Induced Plant Resistance and Susceptibility to Late-Season Herbivores of Wild Radish

Wild radish is an annual plant that exhibits broad spectrum induced resistance to herbivores. In two experiments, we placed potted plants [control, manually clipped, and damaged byPieris rapae(L.) larvae] in the field and assayed for oviposition byP. rapae(a specialist herbivore), damage by flea beetles (a specialist herbivore), and damage by rabbits (a generalist herbivore). Induced responses attracted oviposition byP. rapaeand increased damage by flea beetles, while having a minimal effect on rabbit herbivory. Plant families had different levels of resistance to herbivory by rabbits and to oviposition byP. rapae,but not to herbivory by flea beetles. Manual clipping was a poor inducer of plant responses. Induced responses in wild radish can be a double-edged sword, increasing herbivory by some herbivores under certain conditions, while reducing herbivory by other herbivores.