Behavioral responses of pyrethroid-resistant Anopheles gambiae mosquitoes to insecticide-treated bed net

Long-lasting insecticidal nets are an effective tool in reducing malaria transmission. However, with increasing insecticide resistance little is known about how physiologically resistant malaria vectors behave around a human-occupied bed net, despite their importance in malaria transmission. This study assessed the host-seeking behavior of the major malaria vector Anopheles gambiae s.s, when an intact human-occupied treated bed net is in place, with respect to their insecticide resistance status under semi-field conditions. Pyrethroid resistant and susceptible females of Anopheles gambiae s.s were released inside a semi-field environment housing a hut which was occupied by a human host sleeping under treated or untreated bed net trap. Mosquitoes resting inside the hut or exiting and resting outside were collected using a prokopack aspirator, window exit trap and clay pots. The proportion of resistant females caught in the treated bed net trap was higher compared to the susceptible females (OR=1.445; P<0.00019). Resistant mosquitoes were less likely to exit the house when a treated bed net was present compared to the susceptible mosquitoes. The susceptible females were 2.3 times more likely to stay outdoors away from the treated bed net (OR=2.25; P<0.0001).The resistant mosquitoes showed significantly reduced avoidance behavior compared to the susceptible mosquitoes that were observed to exit the house and remained outdoors when a treated bed net was used. However, further investigations of the behavior of resistant mosquitoes under natural conditions should be undertaken to confirm these observations and improve the current intervention which are threatened by insecticide resistance and altered vector behavior.