Effects of climate warming on host–parasitoid interactions

Parasitoids are key regulators of the population dynamics of their arthropod hosts, are integral to the structure and dynamics of food webs, and provide ecosystem services by suppressing agricultural pests. Despite their ecological and functional importance, relatively few studies have considered the effects of a warming climate on host–parasitoid interactions. The three primary modes through which parasitoids might respond to a warming climate are by (i) shifting distributions into cooler environments, (ii) altering phenology, and (iii) adjusting to persist in situ through phenotypic plasticity or evolutionary adaptation. Here, we focus on examples of altered distributions and phenology in response to climate warming. We suggest that the responses of parasitoids to elevated temperatures and the population dynamic consequences for their hosts will be linked to two key traits: the dispersal ability of both partners, and the host specificity of parasitoids. Effects of climate warming on host–parasitoid interactions will be complicated by interactions with other co-occurring environmental changes, such as elevated carbon dioxide and nitrogen, and to interactions with competitors, mutualists, and antagonists. These factors will complicate efforts to generate predictive models of host–parasitoid interactions, for example in the context of the ecosystem service of biological pest control.