Phytochemical Composition and Larvicidal Activity of Sida acuta Oil Extract Against Aedes aegypti Larvae

Mosquito-borne diseases remain a major public health challenge globally, necessitating the search for eco-friendly alternatives to synthetic insecticides. Thus, this study investigated the phytochemical composition and larvicidal activity of Sida acuta leaf oil extract against Aedes aegypti larvae under varying treatments. Whole plant samples were collected in the morning (0600–0700 hours) and evening (1800–1900 hours), thereafter, identified, air-dried, then ground into fine powder, and extracted using n-hexane for a standing period of three days. Phytochemical constituents were determined using standard qualitative and quantitative methods. Eggs of Ae. aegypti mosquito were hatched in the laboratory during which the reared first-instar larvae of Ae. aegypti were exposed to varying concentrations of the oil extract at 12.5, 25, 37.5, 50, 62.5, and 125 ppb, respectively. Larvae knocked-down within the first hour exposure period were recorded immediately, and thereafter mortality was monitored at 24, 48, and 72 hours, respectively, post-exposure. Our qualitative analysis indicated high levels of alkaloids, steroids, and phenols, while flavonoids, tannins, and glycosides were present in low concentrations. Terpenoids were detected at low level in morning collection extract but were absent in evening extract. Anthraquinones and saponins were not detected in both time of day extracts. Quantitative screening confirmed the presence of flavonoids, phenols, tannins, alkaloids, saponins, terpenoids, cyanides, oxalates, and phytates. Larvicidal testing revealed lowest mortality rate of 1% for the morning extract in 50 ppb treatment and highest mortality rate of 3% for the evening extract in 62.5 ppb treatments after 72 hours exposure period. No significant difference (P > 0.05) was observed in the mortality rate in relation to treatments as well as between times of day. These findings demonstrate that Sida acuta leaf oil extract contains various bioactive phytochemicals. The larvicidal efficacy of Sida acuta against Ae. aegypti under the tested conditions was quite low which implies resistance but a more efficacious larvicidal activity maybe observed in the near future with increase in concentrations. In conclusion, Sida acuta leaf oil extract is a potential plant-based biopesticide for use in mosquito vector control.