Explore the vast range of titles available.

Using transmission electron microscopy, we examined the body cuticle ultrastructures of phoretic and parasitic stages of the parasitaphelenchid nematodes Bursaphelenchus xylophilus, B. conicaudatus, B. luxuriosae, B. rainulfi; an unidentified Bursaphelenchus species, and an unidentified Parasitaphelenchus species. Nematode body cuticles usually consist of three zones, a cortical zone, a median zone, and a basal zone. The phoretic stages of Bursaphelenchus spp., isolated from the tracheal systems of longhorn beetles or the elytra of bark beetles, have a thick and radially striated basal zone. In contrast, the parasitic stage of Parasitaphelenchus sp., isolated from bark beetle hemocoel, has no radial striations in the basal zone. This difference probably reflects the peculiar ecological characteristics of the phoretic stage. A well-developed basal radially striated zone, composed of very closely linked proteins, is the zone closest to the body wall muscle. Therefore, the striation is necessary for the phoretic species to be able to seek, enter, and depart from host/carrier insects, but is not essential for internal parasites in parasitaphelenchid nematodes. Phylogenetic relationships inferred from near-full-length small subunit ribosomal RNA sequences suggest that the cuticle structures of parasitic species have apomorphic characters, e.g., lack of striation in the basal zone, concurrent with the evolution of insect parasitism from a phoretic life history.

Bursaphelenchus xylophilus is the nematode responsible for a devastating epidemic of pine wilt disease in Asia and Europe, and represents a recent, independent origin of plant parasitism in nematodes, ecologically and taxonomically distinct from other nematodes for which genomic data is available. As well as being an important pathogen, the B. xylophilus genome thus provides a unique opportunity to study the evolution and mechanism of plant parasitism. Here, we present a high-quality draft genome sequence from an inbred line of B. xylophilus, and use this to investigate the biological basis of its complex ecology which combines fungal feeding, plant parasitic and insect-associated stages. We focus particularly on putative parasitism genes as well as those linked to other key biological processes and demonstrate that B. xylophilus is well endowed with RNA interference effectors, peptidergic neurotransmitters (including the first description of ins genes in a parasite) stress response and developmental genes and has a contracted set of chemosensory receptors. B. xylophilus has the largest number of digestive proteases known for any nematode and displays expanded families of lysosome pathway genes, ABC transporters and cytochrome P450 pathway genes. This expansion in digestive and detoxification proteins may reflect the unusual diversity in foods it exploits and environments it encounters during its life cycle. In addition, B. xylophilus possesses a unique complement of plant cell wall modifying proteins acquired by horizontal gene transfer, underscoring the impact of this process on the evolution of plant parasitism by nematodes. Together with the lack of proteins homologous to effectors from other plant parasitic nematodes, this confirms the distinctive molecular basis of plant parasitism in the Bursaphelenchus lineage. The genome sequence of B. xylophilus adds to the diversity of genomic data for nematodes, and will be an important resource in understanding the biology of this unusual parasite.

In 2022, EFSA was mandated by the European Commission's Directorate‐General for Health and Food Safety (M‐2022‐00070) to provide technical assistance regarding the list of Union quarantine pests qualifying as priority pests, as specified in Article 6(2) of Regulation (EU) 2016/2031 on protective measures against plant pests. As part of Task C, EFSA conducted comprehensive expert knowledge elicitations on candidate priority pests, focusing on the lag period, rate of expansion and impact on production (yield and quality losses) and the environment. This report provides the rationale for the dataset on Bursaphelenchus xylophilus, delivered to the European Commission's Joint Research Centre, to feed into the Impact Indicator for Priority Pest (I2P2) model and complete the pest prioritisation ranking exercise.

