Abstract:
The susceptibility of larvae and adult Anopheles gambiae in Akure metropolis to synthetic and botanical insecticides was investigated at ambient temperature (28 ±30C) and relative humidity (75 ± 5%). An. gambiae samples were collected from 10 locations across Akure, Ondo State. The locations include Oba-Adesida; Akure High School; Alagbaka; Oke-Aro; Aule; Oja-Oba; Oda; Oke-Ijebu; Shagari; and FUTA. Synthetic insecticides (Cypermethrin and Dimethyl dichlorovinyl phosphate, DDVP) and acetone extracts of two botanicals (Piper guineense and Eugenia aromatica) were assayed against A. gambiae larvae and adult. The assays were carried out at different concentrations. Adult knockdown (KD) and mortality of larvae and adults were recorded. The result obtained on the mortality and knockdown effect of cypermethrin on both the larvae and adult stages of A. gambiae in Akure metropolis showed that the Alagbaka (100%) population was the most susceptible, while the Oke-Aro (larvae) (78.75%) and Oba-Adesida (Knock down (63.33%) and adult mortality (33.33%), were more tolerant than their counterparts. The Aule larvae (100%) and adult (100%) populations were the most susceptible to DDVP knockdown and mortality effects while Oja-Oba (40.74% for KD; and 10.00% for mortality) was the least susceptible. Furthermore, within the metropolis, the Oja-Oba larvae (94.94%) and adult population was the most tolerant to mortality (30%) and knockdown (40.74%) effect of P. guineense while the Alagbaka population (100%) was the most susceptible. The Oja-Oba larvae (51.84%) and adult population was the most tolerant to mortality (36.67%) and knockdown (74.07%) effect of E. aromatica extract while the Alagbaka (100%) and FUTA (100%) populations were the most susceptible. Generally, the result on the tolerance magnitude suggests that, the centre of the town seems to be the hot spot of tolerance to KD and mortality for both synthetic and botanical insecticides. From the various results obtained from this research, it could be concluded that updating our knowledge of A. gambiae response to synthetic and botanical insecticides is vital in planning and implementing evidence based vector control programs. This will be helpful to preserve the efficacy of current insecticidal control methods, while slowing down or preventing the development of tolerance.
