Nicotine can disrupt the nervous system of insects, rendering them infertile, disrupting motor function, and brain function.

“It can render them infertile, which is not to say that it renders humans infertile. We want to say, again, it is not the case that nicotine renders humans infertile, but it can make certain insects infertile. It can actually disrupt their motor function and their brain function, and the reasons that it has such different effects on insects, in other words, it can kill them or prevent them from reproducing, and therefore explains why plants probably evolved to have this plant alkaloid, nicotine.”