts and the five fractions were individually impregnated on nylon netting strips and evaluated against the three mosquito species. Results showed that the highest contact irritancy was elicited by the crude extract at 5% concentration against Ae. aegypti (43.70% escaped). Results of the spatial activity index (SAI) showed that fractions F3 and F5 at 2.5% demonstrated the strongest repellency against Ae. aegypti (SAI = 0.84) and An. minimus (SAI = 0.83), respectively. Both the crude extract and its components did not cause any knockdown or mortality. These findings suggest that fractionation of A. paniculata extracts is valuable in assessing their spatial repellent efficacy against mosquitoes. Fractions F3 and F5 hold promise as natural mosquito repellents and could contribute to developing effective mosquito control strategies.
... 58 Moreover, it is a thermosensitive method so precautions must be taken otherwise the extract material's potency can deteriorate 59 and it's mechanism of action is shown effectively in figure:1 d) Insecticidal: Prime activity of citronella essential oil is mosquito repellent activity. 60,61 For million yrs. they are used as insect repellent prior to the manufacture of synthetic insect repellent like DEET. ...
Citronella grass, scientifically known as Cymbopogon nardus or Cymbopogon winterianus, is a tropical plant that is well-known for its strong citrus aroma. This grass is widely cultivated for the extraction of citronella oil, which is used invarious products such as insect repellents, candles, and oils. The main reason for cultivating citronella grass is to extractcitronella oil, which has a strong lemon-like scent. This oil is known for its insect-repelling properties and is commonlyused in natural insect repellents. Citronella oil is a natural insect repellent. It is often used in outdoor candles, sprays, andlotions to help keep mosquitoes and other insects at bay. While citronella oil is not typically used in cooking, the leavesof citronella grass can be used to flavor certain dishes. However, it's important to note that there are different varieties ofcitronella grass, and not all are suitable for culinary purposes. Citronella grass is sometimes grown as an ornamental plantin gardens and landscapes due to its tall, slender stems and attractive, feathery leaves. Citronella grass is a tropical plantand thrives in warm, humid conditions. It is often grown in well-drained soil and requires regular watering. It can becultivated in containers or planted directly in the ground. Citronella grass can be propagated through seeds or by dividingexisting clumps. It's a relatively low-maintenance plant, but it does require adequate sunlight to thrive. There are differentvarieties of citronella grass, with Cymbopogon nardus and Cymbopogon winterianus being the most commonly cultivatedfor citronella oil production.
Key words- Cymbopogon nardus, Citronella oil, Antioxidant effects
(
... SD=Standard deviation with 52.4% repellency against Anopheles dirus and 100% repellency against C. quinquefasciatus for 8 h. A study by Tawatsin et al.[24] demonstrated that 25% citronella essential oil had 100% repellency against A. aegypti and A. dirus for 3 h and 100% repellency against C. quinquefasciatus mosquitoes for 8 h. The effectiveness of citronella essential oil in repelling mosquitoes was shown to depend on the formulation type in a report by Solomon et al.[10]. ...
Background and Aim
Mosquitoes carry numerous diseases of medical and veterinary significance. While citronella essential oil is safe as a mosquito repellent, extensive research does not document its ability to deter mosquitoes from animals. This study assessed the citronella essential oil bath bomb’s ability to repel Culex quinquefasciatus mosquitoes in dogs.
Materials and Methods
Citronella essential oil’s chemical composition was analyzed using gas chromatography-mass spectrometry (GC-MS). Through freeze-thaw testing, a bath bomb formulation containing 6% w/w citronella essential oil was assessed for its physical and chemical stability. Thirty-two healthy client-owned mixed-breed dogs were employed to test the mosquito-repellency effects of citronella essential oil (treatment group) and olive oil (control group) bath bomb formulations. Bath bombs were tested for irritation effects on animal skin for 15-day post-application.
Results
Thirty-six compounds were identified through GC-MS, with citronellal (23.38%), δ-cadinene (12.25%), and geraniol (9.09%) being the most prevalent constituents. The bath bomb maintained its original physical properties after undergoing six freeze-thawing cycles and retained over 90% of its citronella essential oil. About 100%, 69.28%, and 65.58% mosquito repellency were displayed by the citronella essential oil bath bomb at 3 h, 6 h, and 8 h, respectively. None of the test animals exhibited skin irritation during the study.
Conclusion
The citronella bath bomb effectively repelled C. quinquefasciatus in dogs without irritating their skin. The formulation’s physical and chemical stability is demonstrated by the results of freeze-thaw stability testing. Further studies should be conducted to evaluate the repelling activity against other mosquito species.
... Among these EOs, Cymbopogon spp., Eucalyptus spp., Lippia spp., and Ocimum spp. have been tested on mosquito species to assess their repellent properties (Tawatsin et al. 2001;Oyedele et al. 2002;Omolo et al. 2004;Dekker et al. 2011;Deletre et al. 2013). Studies have shown that permethrin and DEET, two chemicals, are repellents (Deletre et al. 2016). ...
Using chemical insecticides remains the main way to prevent and manage dengue and malaria, two main mosquito-borne diseases. However, the vectors of these diseases have developed resistance to chemical insecticides. Essential oils (EOs) could be used as alternatives because besides their larvicidal and adulticidal properties, they have repellent properties. In Burkina Faso, studies on the repellent properties of essential oils on mosquitoes remained limited. The EOs extracted from five plants (Cymbopogon citratus, Cymbopogon nardus, Eucalyptus camaldulensis, Lippia multiflora, and Ocimum america-num) collected in Ouagadougou were tested on populations of Aedes aegypti and Anopheles gambiae s.l collected in Bobo-Dioulasso and the Kou of Valley, respectively. Susceptible strains of the two species were also tested. DEET and permethrin were used as positive controls. Most of the 5 EOs tested produced irritant effects on adults of Aedes aegypti and Anopheles gambiae. The irritant effects on mosquito adults were significantly influenced by the concentration of the EOs and species of mosquitoes. On Anopheles gambiae s.l, the repellent-irritant effects of Cymbopogon citratus, Cymbopogon nardus, and Eucalyptus camaldulensis EOs were very close to DEET. On Aedes aegypti, all our EOs had higher repellent-irritant effects and some of them were very close to DEET. EOs could be used as alternative repellents to pyrethroids in vector control.
