Nontarget Herbivory by a Weed Biocontrol Insect is Limited to Spillover

The biocontrol weevil Mogulones crucifer, released in Canada since 1997 but not approved in the USA, is known to sporadically use native nontarget relatives of its target weed for feeding, oviposition, and larval development. Catton et al. released M. crucifer in outbreak densities in patches of mixed target and nontarget plants and nontarget plants in isolation from the target weed to determine if this nontarget herbivory is a spillover effect, or if the weevil establishes and sustains populations on the native plant.