An Investigation of the Lethality of Picralima Nitida, Family Apocynaceae in Malaria Vector Control

Abstract

Insecticides resistance and the corresponding health and environmental challenges that arises as a result of the use of synthetic chemical based insecticides prompts the search for better alternative control measures which are more effective, specific in action and less toxic. The 4th instar larvae of Anopheles spp, the vector of the deadly plasmodium were evaluated in this research against aqueous and methanolic leaf extracts of the plant Picralima nitida. Results revealed that aqueous leaf extract of the test plant had a mean mortality of 11 at 24hrs exposure and concentration of 5.0mg/ml. 95% mortality was also recorded at 5.0mg/ml after 48hrs exposure. Methanolic leaf extract had a mean mortality of 7.7 at 48hrs exposure time and same concentration of 5.0mg/ml. however, at 72hrs exposure, (concentration 5.0mg/ml), the mean mortality increased to 19.3 (97% mortality). The Median Lethal Time evaluated using probit analysis at 95% Confidence Limit showed the average lethal time of the test organism Anopheles larvae to the methanolic extract to be 55hrs and 29hrs for the aqueous leaf extract. This result hence supports the fact that leaf extracts of P. nitida can be used as a source of eco-friendly alternatives in the control of mosquito vectors, if developed.

Keywords: Resistance, Insecticides, Anopheles spp, Eco-friendly, Larviciding