... There are numerous ways to assess the efficacy of treated textiles for impregnated textiles. The methods are cone test, cage test, field test and excito chamber (Sritabutra et al. 2011;Standards 2006;Tawatsin et al. 2001;WHO 1996). Textiles impregnated with repellents like LLINs drive the vector away from the treated surface, or depending on the concentration may cause knock down or mortality. ...
... Similar results were reported in essential oils with a higher content of phenylpropanoids [159], eugenol [160][161][162][163] and sesquiterpenes [164]. The larvicidal activity of a few species of Cinnamomum was corroborated with the present findings [158,[165][166][167][168][169][170][171][172][173]. Efficient larvicidal activity of larval and adult individuals of A. aegypti essential oil-based terpene compounds. ...
The chemical profiles of essential oils (EOs) of 7 Cinnamomum species (C. sulphuratum, C. perotettii, C. verum, C. wightii, C. camphora, C. glanduliferum, and C. malabatrum) composed from assorted parts of Western Ghats were analyzed. The antioxidant, antibacterial, and larvicidal potentialities of 7 essential oils were also investigated. Cinnamomum verum was observed to have the maximum yield (1.96%) of EO followed by C. malabatrum (1.71%). GC-MS analysis of EOs reported the highest amount of eugenol (38.04%), shyobunol (13.31%) in C. verum, whereas C. perrottetii identified 14–42 phytocompounds including terpenes, sesquiterpenes, monoterpenes, diterpenes, and phenylpropanoids, esters, aldehydes, and fatty acids. In the antibacterial activity, the higher zone of inhibition of C. malabatrum showed against S. pyogenes (28 ± 2.5 mm) and E. faecalis (27 ± 1.24 mm) followed by C. verum has shown notable inhibition zone against K. pneumoniae (26 ± 1.15 mm) and S. flexneri (24.33 ± 0.88 mm), with MIC value against C. verum, showed MIC value (1.17 ± 0.34 μg/mL) against S. flexneri, S. pyogenes, and K. pneumonia. All the Cinnamomum oil samples exhibited appreciable antioxidant radical scavenging activities with IC50 values ranged 10.83–15.06 μg/mL. All the oil samples showed promising larvicidal activity against the late-third instar larvae of Aedes aegypti. Extending the present study with in vivo and in vitro animal studies will confirm the potentiality of Cinnamomum oils in the field of biomedicine to detect novel medicines.
... aegypti larvae showed an LC50 of 2.084 ppm (Susilowati et al. 2021), while C. xanthoriza essential oil showed an LC50 of 25.94 ppm (Pereira et al. 2022). Essential oils of the rhizome plant of C. longa and Z. cassumunar have repellent activity for 4 to 8 hours against adult mosquito vectors (Tawatsin et al. 2001;Phasomkusolsil & Soonwera 2010), including the compound of (−)-terpinen-4-ol in C. cassumunar against Aedes albopictus (Li et al. 2021). Z. zerumbet essential oil 10% had a repellent activity of 72-99.1% against Ae. ...
The insecticidal potential of several plant secondary metabolites provides new hope for dengue vector control in endemic areas. This study evaluated the susceptibility of Aedes aegypti mosquitoes to the larvicidal and repellent activity of rhizome plant extracts. Sixteen extract types of Kaempferia galanga, Alpinia galanga, Zingiber zerumbet, and Curcuma aeruginosa resulted from a maceration extraction based on methanol, ethyl acetate, n-hexane, and butanol solvents were occupied. The temephos-susceptible third-instar-larvae of Ae. aegypti were subjected to larvicidal bioassay. Concentration levels of 50, 100, 250, 500, and 1,000 ppm were used in the initial bioassay test five times replicated where each replicate consisting of 20 larvae. Larval mortality was calculated in 24h and 48h post-exposure. A total of 50 laboratory strain Ae. aegypti aged 3-5 days were placed in a chamber. Repellent cream was applied to the right arm while the left arm served as a control. The arms were inserted into the chamber and the number of mosquitoes perched within 30 minutes were counted. Post-exposure of 50% and 90% lethal exposure (LC50-LC90) and 50% and 90% effective concentration (EC50-EC90) were Serangga 2024, 29(1): 49-69. Sayono et al. ISSN 1394-5130 50 determined. Within 24 hours, seven extract types indicated effective larvicidal concentrations, namely n-hexane extracts of K. galanga, A. galanga, Z. zerumbet, C. aeruginosa with the LC50 of 18.693, 41.926, 109.247, and 205.500 ppm; methanol of C. aeruginosa (179.291 ppm); and ethyl acetate of A. galanga (306.200 ppm). Six extract types showed the lowest concentrations of repellents, namely ethyl acetate and methanol of A. galanga (1.558% and 2.629%); methanol, ethyl-acetate, and n-hexane of Z. zerumbet (2.525, 3.946 and 4.481%); and n-hexane of K. galanga (4.338%). Aedes aegypti larvae were susceptible to the hexane extract of four rhizome plants while the adults were susceptible to Z. zerumbet and K. galanga extracts. Of these, the hexane extract of the K. galanga affect most or kills/repell more both adult and larvae of Aedes. The stability of extracts, the practical formulation of larvicides and repellents; and the isolation of chemical compounds are important to be investigated in the future.
... Ces résultats confirment donc la conclusion selon laquelle l'efficacité des huiles essentielles et des extraits de plantes contre les moustiques couvre une période relativement courte (Rozendaal, 1997 ;Barnard, 2000). De nombreuses études ont démontré que certains additifs tels que la paraffine liquide (Oyedele et al., 2002), la vanilline (Tawatsin et al., 2001), l'acide salicylurique (Stuart et Estambale, 2003) et les huiles de moutarde et de noix de coco (Das et al., 1999), améliorent la rémanence des produits répulsifs topiques d'origine végétale. La présente étude qui porte sur l'huile de soja et de coco comme additif, a montré que le taux de répulsion 3 heures après application de la formulation contenant 6% de C. anisata + huile de soja 5% et celle contenant 6% de C. anisata + huile de coco 5%, était de 77,14% et 83,57% respectivement. ...
