Mating status and body size in Aedes albopictus (Diptera: Culicidae) affect host finding and DEET repellency

Abstract

Variations in the conditions accompanying mosquito development and mating can result in females of variable size that have not been inseminated. In this study, we compared the host finding activity of mated and unmated large and small Aedes albopictus (Skuse) and the repellency to these mosquitoes of 25% DEET. The percentage of females seeking the source of human odor in an olfactometer was significantly influenced by body size (P = 0.007) but not mating status (P = 0.07). Most respondents were large (71%) but 40% of all host seeking females were not inseminated. Landing rates by Ae. albopictus on human skin were influenced in screened cage tests by mating status (P < 0.0001) and body size (P = 0.004). Mated females exhibited the highest landing rates (17.3% [large] and 12.7% [small]) followed by unmated large females (7.3%) and unmated small females (6.4%). The Complete Protection Time (CPT) from mosquito landing provided by 25% DEET was significantly influenced by mating status (P = 0.002) and body size (P = 0.025). Unmated small females were repelled longer (7.5 h) than unmated large females (7.0 h) and longer than small and large mated females (6.3 h and 5.6 h, respectively). CPT using 25% DEET was inversely related to mosquito landing rate in all treatment groups with 75 min more protection on average from bites by unmated females compared with mated females.