|Barnard, Donald - Don|
Submitted to: Medical and Veterinary Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/18/2000
Publication Date: N/A
Citation: Interpretive Summary: Insect repellents intended for application on skin are not normally evaluated for other kinds of biological activity. However, when scientists at the ARS Center for Medical, Agricultural, and Veterinary Entomology in Gainesville, Florida and the University of Florida tested the mosquito repellent, deet, and two experimental repellents in the laboratory they found that the repellent-treated water in bioassay containers killed mosquito larvae for as long as 6 months. Subsequently, in tests of the larvicidal activity of each repellent under field conditions, one experimental repellent killed mosquito larvae for up to 6 weeks. Based on the results of the field study, it was concluded that oviposition repellents could be useful for mosquito control under certain circumstances. For explame, in urban/suburban environments, where container inhabiting mosquitoes abound, repellent-treated containers could be strategically placed to direct gravid females from their normal oviposition sites to attractant-enhanced lethal ovitraps that would trap and kill them.
Technical Abstract: Toxicity and persistence of 3 topical skin repellents, AI3-37220, AI3- 35765, and N, N-diethyl-3-methylbenzamide (AI3-22542 or deet) as larvicides to the laboratory populations of Anopheles albimanus and Aedes albopictus and a natural population of Ae. albopictus were evaluated in the laboratory and field. The LC 50 values of AI3-37220, AI3-35765 and deet ranged from 0.005% to 0.021% for the 1st-instar larvae, and from 0.015% to 0.034% for the 4th-instar larvae of Ae. albopictus and An. albimanus. In the laboratory tests, an application rate of 0.1% of AI3-37220 killed > 90% of the 1st-instar larvae of both species for 32-34 weeks, and the 4th-instar larvae of Ae. albopictus for 14.3 weeks, and An. albimanus for 6.3 weeks. The same concentration of AI3-35765 killed > 90% of the 1st-instar larvae of Ae. albopictus for 13 weeks and An. albimanus for 4 weeks, and the 4th- instar larvae of both species for 2-2.7 weeks. An application rate of 0.1% of deet killed > 90% of the 1st-instar larvae of Ae. albopictus for 3.7 weeks and An. albimanus for 3 weeks, and the 4th- instar larvae of both species of mosquitoes for 1 day. In the field tests, AI3-37220 provided 100% of larval control of Ae. albopictus for 9 weeks, AI3-35765 for 6 weeks, and deet for 1-2 weeks in the artificial containers. AI3-37220 and AI3-35765 provided 100% of larval control for 4-5 weeks, but deet provided 100% of control for 2 weeks in used tires. AI3-37220 and AI3-35765 provided 100% larval control of Aedes mosquitoes for 6 weeks, but deet provided 100% larval control for 4 weeks in the flower vases in a large urban cemetery. The topical skin repellents are potential larval control agents when the repellents are used as ovipositional repellents for container-inhabiting mosquitoes.