Endure and call for help: strategies of black mustard plants to deal with a specialised caterpillar

Plants have evolved inducible resistance and tolerance mechanisms against insect herbivores. Resistance mechanisms that affect herbivorous insects directly can be effective against generalist herbivores, but will not deter specialist herbivores from attacking the plant. Tolerance mechanisms and indirect plant resistance are more likely effective strategies used by plants when dealing with specialist herbivores. However, inducible indirect resistance and tolerance mechanisms have rarely been investigated within the same study system.
We studied multiple tolerance mechanisms and the role of natural enemies in reducing fitness loss of Brassica nigra plants incurred by feeding by the specialist herbivore Pieris brassicae. For this, we measured the changes in carbon and nitrogen triggered by herbivore attack and quantified plant biomass and seed production under field conditions, in the presence or absence of natural enemies of the herbivores. We also assessed whether B. nigra increased sel...