Transcriptome Responses in Herbivorous Insects Towards Host Plant and Toxin Feeding

Food source is a major determinant of physiological performance and a strong selection force for insect herbivores. The ability to adequately respond to chemical challenges posed by their host plants is the primary determinant of larval fitness. Most herbivorous insects must consume large quantities of plant material to meet their nutritional requirements and, at the same time, cope with numerous mechanical, chemical and protein-based defenses posed by their sessile hosts. Despite the importance of host plants on essential life history traits of insect herbivores, data on global responses to both individual plant-derived compounds and plant feeding is scarce. Here we discuss the existing data on herbivore responses to host plant exposure, toxin feeding or nutrient limitations and make an attempt at identifying changes in genome-wide expression patterns of generalist and/or specialist herbivores. While generalists face an array of different plant defenses, and therefore likely need to invest in broad detoxifying strategies, specialist herbivores need to fine tune their adaptation to specific plant defenses.