What are some common insect growth regulators used for mosquito control?

Insect growth regulators (IGRs) are substances that disrupt the development of insects, particularly in their larval stage, making them highly effective in mosquito control. Methoprene is a well-known IGR that mimics the hormones responsible for insect growth and development. When used in a briquette form, it can be introduced into water bodies where mosquitoes breed, effectively preventing larvae from maturing into adults and thereby reducing the overall mosquito population.

The other options listed are not classified as insect growth regulators. Permethrin and pyrethroids are types of synthetic insecticides that work by disrupting the nervous system of adult mosquitoes. Although effective in controlling adults, they do not interfere with the growth and development of larvae. Malathion is an organophosphate insecticide that also targets adult insects and does not have the same mode of action as an IGR. Therefore, methoprene briquettes are specifically categorized as IGRs and serve a different purpose in mosquito control compared to the other substances mentioned.