The aim of this review was to undertake a survey of researchers working with plant-parasitic nematodes in order to determine a ‘top 10’ list of these pathogens based on scientific and economic importance. Any such list will not be definitive as economic importance will vary depending on the region of the world in which a researcher is based. However, care was taken to include researchers from as many parts of the world as possible when carrying out the survey. The top 10 list emerging from the survey is composed of: (1) root-knot nematodes (Meloidogyne spp.); (2) cyst nematodes (Heterodera and Globodera spp.); (3) root lesion nematodes (Pratylenchus spp.); (4) the burrowing nematode Radopholus similis; (5) Ditylenchus dipsaci; (6) the pine wilt nematode Bursaphelenchus xylophilus; (7) the reniform nematode Rotylenchulus reniformis; (8) Xiphinema index (the only virus vector nematode to make the list); (9) Nacobbus aberrans; and (10) Aphelenchoides besseyi. The biology of each nematode (or nematode group) is reviewed briefly.

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Top 10 plant-parasitic nematodes in molecular plant pathology

Top 10 plant parasitic nematodes in molecular plant pathology in (Abstracts from the 6th International Congress of Nematology, Cape Town, South Africa, 4-9 May 2014)

The BAWBILT bases in Europe.- The Bawbilt Context in Europe.- The Directory of European Experts.- The Bawbilt Database.- Damage and Control of Bawbilt Organisms an Overview.- Bark Beetles.- Taxonomy and Systematics of Bark and Ambrosia Beetles.- Genetic Tools in Scolytid Research.- General Biology of Bark Beetles.- Chemical Ecology of Bark Beetles in a Complex Olfactory Landscape.- Host Resistance to Bark Beetles and Its Variations.- Fungal Associates of European Bark Beetles With Special Emphasis on the Ophiostomatoid Fungi.- Research on Parasitoids and Predators of Scolytidae - A Review.- Pathogens in Bark Beetles.- Bark Weevils.- Taxonomy and Systematics of Bark Weevils.- General Biology and Life Cycles of Bark Weevils.- Semiochemicals in the Life of Bark Feeding Weevils.- Hylobius Abietis - Host Utilisation and Resistance.- Fungi Associated With Hylobius Abietis and Other Weevils.- Parasitoids, Predators, Nematodes and Pathogens Associated with Bark Weevil Pests.- Damage, Control and Management of Weevil Pests, Especially Hylobius Abietis.- Buprestids and Longhorns.- Biology, Ecology and Economic Importance of Buprestidae and Cerambycidae.- Natural Enemies of Cerambycidae and Buprestidae Infesting Living Trees.- "Non-Coleopteran" Bawbilt organisms.- "Non-Coleopteran Insects".- Research needs and priorities for Europe.- General Conclusions and Research Priorities for Bawbilt Organisms in Europe.

Bark and Wood Boring Insects in Living Trees in Europe, a Synthesis

Although numerous species distribution models have been developed, most were based on insufficient distribution data or used older climate change scenarios. We aimed to quantify changes in projected ranges and threat level by the years 2061-2080, for 12 European forest tree species under three climate change scenarios. We combined tree distribution data from the Global Biodiversity Information Facility, EUFORGEN and forest inventories, and we developed species distribution models using MaxEnt and 19 bioclimatic variables. Models were developed for three climate change scenarios – optimistic (RCP2.6), moderate (RCP4.5) and pessimistic (RPC8.5) – using three General Circulation Models, for the period 2061-2080. Our study revealed different responses of tree species to projected climate change. The species may be divided into three groups: “winners” – mostly late-successional species: Abies alba, Fagus sylvatica, Fraxinus excelsior, Quercus robur and Q. petraea; “losers” – mostly pioneer species: Betula pendula, Larix decidua, Picea abies and Pinus sylvestris and alien species – Pseudotsuga menziesii, Q. rubra and Robinia pseudoacacia, which may be also considered as “winners”. Assuming limited migration, most of the species studied would face significant decrease of suitable habitat area. The threat level was highest for species that currently have the northernmost distribution centers. Ecological consequences of the projected range contractions would be serious for both forest management and nature conservation.

