Mosquito biting activities below human host skin

Female mosquitoes rely on chemical and physical cues to locate a host for blood feeding and guide their decisions to bite. Upon landing, they explore the host skin surface and select suitable bite-sites. While surface behaviors exhibited by the female can be observed via high-speed videography, quantifying the real-time biting activities upon penetrating the host skin during blood feeding remains challenging. We performed a study using olfactory-defective mosquitoes to determine the relative contribution of olfaction in the biting behavior on a human host. We used an electrophysiological assay to compare the biting profiles of wild type Anopheles coluzzii mosquitoes to sensory-impaired mutant counterparts. We also explored genera-specific biting differences between wild type An. coluzzii and Aedes aegypti mosquitoes, which differ in their preferred time of biting activity (night vs day), and which might have developed unique biting strategies since their divergence >150 mya. Using change point detection algorithm, we confirmed five distinct phases of the biting in different genotypes and species of mosquitoes below the human host skin surface: skin piercing, blood vessel searching, blood ingestion, mouthpart withdrawal, and full mouthpart retraction. Temporal analysis of these various biting phases indicates that only the duration of blood vessel searching differs between the mosquito genera (15 s shorter in An. coluzzii vs. Ae. aegypti), but not between genotypes of An. coluzzii. We are currently applying computational time-series feature analysis to compare the shapes of these biting phases to reveal their underlying patterns.