Pine wilt disease: A global threat to forestry

Pines are the most economically important trees in the world and, together with eucalyptus, they dominate commercial forests. But the success of a relatively small number of widely planted species, such as Pinus pinaster, the maritime pine, comes at a price. Pines are attractive to damaging pathogens and insect pests, including the pinewood nematode (PWN), Bursaphelenchus xylophilus, the causal agent of pine wilt disease (PWD). Originally described in Japan, PWD has caused widespread destruction to forests in countries such as China, Taiwan, Portugal, Spain and the United States. PWN causes irreparable damage to the vascular system of its pine hosts, leading to mortality within 3 months. Pine sawyer beetles (Monochamus spp.) are key vectors of PWD, introducing the PWN to healthy trees during feeding. Other organisms contribute to PWD spread and development, including bacteria, fungi and bark beetles. Control measures include tree felling to prevent vector transmission of PWN, insecticide treatments, trapping of Monochamus spp. and tree breeding for plant resistance. The PWN is a quarantine pathogen and subject to regular legislation and phytosanitary measures aimed at restricting movement and preventing introduction to new areas. Current research is investigating the use of biopesticides against PWN and Monochamus spp. This review examines the biology, epidemiology, impact and management of PWD through published research, grey literature and interviews with people directly involved in the management of the disease in Portugal. This review describes the global impact, biology and management of pine wilt disease and includes interviews with those directly involved in tackling the problem in Portugal.image