Dans le but de trouver un additif pour améliorer l’effet répulsif de l'huile essentielle de Clausena anisata contre les moustiques, la présente étude a évalué l’effet de l’huile de coco et celle de soja sur la rémanence de l’huile essentielle de C. anisata. Trois heures de temps après application, le pied gauche des volontaires traité a été introduit dans une cage contenant 25 femelles Culex quinquefasciatus élevées au laboratoire. Le nombre de moustiques qui venaient se poser sur le pied traité était compté sur une durée
de 15 minutes et le nombre de moustiques effectivement gorgés de sang était déterminé. Les variantes suivantes ont été testées : Clausena 6%, Clausena 6% + huile de Coco 5%, Clausena 6% + huile de Soja 5% et DEET (30%). Pour chaque variante 10 répétitions ont été effectuées. Les résultats ont montré que trois heures de temps après application, le taux de répulsion des différentes formulations testées était de 72,14% ; 77,14% ; 83,57% et 92,87% respectivement pour Clausena 6%, Clausena 6% + huile de soja 5%, Clausena 6% + huile de Coco 5% et DEET. Ces résultats indiquent que l’huile de coco améliore plus l'effet répulsif de l'huile essentielle de C. anisata, avec un taux de répulsion proche de celui obtenu avec le répulsif chimique (DEET-30%). L'huile de coco
peut donc être utilisée comme additif pour la formulation d'un répulsif anti-moustiques à base de l'huile essentielle de C. anisata.
... The usual human bait technique according to World Health Organisation (WHO) guidelines, was used to establish and assess the mosquito-repellent efficacy [12][13] . All chemicals used in the formulations are GRAS (generally regarded as safe) listed and are absolutely safe for human use. ...
Background & objectives
Hantavirus and leptospirosis infections are zoonotic diseases with similar clinical and laboratory findings. The aim of this study is to identify the distinguishing features of these two diseases, for which a definitive diagnosis can take a long time.
Methods
Between September 2021 and June 2023, a total of 45 patients who were admitted to our hospital and were diagnosed with hemorrhagic fever with renal syndrome (HFRS) or leptospirosis were retrospectively evaluated. Patients were compared in terms of demographic data, clinical, and laboratory parameters. The role of these variables in predicting HFRS or leptospirosis was investigated. The two diseases were compared with regard to outcomes. Receiver operating characteristics were employed for the calculation of cut-off values, sensitivity, specificity, and positive and negative predictive values for parameters showing significant differences. A statistical significance level of p<0.05 was considered.
Results
Fifteen patients diagnosed with HFRS and thirty patients diagnosed with leptospirosis were included in the study. In both groups, hospital admissions were observed with non-specific and similar symptoms. There was no statistically significant difference observed between the two groups in terms of length of hospital stay, blood product transfusion, requirement for hemodialysis, intensive care unit admission, the rate of return to normal renal function and mortality. Elevated ferritin levels were statistically significant in favor of HFRS, while lymphopenia, elevated bilirubin, CRP, and ESR were statistically significant in favor of leptospirosis.
Interpretation & conclusion
The use of laboratory findings and clinical symptoms can aid in the challenging task of accurately diagnosing and using appropriate treatment for these two diseases.
... The repellent effect of O. americanum might enable local communities to prevent paludism and other insect-borne diseases. Previous research works revealed that O. americanum is widely used as a repellent against many insects such as Aedes aegypti, Anopheles dirus, and Culex quinquefasciatus (Ali et al. 2022, Cavalcanti et al. 2004, Chan et al. 2021, Chokechaijaroenporn et al. 1994, Tawatsin et al. 2001, Win and Thar 2019, Zengin et al. 2019. Biochemical investigations support this endogenous knowledge. ...
Background: Ocimum americanum is an aromatic species from the family of Lamiaceae. It has significant socioeconomic potential and is used by the local population in Burkina Faso. Although the species makes a significant contribution to household well-being, the organizations in charge of natural resource management are unaware of and undervalue its socioeconomic value. This study was initiated to assess local communities’ perception of the uses and management techniques of Ocimum americanum to establish sustainable strategies for its better valorization. Methods: An ethnobotanical survey was conducted in 21 villages covering three phytogeographical sectors of Burkina Faso. All, 160 farmers were interviewed. Relative frequency of citation (RFC) and use value (UV) were used to express the results. Results: The results showed that socio-cultural factors significantly affect the use value of the species at a threshold of 5%. The primary uses of wild basil are traditional medicine, food, conservation of seeds and foodstuffs, fodder, insect repellant, and tradimystics. The species is still found in the wild, although the majority of informants (54.9%) reported a decline in its population, making it threatened with extinction. However, for beneficial purposes, 24.5% of respondents keep the species in paraculture. Conclusion: This study demonstrates how important this species is to local communities. The endogenous knowledge collected among the local population could serve as a baseline for the valuation of the species. Keywords: Ocimum americanum, ethnobotanical survey, endogenous knowledge, Burkina Faso
... It has been found to have insecticidal properties agains t various insects, including mosquitoes, flies, and cockroaches. Its mode of action is thought to be disrupting the insects' nervous sys tem, leading to paralysis and death [12][13][14][15][16][17][18][19][20]28]. α-pinene is a monoterpene that is commonly found in essential oils of pine trees, as well as in other plants such as rosemary and eucalyptus. ...
Using plant essential oils (EOs) as a pesticide alternative has gained increasing interest as a promising strategy to reduce the harmful effects of chemical pesticides. This study aims to investigate the chemical composition of Eucalyptus globulus Labill and Rosmarinus officinalis L. essential oils and evaluate their impacts against Blattella germanica L. under laboratory conditions. The essential oils were prepared from dried leaves using hydro-distillation (HD) as a chemical extraction method. The gas chromatography-mass spectrometry (GC-MS) was employed to analyze and identify their chemical compounds. Bioassays were conducted using the standard contact method recommended by the World Health Organization, and the data were analyzed using the probit regression model. By GC-MS analysis, the major components included 1,8-cineole (50.67%), alpha-pinene (17.48%), limonene (4.26%) for eucalyptus and alpha-pinene (20.67%), camphor (10.69%), 1,8-cineole (9.38%), Borneol (9.02%), comphene (7.15%), and limonene (4.88%) for rosemary. The LD50 values were 9. 27, 10.54, and 3.23 %, and LD95 values increased to 27.2, 22.3 %, and 14.3% for rosemary, eucalyptus, and their mixture. The EOs mixture had a higher repellent effect with a repellency rate of 98.9% at a concentration of 3% compared to 93.3% and 90% at a concentration of 5% for rosemary and eucalyptus alone.
... Turmeric EO showed signifcance in both insect repellent and insecticidal activity against white termites (Odontotermes obesus) (Fouad and da Camara, 2017). Both daytime and night-time biting mosquitoes were demonstrated to be repelled (Tawatsin et al., 2001). Isolated ar-turmerone and turmeric oil effective against mosquitos Aedes aegypti larvae (LD100 = 50 µg/mL) (Roth et al., 1998). ...
