Abstract
Bio-pesticides are certain types of pesticides derived from such natural materials as animals, plants, bacteria and certain minerals. The perfect pesticide is one, which is easily applied, reasonably inexpensive, non-toxic to non-target organisms, and eliminates the pest quickly before it becomes a threat. Certain types of bacteria have been developed to use as pesticides that are very close to perfect pesticide model and Bacillus was one of the most crucial and important genus (Rishikesh et al., 1983) in this connection, And also as a suitable replacement to chemical pesticides. 11 potent Bacillus spp. were isolated from different soil samples like garden soil, agricultural soil, animal dung contaminated soil etc. as a control strategy of mosquitoes larvae. This 11 potent isolates (B.t 1, B.t 2, B.t 3, B.t 4, B.t 5, B.t 6, B.t 7, B.t 8, B.t 9, B.t 10, B.t 11) were confirmed as Bacillus based on microscopic observation and biochemical characterization. Further parasporal crystal was observed by phase contrast microscopy and larvicidal protein was extracted, and it was quantified by Folin Lowery’s method. Isolate coded as B.t 1 showed highest protein concentration so it was use to check larvicidal activity against 2 types of larvae which was Aedes and Culex. The larvicidal activity (Which were measured by mortality rate and change in morphology of the larvae) was observed at 10-1, 10-2, 10-3, 10-4, 10-5 & 10-6 dilution Factors and at interval of every 2 hours. B.t 1 isolate which was confirmed as Bacillus flexus by 16S rRNA sequencing showed 100% mortality of both larvae at the highest concentration of 10-1 and 10-2 at 24 hours while 100% mortality was recorded in other dilution factors at 48 hours which was observed by change in morphology in phase contrast microscope. In control system (Distilled water) no mortality was recorded also after 72 hours. From this study, it is concluded that Bacillus flexus is a very potent biolarvicide that brings about mortality of mosquito larvae at short duration of time. The present study proved that the mosquitocidal properties of the Bacillus flexus isolated from soil was evaluated as target species of mosquito vectors. This is an ideal eco-friendly approach for the vector control programs.