Susceptibility Status of Anopheles Gambiae S.I. to DDT and Permethrin in Lagos State, Nigeria.

Abstract

Malaria is of public health importance in Nigeria and may retain its status, if new intervention methods are not introduced or the current ones monitored. This study was carried out in Alimosho, Kosofe, Ibeju-Lekki and Badagry Local Government Areas (LGAs) of Lagos State to assess the susceptibility status of Anopheles gambiae s.l., a dominant malaria vector in the localities to DDT 4% and Permethrin 0.75%. Anopheles larvae were collected from larva habitats in both LGAs, reared to adults and fed with 10% sucrose solution. Nonblood fed 2-5 days old female mosquitoes were exposed to discriminating doses of DDT and permethrin according to the standard WHO procedures. The knockdown effect was recorded at interval of 10 minutes and mortality scored 24hours after exposure. Species identification was done by morphological characteristics. Results from the study showed that Anopheles gambiae s.l. are resistant to DDT (4%) and permethrin (0.75%) with 24hr post exposure mortality ranging from 15.00-24.0% and 4.25-22.0% respectively. The Knockdown Time (KDT) ranged from 30.8-941.95minutes for DDT and 12.6-85.51minutes for permethrin. KDT95 50 ranges from 117.49-27524.22 minutes and 117.49-412.1 minutes for DDT and permethrin respectively. All the LGAs showed high level of resistance to DDT and permethrin. The high level of insecticide resistance recorded in this study could be detrimental to the elimination of malaria. Therefore, integrated vector management is needed to effectively carry out to manage the development of insecticide resistance.