Plant and insect functional traits influence herbivore performance under climate change

Climate change is expected to disrupt many trophic interactions, including those between insect herbivores and their host plants, which could have detrimental effects at the ecosystem level. However, the response of insect herbivory to climate change can vary widely across species, and an understanding of the mechanisms underlying this variation is lacking. Here we examine whether functional traits of insect herbivores and their host plants influence how climate change affects herbivore performance. Information on sixteen functional traits across 86 insect and 93 plant species were collated from values in literature and combined with a dataset of 109 climate manipulation studies measuring herbivore performance. We identified clusters within both plant and insect functional trait values which aligned closely with the fast‐slow continuum of ecological strategies (woody, perennial plants and chewing insects were larger and had greater longevity/slow development, while non‐woody, annual plants and sucking insects were smaller and had shorter longevity/fast development). We found that herbivores performed better on woody plants exposed to drought conditions or elevated temperatures, but not on non‐woody plants. Sucking insects performed worse on plants exposed to elevated CO 2 , while chewing insect performance did not appear to differ between plants exposed to ambient or elevated CO 2 . When insects were exposed to elevated temperatures, we found that both chewing and sucking insects performed better, but when both plants and insects were exposed to elevated temperatures, sucking insects performed worse and chewing insects performed better. Generally, we found insects with slower life history strategies appeared to be less vulnerable to climate change, while plants with slower life history strategies appeared to be more vulnerable. This research identifies key functional trait relationships that could enhance our ability to predict the vulnerability of plant–insect interactions to projected climate change and guide conservation efforts.