Where cry protoxin produced by Bacillus tthuringiensis is converted to active toxin in insect ?

The cry protoxin produced by Bacillus thuringiensis (Bt) is converted to an active toxin in the midgut of susceptible insect larvae due to the alkaline pH of the midgut.

The active toxin then binds to specific receptors on the midgut epithelial cells of the insect larvae and creates pores that disrupt the cell membrane, causing osmotic imbalance and ultimately leading to cell death. This results in the death of the insect larvae.