The risk of pine wilt disease to Australia and New Zealand

Abstract

Currently Australia and New Zealand are free of Bursaphelenchus xylophilus, the pinewood nematode (PWN), which causes the pine wilt disease, and its primary vectors Monochamus spp. Both countries have increasing interest in this pest due to the significant area of exotic pine plantations, predominantly Pinus radiata, and native conifer species that could be susceptible to PWN. Although the current phytosanitary measures and surveillance programmes in New Zealand and Australia minimise the risk of entry of PWN, both countries have favourable climatic conditions for its establishment. In addition, there are significant uncertainties in the susceptibility of Pinus species to PWN and the potential vector status of native cerambycid beetles. A screening study was conducted in 2003 using 12-month old seedlings from Queensland of P. elliottii, P. caribaea. var hondurensis and $\mathrm{F}1$ and $\mathrm{F}2$ hybrid clones of these parents to determine their potential susceptibility to PWN and Bursaphelenchus mucronatus. Results illustrated the limitations of screening young plants in determining the susceptibility of older trees. The pest risk assessment conducted in 2004 and the screening study confirmed that maintenance of strong quarantine and surveillance programs and development of molecular or physiological markers for identification of PWN resistance in planting stocks of Pinus species and native species is indispensable to prevent the introduction of pine wilt disease in New Zealand and Australia.