Q.Bacillus thuringiensis plays an important role in Integrated Pest Management strategy. Explain how. Name any two crops that are protected efficiently from pests.
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Start your 14-day free trial to unlock the full solution →The bacterium Bacillus thuringiensis (Bt) produces a protein toxin that kills specific insect pests without harming beneficial organisms, making it a cornerstone of Integrated Pest Management (IPM). Two crops efficiently protected by Bt are cotton and maize.
Integrated Pest Management, or IPM, is not about wiping out every insect in the field. It is a smarter, more sustainable strategy that combines biological, chemical, and cultural methods to keep pest populations below the level where they cause economic damage. The goal is to minimise the use of broad-spectrum chemical pesticides, which often kill natural predators and pollinators, and lead to pest resistance. This is where Bacillus thuringiensis enters the picture as a biological weapon.
Bacillus thuringiensis is a soil-dwelling bacterium that, during sporulation, produces a crystalline protein called the Bt toxin. What makes this toxin remarkable is its specificity. When certain insect larvae ingest the bacterium, the alkaline conditions in their gut dissolve the crystal, releasing a protein that binds to specific receptors on the gut wall. This creates pores, causing the gut to rupture and the insect to die. The key point is that the toxin is harmless to humans, most beneficial insects, birds, and other animals because their gut environment or receptor sites are different.
The Bt toxin is not a general poison. It is highly specific to certain orders of insects, particularly Lepidoptera (caterpillars), Coleoptera (beetles), and Diptera (flies). This specificity is what makes it ideal for IPM.
In the IPM framework, Bt is used in two main ways. First, as a spray formulation — farmers can apply a suspension of Bt spores and crystals directly to crops. This is a biological pesticide that targets the pest without nuking the entire ecosystem. Second, and more famously, the gene responsible for producing the Bt toxin has been isolated and introduced into crop plants themselves. These are the Bt crops, such as Bt cotton and Bt maize. The plant now produces the toxin in its tissues, providing built-in protection from the inside out. …
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