Modelling geographical variation in voltinism of Hylobius abietis under climate change and implications for management

Hylobius abietis develop in conifer root‐stumps and emerging adults attack replanted trees. Development is largely semi‐voltine and this is an important determinant of economic impact, influencing the length of a fallow period or the frequency of chemical control. A simulation model followed a generation of weevils through the life cycle to predict voltinism based on temperature in the root‐stump microhabitat modelled from air temperature. Daily air temperatures for representative U.K. locations simulated from the U.K. Climate Projections 2009 Weather Generator for the 2030–2070s were used to predict the potential effect of climate change on voltinism. The life cycle currently takes 2–3 years in the north and west (N&W) of the U.K. but, in the south and east (S&E), a 2‐year cycle predominates. From the 2030s onwards, a predominant 2‐year life cycle in the N&W was predicted to reduce economic impact in this region. In the S&E, however, the predicted 1–2‐year cycle would be unlikely to reduced the period over which pest management was required. Changes in voltinism to the 2070s revealed different temporal patterns, emphasizing the importance for management of modelling local, as well as regional scale variation in the effects of climate change in Europe.