Responding positively to plant defences, a candidate key trait for invasion success in the New Zealand grass grub Costelytra zealandica
Occasionally, exotic plant introductions lead to the emergence of an invasive insect within its native geographical range. Such emergence could be explained by a pre-adaptation of the insect to break through the defences of the new encountered host. We investigated the fitness responses of two New Zealand endemic scarabs (Costelytra brunneum and C. zealandica) when given a diet of an exotic pasture species, Trifolium repens, whose defences were artificially triggered by the phytohormone jasmonic acid.