State-dependent attacks in a mosquito

Abstract

Mosquito biting frequency and meal size are considered to be important parameters in the epidemiology of insect-vectored diseases such as malaria. Because both parameters are likely to depend on the size and energetic state of adult mosquitoes, the present study investigates the effects of body size and energy state on attack behaviours in the malaria mosquito, Anopheles gambiae. Attack rates are measured as well as total time spent before giving up for individual females when provided with an unobtainable human hand (i.e. mosquitoes are dislodged every time that they land). The factorial design considers two body sizes, small and large, as well as three sugar deprivation states, 0, 1 and 2 days. The results reveal a positive effect of size on attack rate and a nonlinear effect of energy state, where mosquitoes of intermediate energy state show lower attack rates than either 2-day food-deprived or nondeprived mosquitoes. Moreover, attack rate is negatively associated with persistence time in nondeprived and 2-day food-deprived Anopheles but is unrelated to persistence time in 1-day food-deprived mosquitoes, Interestingly, although persistence times are generally inversely related to attack rates, they are not significantly influenced by either energetic or size states.