Name an effective larviciding agent used in vector control.

Bacillus thuringiensis israelensis (Bti) is an effective larviciding agent used in vector control because it specifically targets the larvae of certain mosquito species. Bti is a naturally occurring bacterium that produces toxins harmful to aquatic insect larvae, particularly those of mosquitoes and black flies, while being safe for humans, animals, and beneficial insects. This specificity is crucial in integrated pest management, as it allows for control of mosquito populations without harming non-target species or disrupting the ecosystem.

Using Bti as a larvicide provides a biological control method that can be applied in various water bodies where mosquito breeding occurs. It is effective even in low concentrations and has a relatively short residual activity, meaning it does not persist in the environment longer than necessary. This makes it an excellent choice for controlling vector populations without contributing to long-term chemical resistance, as might occur with other insecticides that target adult insects directly.

In contrast, the other options are chemical insecticides that may not specifically target larvae or could have broader ecological impacts, including toxicity to non-target species.