... Vetiveria zizanioides EO (vetiver oil) was previously evaluated as an insect repellent against several species of mosquitoes (Tawatsin et al. 2001, Trongtokit et al. 2005, Nararak et al. 2016. In our study, VZ EO showed higher irritancy (91.67%) than DEET (88.33%) against the lab strain but a lower repellency (Table 1). ...
Efficacies of essential oils (EOs) of Vetiveria zizanioides (L.) Nash. (Poales: Poaceae) (VZ EO), Cananga odorata (Lam) Hook. F. & Thomson (Magnoliales: Annonaceae) (CO EO), and crude extract (CE) of Andrographis paniculata (Burm.F.) Wall ex. Nees (Lamiales: Acanthaceae) (AP CE), against laboratory (lab) and field strains of Culex quinquefasciatus Say were investigated. Irritant and repellent activities of individual and binary mixtures of plant extracts were compared with N,N-diethyl-m-toluamide (DEET) using an excito-repellency system. The irritant activity (direct tarsal contact), the mean percent escape response of VZ EO (91.67%, 83.33%), and CO EO (80%, 88.33%) were not significantly different compared with DEET (88.33%, 95%) against lab and field strains, respectively. Similarly, irritant responses in combinations (1:1 and 1:2, v:v) of either VZ EO or CO EO with AP CE were not significantly different from DEET against both strains (P > 0.001). The repellent activity (no tarsal contact), the mean percent escape response of VZ EO (68.33%), CO EO (61.67%), and VZ EO+AP CE (1:1, v:v) (81.67%) against lab strain and CO EO (85%) against field strain were not significantly different from that of DEET (P > 0.001). Interestingly, the greatest contact irritancy of VZ EO+AP CE (1:1, v:v) (96.67%) (P = 0.0026) and a stronger repellency response of CO EO (85%) (P = 0.0055) produced significantly different patterns of escape response compared with DEET against both lab and field strains, respectively. The EOs of VZ EO and CO EO or their mixture with AP CE showed potential as plant-based active ingredients for mosquito repellents. In addition, the major chemical constituents of VZ EO were β-vetivone (6.4%), khusimol (2.96%), and α-vetivone (2.94%) by gas chromatograpy-mass spectrometry.
... Approximately 344 plant species have been described as having mosquitocidal activity on biting adult mosquitoes (Sukumar et al. 1991, Tawatsin et al. 2001, Phasomkusolsil and Soonwera 2010) while many others have been reviewed as potential larvicidal properties (Shaalan et al 2005). An example of one of these plants is a non-native tree species, Ailanthus altissima (Mill.) ...
... Because of the highly volatile nature of EOs, it has been suggested that the improvement on protection time of 120 minutes observed with C. citratus EO at 50% concentration, can be achieved using a base or fixative substance, such as vanillin, petroleum jelly, mustard, or coconut oils (Das et al., 2003;Keziah et al., 2015;Tawatsin et al., 2001). However, the effectiveness and longevity of repellent products could dependent on a number of variables, like the type of repellent (active ingredients and formulation), the mode of application, environmental factors (temperature, humidity, and wind), the attractiveness of particular people to insects, loss due to removal by perspiration and abrasion, the sensitivity of the insects to repellent, and insect biting density (Ahmad et al., 2011;Govindarajan, 2011;Singha and Chandra, 2011). ...
In Nigeria, re-emergence of diseases caused by Aedes mosquito borne pathogens, and challenges associated with existing control tools occur. This necessitates an improved insecticide-based tool for use in Integrated Vector Management. So, repellent action of Cymbopogon citratus essential oil (EO) on Aedes aegypti (Linn.) was tested. The EO from C. citratus plant sourced from Awka, was extracted by hydro distillation, and the phytochemicals analyzed by Gas Chromatography-Mass Spectrometry. Repellent action of the EO on unfed Ae. aegypti was assessed using "WHO arm-in-cage" method. In triplicate, arms of human volunteers were treated with different concentrations (50.0, 25.0, 12.5, 6.25 and 3.125 % v/v) of the EO and submitted to 25-caged, unfed Ae. aegypti for 1 minute in every 30 minutes. β-cedrenes, kaempferol, and thujopsene dominated the 13 phytochemicals identified. The standard (Odomos®) and all EO concentrations recorded 100 % repellency on application. At 30 minutes, EC 99.9 value was 25.0 %, concentrations ≥ 62.5 % v/v gave 100 % repellency (p > 0.05). At 60 minutes, EC 99.9 value was 30.68 %, concentrations ≥ 12.5 % v/v gave 100 % repellency (p > 0.05). At 90 to 120 minutes, 50 % concentration maintained 100 % repellency (p < 0.05), EC 99.9 value was 48.79 % at 120 minutes. Recording 120 minutes protection time with no adverse effect, 50 % concentration showed equal potency as Odomos®. Research to isolate the active ingredients in the EO for incorporation into beneficial health and economic products is desirable.
... There are numerous ways to assess the efficacy of treated textiles for impregnated textiles. The methods are cone test, cage test, field test and excito chamber (Sritabutra et al. 2011;Standards 2006;Tawatsin et al. 2001;WHO 1996). Textiles impregnated with repellents like LLINs drive the vector away from the treated surface, or depending on the concentration may cause knock down or mortality. ...
... Citratum Bach O. A zadriachtaindica A. gratissimum L. have been tested [18]. One of the aims of the present study was to identify and use the harmless and nontoxic plants base repellents from the plant being cultivable in Iran. ...
The therapeutic and anti-infectious effects of Sambucus ebulus L. have been well documented in the traditional medicine. The purpose of this study was to identify the domestic herbal plant with insect repellent property. Leaf and fruit of Sambucus ebulus L. was collected from Kordkail Kola Sofla rural district and dried. To assess the repellent property, the concentrations of 50 mg/kg, 100 mg/kg, and 250 mg/kg) were prepared. Then 0.4 mL of each concentration was applied on an area of 4 × 6 cm on the shaved Albino (Indian pig) skin and exposed to the mosquito bite. After 30 minutes, the number of adult mosquito bites (three replications) was recorded and analyzed by ANOVA test at a probable level of 5%.The highest phenolic content in the leaf and fruit methanol extract was 155.925 mg/g and of 92.777 mg/g, respectively. Based on IC 50 , the highest level of antioxidant activity in the leaf and fruit methanol extract were 60.09μg/mL and 417.846μg/mL, respectively. The highest repelling property was correlated with the concentration of 250mg/kg of Sambucus ebulus. The repelling effects were 73.4% for the leaf and 78% for fruit extracts. Leaf and fruit extracts of Sambucus ebulus contained phenolic and flavonoid with strong antioxidant effects. The fruit hexane and methanol extracts were better repellent than the leaves, and the methanol extracts effect of these organs was greater.
