In vitro Bioactivity Evaluation of Ziziphus mauritiana Lam. (Bidara) Leaves Extract against Vector Mosquitoes Aedes spp. and Culex quinquefasciatus

Abstract

Ziziphus mauritiana methanol crude extract was evaluated for its insecticidal properties against Aedes aegypti, Ae. albopictus, and Culex quinquefasciatus mosquito larvae. Bioassays against larvae mosquitoes were done following World Health Organization’s guidelines. Late third and/or early fourth instar of mosquito larva were assayed for five different concentrations viz. 100, 150, 200, 250, and 300 mg ml–1 of Z. mauritiana crude extracts. From the results obtained, Aedes aegypti was the most susceptible to Z. mauritiana crude extracts. The percentage of mortality exhibited above 50% of 200, 250, and 300 mg ml–1 in 24, 48, and 72 hr exposure. Thus, it gives the lowest LC50 within 24 hr of exposure (121.98 mg L–1), followed by Ae. albopictus (189.89 mg L–1) and Cx. quinquefasciatus (246.22 mg L–1). Observation of the morphology effect of the dead larvae shows Ae. aegypti was the most affected, followed by Ae. albopictus and Cx. quinquefasciatus. A ruptured midgut was observed in 100 and 200 mg ml–1 concentrations. In contrast, in higher concentrations of 300 mg ml–1, the abdominal segments were indistinguishable, and the head and thorax regions were severely damaged. This study suggested that Z. mauritiana methanolic crude extracts were potent against Ae. aegypti larvae mosquitoes and have the potential to be used as an alternative larvicide in population control. However, further studies are required to establish the potential of Z. mauritiana larvicidal effects in the field setting.