The bumble bees use nicotine to fight off parasites.

Bumblebees that have been infected by parasites seek out flowers with nicotine in the nectar, with the aim to fight off the infection. Nicotine slows the progression of disease in infected bees but has adverse effects when consumed by healthy bees. The bumblebees are not the only animal that uses nicotine as a defense mechanism, the house sparrows also relies on nicotine to fight off infection by using cigarette butts in their nests to ward off mites. Bumblebees infected with parasite always chose sugar solution with nicotine in it than one without, infected bumblebees that consumed nicotine delayed the progress of the infection for a few days, showing lower levels of parasites than those that had not taken the nicotine laced sugar solution.