BACILLUS THURINGIENSIS: THE BIOCONTROL AGENT IN A FOOD WEB PERSPECTIVE

Abstract

Bacillus thuringiensis (Bt) is a facultative anaerobic, motile, gram-positive, spore-forming soil bacterium. The spores have parasporal inclusions made of different insecticidal crystal proteins (ICP), predominantly comprising one or more Cry and ⁄ or Cyt proteins (also known as δ-endotoxins) that have potent and specific insecticidal activity. The insecticidal properties of Bt have been known for over a century and commercial products based on this organism have been available for 70 years, occupying >90% of the biopesticide market. The microbe formulations have great potential in IPM programmes as has become the leading biopesticide in commercial agriculture, forest management and mosquito control. This bacterium is also a key source of genes for transgenic expression to provide pest resistance in plants and microorganisms as pest control agents in genetically modified organisms. Bt may persist as a component of the natural microflora after application to an ecosystem. Owing to their specific mode of action, Bt products are unlikely to pose any hazard to vertebrates or to the great majority of nontarget invertebrates. Yet many carnivorous arthropods and other non target organisms come into contact with Bt toxins not via target herbivore, but via nontarget herbivores.. Understanding its role in the ecosystem is crucial in deriving the best out of this great biocontrol agent.