Risk assessment of the oriental chestnut gall wasp, Dryocosmus kuriphilus for the EU territory and identification and evaluation of risk management options

Castanea spp., Dryocosmus kuriphilus, EU territory, management options, oriental chestnut gall wasp, risk assessment
First published in the EFSA Journal
17 June 2010
11 May 2010
Scientific Opinion


The Panel on Plant Health was requested by the European Commission to deliver a scientific opinion on the risk posed by the oriental chestnut gall wasp, Dryocosmus kuriphilus to the EU territory and to identify and evaluate risk management options. Additional analyses were conducted by the Panel to a) determine the distribution of the endangered area within the EU territory; b) investigate the pattern and rate of pest diffusion and c) consider the environmental risk of introduction of the biological control agent Torymus sinensis identified as a potential management option. The Panel concluded in its assessment that a) Castanea plants for intended planting represent the main pathway for entry of D. kuriphilus to the EU; b) D. kuriphilus has a very high potential for establishment in the EU and the climate is suitable wherever Castanea sativa is grown in southern, central and western Europe; c) the average rate of spread of D. kuriphilus is estimated as 8 km/yr; d) spread within the EU is likely, due to adult dispersal by flight and the movement of plants containing eggs and larvae which remain undetected within dormant buds; e) the potential effects on fruit yield reduction are considered moderate and the environmental impact in Castanea woodland is considered as low; f) all EU chestnut production is endangered but the areas of fruit production with the highest degree day accumulations where D. kuriphilus is absent, e.g. in northern Portugal, northern Spain and south-west France, are identified as particularly at risk; g) management options to reduce likelihood of introduction and spread consist of certifying Castanea planting material from pest free areas/places of production; h) classical biological control and plant varietal resistance are identified as management options to reduce the magnitude of impact.

Panel members at the time of adoption

Richard Baker, Thierry Candresse, Erzsébet Dormannsné Simon, Gianni Gilioli, Jean-Claude Grégoire, Michael John Jeger, Olia Evtimova Karadjova, Gábor Lövei, David Makowski, Charles Manceau, Maria Navajas, Angelo Porta Puglia, Trond Rafoss, Vittorio Rossi, Jan Schans, Gritta Schrader, Gregor Urek, Johan Coert Van Lenteren, Irene Vloutoglou, Stephan Winter and Marina Zlotina
Panel on Plant Health
PLH [at] efsa.europa.eu
EFSA Journal 2010; 8(6):1619
Question Number
On request from
European Commission