Purpose of Review
This review aims to effectively highlight the essential characteristics of commercially approved repellent active ingredients while exploring their known mechanisms of action. Understanding these factors is crucial for developing more effective repellents in the future.
Recent Findings
Several commercial products have been developed to protect individuals from mosquito bites. In Argentina, over 75% of the products registered by the National Administration of Drugs, Food, and Medical Technology (ANMAT) are based on DEET, while 12% use IR3535. ANMAT regulates these products, ensuring their quality and safety for human use.
Summary
The mosquito Aedes aegypti (L.) transmit of Zika, yellow fever, chikungunya, and dengue. Due to their obligate hematophagy, they pose a significant threat to public health. They exhibit great adaptability to multiple environments across varying latitudes and altitudes and show a strong preference for humans. Insect repellents provide critical topical personal protection against infectious diseases transmitted by arthropods. This work provides essential insights for selecting the ideal repellents. By focusing on their mode of action, origin, effectiveness, and ANMAT approval status, you’ll be empowered to make informed decisions for optimal protection.
The rising prevalence of mosquitos borne deadly illnesses has made mosquitoes repellent usage common in Pakistan, with coils the popular choice. In order to estimate safe limits for humans three most commonly used type of mosquito repellent coils in Pakistan were compared for phyto-genotoxicity (DNA damage) using chromosomal aberration assay in Chickpea (Cicer arietinum L.) root tip cells. Chickpea seeds per treatment were incubated in coil smoke of five brands (PPJ, KRD, KCEP, GNA, TL) for 20, 40 and 60 minutes in approximately 24 by 24 inch Paper carton. Germination percentage was recorded by sowing seeds in sand pots. Genotoxic effects were assessed using a plant chromosomal aberration assay, measuring the Mitotic index, abnormality index and types of chromosomal aberrations were recorded to categorize different repellents. All the incubations of coils inhibit germination of chickpea seed as compared to positive control. The inhibitory effects on germination were more pronounced as the incubation increases except PPJ. For Mitotic index highly significant variation (p≥0.01) were found among all coils and their doses (20, 40, 60 minutes). KRD exhibited non-significant variations for only 60 minutes incubation. Decreasing trends for mitotic index with increasing doses was observed for most of treatments. For abnormality index highly significant variation (p≥0.01) were found among all the doses for KRD, where as PPJ and TL exhibited non-significant variations between 40 and 60 minutes incubation. Based on the Mitotic Index and abnormality index results, KCEP and KRD coils demonstrated highest genotoxicity. Therefore, these brands of coils should not be used and other brands may also be avoided
N, N‐diethyl‐meta‐toluamide (DEET) has been considered the ‘gold standard’ for insect repellent use since the 1950s and constitutes most insect repellents on the market. However, conflicting data in the scientific literature and confusing information in the media are at the core of debates about the safety of DEET insect repellents for the protection of children against arthropod bites. The few fatal occurrences involving DEET insect repellents and complications of their use in the pediatric population are typically the result of accidental overdoses or misuse of insect repellents that disregard warnings on product labels. With appropriate application, the safety record of DEET insect repellents continues to be excellent with few side effects. The purpose of this review is to provide a summary of the literature on safety outcomes of DEET insect repellent use in children; outline the pediatric recommendations relating to DEET insect repellents; and provide an overview of EPA‐approved and naturally derived alternatives to DEET that possess low toxicity while providing a similar level of protection to synthetic insect repellents.
Background & objectives
At present the use of synthetic pesticides to manage insects and other arthropods creates a number of issues that are related to the environment and public health. The goal of the present study was to find the repellent activity of Vitex negundo and Curcuma longa herbal extract against the wild species Simulium (blackfly) bite.
Methods
We have studied Simulium biting behavior and tested the repellency of herbal extract obtained from Vitex negundo L. (Lamiales: Lamiaceae) and Curcuma lonaga L. (Zingiberal: Zingiberaceae) along with their essential oils in three locations in Arunachal Pradesh, India on human volunteers' resistance to Simulium (blackflies). The reported herbal extracts were incorporated to topical drug delivery vehicle as a cream and gel.
Results
The methanolic extract of Vitex negundo cream and gel formulation showed >2 h safety at 5% concentration and >5 h safety at 10% concentration at all the testing sites followed by ethyl acetate extract. Whereas, chloroform extract of Curcuma longa cream and gel formulation provided >1 h safety at 5% concentration and >4 h safety at 10% concentration.
Interpretation & conclusion
At an optimum concentration of 10%, the methanolic extract of vitex negundo cream provided complete protection times (CPTs) 320.4, 358.6, and 346.4 minutes, respectively. This finding offers confirmation of the methanolic extract and chloroform extract potential for use in new blackfly repellents.
Mosquitoes (Diptera: Culicidae) pose a serious threat to humans worldwide, known to transmit various pathogens that cause infectious diseases and arboviruses, which are viral diseases such as chikungunya, dengue, Rift Valley fever, yellow fever, malaria, elephantiasis, Murray Valley encephalitis, Japanese encephalitis, Saint Louis encephalitis virus, West Nile virus, Eastern equine encephalomyelitis virus, Highlands J virus, Everglades virus, and crosse encephalitis virus. The emergence of widespread insecticide resistance and the potential adverse environmental problems associated with synthetic insecticides have highlighted the need for alternative methods to control the spread of mosquito populations, making it an important research priority. Safe and innovative tools, such as plant-based repellents, have recently been implemented to enhance mosquito
management strategies. Plant-based repellents play a crucial role in the development of natural products as alternatives to chemical control methods. Plant extracts and essential oils, which are biodegradable, target-specific, eco-friendly, and have potent effects against mosquitoes, are reviewed in this article. These plant-based repellents offer promising potential for effective mosquito management, providing a safer and environmentally friendly approach to control mosquito populations and reduce the spread of mosquito-borne diseases. Properly formulated and used in combination with other integrated vector management strategies, plant-based repellents can contribute to sustainable and effective mosquito control efforts.
