The hornworm larvae feed off of coyote tobacco plants. Hornworms possess the cytochrome P450 6B46 which passes the nicotine from the midgut to the hemolymph, which can then be used on the exhale of the spiracles. Basically the caterpillar uses their nicotine induced halitosis to defend themselves from being eaten by wold spiders. This was validated by doing an experiment where cytochrome P450 6B46 was silenced in some larvae and left alone in others. Unfortunately, the silenced cytochrome P450 6B46 where eaten up by predators because they did not acquire bad breath. The larvae with functional cytochrome P450 6B46 where less likely to be consumed by predators. The original article by Pavan Kumar, Sagar S. Pandit, Anke Steppuhn, and Ian T. Baldwin can be found here.