Overcompensating plants: their expression of resistance traits and effects on herbivore preference and performance

Overcompensation is a plant tolerance response in which plants have higher fitness after herbivory than without damage. Although it has been demonstrated that plants are able to simultaneously express resistance and tolerance traits, it remains unclear whether overcompensating plants are also inducing resistance-mediating secondary metabolite production and how herbivores perform on plants that overcompensate. Our previous work has shown that a potato variety [Solanum tuberosum L. cv. Pastusa Suprema (Solanaceae)] from Colombia can express overcompensatory responses to damage by larvae of the Guatemalan potato moth, Tecia solanivora Povolny (Lepidoptera: Gelechiidae). Here we investigated (1) whether potatoes that express overcompensatory responses also induce resistance traits and (2) how the previous damage affects Guatemalan potato moth preference and performance. Our results show that larval feeding not only systemically induces higher tuber biomass but also an increased production of resistance-related compounds, such as phenolics and proteinase inhibitors. Pupal mass increased with increasing tuber size, whereas changes in tuber secondary metabolism did not correlate with any metric of larval performance. Oviposition preference did not change between induced and undamaged plants. Our data show that potato plants expressing overcompensatory responses also induce secondary compounds known to increase resistance against herbivores. However, the induced response was relatively small, reducing the opportunities for a negative effect on the herbivore. Hypotheses for why larvae perform better in larger tubers and are not affected by the secondary metabolism are discussed. From an ecological and agricultural point of view, our results suggest that the expression of overcompensatory traits could have positive effects on herbivore performance.