Which statement about insect growth regulators is true?

• A. They only affect adults
• B. They only affect immatures
• C. They have no effect
• D. They affect both adults and immatures

Answer: (D)

Insect growth regulators work by interfering with the hormonal controls of insect development and reproduction. Because these hormones govern processes in both immature stages (like larval molting and metamorphosis) and adult reproductive function, IGRs can produce effects across life stages. Some products disrupt immature development so insects never reach the adult form, while others can reduce adult fecundity or hatch rates. Because of these broad or stage-spanning effects, the statement that IGRs affect both adults and immatures is the accurate one.