Consequences of Climate Change for Aphid-Based Multi-trophic Systems

Climatic models predict a 1.7–4.9◦C increase in mean global temperatures from 1990 to 2100. In ecosystems in general, multitrophic interactions often result from a long co-evolutionary process specific to a particular environment and relatively stable climatic conditions. Temperature changes may differentially affect the biology of each of the component species of a system: for example, the herbivores, their natural enemies (parasitoids, predators and pathogens), and hyperparasitoids. The endosymbionts of these different insects are also affected, and their functions can be altered by temperature increase. Such effects could destabilise system dynamics even lead to extinctions. The effects of climatic change are likely to be relatively more important in higher trophic levels that depend on the capacity of lower trophic levels to adapt to these changes. This paper addresses the effects of climate on insect communities, focusing on aphids, aphids parasitoids and predators, and hyperparasitoids. For each trophic level, the general effect of temperature change on insects is discussed, with emphasis on species belonging to aphid-based communities. The effects of climate change on communities can be short-term or long-term. Short-term consequences include the direct effects of temperature on different life history traits such as development time (which affects the annual number of generations), metabolic rate (which affects activity levels, longevity, and fecundity), and sex allocation. Potential effects on endosymbiont survival, virus transmission, geographical distribution of species and phenological synchronisation between trophic levels are also discussed. Long-term effects involve genetic changes in populations associated with climatic adaptations