Permethrin and DDT resistant Anopheles gambia and Culex quinquefasciatus in Southern Ghana
Insecticides play a major role in controlling the spread of malaria. However, this means of protection is losing its efficacy due to the development of resistance to commonly used insecticides. Pyrethroids are often used in vector control projects due to lower human toxicity, high insecticidal potency and rapid knockdown (KD) effects. Anopheles gambiae is a major vector of malaria in West Africa and has shown pyrethroid resistance in several countries. The other species tested, Culex. quinquefasciatus, is not a vector of malaria but causes important inconvenience to the locals. In this study A. gambiae and C. quinquefasciatus larvae were collected from five separate locations in Central and Western Ghana: Amamoma, Duakor, North O.L.A., Okyereko and Sekondi. Adult mosquitoes were exposed to permethrin (0.75%) and DDT (4%) according to WHO protocol. Knockdown, mortality and resistance were recorded over a 24-hour period. Six experiments were conducted under WHO protocol resulting in an 4.65% average mortality for A. gambiae and an 80.53% for C. quinquefasciatus. These results support the hypothesis that resistance continues to rise in Anopheles mosquitoes despite new insecticide combinations. Recording and understanding resistance is essential for effective vector control and disease prevention using different insecticides combinations in impregnated nets.