Bioactive potential of L. camara and O. gratissimum extracts in the control of mosquito larvae: An ecologically friendly approach

Abstract

In the present study, the larvicidal efficacy of the extracts of the weeds Lantana camara Linn (L. camara) and Ocimum gratissimum Linn (O. gratissimum) was evaluated against the larvae of the malaria vectors A. aegypti, An. subpictus, and C. quinquefasciatus. The ethanol, n-hexane and diethyl ether crude leaf extracts were evaluated in a preliminary screening for larvicidal activity at 20,40,80,160,320 and 640 mg/l concentrations. 20 larvae of each species were introduced in different sterile Petri dishes in aqueous media under a controlled environment to assess biological activity. The larvicidal activity of both extracts was evaluated at 6 and 12-h post-exposure time points by observing the movement of each larva. The obtained data were subjected to probit analysis to determine the lethal concentrations that kill 50% and 90% (LC50 and LC90) of the treated larvae. The results revealed a noticeable larvicidal activity following 12 h of exposure. The extract of L. camara leaves exhibited an LC50 range between 18.66 and 51.35 mg/l and an LC90 range between 87.78 and 312.21 mg/l. Moreover, for the extract of O. gratissimum leaves, the LC50 range was 52.26 to 59.09 mg/l and the LC90 range was 260.22 to 348.23 mg/l. Taken together, the results indicate that the extracts of L. camara and O. gratissimum leaves may be useful as effective, economical, and eco-friendly larvicidal agents. However, additional studies are needed to explore the bioactive components of the weeds that exhibit larvicidal activity along with their mode of action.