The effectiveness of permethrin and deet, alone or in combination, for protection against Aedes taeniorhynchus

Field tests were conducted to compare the degree of protection from bites by the mosquito Aedes taeniorhynchus (Wiedemann) provided by wearing clothing treated with permethrin [(3-phenoxyphenyl)methyl (+/-) cis/trans 3-(2-dichloroethenyl)2, 2-dimethylcyclopropanecarboxylate] with that provided by applying deet (N,N-diethyl-m-toluamide) to exposed skin or by applying deet and wearing the treated clothing. Human test subjects were exposed to natural populations of mosquitoes for a 9-hour daytime period (total of 8 days/treatment) while using one or both protection methods. Unprotected test subjects were also exposed for short periods each day as a check to determine the overall biting rate of mosquitoes. The combined use of both protection methods was the most effective treatment in preventing bites, resulting in an average of 1.5 bites/9-hour day, compared with 53.5 and 98.5 bites on subjects protected only with treated clothing or deet, respectively, and 2,287 bites (extrapolated) on subjects who wore untreated clothing during the same time period. Measurements also indicated that the toxic effect of permethrin reduced biting rates by greater than 90% within the immediate area where subjects wore permethrin-treated uniforms for 9 hours.