The Bt toxin in Bt crops kills insects by:

The Bt toxin is produced by the bacterium Bacillus thuringiensis and is used in genetically modified (Bt crops) to protect against insect pests. When insects consume Bt toxin, it is activated in their alkaline gut environment. The toxin binds to specific receptors on the gut epithelial cells, leading to the formation of pores (holes) in the cell membrane. This causes leakage of cellular contents, disrupting osmoregulation and eventually leading to gut paralysis and insect death.