Effects of partial blood engorgement and pretest carbohydrate availability on the repellency of deet to Aedes albopictus.

The pretest availability of 10% sucrose solution and/or partial blood engorgement in Aedes albopictus Skuse significantly influenced mosquito attack rates and the time of repellent protection in laboratory bioassays. In 46 cm L x 38 cm W x 37 cm H cages used in USDA repellent tests, non-blood-fed and partially blood-fed mosquitoes attempted to bite at similar rates. In small cages (5 cm dia. x 4 cm H), holding individual females, mean mosquito attack rates were reduced when females were partially blood fed, compared with those not blood fed. The protection period from bites by Ae. albopictus using 25% ethanolic deet (N,N diethyl-3-methylbenzamide) increased significantly in small and USDA standard cages when females had pretest access to sucrose solution, compared with females starved for 12 h. Partial blood engorgement in mosquitoes affected repellent protection time in USDA standard test cages but not in small cages.