ACTIVITY OF ACETYLCHOLINESTERASE IN Anopheles gambiae IN AKURE METROPOLIS AND ITS INHIBITION BY ESSENTIAL OILS (Piper guineense Schumacher and Syzygium aromaticum L.Merr. and Perry)

Abstract

This study investigated the activity of Acetylcholinesterase (AChE) in Anopheles gambiae collected from ten (10) locations in Akure metropolis and its inhibition by essential oils of Piper guineense and Syzygium aromaticum. The ten locations are Oba-Adesida, Akure High School, Alagbaka, Oke-Aro, Aule, Oja-Oba, Oda, Oke-Ijebu, Shagari, and Federal University of Technology, Akure (FUTA). Essential oils of two botanicals (P. guineense and S. aromaticum) were extracted by hydrodistillation method. An. gambiae adults and larvae were assayed for Acetylcholinesterase (AChE) activity with and without inhibitors. The percentage inhibition of the An. gambiae (adults and larvae) treated with different concentrations of 25μl/ ml and 50μl/ml were calculated whereby AChE activity inhibition was recorded for both adults and larvae populations across the various locations. The highest AChE activity was observed among the Oja oba An. gambiae population while the lowest was observed among the FUTA An. gambiae population. Other populations from Oba Adesida, Oke-Aro, Aule, Oda also had high activities. Anopheles gambiae population (larva and adult) from FUTA had the highest inhibition by both botanicals while the Oja oba population was least inhibited. Furthermore, the spatial distribution of AChE activity magnitude from the referenced locations within the metropolis indicated that thelocations north of the metropolis showed low activities compared with the southern locations with high AChE activity whereas the centre of the metropolis (Oja oba) is the hotspot of activity. The inhibition magnitude of the An. gambiae (adults and larvae) assayed with inhibitors across the various locations showed differences in levels of inhibition by the plant materials. Therefore, vector control programmes need to carefully consider the enzyme profiles of local mosquito populations in order to base their resistance management strategies on sound scientific data