Generalist and specialist lepidopteran larvae elicit different transcriptional responses in Nicotiana attenuata, which correlate with larval FAC profiles

Unlike generalist herbivores, specialists are believed to share a history of evolutionary interactions with their host plants. We determine whether a specialist lepidopteran species alters plant metabolism differently from two generalist species despite similarities in feeding mode and larval elicitors. With a cDNA microarray enriched in defence-related genes, we compared the transcriptional responses elicited in the native tobacco Nicotiana attenuata by the oligophagous larvae of Manduca sexta and the polyphagous larvae of Heliothis virescens and Spodoptera exigua, which are all members of N. attenuata's natural herbivore community. We found the differences in plant responses to be correlated with the profile of larval elicitors [fatty acid-amino acid conjugates (FAC)] and discuss how variation in FAC composition may shape the interaction between generalist or specialist lepidopteran larvae and plants.