How can plant isoprenoids interfere with the development of insects that eat the plants?

Certain plants produce isoprenoids that function as a defense mechanism by interfering with the development of insects that feed on them. These plant-derived substances are chemically similar to the juvenile hormones that regulate an insect's growth and maturation.12

Insects require these hormones to be present during larval development but must have them absent during the critical transition from larva to adult. When an insect consumes a plant containing these interfering isoprenoids—specifically certain terpenes found in plants like evergreen trees and ferns—the compounds disrupt this hormonal balance. This interference prevents the insect from reaching sexual maturity, effectively stopping the larvae from developing into functional adults or preventing eggs from hatching. By inhibiting the maturation process, these compounds serve as a natural chemosterilant, protecting the plant from further predation.21