Pine wilt disease (PWD) is a global quarantine disease of forests that mainly affects Pinaceae species. The disease spreads rapidly. Once infected, pine trees have an extremely high mortality rate. This paper provides a summary of the common techniques used to detect PWD, including morphological-, molecular-, chemical- and physical-based methods. By comprehending the complex relationship among pinewood nematodes, vectors and host pine trees and employing the available approaches for nematode detection, we can improve the implementation of intervention and control measures to effectively reduce the damage caused by PWD. Although conventional techniques allow a reliable diagnosis of the symptomatic phase, the volatile compound detection and remote sensing technology facilitate a rapid diagnosis during asymptomatic stages. Moreover, the remote sensing technology is capable of monitoring PWD over large areas. Therefore, multiple perspective evaluations based on these technologies are crucial for the rapid and effective detection of PWD.

was detected in association with the pine sawyer beetle ( ) during the implementation and testing of cross traps with insect attractants as an efficient tool for detection survey for pine wood nematode ( ) in Bosnia and Herzegovina and Georgia in 2017 and 2018, respectively. This nematode was characterized by morphological, morphometric and molecular features. This is the first report of in association with a in Bosnia and Herzegovina and in Georgia.

The nematode genus Bursaphelenchus is a highly divergent group. This genus mainly consists of mycophagous entomophilic species, but some species have specialized as obligate or facultative plant parasites, facultative insect parasites, or exhibit feeding dimorphism (phenotypic plasticity) leading to mycophagous and predatory forms. In the present study, a new Bursaphelenchus species, B . suri n. sp. was isolated from fresh syconia (figs) of Ficus sur and is described and illustrated based on its typological characters and molecular phylogenetic status. The new species is characterized by its highly derived feeding structures found in obligate plant parasites, lip possessing a labial disc and a long and thick stylet with a long conus and extremely well-developed basal swellings. In addition, slender body of both sexes is characteristic of the species. The new species is phylogenetically and typologically closely related to B . sycophilus , i.e., these two species share the characteristic feeding structures and form a well-supported clade within the B . fungivorus group in the genus. Biologically, these two species are both isolated from fresh figs of the section Sycomorus . However, the new species differs from B . sycophilus by the length of the female post-uterine sac and the shape of the male spicule, i.e., the new species has a long post-uterine sac and spicule condylus without dorsal recurvature. Thus, the new species is the second obligate fig parasite of the genus, and the evolutionary relationship between the B . suri n. sp. and B . sycophilus clade and section Sycomorus figs is hypothesized as an example of adaptive radiation with more species to be discovered.

The quarantine nematode Bursaphelenchus xylophilus is the causal agent of pine wilt disease in Asia and Europe. Differentiation between B. xylophilus and other related, non-pathogenic species can be ambiguous when based exclusively on morphological characters. The morphology of B. mucronatus and B. fraudulentus most closely resembles that of B. xylophilus. Moreover, all of these nematodes are found in both Asia and Europe and can colonise various species of pine. Therefore, for phytosanitary purposes it is necessary to identify the three species precisely and rapidly. In this paper we described the results of the optimized multiplex real-time PCR protocol that utilizes two universal primers and three specific TaqMan probes to identify and differentiate the three Bursaphelenchus species, simultaneously. Species-specific real-time PCR reactions gave expected products for B. xylophilus, B. mucronatus and B. fraudulentus templates. The optimized primer combination together with designed species-specific probes has produced reliable results in multiplex PCR assays with eleven geographically distant isolates of B. xylophilus, eleven of B. mucronatus, seven of B. fraudulentus, and no cross-reactions were observed between tested samples and with other species (i.e., B. piniperdae, B. pinophilus, B. populi and Parasitaphelenchus papillatus). All species-specific real-time PCR reactions performed on DNA extracted from a single nematode individual consistently gave specific amplicons, confirming the reproducibility of the method. Moreover, the conducted study revealed that 30 fg was the lowest DNA input still detected in multiplex real-time PCR analysis. The described approach is simple, time-saving, and reliable in comparison to conventional PCR, and it can be used for simultaneous identification of the above three species within the xylophilus group.

