Chemical composition and evaluation of mosquito larvicidal activity of Vitex payos extracts against Anopheles gambiae Giles S.S larvae

AIM: The aim of this study was to evaluate the acetone and methanol root bark extracts of Vitex payos and different fractions thereof, following acetone extraction and column chromatographic separation, for their immediate toxicity and long term effects on An. gambiae Giles sensu stricto larvae under semi-field conditions. MATERIALS & METHOD: Third and early fourth instars of An. gambiae larvae were exposed to acetone and methanol extracts of V. payos root bark and the acetone chromatographic fractions. Their effects on larval, pupal and adult stages were recorded. Consequently, GC/MS analysis on the extracts was carried out. RESULTS: Larvicidal effects of the extracts and fractions were found to be largely associated with phytoecdysteroids and saponins which tested positive in the test materials. The fractions were more potent than the crude extracts. Long-term (11-14 days) post-exposure observations at lower doses showed that the extracts achieved over 90% adult growth inhibition with morphogenetic variations and behavioral changes. CONCLUSION: Extracts and chromatographic fractions from V. payos possess larvicidal and/or IGR principles which can be used in the local communities where most of the people cannot afford synthetic larvicides.