Which of the following is a biological control agent for mosquitoes?

The chosen answer, Bacillus thuringiensis israelensis (Bti), is recognized as a biological control agent for mosquitoes because it is a naturally occurring bacterium that targets and kills mosquito larvae in aquatic environments. Bti produces toxins that are specifically harmful to the larvae of certain insect species, making it an effective and environmentally friendly method for mosquito control. Unlike synthetic pesticides, Bti does not pose significant risks to non-target organisms, such as beneficial insects, fish, or other wildlife.

In contrast, Malathion, DDT, and Pyrethrin are all chemical control agents. Malathion and DDT are synthetic insecticides that are designed to kill a wide range of insects, including adult mosquitoes, but they can have detrimental effects on non-target species and the environment. Pyrethrin, derived from chrysanthemum flowers, targets a broader spectrum of insects and, while it is considered less toxic than some synthetic chemicals, it is still not classified as a biological agent. Thus, Bti stands out as a distinct biological control option for mosquito management.