Climate Change Impacts: Insects

Abstract Climate exerts powerful effects on the distribution and abundance of the earth's insect species, and we should expect climate warming to generate changes for many insect populations and the ecosystems they inhabit. A substantial scientific literature provides a foundation for describing how insect species are responding to recent climatic trends on the basis of insect physiology, and predicting generalised species distributions and population dynamics for the future. Warmer temperatures generally lead to more rapid development and survival in insects in mid‐ to high latitudes, which can account for detectable and unambiguous shifts in a range of insect species over the past half century. Increased warmth also advances the onset of insect life cycles for the many species that use thermal cues to match the timing of life history events with the changing seasons. Owing to their relatively short life cycles, high reproductive capacity and high degree of mobility, insects’ physiological responses to warming temperatures can also generate particularly large and rapid effects on species population dynamics. Key Concepts: Warmer temperatures associated with climate changes will tend to influence (and frequently amplify) insect species’ population dynamics directly through effects on survival, generation time, fecundity and dispersal. Individual insect species’ responses to climate change, however, will depend on their geographic range, trophic level and natural history. Insect populations in mid‐ to high latitudes are expected to benefit most from climate change through more rapid development and increased survival. Much less is known about the effects of increased warming on tropical insect species. Insect species’ mortality may decrease with warmer winter temperatures, thereby leading to poleward range expansions. The physiological effects of climatic warming on insects species can also act indirectly through trophic interactions (i.e. host plants and natural enemies). Insects feature prominently among the documented range expansions that illustrate biological responses to recent climate change. Because insect species in general have relatively short life cycles, high reproductive capacity and high degree of mobility, the physiological responses to warming temperatures can produce large and rapid effects on species population dynamics.