Bioinsecticidal Efficacy and Antioxidant Potency of Jatropha curcas and Ocimum gratissimum against Anopheles gambiae complex in Gombe State, Northeast Nigeria

Abstract

Background: Safer control measures against malaria vectors can address the problems of pollution and resistance from synthetic insecticides. This study aimed to determine the susceptibility of malaria vectors to methanolic leaf extracts of Jatropha curcas and Ocimum gratissimum and their antioxidant profiles. Methods: Fresh leaves of Jatropha curcas and Ocimum gratissimum were collected from Bajoga in northern Nigeria. The leaves were taxonomically identified and crude extracts were obtained. Larvae of Anopheles mosquito were reared to the adult stage and the adult females were used for the adulticidal bioassay. CDC bottles were coated with 0.2g/L to 0.8g/L methanol leaf extracts of the plants and 10 – 25 female Anopheles were introduced into each test bottle to observe mortality. Mortality was assessed at 0 hour, after 2 hours and after 24 hours. Lethal Concentrations and mortality were determined using LC⁵⁰ and LC⁹⁰.  Standard procedures were followed for qualitative and quantitative screening and antioxidant activity. Excel spreadsheet was used for data analysis. Results: Findings revealed adulticidal efficacy of Jatropha curcas and Ocimum gratissimum of 100% mortality with LC⁵⁰ value of 0.01g/L and LC⁹⁰ value of 0.4g/L after 24 hours against Anopheles gambiae. Qualitative phytochemical screening of the leaf extract of Jatropha curcas showed alkaloids, flavonoids, tannins, saponins anthraquinones, phenolics, and glycosides while that of Ocimum gratissimum had steroids in addition. The percentage inhibition of 2,2-diphenyl-1-picryl-hydrazyl-hydrate radical scavenging potential was dose-dependent. Ocimum gratissimum showed higher inhibition potency than Jatropha Curcas. Conclusion: The study reported adulticidal efficacy of the two plants which can be purified for controlling malaria vectors.