Genetic Basis of Human Host Preference in Anopheles gambiae

Anopheles gambiae, the main vector of malaria in sub-Saharan Africa, is a highly anthropophilic mosquito. That is, it is highly adapted to blood feeding on humans, and rarely feeds on other mammals in nature. Needless to say, this aspect of its biology is one of the major reasons it is such and efficient malaria vector. It is well known that An. gambiae‘s preference for humans is based on its attraction to human sweat. In collaboration with Dr Willem Takken from the Wageningen University in The Netherlands, we are conducting a mapping experiment to identify quantitative trait loci (QTL) responsible for An. gambiae‘s attraction to humans. For this we are crossing the

anthropophilic An. gambiae with the zoophilic An. quadriannulatus. Backcross females are analyzed for host preference in an “olfactometer” in Dr Takken’s lab (see Figure 2).

The genotyping of the backcross females and the QTL mapping analysis is performed in our lab at Texas A&M. Additional approaches are used to hone in on candidate genes within the identified QTL.

We have identified 6 QTL for human host preference in Anopheles gambiae. Several olfaction genes are located inside these QTL and we are studying their molecular evolution to identify those involved in the recent adaptation of this species to its human host. In addition, we have compared the transcriptomes of the antennae of An. gambiae and its zoophilic sister species An. quadriannulatus and have identified a number of olfaction genes expressed at higher levels in An. gambiae. This data is currently being prepared for publication.