Qualitative Phytochemical Screening and Larvicidal Efficacy of Physic Nut (Jatropha curcas) Leaves, Stem-bark and Root Extracts on Mosquito Larvae

Abstract

The advance of battle by mosquito species to artificial chemicals has obliged the unrelenting pursuit of nontoxic ones from plants. This study screened the qualitative phytochemicals and evaluated the larvicidal efficacy of extracts of Jatropha curcas leaves, stem-bark and root extracts against third and fourth mosquito instar larvae. The J. curcas obtained were subjected to extraction by maceration. Qualitative phytochemical screening of ethanolic stem-bark, aqueous and ethanolic root extracts plants showed the presence of phenols, saponins, steroids flavonoids, alkaloids, glycosides, carbohydrates and terpenoids. The aqueous extracts of the leaves and stem-bark showed the presence of alkaloids, cardiac glycosides, phenols, saponins, and terpenoids whereas, ethanolic leaves extract had similar phytochemicals with the leaves and stem-bark aqueous extracts but did not have steroids. Twenty-four (24) hours exposure of different concentrations (2.0mg/ml, 4.0mg/ml, 6.0mg/ml, 8.0mg/ml, 10 mg/ml) of various extracts showed that larval mortality increased significantly (P<0.05) with increase in extracts concentration. Aqueous stem-bark extract showed highest mortality with 87% against third mosquito instar larvae followed by aqueous, ethanolic root extracts against third and fourth mosquito instar larvae respectively with 85% larval mortality. However, least mortality was observed in ethanolic leaf extract with 5% larval mortality against fourth mosquito instar larvae. Low LC₅₀ and LC₉₀ values were noticed in ethanolic root and aqueous stem-bark extracts with 2.19mg/ml and 11.51mg/ml respectively. Whereas the highest LC₅₀ and LC₉₀ values were noticed in both ethanolic leaves extracts with 14.09mg/ml and 26.20mg/ml respectively against fourth mosquito instar larvae. Conclusively, aqueous stem-bark and ethanolic root extracts can be harnessed to control 50% and 90% mosquito instar larval mortality respectively. However, there is a need to ascertain the quantities of bioactive components of J. curcas and its toxicity to non-target organisms.