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How has the bacterium Bacillus thuringiensis helped us in controlling caterpillars of insect pests?

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Bacillus thuringiensis (Bt) is a widely employed biological control agent within the realm of agriculture, renowned for its pesticidal efficacy. This bacterial species synthesizes a crystalline protein, namely an endotoxin, which exhibits negligible harm to humans, animals, and beneficial organisms, yet poses significant toxicity to specific insect pests, particularly those of the caterpillar order.

The Mechanism of Bt Action:

1. Production of the Endotoxin: Bt organically generates an endotoxin, which remains inert to non-target species due to its specialized mode of operation.
2. Ingestion by Caterpillars: Upon feeding on treated foliage, caterpillars unknowingly ingest this endotoxin, thereby introducing it into their digestive tract.
3. Activation in Alkaline Conditions: The alkaline environment of the caterpillar's gut catalyzes the endotoxin's activation, a prerequisite for its pesticidal action.
4. Binding and Disruption of Intestinal Lining: The activated endotoxin connects to distinct receptors present on the caterpillar's gut epithelium, precipitating cell lysis and thus compromising the integrity of the gut barrier.
5. Consequent Pest Mortality: As a result of the disrupted intestinal lining, the caterpillar's ability to digest food is severely impaired, leading to starvation and ultimately death. This process contributes to the diminution of the pest population and the preservation of crops.

Posted by

Gurleen Kaur

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