Energy-state dependent responses of Anopheles gambiae to an unobtainable host

Understanding how blood-seeking behavior changes with different energy levels in the malaria mosquito Anopheles gambiae (Diptera: Culicidae), when confronted with an unobtainable blood-host, is of interest for vector control strategies. I used a straight-tube olfactometer to mimic a domicile containing (i) a simulated blood-host (human foot smell) protected by either a plain bednet or a DEET impregnated net and (ii) a sugar source (honey scent) some distance away. I manipulated the mosquito’s energy level by withholding sugar sources from females for different lengths of time. Whenever DEET was present, virtually no mosquitoes interacted with the blood-host scent at any energy level. Yet, energy levels influenced response to foot odour, probing persistence, residence time when DEET was not present. This suggests that control strategies using mosquito repellents can ignore the presence of alternative food sources (such as sugar) in the field unless the chemical efficacy is not retained over time.