Which insect pathogen is known to stop digestion in insects?

The correct choice is Bacillus thuringiensis var. israelensis (Bti), which is well-known for its specific action against certain aquatic insects, particularly mosquito larvae. When ingested by these insects, Bti produces a toxin that disrupts the normal digestive processes. This action leads to paralysis and eventual death, which effectively stops the insect’s ability to digest food and survive.

Bti's efficacy is largely due to its life cycle and environment; it thrives in water, making it ideal for targeting pests in aquatic settings. Unlike some other strains of Bacillus, Bti does not impact other non-target organisms significantly, providing a targeted approach for pest control in aquatic ecosystems.

The other choices do not have the same specific impact on digestion in insects. For example, Bacillus cereus is a broad-spectrum bacterium that can cause food poisoning in humans and does not primarily target insects, while Bacillus subtilis is more commonly associated with soil and plant interactions rather than insect pathology. Bacillus anthracis, known for causing anthrax, is not involved in pest control and poses a much greater risk to mammalian health than to insect populations. Thus, Bti is the only choice that aligns with the context of stopping digestion in aquatic insects