Assessment of larvicidal activities of bacillus species isolated from soil against the mosquito aedes aegyptia (diptera: culicidae) in Sokoto, northwestern Nigeria

Three Bacillus species ( B. cereus , B. sphaericus and B. thuringiensis ) known to have potentials for mosquito larvicidal properties were tested against Aedes mosquito larvae. The Bacillus species showed pronounced larvicidal activities with B. cereus having 60% mortality, B. sphaericus 84% and B. thuringiensis 56% against the mosquito tested. The lethal concentrations (LC 50 ) determined were 0.033, 0.033 and 0.029 for B. cereus , B. sphaericus and B. thuringiensis respectively. Aedes mosquitoes were more sensitive to B. thuringiensis than to other Bacillus species with determined potency of 827 ITU/mg. These results compared favourably with that of the standard B. thuringiensis from Paris, France, which recorded 100% mortality against the mosquito. There was no significant difference (P > 0.05) between the local isolates but variation exists (P < 0.05) when compared with the standard B. thuringiensis powder. Post experimental analysis using the Least Significant Difference test (LSD = 16.84) showed that the standard strain stands out different from the other three isolates. These findings strengthen the earlier reports that B. thuringiensis is a good control agent for Aedes mosquito. There is, however, the need to continue further search for Bacillus species with larvicidal potentials. Keywords : Bacillus Species, Larvicidal Activity, Soil, Sokoto, Aedes Mosquitio.