Comparative Larvicidal Properties and Detoxification Machinery of Bioactive Fractions of Leaf Extracts of Hyptis Suaveolens and Chromolaena Odorata on Anopheles gambiae s.l from North West Nigeria.

Malaria is endemic in Nigeria and the impact of chemical insecticides is being undermined by widespread resistance in mosquito vectors. This calls for development of alternative bio-insecticidal approach. The aim of this work was to determine the active fractions of leaves of Hyptis. suaveolens and Chromolena. odorata with insecticidal potential on the larva of Anopheles gambiae s.l. Leaf extracts of the two plants were screen for phytochemicals and the active fractions were subjected to GC-MS analysis. In addition, the detoxification enzymes (GST, esterase and cytochromes P450) as well Glutathione levels on the susceptible and resistant individuals of the larvae were biochemically assayed. Larval bioassay was carried out by the standard procedure described by WHO. The phytochemicals detected include flavonoids, tannins, saponins, terpenoids, alkaloids, phenols and phlobatannins. Butanol fracton of H. suaveolens displayed higher larvicidal activity (LC50 2167.92ppm) followed by the aqueous fraction (LC50 2613.01ppm). Both butanol and aqueous fractions of C. odorata also displayed larvicidal activities (LC50 3117.97ppm; LC50 3497.27ppm) respectively, but were lower than that observed in Hyptis suaveolens. Biochemical assay of the detoxification enzymes showed significance difference at P <0.05 between the resistant and susceptible larvae for all enzymes. There was however no significant difference in the levels detoxification enzymes in both resistant and susceptible individuals for butanol and aqueous fractions of H. suaveolens when compared with their corresponding fractions of C. odorata at P< 0.05 respectively. The observations recorded in this study showed a promising larvicidal potential of these two plants which if further characterized could offer a promising novel bioinsecticide compound that could substitute the present classes of chemical insecticides used in malaria vector control