Beyond Nature and Nurture: Phenotypic Plasticity in Blood-Feeding Behavior of Anopheles gambiae s.s. When Humans Are Not Readily Accessible

To test for the effects of host accessibility oil blood-feeding behavior, we assessed degrees of anthropophily of the malaria mosquito Anopheles gambiae at two stages of the behavioral sequence of host foraging in a rice growing area near Bobo-Dioulasso, Burkina Faso, where humans are not readily accessible because of years of generalized use of (mostly non-impregnated) bed nets. First, patterns of lost selection were assessed by the identification of the blood meal origin of indoor-resting samples. Inherent host preferences were then determined by two odor-baited entry traps, set side by side in a choice arrangement, releasing either human or calf odor. The proportion of feeds taken oil humans was around 40%, whereas 88% of trapped An. gambiae chose the human-baited trap, indicating a zoophilic pattern of host selection despite a stronger trap entry response with human odor. This paradox can be interpreted as the evolution of a plastic strategy of feeding behavior in this field population of An. gambiae because of the greater accessibility of readily available, although less-preferred, hosts.