Phytochemical screening and larvicidal effects of methanolic leave extract of Ocimum gratissimum on Anopheles species larva in Gombe, Gombe State Nigeria

Abstract

Mosquito vectors are among the well-known group of insect that transmit a number of deleterious human diseases, which has pose a major public health challenges affecting development of poorest countries in the world. Vector control is therefore an essential requirement in the control of these diseases. The emergence of insecticide resistance and their effects on non-target population and the environment has necessitated an urgent search for development of new and improved vector control methods that are ecofriendly, economical and effective as well as safe for non-target organisms and the environment. The present study aims to access the larvicidal efficacy of Ocimum gratissimum extracts against Anopheles species larvae. The Ocimum (scent) leaf methanolic extract was obtained using a cold method of extraction, the phytochemical investigation was studied using a simple qualitative analysis and a biological test to determine it larvicidal properties as per the WHO standard protocol. The percent yield of the methanolic extract from leaves of Occimum gratissimum was 8.14%. Presence of alkaloids, flavonoids, tannins, steroids, saponins, antraquinones, phenolics and glycosides have been observed. The biological test revealed that the methanolic extract from Occimum gratissimum has remarkable larvicidal properties with an LC50 and LC90 values of 4.28 and 24.40 mg/ml after a period of 72 hours respectively. This may offer great prospective as new control agents against Anopheles spp which is considered a threat to human health in the World especially Nigeria. The Ocimum gratissimum plant extracts tested in our study showed potent larvicidal properties that have potential to be developed as a natural insecticides.