Herbivory of a biocontrol agent on a native plant causes an indirect trait-mediated non-target effect on a native insect

Identifying food web linkages between biocontrol agents of invasive plants and native species is crucial for predicting indirect non-target effects. Biocontrol insects can integrate into food webs within recipient habitats and influence native insects through apparent competition (altering shared natural enemies) or density-mediated exploitation competition (changing density of native plants). However, whether and how trait-mediated exploitation competition (modifying native plant chemical defenses and volatiles profiles) can produce indirect non-target effects remains largely overlooked, despite plant phenotypic responses to insect herbivory being common and widely documented.

The beetle Agasicles hygrophila was introduced into China for management of weedy Alternanthera philoxeroides, but it also attacks the native congener A. sessilis, which may have indirect non-target effects on the native beetle Cassida piperata that also feeds on A. sessilis. Here, we examined the relationship...