Insecticide Resistance in Indoor and Outdoor-resting Anopheles gambiae s.l. in Northern Ghana

Objective We examined the association between survival of insecticides and mosquitoes resting inside homes (indoor) and outside houses (outdoor) in two communities in Northern Ghana. Methods We collected live adult mosquitoes indoors and outdoors from the two communities. We generated offspring from a subset of mosquitoes and exposed them to four insecticides using methods recommended by WHO. We subsequently evaluated the heritable factors responsible for survival of insecticides in the two mosquito groups. Results Survival to two insecticides - DDT and deltamethrin were substantially high in both mosquitoes resting indoors and outdoors. This was very different between the two groups. Only few mosquitoes survived bendiocarb while almost all indoor and outdoor mosquitoes could not survive malathion. We did not observe large differences in survival of the two mosquito populations to both bendiocarb and malathion insecticides.   Furthermore, we identified certain heritable factors responsible for survival to DDT and deltamethrin in the two mosquito groups and these differed significantly between the mosquito groups. Conclusions Our work showed that mosquitoes resting indoors and outdoors are displaying different survival ability to the insecticides for malaria control at the study sites. This shows that resting behavior of mosquitoes can threaten the effectiveness of insecticides for malaria control and should be actively monitored.