Scientific Opinion on the phytosanitary risk associated with some coniferous species and genera for the spread of pine wood nematode

The European Commission requested the Panel on Plant Health to deliver a scientific opinion on the phytosanitary risk of plants (other than fruits and seeds) of Pinus pinea and of the genera Chamaecyparis, Cryptomeria and Juniperus for the spread of pine wood nematode (PWN) via movement of infested plants or untreated plant products or by supporting natural spread of PWN in conjunction with European species of the vector. The Panel analysed the data submitted by Portugal regarding surveys on the Tróia Peninsula where P. pinaster and P. pinea co-occur, and the related laboratory results of Naves et al. (2006) on feeding and oviposition preferences of Monochamus galloprovincialis. The Panel also undertook a comprehensive review of the literature. The zero infestation of PWN recorded on P. pinea on the Tróia Peninsula was not significantly different from the result for P. pinaster, because of the small P. pinea sample. Hence, the conclusion that P. pinea is not a host plant for PWN is not supported by the data submitted, principally because of low statistical confidence arising from the few P. pinea trees present. Moreover, the limited presence of P. pinea in the study areas means that the results are representative neither of the Tróia Peninsula nor of other parts of Portugal. Naves et al. (2006) recorded some oviposition by M. galloprovincialis on P. pinea, but less than on other hosts. No differences in feeding of M. galloprovincialis on P. pinaster and P. pinea were detected, thus potentially allowing PWN transmission to trees by this route. The available information regarding the genera Chamaecyparis, Cryptomeria and Juniperus as potential hosts of Monochamus spp. and PWN suggests overall a low susceptibility to PWN or its vectors; the uncertainty concerning PWN is high and would require supplementary research.