Phyllotreta striolataflea beetles use host plant defense compounds to create their own glucosinolate-myrosinase system

Significance Associations of plants and herbivores are regarded as the result of coevolution, which has produced an astonishing diversity of plant defenses and corresponding insect counteradaptations. We focus on the leaf beetle Phyllotreta striolata , which is adapted to the glucosinolate-myrosinase system present in its cruciferous host plants. We show that P. striolata adults not only selectively sequester intact glucosinolates from their host plants but also express their own myrosinase, a member of the β-glucosidase family capable of hydrolyzing glucosinolates to form toxic degradation products. Our results reveal the convergent evolution of a glucosinolate-myrosinase system in P. striolata that enables this herbivore to use glucosinolate hydrolysis products for its own purposes.