author(s)
Deepak T, Shashank AS, Dr. Shivaraj Y and Dr. Asiya Nuzhat FB

abstract
In this current situations the bacteria, Bacillus thuringiensis is a gram positive, rod shaped and aerobic soil bacteria. Bt is a bacterium that is not toxic to humans or other mammals but is toxic to certain insects when ingested. Bt works as an insecticide by producing a crystal-shaped protein (Cry toxin) that specifically kills certain insects. These bacteria produces a proteinaceous parasporal crystal in the sporangium at the time of sporulation. These proteins possess insecticidal properties and are called Bt-toxins or delta endotoxins and also called as insecticidal crystal proteins (ICPs). It is not a single toxin but a class of toxic proteins produced from protoxin that are degraded by proteolytic enzyme to form smaller toxic peptides. In this study the mosquito larva are considered as predators which feed on some protozoan’s and bacteria, the fixation of concentration levels to larva was 9 gm of (Serotype 14) Bt induced to 10 liter of water which contains 100 mosquito larvae. When these larvae feed on Bacteria, Bacillus thuringiensis it show behavioral changes like erratic swimming, slow motility and larva move towards the surface of water and regurgitation because of Bt-crystals effects on enzyme present in the larvae i.e. Cytochrome-c-Oxidases due to oxidative stress and the liberated crystal toxin like Cry-II and Cry-IV bind into the larva gut cell membrane it shows the slight histological changes also and it paralyzes the digestive tract and forming a pore in that regions and results in the death of the larva. This show the toxins nature of Bacillus thuringiensis bacteria against the mosquito larvae.