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How much does climate change threaten European forest tree species distributions

Climatic warming may lead to increased or decreased future forest productivity. However, more frequent heat waves, droughts and storms and accompanying pathogen attacks are also expected for Europe and are considered to be increasingly important abiotic and biotic stress factors for forests. Adaptive forestry can help forest ecosystems to adapt to these new conditions in order to achieve management goals, maintain desired forest ecosystem services and reduce the risks of forest degradation. With a focus on central Europe, this paper presents the following management strategies: (1) conservation of forest structures, (2) active adaptation, and (3) passive adaptation. The feasibility and criteria for application of the different strategies are discussed. Forest adaptation may entail the establishment of “neonative” forests, including the use and intermixing of native and non-native tree species as well as non-local tree provenances that may adapt better to future climate conditions. An integrative ...

Adaptive forest management in central Europe: Climate change impacts, strategies and integrative concept

A survey of aphelenchid nematodes (Nematoda: Aphelenchida) associated with maritime pine, Pinus pinaster, was conducted in Portugal in 1996 and 1999. A Bursaphelenchus species has been identified for the first time in the Iberian Peninsula. B. xylophilus is reported for the first time in Europe. It was found in very high numbers - up to 38 000 per 10 g of pine wood - inside a few declining trees infested with curculionid, cerambycid and scolytid beetles. Morphological observations, including shape of spicules, bursa, vulva, female tail end and stylet as well as morphometrics, were in accordance with the species description. Species-specific DNA fragment patterns were obtained using ITS-RFLP analysis, with five different restriction enzymes. The importance and implications of this finding are discussed. Premiere signalisation de Bursaphelenchus xylophilus au Portugal, at en Europe - Une enquete sur les nematodes Aphelenchides (Nematoda: Aphelenchida) associes au pin maritime (Pinus pinaster) a ete realisee au Portugal de 1996 a 1999. Une espece de Bursaphelenchus a ete identifiee pour la premiere fois dans la Peninsule Iberique. B. xylophilus est signale pour la premiere fois en Europe. Il a ete trouve en tres grand nombre - jusqu'a 38 000 individus pour 10 g de bois de pin - dans des arbres deperissants infestes par des Coleopteres Curculionides, Cerambycides et Scolytides. Les observations concernant la morphologie - en particulier la forme des spicules, la bourse, la vulve, l'extremite de la queue de la femelle et le stylet - de meme que les donnees morphometriques correspondent a la description de l'espece. Des sequences de fragments d'ADN specifique de l'espece ont ete obtenus par analyse ITS-RFLP a l'aide de cinq enzymes de restriction. L'importance et les implications de cette decouverte sont discutees.

First report of Bursaphelenchus xylophilus in Portugal and in Europe

RFLP analysis of the internal transcribed spacer (ITS) regions of ribosomal DNA has become a valuable tool for differentiation of Bursaphelenchus species. Restriction cleavage of amplified rDNA using five restriction enzymes (RsaI, HaeIII, MspI, HinfI and AluI) has provided species-specific ITS-RFLP patterns for 26 species of Bursaphelenchus and two intraspecific types so far, five of which are presented here for the first time. The technique has proved very valuable for differentiation of the pinewood nematode, B. xylophilus, from other Bursaphelenchus species during plant quarantine inspections. ITS-RFLP analysis has also been used effectively during investigations on the distribution of Bursaphelenchus species. ITS-RFLP patterns have been employed as additional identification criteria in the description of several new Bursaphelenchus species.

ITS-RFLP patterns for differentiation of 26 Bursaphelenchus species (Nematoda: Parasitaphelenchidae) and observations on their distribution

Restriction analysis of amplified ribosomal ITS sequences has provided species-specific fragment patterns for nematodes of several genera, including Bursaphelenchus. We used restriction enzymes RsaI, HaeIII, MspI, HinfI and AluI to produce ITS-RFLP reference profiles of 44 Bursaphelenchus species, including two intraspecific types in each of B. mucronatus and B. leoni. In addition, reference profiles of Aphelenchoides stammeri and Ruehmaphelenchus asiaticus were produced. Reference profiles of six species are shown here for the first time. Identical ITS-RFLP patterns were usually obtained from different isolates and from individual specimens of the same species. However, in the case of B. 'corneolus', B. lini, B. singaporensis and B. sexdentati, additional bands in the patterns of certain isolates or individual nematodes were observed which may be explained by ITS sequence microheterogeneity, i.e., the presence of ITS sequence variants within the number of rDNA tandem repeats. Since these 'extra' bands appeared only with one out of the five restriction enzymes employed, they did not seriously impair identification of species based on the overall reference patterns. ITS-RFLP analysis has proved valuable for differentiation of the pathogenic pine wood nematode, B. xylophilus, from related species. In many recent descriptions of new Bursaphelenchus species, ITS-RFLP profiles have been used as additional species identification criteria. Comparison of profiles from isolates of many different origins has provided new information on intraspecific types or genetically distinct provenances of several Bursaphelenchus species.

