Insects in a warmer world: ecological, physiological and life-history responses of true bugs (Heteroptera) to climate change

Focusing on the southern green stink bug, Nezara viridula (Pentatomidae), in central Japan the effects of climate change on true bugs (Insecta: Heteroptera) are reviewed. In the early 1960s, the northern edge of the species's distribution was in Wakayama Prefecture (34.1°N) and distribution was limited by the +5°C coldest month (January) mean temperature isothermal line. By 2000, N. viridula was recorded 70 km further north (in Osaka, 34.7°N). Historical climate data were used to reveal possible causes of the northward range expansion. The increase of mean and lowest winter month temperatures by 1–2°C in Osaka from the 1950s to the 1990s improved potential overwintering conditions for N. viridula. This promoted northward range expansion of the species. In Osaka, adult diapause in N. viridula is induced after mid‐September, much later than in other local seed‐feeding heteropterans. This late diapause induction results in late‐season ineffective reproduction: some females start oviposition in autumn when the progeny have no chance of attaining adulthood and surviving winter. Both reproductive adults and the progeny die. A period from mid‐September to early November represents a phenological mismatch: diapause is not yet induced in all adults, but it is already too late to start reproduction. Females that do not start reproduction but enter diapause in September have reduced postdiapause reproductive performance: they live for a shorter period, have a shorter period of oviposition and produce fewer eggs in smaller egg masses compared with females that emerge and enter diapause later in autumn. To some extent, N. viridula remains maladapted to Osaka environmental conditions. Ecological perspectives on establishment in recently colonized areas are discussed. A review of available data suggests that terrestrial and aquatic Heteroptera species respond to climate change by shifting their distribution ranges, changing abundance, phenology, voltinism, physiology, behaviour, and community structure. Expected responses of Heteroptera to further climate warming are discussed under scenarios of slight (<2°C) and substantial (>2°C) temperature increase.