DOI: 10.1111/j.1466-8238.2006.00302.x © 2007 The Authors 460 Journal compilation © 2007 Blackwell Publishing Ltd www.blackwellpublishing.com/geb Global Ecology and Biogeography, (Global Ecol. Biogeogr.) (2007) 16, 460–471 RESEARCH PAPER Blackwell Publishing Ltd Modelling the effects of climate change on the potential feeding activity of Thaumetopoea pityocampa (Den. & Schiff.) (Lep., Notodontidae) in France Christelle Robinet 1, †*, Peter Baier 2 , Josef Pennerstorfer 2 , Axel Schopf 2 and Alain Roques 1 ABSTRACT Aim We investigated whether climate change has affected the potential feeding activity of a winter active larva, the pine processionary moth (PPM), Thaumetopoea pityocampa L., and whether it may explain its range expansion. Location The study area is France and, at a smaller scale, the Paris Basin. Methods We used a statistical model derived from Huchon and Démolin [1970 Revue Forestière Française (special issue: La lutte biologique en forêt), 220–234] to test whether their model, updated with climate change, could explain the observed range expansion. Since Battisti and colleagues have recently shown that climate could affect survival of the PPM through its effect on feeding activity, we also developed a mechanistic model based on larval feeding requirements (night air temperature above 0 °C and temperature inside the nest above 9 °C on the preceding day). We reconstructed the geographical distribution of feeding activity and we compared the resulting change with the PPM range expansion. Results The statistical model did not successfully predict the observed expansion but the mechanistic model showed considerable change in the feeding activity of the PPM. In the Paris Basin, the PPM border coincided with a zone unfavourable for feeding activity in the period 1992–96. Feeding conditions became more favourable in the period 2001–04, and the PPM succeeded in crossing this zone. Over larger temporal and spatial scales improved feeding conditions in the north-western part of France were forecast by the mechanistic model. Main conclusions (1) The range distribution of the PPM in the Paris Basin is no longer limited by unfavourable feeding conditions. (2) The pattern of range expan- sion of the PPM is now governed mainly by its dispersal capabilities and host tree distribution. (3) At the country scale, this approach gives an approximate prediction of the potential distribution of the PPM, though the model may not be reliable in mountainous regions. Keywords Bioclimatic envelope, climate change, feeding activity, forest defoliator, modelling, range expansion, spatial dynamics, Thaumetopoea pityocampa. *Correspondence: Christelle Robinet, INRA Zoologie Forestière, Avenue de la pomme de pin, BP 20619 Ardon, 45166 Olivet, France. E-mail: robinet@orleans.inra.fr †Present address: USDA Forest Service, 180 Canfield Street, Morgantown, WV 26505, USA. 1 INRA UR 633 Zoologie Forestière, Avenue de la pomme de pin, BP 20619 Ardon, 45166 Olivet, France and 2 BOKU — Department of Forest and Soil Sciences, Institute of Forest Entomology, Forest Pathology & Forest Protection, Hasenauerstr. 38, A-1190 Vienna, Austria INTRODUCTION The world’s climate has significantly warmed by 0.6 ± 0.2 °C during the last century and the mean global temperature is projected to increase by 1.4–5.8 °C by 2100 (IPCC, 2001). Europe has warmed more than the global average, with an increase of 0.95 °C, and winter temperatures have increased more than those in summer (European Environment Agency, 2004). The overall response of ecosystems remains difficult to predict, but many recent studies have already highlighted the impact of global cli- mate change on animal and plant species (Hughes, 2000; Walther et al., 2002; Parmesan & Yohe, 2003; Root et al., 2003). They show a great variety of reactions and, in particular, the shift of species ranges. Thus, European species whose distributions are closely