Key message This study demonstrates the potential of Beauveria bassiana (Bals.—Criv.) Vuill. to control Bursaphelenchus mucronatus (Mamiya and Enda), which is close to Bursaphelenchus xylophilus (Steiner and Buhrer) Nickle but is a non-quarantine pathogen and, therefore, may be used as an alternative organism on which to perform in vivo assays without biological risk. Context Pine wilt disease (PWD) is a serious threat for conifer forests worldwide. It is caused by Bursaphelenchus xylophilus , the pine wood nematode (PWN). In affected areas, eradication and subsequent disease containment measures are being implemented. The latter are, to date, based on control strategies for the insect vectors ( Monochamus spp.) and on screening for genetic resistance in tree hosts. However, an integrated pest management strategy which also implements nematode control is still not fully developed. Aims This study aimed to use Bursaphelenchus mucronatus , as an organism on which to demonstrate the nematicidal potential of Beauveria bassiana , an entomopathogenic fungus successfully tested on Monochamus spp., on PWN under in vivo conditions. Methods To this end, a pathosystem was built to simulate these conditions and to bring the nematode B. mucronatus , the insect vector, and the fungus into contact. Results The results show (i) very similar responses of the two nematodes confronted to the fungus and its mycotoxin beauvericin under in vitro conditions and (ii) a remarkable antagonistic effect of B. bassiana on B. mucronatus also on the abovementioned pathosystem (in vivo conditions). Conclusion Our findings have significant implications for the pine wilt disease control. In particular, this study demonstrates the potential of B. bassiana as a biological control tool to be implemented in a future integrated disease management strategy.

The pinewood nematode, Bursaphelenchus xylophilus, is one of the greatest threats to coniferous forests worldwide, causing severe ecological damage and economic loss. The biology of B. xylophilus is similar to that of its closest relative, B. mucronatus, as both species share food resources and insect vectors, and have very similar morphological characteristics, although little pathogenicity to conifers has been associated with B. mucronatus. Using both nuclear and mitochondrial DNA markers, we show that B. xylophilus and B. mucronatus form distinct phylogenetic groups with contrasting phylogeographic patterns. B. xylophilus presents lower levels of intraspecific diversity than B. mucronatus, as expected for a species that evolved relatively recently through geographical or reproductive isolation. Genetic diversity was particularly low in recently colonised areas, such as in southwestern Europe. By contrast, B. mucronatus displays high levels of genetic diversity and two well-differentiated clades in both mitochondrial and nuclear DNA phylogenies. The lack of correlation between genetic and geographic distances in B. mucronatus suggests intense gene flow among distant regions, a phenomenon that may have remained unnoticed due to the reduced pathogenicity of the species. Overall, our findings suggest that B. xylophilus and B. mucronatus have different demographic histories despite their morphological resemblance and ecological overlap. These results suggest that Bursaphelenchus species are a valuable model for understanding the dispersion of invasive species and the risks posed to native biodiversity and ecosystems.

Pine wilt disease is a devastating forest disease caused by the pinewood nematode Bursaphelenchus xylophilus , which has been listed as the object of quarantine in China. Climate change influences species and may exacerbate the risk of forest diseases, such as the pine wilt disease. The maximum entropy (MaxEnt) model was used in this study to identify the current and potential distribution and habitat suitability of three pine species and B. xylophilus in China. Further, the potential distribution was modeled using the current (1970–2000) and the projected (2050 and 2070) climate data based on two representative concentration pathways (RCP 2.6 and RCP 8.5), and fairly robust prediction results were obtained. Our model identified that the area south of the Yangtze River in China was the most severely affected place by pine wilt disease, and the eastern foothills of the Tibetan Plateau acted as a geographical barrier to pest distribution. Bioclimatic variables related to temperature influenced pine trees’ distribution, while those related to precipitation affected B. xylophilus ’s distribution. In the future, the suitable area of B. xylophilus will continue to increase; the shifts in the center of gravity of the suitable habitats of the three pine species and B. xylophilus will be different under climate change. The area ideal for pine trees will migrate slightly northward under RCP 8.5. The pine species will continue to face B. xylophilus threat in 2050 and 2070 under the two distinct climate change scenarios. Therefore, we should plan appropriate measures to prevent its expansion. Predicting the distribution of pine species and the impact of climate change on forest diseases is critical for controlling the pests according to local conditions. Thus, the MaxEnt model proposed in this study can be potentially used to forecast the species distribution and disease risks and provide guidance for the timely prevention and management of B. xylophilus .