Sequestration of plant-derived glycosides by leaf beetles: A model system for evolution and adaptation

Leaf beetles have developed an impressive repertoire of toxins and repellents to defend themselves against predators. Upon attack, the larvae discharge small droplets from glandular reservoirs on their back. The reservoirs are “bioreactors” performing the late reactions of the toxin-production from plant-derived or de novo synthesised glucosides. The import of the glucosides into the bioreactor relies on a complex transport system. Physiological studies revealed a functional network of transporters guiding the glucosides through the larval body into the defensive system. The first of the involved transporters has been identified and characterised concerning selectivity, tissue distribution, and regulation. The development of a well-tuned transport system, perfectly adjusted to the compounds provided by the food plants, provides the functional basis for the leaf beetle defenses and their local adaptation to their host plants