HORTICULTURE

Detailed explanation-1: -Bt toxins are initially inactive protoxins but after ingestion by the insect these inactive toxins become active due to the alkaline pH of the gut which solubilizes the crystals. Hence, high pH value is required to make Bt toxins active.

Detailed explanation-2: -The alkaline pH (8.6 approximately) of the gut in insects triggers activation of protoxin ( inactive crystallized form) to active Bt toxin after ingestion.

Detailed explanation-3: -Spores made by Bt damage the gut of insect larvae after the larvae eat them. The insect gut must have a pH of 9.0 to 10.5 (high pH) in order to activate the toxin.

Detailed explanation-4: -The Bt toxin is a crystal protein produced by the bacterium Bacillus thuringiensis through the process of sporulation. Initially, these protoxins are inactive after ingestion by the insect, changing the environment, which has to have high pH of the gut or alkaline pH, making them active.