Insect Growth Regulators (IGRs) function by:

Insect Growth Regulators (IGRs) function by:

• A. They instantly kill pests on contact.
• B. They repel pests from treated areas.
• C. They block metamorphosis, preventing adulthood.
• D. They increase reproduction rates.

Answer: (C)

IGRs work by disrupting how the insect develops, not by killing it right away. They interfere with the hormones or processes that control metamorphosis, so immature pests can’t mature into adults. Some IGRs mimic juvenile hormone, keeping larvae in their immature stage, while others stop proper molting by inhibiting chitin synthesis. The result is fewer adults to reproduce, leading to long-term population suppression rather than immediate mortality. That’s why the correct statement is that IGRs block metamorphosis, preventing adulthood. They don’t instantly kill on contact, don’t repel pests, and don’t increase reproduction.

IGRs work by disrupting how the insect develops, not by killing it right away. They interfere with the hormones or processes that control metamorphosis, so immature pests can’t mature into adults. Some IGRs mimic juvenile hormone, keeping larvae in their immature stage, while others stop proper molting by inhibiting chitin synthesis. The result is fewer adults to reproduce, leading to long-term population suppression rather than immediate mortality. That’s why the correct statement is that IGRs block metamorphosis, preventing adulthood. They don’t instantly kill on contact, don’t repel pests, and don’t increase reproduction.