West Nile Virus (WNV) has afflicted different countries around the world, affecting not only humans but also animals such as horses and birds. It is an arbovirus that is transmitted to humans by mosquito bites. Initially, the epidemic was localized to Africa, Asia, Europe, and the Middle East. A recent outbreak of WNV has been currently transpiring in the USA. Our article aims to unriddle this ongoing outbreak in the United States of America (USA) to help annihilate this year-round pitfall infection. As of November 15, 2022, Centers for Disease Control and Prevention (CDC) has reported 913 cases of WNV in humans in the United States of America, out of which 639 (70%) were categorized as neuroinvasive and 274 (30%) were categorized as a non-neuroinvasive disease. Concerned authorities should swiftly act before it reaches to an alarming level, to prevent aggravation of the existing challenges amidst COVID-19 and Monkeypox pandemics in the United States. Decreasing breeding habitats, sustainable surveillance of mosquito larvae, biological and microbial larval control methods (fish and copepods), chemical control methods (larvicides), controlling adult mosquito vector population (hot or cold aerosols), and active practice of community based preventive measures would bring deliverance to the United States from WNV. This brief article discusses the ongoing outbreak of WNV in the USA and also highlights epidemiology and preventive measures related to WNV infection.
Background
The process of wound healing is a complicated series of organized biochemical and cellular phenomena that restore the integrity of the skin and subcutaneous tissue. A drug molecule can be transported to the site of action through a variety of carriers, including niosomes or non-ionic surfactant vesicles. They can trap medications that are both hydrophilic and hydrophobic. It has been demonstrated that curcumin has strong analgesic, anti-inflammatory, and wound-healing qualities.
Method
In the current study, an effort has been made to create a curcumin-loaded niosomal gel for efficient wound healing therapy. Utilizing non-ionic surfactants (Span 60, Span 20, Tween 20, and Tween 60) and cholesterol at various concentrations, a modified thin-film hydration process was used to create niosomal gels containing curcumin. Particle size, shape, entrapment effectiveness, deformability, and in vitro skin penetration were used to describe the vesicles. The 1% carbopol 940 gel was then made using the improved formulation. In wound-induced rats, the effectiveness of the in vivo wound healing was assessed.
Result
The manufactured niosomes were discovered to be homogeneous in size and spherical in shape. According to the IR spectrum study, the medication and formulation additives did not interact. It was discovered that the niosomal gel (S-3) loaded with curcumin was not irritating to the skin. According to studies on in vivo wound healing, curcumin-loaded niosomal gel exhibited the highest percentage of wound contraction. Following 21 days of niosomal gel treatment, the histopathological evaluation found a noticeable improvement in the skin's histological architecture. Curcumin-loaded niosomal gel was easily made using the thin film hydration process.
Conclusion
The results of this study demonstrate the potential of niosomal gel as a cutting-edge therapeutic strategy for wound healing.
As the world’s population grows, the needs for feeding it follow the same path. Considering these conditions, ensuring the quantity and quality of raw materials, such as cereals, seems imperative. Stored product insects are responsible for significant losses in the post-harvest stages of agricultural products and the available chemical methods for their control are decreasing, due to their negative impact on the environment and humans. To this end, the evaluation of the efficacy of non-chemical methods for the management of storage insects is crucial. In the present study, we conducted two trials of choice tests based on rice fortified with basil to determine its potential as a non-chemical repellent of stored product insects. In the first trial, we evaluated the repellent activity of rice enriched with basil on adults of Sitophilus oryzae, Rhyzopertha dominica, Tribolium castaneum and Oryzaephilus surinamensis, as well as on T. castaneum larvae. In the second trial, the same procedure was followed with deltamethrin-treated rice fortified with basil. The results of the first trial showed that for most of the insect species tested, the rice fortified with basil was moderately repellent, while for O. surinamensis, it was attractive. Surprisingly, in the second trial, the deltamethrin-treated rice fortified with basil showed a repellent effect on O. surinamensis adults and T. castaneum larvae, while no repellency was observed for the rest of insect species examined. Observation time was not significant for any of the insect species, combinations and trials, with the exception of the rice fortified with basil vs. Blanc combination in O. surinamensis. Our findings suggest that the use of deltamethrin-treated rice fortified with basil was effective as a repellent for O. surinamensis adults and T. castaneum larvae.
Vector-borne diseases, particularly the arboviruses dengue, Zika, chikungunya, and yellow fever caused by the Aedes aegypti mosquito, have been driving the use of repellents worldwide. The most representative synthetic repellent, DEET stands out as the market's oldest and most efficient repellent. It is considered a reference standard but presents considerable toxicity, not recommended for children up to 6 months old and pregnant women. For this reason, alternatives have been sought, and natural repellents derived mainly from essential oils have been studied, highlighting the essential oils of lemon (Corymbia citriodora), citronella (Cympobogon sp.), Andiroba (Carapa guianensis). However, the development and commercialization of products containing natural repellents are significantly lower when compared to DEET and other synthetic repellents. In order to understand the reasons, aspects related to safety, mechanism of action, efficacy as well development and complexity of the products were evaluated. It is concluded that, as for safety, there is lacking information in the literature regarding the effects on non-target organisms and robust toxicity data. The mechanism of action is based on theories, with less information on the exact mode of action, molecular targets, and interaction with the olfactory and taste receptors of insects. Despite being a current trend to search for actives from natural sources highly present in essential oils, however they reduced action time because due to rapid evaporation after application to the skin, thus requiring repellent vehicles. The development and complexity related to these products bring challenging aspects, beginning on the plant cultivation and extraction processes to produce essential oils with a more homogeneous chemical composition towards the formulation stabilization processes due to fast evaporation and short action time, with the use of pharmaceutical technology such as encapsulation techniques.
There are many life-threatening insects in nature and the most dangerous ones are mosquitoes. People have taken herbal precautions against them since ancient times. Although several chemical and synthetic insect repellents exist in the market, the plant-based protection methods have never been given up such that there is a trend towards producing and commercializing plant-based insect repellents in recent years. In the light of ethnobotanical studies, new insect repellent plants and formulations are being explored, developed and tested. In literature, there are a lot of research on plant-based repellents some of which are reviewed in this article. Information about the most frequently used plant-based repellents and related studies are presented. Different application methods of the plant-based repellents on the textiles are explained with their a few examples in literature. Also, common test methods used for determining the effectiveness of insect repellents and repellent treated textiles are stated and the importance of the standardization of these test methods is emphasized. It is understood that usage of plant-based insect repellents in practice can be beneficial and useful if stayed within their safe concentration limits.
