How do horticultural oils and insecticidal soaps work to control pests?

How do horticultural oils and insecticidal soaps work to control pests?

• A. They coat the insect and disrupt its ability to retain moisture.
• B. They destroy the insect's exoskeleton on contact.
• C. They block photosynthesis in the leaf tissue.
• D. They attract parasitoid wasps to the pest.

Answer: (A)

The main idea is that these pesticides kill pests by smothering and causing dehydration through a coating on the insect’s body. Horticultural oils lay a thin film over the insect, blocking spiracles and impeding respiration, which leads to water loss and death. Insecticidal soaps, which are fatty acid salts, spread on the insect and disrupt the waxy cuticle and cell membranes, also causing leakage and desiccation. Because the effect relies on contact, thorough coverage is essential and the products are most effective against soft-bodied pests. They don’t physically destroy the exoskeleton, they don’t block photosynthesis, and they don’t work by attracting parasitoids. So coating the insect and disrupting its ability to retain moisture is the correct explanation.

The main idea is that these pesticides kill pests by smothering and causing dehydration through a coating on the insect’s body. Horticultural oils lay a thin film over the insect, blocking spiracles and impeding respiration, which leads to water loss and death. Insecticidal soaps, which are fatty acid salts, spread on the insect and disrupt the waxy cuticle and cell membranes, also causing leakage and desiccation. Because the effect relies on contact, thorough coverage is essential and the products are most effective against soft-bodied pests. They don’t physically destroy the exoskeleton, they don’t block photosynthesis, and they don’t work by attracting parasitoids. So coating the insect and disrupting its ability to retain moisture is the correct explanation.