Mosquito Larvae Biocontrol Potential of Bacillus Thuringiensis Isolated from Soil Samples

Abstract

Mosquitoes as vectors have been transmitting several etiological agents of important human diseases, including malaria, causing millions of deaths every year. Overcoming insecticide resistance becomes a lingering challenge for recording a successful Mosquito control. In this research work, Larvicidal potential (LP) of Bacillus thuringiensis isolated from different soil samples were tested as a control strategy of Mosquitoes and monitoring of larvae susceptibility. Mosquito larvae were assessed by isolation from different soil habitats in Yobe State. Confirmation of the isolated organisms to be Bacillus thuringiensis was based on biochemical characterization and microscopic observation. Two out of the five isolates of Bacillus thuringiensis obtained from the soil samples labeled P1 and Ga2 were used for carrying the study. At the intervals of 4, 12 and 24 hours, the Larvicidal activity (LA) on the mosquito larvae (which were measured by mortality rate and change in morphology of the larvae) were observed and recorded at 10-1 , 10-2 , 10-3 , 10-4 , and 10-5 dilution factors. The isolates of Bacillus thuringiensis showed a slight level of variation in their LA. Both isolates P1 and Ga2 caused 100% mortality of the larvae at the highest concentration of 10-1 at 4 hours while 100% mortality was recorded in other dilution factors at 12 hours. From this study, it is concluded that Bacillus thuringiensis is a very potent biolarvicide that brings about mortality of mosquito larvae at a short duration of time.