Efficacy of Piperonyl Butoxide (PBO) synergist on Pyrethroid and Dichlorodiphenyl Trichloroethane (DDT) resistant mosquitoes in Lekki, Lagos State, Nigeria

Abstract

Vector control using insecticide is an integral part of the global strategy for management of mosquito-borne diseases.. The development of  insecticides resistance is a major concern in mosquito control. We evaluated the effect of piperonyl butoxide (PBO) synergist on dichlorodiphenyl trichloroethane (DDT) and pyrethroids resistant Anopheles gambiae s.l., Culex quinquefasciatus and Aedes aegypti in Lekki peninsula area of Lagos
State, Nigeria. Mosquito larval collected from breeding sites in Lekki peninsula were allowed to emerge in the insectary and identified using  appropriate morphological keys. Two-three days old female adults were subjected to susceptibility assays using WHO kits and insecticides impregnated test papers. Twenty (20) female adult mosquitoes of each genus were exposed to DDT (4 %) and permethrin (0.75 %) alone.  Subsequently, another set of 20 of each genus were pre-exposed to PBO (4 %) for 1 hour before exposing them to permethrin and DDT, all assays were carried out in four biological replicates. The knockdown time was recorded as the time intervals for 60 minutes and mortality at 24 hour. Resistance to DDT was detected with percentages mortality of 55, 60 and 87.5 % for An. gambiae, Cx. quinquefasciatus and Ae. aegypti species respectively. Pre-exposure of mosquitoes to PBO significantly suppressed (p<0.05) resistance to both DDT and permethrin in all the mosquito  species indicating the activities of P450 monooxygenase as a detoxifying enzymes mediating resistance to DDT and pyrethroids. Therefore, PBO should be incorporated in insecticide resistance management strategies in this area and others with similar mosquitos’ resistance profile.

Keywords: Mosquitoes, Dichlorodiphenyl trichloroethane, Pyrethroids, Piperonyl butoxide, Insecticides resistance