Insect Detoxification and Sequestration Strategies

Plants defend themselves from insect herbivores with a vast array of chemical defenses, yet insects have evolved several mechanisms for detoxifying these and even sequestering them for their own use. Gene duplication within the large cytochrome P450 gene family plays diverse roles in detoxification, employing fine-tuning of substrate specificity, transcriptional control, and insensitivity to plant-derived P450 inhibitors. Multiple mechanisms exist for avoiding activation of glucosinolates and cyanogenic glucosides, and sequestering or even synthesizing the latter. Housekeeping enzymes have been re-directed to novel detoxicative functions. Often the primary molecular target of the plant toxin has mutated to a less sensitive form; multiple parallel evolutionary responses of this type can be seen in communities of herbivores consuming plants posing the same chemical challenges. These and other mechanisms have enabled insects to continue to exploit plants for food throughout the long history of their coevolutionary struggle.