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Pine wilt disease (PWD) is a devastating plant disease caused by the pinewood nematode (PWN, Bursaphelenchus xylophilus) that is transmitted by several beetle species in the genus, Monochamus. Once present, the disease is difficult to control. Prevention rather than control is regarded as an effective strategy for PWD management. Central to this prevention strategy is the ability to predict the potential distribution of the disease. Here, we employed an integrated MaxEnt and CLIMEX approach to model the potential distribution of PWD under various climate‐change scenarios. Our results indicate that rising temperatures and lower humidity under climate change will render some of the northern regions of China more suitable for the nematode and these beetles, causing the gradual northward movement of PWD. Furthermore, suitable habitats for three pine species, Pinus massoniana, P. taiwanensis and P. shurbergia, overlap with PWN and Monochamus, suggesting that these three species are potentially at high risk of PWD. Thus, PWD management should target the northern regions of China and the three pine species that are most susceptible to PWD. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Abstract Pine wilt disease (PWD) is a devastating plant disease caused by the pinewood nematode (PWN, Bursaphelenchus xylophilus) that is transmitted by several beetle species in the genus, Monochamus. Once present, the disease is difficult to control. Prevention rather than control is regarded as an effective strategy for PWD management. Central to this prevention strategy is the ability to predict the potential distribution of the disease. Here, we employed an integrated MaxEnt and CLIMEX approach to model the potential distribution of PWD under various climate‐change scenarios. Our results indicate that rising temperatures and lower humidity under climate change will render some of the northern regions of China more suitable for the nematode and these beetles, causing the gradual northward movement of PWD. Furthermore, suitable habitats for three pine species, Pinus massoniana, P. taiwanensis and P. shurbergia, overlap with PWN and Monochamus, suggesting that these three species are potentially at high risk of PWD. Thus, PWD management should target the northern regions of China and the three pine species that are most susceptible to PWD.

Abstract Key message The invasive pine wood nematode is a major threat to pine forests worldwide, causing extensive tree mortality. Although scientific knowledge and control measures are continuously improving, important gaps remain. We argue that some key questions, notably related to early detection and pest management, need to be urgently tackled in countries at risk of invasion such as France.

Monochamus alternatus Hope, 1842, is a major forest pest that hosts the pathogenic pinewood nematode (PWN), Bursaphelenchus xylophilus (Steiner and Buhrer, 1934) Nickle 1970. Taxonomically, M. alternatus is currently divided into two subspecies, based on morphology and geography: Monochamus alternatus alternatus Hope, 1842 in China, Taiwan, Tibet, Vietnam, and Laos and Monochamus alternatus endaiMakihara, 2004 in South Korea and Japan. Despite their economic importance, the subspecies taxonomy of M. alternatus has never been tested after the first description. In this study, we aimed to reassess the subspecies taxonomy of M. alternatus using molecular and morphological data. For morphological analysis, we examined three major morphological characters (pronotal longitudinal band, granulation on humeri, and elytral proximomedial spine) from 191 individuals from China, Korea, and Taiwan. Population genetic structures were examined using 85 de novo sequences and 82 public COI sequences from China, Korea, Japan, Malaysia, Taiwan, and a few intercepted specimens from the United States. All the genetic data were aligned as three different multiple sequence alignments. Individuals from each subspecies were morphologically and genetically scattered, not clustered according to subspecies in any of the analyses. Therefore, a new synonymy is proposed: Monochamus alternatus Hope, 1842 = Monochamus alternatus endai, syn. n. This study suggests a more robust classification of M. alternatus for the first time and ultimately will pose a substantial impact on implementing quarantine or forestry policies. [ABSTRACT FROM AUTHOR]

Ips bark beetles (Ips species; Coleoptera: Curculionidae: Scolytinae) play an important role in forest ecosystems by attacking injured, stressed, or dying pine (Pinus) trees. Management of Ips bark beetles has largely focused on prevention by maintaining tree health through silvicultural treatments including thinning to reduce basal area or prescribed fire. However, there is conflicting evidence of whether prescribed fire leads to increased bark beetle populations and, subsequently, increased tree mortality. Recent outbreaks of Ips bark beetles in the southeastern U.S. have caused renewed interest in the interactions between pine management and bark beetle populations. We monitored Ips populations following prescribed fire in intensively managed pine stands and quantified Ips damage. We captured over 361,000 Ips bark beetles with I. avulsus being the most abundant of the three species collected. While we found high variation among Ips populations across study sites and years, there was a significant increase in bark beetle populations after prescribed fire followed by a significant decline the next year. While Ips populations increased up to three-fold after prescribed burns, damage ratings in burned stands were no different than unburned stands which had significantly lower bark beetle populations. Unburned stands had higher basal area and a higher average tree damage rating, but the lowest number of Ips bark beetles. A total of 14,071 facultative (e.g., Monochamus = 9775) and obligate (e.g., Thanasimus dubius = 4296) predators were collected during the study across all sites and the ratio of predators: Ips also significantly increased following prescribed fire. These data suggest that while Ips are ubiquitous and abundant in pine forests being managed with prescribed fire, natural mechanisms such as predator activity mediate their overall damage and impact to southeastern pine stands. • Ips bark beetles are ubiquitous in pine stands regardless of damage or mortality. • Prescribed fire results in significant increases in bark beetle trap collections. • Natural enemies also increase significantly in response to prescribed fire. • Two years after prescribed fire, Ips bark beetles decline, likely due to predators. [ABSTRACT FROM AUTHOR]