Question

the newest class of insecticides is insect growth regulators. they control insects by ______.
a. poisoning them
b. killing their eggs
c. changing their normal growth cycle
d. all of the above

Explanation:

Insect growth regulators (IGRs) are a class of insecticides. Their mechanism of action is to interfere with the normal growth and development processes of insects, such as molting, metamorphosis, etc., rather than directly poisoning (option a is incorrect as they don't act like typical poisons) or specifically killing eggs (option b is not their primary mode; some may affect egg development indirectly but the main action is on growth cycle). So they control insects by changing their normal growth cycle.

Answer:

c. changing their normal growth cycle