Do herbivores use chemical camouflage against their plant prey?

Because plants are unable to move or otherwise physically evade attack by slugs and other herbivores, they have evolved chemically based defenses against herbivory. These include both constitutive defenses and inducible ones that plants activate in response to a threat. While plants are generally thought to respond to herbivores after being attacked, there is also increasing evidence that plants can detect and respond to herbivore cues such as kairomones, non-attack related substances produced by a predator that benefit its prey. Slugs and snails are important herbivores both in managed and natural ecosystems. They move using locomotion mucus, a complex mixture of bioactive compounds whose composition varies between species. While locomotion mucus from the slug Arion subfuscus alters Brassica nigra germination speed as well as seedling biomass and subsequent herbivory, we do not know whether mucus from other mollusk species will have similar effects. This is important since mucus from the slug Deroceras reticulatum, a major agricultural pest, contains salicylic acid, a hormone that prevents the induction of jasmonic-acid-mediated plant defenses against chewing and rasping herbivores. We used B. nigra as a model system to assess plant responses (measured as germination rate and speed) to locomotion mucus from D. reticulatum and seven other mollusk species that co-occur with B. nigra in southern New England. Seeds were exposed via mucus-laden moist dirt (treatment) or moist dirt only (control). We hypothesized that while mucus from most mollusks would alter germination, D. reticulatum mucus would not.