Comparative Sensitivity of Mosquito Species and Strains to the Repellent Diethyl Toluamide1

The median effective dosage (ED50) of N,N-diethyl-m-toluamide (deet) was determined for 18 strains of Anopheles stephensi Liston, An. albimanus Wiedemann, An. quadrimaculatus Say, Culex pipiens L., Cx. tarsalis CoquilIett, Aedes aegypti (L.) and Ae. taeniorhynchus (Wiedemann). The results obtained suggested that differences in levels of sensitivity to deet were a function of the taxonomic distance between the strains compared. Of the 18 species and strains tested, a strain of Cx. pipies (ED50=0.011 mg/cm2) was the most sensitive and a strain of An. albimanus (ED50=0.076 mg/cm2) was the most tolerant. Individual, mosquitoes within the strains tested also differed in their levels of sensitivity to deet.