INFLUENCE OF NEOBACILLUS NIACINI ON ADULT MOSQUITO NUTRITIONAL RESERVE

Mosquitoes remain among the most important vectors of human diseases, transmitting pathogens responsible for malaria, dengue, yellow fever, filariasis, and other infections. Conventional insecticides, though widely used, have led to widespread resistance in mosquito populations and created environmental and health concerns. This study examined the influence of Neobacillus niacin on the nutritional reserves and detoxifying enzyme activities of adult Culex mosquitoes reared from larvae exposed to Neobacillus niacin. Culex larvae were collected from New York Bosso Campus, Minna, Niger State, and reared under controlled laboratory conditions. Fourth-instar larvae were treated with Neobacillus niacin at concentrations of 0.5 mL and 1 mL, while untreated larvae served as the control. Upon emergence, adult mosquitoes were analyzed for lipid, glucose, glycogen, and protein contents, as well as esterase and glutathione-S-transferase (GST) enzyme activities. The biochemical assays revealed a notable depletion of major nutritional reserves in adults that had been exposed as larvae. Lipid content decreased from 32.18 µg/mosquito (0.5 mL) to 35.79 µg/mosquito (1 mL), glycogen from 32.96 µg to 33.12 µg, protein from 27.32 µg to 26.32 µg, and glucose from 25.94 µg to 17.62 µg. Esterase activity increased from 163.46 to 201.24 nmoles 1-naphthol/min/mg protein, while GST activity declined from 0.40 to 0.27 mM/min/mg protein, indicating metabolic stress. Mortality reached 100% within three days of exposure, and survivorship decreased below 30%. These findings suggest that Neobacillus niacin exposure during larval development significantly disrupts adult mosquito metabolism, depleting energy reserves and impairing enzyme functions. The study concludes that Neobacillus niacin possesses strong entomopathogenic potential and can serve as an effective biological control agent for managing Culex mosquito populations.