[01] Bello A., Department of Microbiology, Faculty of Science, Ahmadu Bello University, Zaria, Nigeria. [02] Machido D. A., Department of Microbiology, Faculty of Science, Ahmadu Bello University, Zaria, Nigeria. [03] Inabo H. I., Department of Microbiology, Faculty of Science, Ahmadu Bello University, Zaria, Nigeria.

Application of chemical insecticides poses a wide range of problems in the environment. In addition to this, these chemicals are non specific and are implicated as carcinogens. All these necessitated the search for an eco-friendly biological alternative for the control of insect pests and vectors in environment such as the use of Bacillus thuringiensis known to habour insecticidal crystals. Bioassay to assess the insecticidal activity of the isolates was carried out on Aedes aegypti larvae using 3 different concentrations of spore crystal mixture (100, 75 and 50 ppm) alongside one control. In each case, 10 larvae were exposed in triplicates for Aedes aegypti. The mortality range of Aedes aegyti was between 40.00% and 100.00%. The concentrations of the spore crystal mixture which kill 50% of the exposed populations in standard bioassays (LC₅₀) were determined by probit analyses. The LC₅₀ using was between 118.03ppm and 55.79ppm. The results of this research shows that the isolates from the soils in Zaria can serve as biocontrol agent for the control of mosquito by targeting their larvae stage hence controlling the diseases they spread.

Larvicidal, Bacillus Thuringiensis, Aedes Aegyti, Biocontrol, LC ₅₀

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