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Savanna Journal of Basic and Applied Sciences 3(2):92-103
Larvicidal Activity and Lethal Concentrations of Nicotianna tabacum L. and Datura metel L. (Solanales: Solanaceae) on Mosquito Larvae
Yahaya, M.M., Bandiya H.M., Ladan M.U., and Ridwan N.A

ABSTRACT
Leaves and seed kernel extracts of Nicotina tabacum (L.) were assayed for larvicidal activity against 4th instar larvae of Aedes, Anopheles and Culex mosquitoes. Mosquito larvae of those genera were collected from breeding site and reared in the laboratory for continued source of larvae. The plants parts used were extracted with hexane, chloroform and methanol in increasing order of polarity. Each extract was formulated into 0.9, 1.6. 2.4. 3.5 and 4.0mg/mL concentrations and then tested against 25 larvae of each genus alongside control setting over 12 to 72 hrs periods. Phytochemical screenings of the most active extracts were carried out for searching the active ingredients. Data was analyzed through Analysis of Variance and lethal concentrations of the extracts were determined. The hexane extract of D. metel (LC50 2.58 ±0.1mg/mL) exhibited the highest larvicidal activity with more than 70% mortality on Aedes and Anopheles larvae when 4.0mg/mL was applied after 72hrs. Culex larvae were less susceptible to all concentrations of the extracts. Though larvicidal activity was observed to be indirectly proportional to concentrations and larval exposure periods, significant differences (p <0.05) in the means of larval death were observed. The active extracts were found to contain alkaloids, saponins steroids, flavonoids and glycosides from moderate to high quantity which could be responsible for larvicidal activity. Future formulation studies, toxicity profile and possible mechanism of action may lead to the development of potential insecticidal products