Bacillus thuringiensis (Bt) is a bacterium used as a microbial biocontrol agent or bio-pesticide. It produces toxic protein crystals (Cry proteins) that kill specific insect pests like lepidopteran larvae (caterpillars), coleopterans (beetles), and dipterans (flies, mosquitoes). It is widely used in agriculture either as sprays (spores) or through transgenic crops (Bt cotton) to control insect pests , , .