Sixteen commercial insect repellents (6 botanical and 10 synthetic organic products) in spray formulations were evaluated in the laboratory for adult knockdown (KD) and mortality of laboratory-reared female Aedes aegypti, Aedes albopictus, and Anopheles quadrimaculatus. All tested products produced significant posttreatment KD and 24 h mortality of all 3 mosquito species. In our study, the synthetic organic repellents induced faster KD and KD of higher magnitude in adult mosquitoes than the botanical product repellents except geraniol-based MosquitoSafe. All tested formulations except 2 botanical repellent products caused 100% 24 h mortality of Ae. aegypti and all but 1 caused 100% 24 h mortality of Ae. albolpictus and An. quadrimaculatus.
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"By simulating high biting pressure that increased over time as is seen in the field due to the circadian rhythm of the local malaria vectors , the authors ensured that the repellent worked extremely well against the predominant malaria vector species before going to the more dangerous field setting. It is known that repellents have varying effects on the other mosquito species present in the field [6,31]. As a result, the effect of the repellent in the field might be over or underestimated depending on the other species present in the field. "
[Show abstract][Hide abstract] ABSTRACT: Before topical repellents can be employed as interventions against arthropod bites, their efficacy must be established. Currently, laboratory or field tests, using human volunteers, are the main methods used for assessing the efficacy of topical repellents. However, laboratory tests are not representative of real life conditions under which repellents are used and field-testing potentially exposes human volunteers to disease. There is, therefore, a need to develop methods to test efficacy of repellents under real life conditions while minimizing volunteer exposure to disease.
A lotion-based, 15% N, N-Diethyl-3-methylbenzamide (DEET) repellent and 15% DEET in ethanol were compared to a placebo lotion in a 200 sq m (10 m x 20 m) semi-field system (SFS) against laboratory-reared Anopheles arabiensis mosquitoes and in full field settings against wild malaria vectors and nuisance-biting mosquitoes. The average percentage protection against biting mosquitoes over four hours in the SFS and field setting was determined. A Poisson regression model was then used to determine relative risk of being bitten when wearing either of these repellents compared to the placebo.
Average percentage protection of the lotion-based 15% DEET repellent after four hours of mosquito collection was 82.13% (95% CI 75.94-88.82) in the semi-field experiments and 85.10% (95% CI 78.97-91.70) in the field experiments. Average percentage protection of 15% DEET in ethanol after four hours was 71.29% (CI 61.77-82.28) in the semi-field system and 88.24% (84.45-92.20) in the field.
Semi-field evaluation results were comparable to full-field evaluations, indicating that such systems could be satisfactorily used in measuring efficacy of topically applied mosquito repellents, thereby avoiding risks of exposure to mosquito-borne pathogens, associated with field testing.
"Moreover, some repellents have been reported to have toxic properties. Xue et al. (2003) found that aerosol applications of Skin-So-SoftH, containing 0.1% citronella, in laboratory wind tunnel studies produced 90% mortality of adult Ae. aegypti (L.) with 100% mortality of Ae. albopictus and Anopheles quadrimaculatus Say adults at 24 h posttreatment. In that same study these authors also similarly exposed these same species to NatrapelH, containing 10% citronella, where complete kill occurred at 24 h. "
[Show abstract][Hide abstract] ABSTRACT: The effectiveness of several commercially available products containing plant essential oils against caged female Aedes albopictus and Culex quinquefasciatus was studied. Products operationally applied via an automatic-timed insecticide application system (MistAway) at maximum label rates were EcoExempt MC (9.0 ml/liter, rosemary oil [18% AI], cinnamon oil [2% AI], lemongrass oil [2% AI], plus 78% "other ingredients" in wintergreen oil). Misting System Concentrate (4 ml/liter, oil of Juniperus virginiana [85% AI]), Mosquito Barrier (31.1 ml/liter, garlic oil [99.3% AI], and citric acid [0.5% AI]), and No-See-Um Organic Repellent (99.5 ml/liter, lemongrass [4% AI], citronella [3% AI], castor oil [3% AI], sodium laurate [3%], and garlic oil [1% AI] in an 86% [AI] mixture of wintergreen oil, lecithin, and water). All products were compared with a commercial formulation of synergized pyrethrins, Riptide (9.0 ml/liter, pyrethrins [5% AI], piperonyl butoxide [25% AI]), as a standard. Mortality was the greatest for Riptide to both mosquito species with effectiveness influenced by distance from the nozzle (ranging from > 80% at 3 m to > 10% at 20 m). The essential oil products resulted in < 10% mortality for each species regardless of application exposure distance with the exception of EcoExempt, which gave approximately 13% mortality of caged female Ae. albopictus 6 m from the nozzles.
Full-text · Article · Sep 2011 · Journal of the American Mosquito Control Association
"quinquefasciatus would be 1.378%, 0.414%, 0.145%, and 0.333%, respectively. Because any commercially available DEET insect repellent has a minimum percentage of active ingredient of 7.5% (up to 30%), which is much higher than the LD 95 values of DEET as described above, it is not surprising that Xue et al. (2003) found that commercially available insect repellents in spray formulations produced significant adult knockdown (KD) and 24-h mortality against adult mosquitoes. Recently , the lethal effects of 3 synthetic repellents (DEET, IR3535, and KBR3023) have been evaluated by filter paper tests to assess the knockdown effect and mortality induced by each repellent to Ae. aegypti (Licciardi et al. 2006). "
[Show abstract][Hide abstract] ABSTRACT: The relative toxicities of 8 repellents (DMP, Rutgers 612, DEET, IR3535, Picardin, PMD, AI3-35765, and AI3-37220) were evaluated by topical application against females of Aedes aegypti, Culex quinquefasciatus, Anopheles quadrimaculatus, and An. albimanus. Based on 24-h LD50 values, the most toxic repellent against all 4 mosquito species was AI3-37220, with values of 0.25, 0.20, 0.16, and 0.11 microg/mg for the listed 4 mosquito species, respectively. The least toxic of the 8 repellents tested was DMP, with LD50 values of 5.40, 4.72, 2.50, and 1.83 microg/mg, respectively. Based on the 24-h LD50 values, An. albimanus was the most susceptible species. The findings of the study reported herein provide a comprehensive examination of the toxicities of 4 currently used, 2 formerly used, and 2 experimental repellents against 4 mosquito species.
Full-text · Article · Jul 2009 · Journal of the American Mosquito Control Association