Mosquitoes are one of the deadliest insects in the world Which cause number of vector-borne diseases(e.g Dengue, malaria, Zika virus fever, yellow fever, West Nile fever, Japanese encephalitis) in human being. this vector borne diseases cause millions of death every year in the world, the chemical based mosquito repellents available in the market contain some hazardous chemicals which are likely to cause threat to human being. According to report After using chemical based mosquito repellents, 11.8% people complained of various health issues like breathing problems, headache, irritation in the eyes, bronchial irritation, cold , cough, running nose and skin infections. some of them also developed asthma after using these repellents. So, use of herbal mosquito repellents are one of the option to overcome the problems of chemical based Mosquito Repellents. herbal mosquito repellents are effective, eco friendly and cheaper as compared to chemical based Mosquito Repellents.
By standardized interviews of people in 23 rural villages, in the Oio region of Guinea Bissau, we collected data on which plant species and plant derived products or methods people use to reduce mosquito biting activity. The following plants were used to reduce numbers of mosquitoes indoors at night: fresh or smouldering Hyptis suaveolens Poit. (Lamiaceae), smoke of the bark of Daniellia oliveri Rolfe (Caesalpiniaceae), smoke of the infructescence of Elaeis guineensis Jacq. (Arecaceae), smoke of the seed capsules of Parkia biglobosa (Jacq.) Benth. (Mimosaceae), smoke of the leaves of Azadirachta indica A.Juss. (Meliaceae) and Eucalyptus sp. (Myrtaceae), fresh Ocimum canum Sims (Lamiaceae), and fresh Senna occidentalis (L.) Link (Caesalpiniaceae). In two field experiments we estimated the 'repellent activity' of certain of these plants and compared their efficacies with those of two commercially available mosquito repellents, i.e. 'positive' controls. In the first experiment we tested: smouldering H. suaveolens (85.4% repellency); fresh H. suaveolens (73.2%); burning of the bark of D. oliveri (74.7%); and smoke of the leaves of Eucalyptus (72.2%). In the second experiment we tested: smouldering H. suaveolens (83.6% repellency); fresh H. suaveolens (66.5%); burning of the bark of D. oliveri (77.9%); smoke of the leaves of A. indica (76.0%); smoke of the infructescence of E. guineensis (69.0%); fresh O. canum (63.6%); and fresh S. occidentalis; (29.4%). All the products tested, except S. occidentalis were significantly more effective than the negative control.
The mosquitoes have perhaps attained greater public notoriety than any other arthropods. They include the only organisms able to transmit human malaria, and apart from carrying this and other diseases are almost unrivalled as irritating biting pests. All mosquitoes belong to the family Culicidae, which at present contains about 3450 species and subspecies. These are documented in world catalogues (see Ward, 1992) which are updated every few years. Superficially the adults resemble certain other Nematocera, especially the Chironomidae, Dixidae and Chaoboridae, which like mosquitoes have aquatic immature stages. Mosquitoes, however, are readily distinguished from such similar looking flies by their conspicuous forwardly projecting proboscis and scales on the wing veins.
Essential oils obtained from Ocimum americanum, O. basilicum, O. basilicum fa. citratum, O. gratissimum and O. tenuiflorum, were tested for mosquito repellent and larvicidal activities. All the oils exhibited both activities. O. basilicum showed the strongest larvicidal activity (EC(50) = 81, EC(90) = 113 ppm), while O. gratissimum exhibited the longest duration of action for mosquito repellent activity (more than two hours). Gas chromatographic analysis indicated the presence of camphor, caryophyllene oxide, cineole, methyleugenol, limonene, myrcene, and thymol, all known insect repellents.
Five chemical repellents, a controlled-release repellent formulation, Avon Skin-So-Soft bath oil and permethrin-impregnated clothing fabric were assayed for personal protection against bites of Aedes albopictus. On skin the chemical repellents provided significant (P = 0.05) protection from biting; however, Ae. albopictus was more sensitive to the repellents than the standard, Ae. aegypti. Two experimental repellents provided 6-7 h protection from bites, 25% deet in ethanol provided greater than 8 h protection, a controlled-release formulation containing 35% deet provided greater than 10 h protection, and the Avon product provided 0.64 h protection from bites. Permethrin-treated fabric provided complete protection from mosquito bites through 0-5 washings. Repellent products containing greater than or equal to 12% deet should provide satisfactory protection against Ae. albopictus; the use of permethrin-impregnated clothing should provide additional protection.
Two soap formulations, both containing 20% deet and one each containing permethrin at 0.5 and 1.0%, respectively, were applied to exposed arms and legs of volunteers as personal protection against outdoor human biting mosquitoes in six locations on Penang Island, Malaysia. The predominant mosquito species collected from these locations were Aedes albopictus, Mansonia uniformis, Culex gelidus, Anopheles lesteri and Armigeres subalbatus. Efficacy and residual effects up to 4 hours indicated good protection against these species. Reduction in mosquito landing-biting rates in treated groups ranged from 83.8 to 100.0%. At high densities, small percentages of Ma. uniformis and An. lesteri landed or bit on treated skin. Use of the soap formulations in terms of cost-effectiveness, safety and overall vector control strategy for some tropical diseases is discussed.
A review of the biodistribution and toxicity of the insect repellent N,N-diethyl-m-toluamide (DEET) is presented. Workers using repellent containing this compound may be exposed to greater than 442 g in 6 mo. In human studies, variable penetration into the skin of from 9 to 56% of a topically applied dose and absorption into the circulatory system of approximately 17% have been reported. Excretion of DEET by humans was initially rapid but not as complete as in animal models. Only about one-half of the absorbed DEET was excreted by humans over 5 d. Depot storage of DEET in the skin was also documented. Skin irritant effects, including scarring bullous dermatitis in humans, were reported. One animal study that reported embryotoxicity could not be confirmed by other investigators. The limited testing for mutagenicity and carcinogenicity provided negative results. Neurotoxic effects were observed in workers exposed to 4 g or more per week. Six young girls developed encephalopathies after exposure to unspecified amounts of DEET ranging from small to massive doses. Three of these girls later died. The cause of their death has not been resolved. Because of the lack of information, further research into the absorption, carcinogenicity, and neurotoxic effects is needed.
