Which type of pesticide manipulates hormone levels to disrupt normal insect development?

Insect growth regulators are specifically designed to disrupt the normal hormonal processes involved in insect development and metamorphosis. These substances mimic natural hormones or interfere with hormone signaling pathways. As a result, they can prevent insects from growing or maturing properly, effectively reducing their populations by hindering their life cycle.

The other types of pesticides listed do not primarily function through hormonal manipulation. Neonicotinoids act on the nervous system of insects, causing paralysis and death. Organophosphates also affect the nervous system, inhibiting enzymes that break down certain neurotransmitters. Pyrethroids are synthetic chemicals that likewise target the nervous system, causing nerve overstimulation. None of these mechanisms involve disrupting hormonal levels, which is the defining characteristic of insect growth regulators.