Chemicals in the class pyrrole, thiourea, and quinazoline are showing great promise as pesticides that inhibit energy production. These chemicals are typically referred to as insect growth regulators or IGRs. IGRs act on the endocrine or hormone system of insects. These insecticides are specific for insects, have very low mammalian toxicity, are nonpersistent in the environment, and cause death slowly. Most of the currently registered IGRs mimic the juvenile hormone produced in the insect brain.
Juvenile hormone tells the insect to remain in the immature state.
When sufficient growth has occurred, the juvenile hormone production ceases triggering the molt to the adult stage. IGR chemicals, such as hydroprene, methoprene, pyriproxyfen, and fenoxycarb, mimic the action of juvenile hormone and keep the insect in the immature state. 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.