The repellent action of neem oil (extracted from the seeds of Azadirachta indica A. Juss) was evaluated on mosquitoes at two villages near Delhi, India. Kerosene lamps containing neem oil were burned in the living rooms, and mosquitoes resting walls or attracted to human bait were collected inside rooms from 1800 to 0600 h. Neem oil (0.01-1%) mixed in kerosene reduced biting of human volunteers and catches of mosquitoes resting on walls in the rooms. Protection was more pronounced against Anopheles than against Culex. A 1% neem oil-kerosene mixture may provide economical personal protection from mosquito bites.
Two percent neem oil mixed in coconut oil, when applied to the exposed body parts of human volunteers, provided complete protection for 12 h from the bites of all anopheline species. Application of neem oil is safe and can be used for protection from malaria in endemic countries.
Deet, the lactone CIC-4, and the piperidine compounds A13-37220 and A13-35765 were evaluated for initial repellency against laboratory-reared Anopheles albimanus Wiedemann, An. freeborni Aitken, An. gambiae Giles, An. stephensi Liston, and Phlebotomus papatasi (Scopoli) using a dose-response testing procedure on human volunteers. In addition, deet and CIC-4 were tested against Lutzomyia longipalpis (Lutz & Neiva). In general, the repellency of A13-37220, A13-35765, and CIC-4 was not markedly different from that of deet against each species tested; however, the different species varied greatly in response to the repellents. Overall, An. stephensi, L. longipalpis, and P. papatasi were the most sensitive, and An. albimanus the most tolerant species. The four repellents subsequently were tested against An. stephensi and An. albimanus to determine the duration of repellency. AI3-37220 provided effective (> 90%) protection against An. stephensi bites for 7 h, whereas deet, AI3-35765, and CIC-4 provided 6, 5, and 3 h of protection, respectively. Each of the four compounds provided < 1 h of protection against An. albimanus bites.
A field evaluation of the repellents N,N-diethyl-3-methylbenzamide (deet) and 1-(3-cyclohexen-1-yl-carbonyl)-2-methylpiperidine (AI3-37220, a piperidine compound) was conducted against Anopheles funestus and An. arabiensis in Kenya. Both repellents provided significantly more protection (P < 0.001) than the ethanol control. AI3-37220 was significantly more effective (P < 0.001) than deet in repelling both species of mosquitoes. After 9 h, 0.1 mg/cm2 of AI3-37220 provided 89.8% and 71.1% protection against An. arabiensis and An. funestus, respectively. Deet provided > 80% protection for only 3 h, and protection rapidly decreased after this time to 60.2% and 35.1% for An. arabiensis and An. funestus, respectively, after 9 h. Anopheles funestus was significantly less sensitive (P < 0.001) to both repellents than An. arabiensis. The results of this study indicate that AI3-37220 is more effective than deet in repelling anopheline mosquitoes in western Kenya.
This review is intended to provide the reader with an overview of the all-purpose topical insect repellent N,N-diethyl-3-methylbenzamide (deet), with emphasis on its pharmacokinetics, formulation, and safety aspects. N,N-diethyl-3-methylbenzamide is effective against a variety of mosquitoes, flies, fleas, and ticks, and its protection efficacy depends on factors such as type of formulation, application pattern, physical activity of the user, environment, and species and feeding behavior of the insects. It offers an inexpensive and practical means of preventing the attack of biting insects and, more importantly, the transmission of vector-borne diseases. In both humans and animals, deet skin penetration and biodistribution are rapid and extensive, and metabolism and elimination appear to be complete. As evidenced by over 4 decades of human experience and rigorous animal testing, deet is generally safe for topical use if applied as recommended, although it has occasionally been related to side effects such as toxic encephalopathy, seizure, acute manic psychosis, cardiovascular toxicity, and dermatitis, along with a few cases of death due to extensive skin absorption. N,N-diethyl-3-methylbenzamide may compete in metabolism with and alter the biodistribution properties of other compounds to which a subject is simultaneously exposed, resulting in an added risk of side effects. The appropriate use of formulation techniques and new formulation excipients not only offers a way to extend the duration of protection, but also reduces deet skin penetration. In addition to extended repellency, minimal skin penetration of deet should be an important consideration in the evaluation of a deet formulation during new product development.
Two new repellent formulations, KBR 3023 10% and 20% from Bayer AG, Germany, were evaluated together with DEET 10% and 20% as standard repellent formulations. Evaluation was based on two separate field studies: a daytime study (0900-1700 hr) in a forested orchard on Penang Island and a nighttime study (2100-0100 hr) in a squatter residential area on the adjacent mainland of peninsular Malaysia. Both studies were carried out by exposing humans with bare arms and legs to mosquitoes landing/biting for an eight hour period. Right arms and legs of the human baits were treated with different repellent formulations (KBR 3023 10%, 20% and DEET 10%, 20%) and the left limbs were left untreated to act as controls. The daytime study indicated that all four formulations were equally effective (P < 0.05) as repellents against the predominant Aedes albopictus with greater than 88.5% reduction in landing/biting in the first four hours and not less than 65.0% in the next four hours of the assessment period. In the night study, all four formulations were also found to be equally effective (P < 0.05) in repelling Culex quinquefasciatus, the predominant species. All four formulations provided complete protection against Cx. quinquefasciatus in the first two hours of exposure. The percentage reduction values were maintained above 90.0% for the next six hours of the assessment period. In conclusion, both the KBR 3023 and DEET formulations were found to be equally effective (P < 0.05) in providing a long-lasting reduction in human-mosquito contact in both the day and night field studies.
The repellency of different concentrations (5, 10, 25, 50, 75, and 100%) and combinations of 5 essential oils (Bourbon geranium, cedarwood, clove, peppermint, and thyme) to Aedes aegypti (L.) and Anopheles albimanus Wiedemann when applied to human skin was determined in laboratory tests. Cedarwood oil failed to repel mosquitoes and only high concentrations of peppermint oil repelled Ae. aegypti. None of the oils tested prevented mosquito bite when used at the 5 or 10% concentration. Thyme and clove oils were the most effective mosquito repellents and provided 1 1/2 to 3 1/2 h of protection, depending on oil concentration. Clove oil (50%) combined with geranium oil (50%) or with thyme oil (50%) prevented biting by An. albimanus for 1 1/4 to 2 1/2 h. The potential for using essential oils as topical mosquito repellents may be limited by user acceptability; clove, thyme, and peppermint oils can be irritating to the skin, whereas both human subjects in this study judged the odor of clove and thyme oils unacceptable at concentrations > or = 25%.
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