Predicting plant-herbivore interactions using plant traits: Step to successful biological control

Background/Question/Methods

In spite of the high number of studies on plant-herbivore interaction we still have very little knowledge which would allow us to predict occurrence of plant-herbivore interactions based on plant and insect traits. This knowledge is, however, crucial for selection of optimal biocontrol agents and for evaluating possible dangers that they will attack other species. We work with plant species from Carduoidea subfamily. Many species from this subfamily are among the worst invasive plants in North America and biological control of these species is being implemented in several of these. We aim to predict the degree of herbivory by different groups of herbivores feeding on different plant parts based on wide range of plant traits. We use data collected on these plants collected both in the field and in the common garden conditions. The data collected in the common garden allow us to compare the interactions between plants and herbivores under exactly the same habitat conditions. We predict the interaction with herbivores using a wide range of plant traits and information on plant phylogenetic relationships. To predict plant damage in the field, we also use data on local habitat conditions.

Results/Conclusions

The results suggest that the degree of plant damage is phylogenetically constrained with some groups being more attacked by herbivores than others. The degree of plant leaf damage in the field can be best predicted by moisture of the habitat and specific leaf area of the plant. Both of these traits are also phylogenetically constrained and the relationships become non significant after phylogenetic correction. The specific leaf area and leaf toughness were significant predictors of leaf damage in common garden conditions.

In summary, the data indicate that plant traits allow predicting the degree of plant damage by herbivores. The plant traits as well as herbivore damage are, however, phylogenetically constrained. The relationship between plant traits and herbivore damage can thus be also due to other phylogenetically constrained traits correlated with those under study.