Phytochemical Screening and Larvicidal Activities of Some Ethnobotanicals from North Eastern Nigeria against Culicine (Dipera: Culicidae) Mosquito

This study was aimed to investigate the insecticidal activities of some selected ethnobotanicals against culicine mosquitoes. Various part of plant material collected were extracted using Soxhlet apparatus Methanol and Petroleum ether were used as solvents. Quantitative phytochemical Analysis for the crude extracts was carried out for the presence of azadrachtin, terpenoids, alkaloids, tannins, saponins, glycoside, steroids phenol and flavonoids. The larvicidal potentials of the various crude extracts were then tested against culicine mosquitoes.

More yields of phytochemical constituents (80.78 mg) were found in total of 900 g used for methanol extracts as compared to 57.64 mg found in 900 g used in petroleum ether extracts. All the extracts of methanol and petroleum ether of the different plant used showed larvicidal potentials against culicine 3rd instar larvae. The LC50 of the methanol extracts (37.32, 38.52, 42.05, 45.91, 68.78, 126.56, and 141.73 ppm) of E. globulus, O. kilimanscharicum, H. suaveolens, Neem seeds, neem stem leave and orange peels respectively, are far better than their counterparts of petroleum ether extracts with LC50 (100.25, 115.53, 145.88, 68.44, 114.55, 46.79, and 175.07 ppm). The larvicidal effect of individual isolates of alkaloids, tannin, saponins, azadirachtin, phenol and steroids demonstrated larvicidal potentials against 3rd instar larvae of culicine, where, terpenoids, flavonoids and glycoside showed no larvicidal potentials against culicine larvae. The larvicidal potential of each plant depend on the number of active ingredients and quantity available in each extract.

In conclusion, the present plant extracts have potentials for development of new and safe control products for culicine mosquitoes.