Insects treated with these chemicals are unable to molt successfully to the adult stage, and cannot reproduce normally. These chemicals are known as chitin synthesis inhibitors or CSIs. They are often grouped with the IGRs. The most notable chemical being used as a CSI is the benzoyphenyl ureas. These chemicals inhibit the production of chitin.
Chitin is a major component of the insect exoskeleton.
Insects poisoned with CSIs are unable to synthesize new cuticle, thereby preventing them from molting successfully to the next stage. Insecticides Affecting Water Balance Insecticides with this mode of action include boric acid, diatomaceous earth, and sorptive dusts. Insects have a thin covering of wax on their body that helps to prevent water loss from the cuticular surface. Therefore, when an insect contacts one of these chemicals it absorbs the protective waxy covering on the insect resulting in rapid water loss from the cuticle and eventually death from dessication. Unfortunately, insects that live in environments with high relative humidities, or that have ready access to a water source, show an increased tolerance to silica aerogels and diatomaceous earth.