ITS-RFLP analysis, an efficient tool for differentiation of Bursaphelenchus species

Reliable methods for differentiation of Bursaphelenchus species are important for identification of the pinewood nematode ( B. xylophilus ), a major pest of quarantine significance to the European Union, and other Bursaphelenchus species associated with coniferous trees. The technique of restriction fragment length polymorphism analysis of the amplified internal transcribed spacer region of 1i bosomal DNA (ITS-RFLP) was established for interspecific classification of Bursaphelenchus isolates. The differentiation is based upon species-specific restriction fragment patterns. Five out of fifteen restriction endonucleases tested yielded suitable patterns. The species B. xylophilus, B. mucronatus, B.fraudulentus, B. leoni, and B. sexdentati were clearly identified using this method. In addition, differentiation of the two forms of B. mucronatus was possible which had been detected in previous molecular genetical investigations. Their differentiation is almost impossible on the basis of morphological features. Both forms were found in Germany and Russia by means of ITSRFLP. This research was supported by the European Union under the FAIR Programme with participation of scientists from Austria, Germany, Greece, Ireland and Italy. Identifizierung von Bursaphelenchus -Arten (Nematoda, Aphelenchoididae) auf der Basis von amplifizierter ribosomaler DNA (ITS-RFLP) Verlasliche Methoden zur Differenzierung von Bursaphelenchus -Arten sind wichtig zur Identifizierung des Kiefemholznematoden ( B. xylophilus ), eines Quarantaneschadlings der Europaischen Union, und anderer Bursaphelenchus-Arten, die in Koniferenholz auftreten. Die Technik der Restriktionsfragment-Langenpolymorphismus-Analyse der amplifizierten internen transkribierten Spacer-Region der ribosomalen DNA (ITSRFLP) wurde zur interspezifischen Klassifizierung von Bursaphelenchus -Isolaten etabliert. Die Differenzierung basiert auf speziesspezifischen Restriktionsfragment-Mustern. Funf von funfzehn getesteten Rest:1iktionsendonucleasen lieferten brauchbare Muster. Die Arten B. xylophilus, B. mucronatus, B. fraudulentus, B. leoni und B. sexdentati wurden mit dieser Methode eindeutig differenziert. Auserdem erlaubt die Methode die Unterscheidung zweier morphologisch kaum zu differenzierender Formen von B. mucronatus , die bereits in fruheren molekulargenetischen Untersuchungen erkannt wurden. Das Auftreten beider Formen in Deutschland und Rusland wurde mit Hilfe der ITSRFLP-Analyse nachgewiesen. Diese Untersuchungen wurden durch die Europaische Union im Rahmen des FAIR-Programms gefordert. An dem Forschungsprojekt sind Wissenschaftler aus Deutschland, Griechenland, Irland, Italien und Osterreich beteiligt.

https://ojs.openagrar.de/index.php/NachrichtenblattDPD/article/view/7748/7165

Identification of Bursaphelenchus species (Nematoda, Aphelenchoididae) on the basis of amplified ribosomal DNA (ITS-RFLP)

Summary

We determined the incidence of Bursaphelenchus species in declining Pinus sylvestris stands in the Swiss Alps. A total of 217 trees showing different degree of decline were sampled from various locations in Valais between 2001 and 2004. Bursaphelenchus species were only found in recently dead or dying trees with an overall incidence of 40%. There was a positive relationship between Bursaphelenchus infestation and blue stain in these trees. Five Bursaphelenchus species were identified: Bursaphelenchus vallesianus, Bursaphelenchus mucronatus, Bursaphelenchus sexdentati, Bursaphelenchus leoni and Bursaphelenchus silvestris. The most frequent species were B. vallesianus detected in 75% and B. mucronatus in 20% of all Bursaphelenchus-positive trees. Bursaphelenchus vallesianus is a recently described species within the B. sexdentati group, and could be a contributing factor in the observed pine decline in Valais.

Resume

Des forets de pins sylvestres (Pinus sylvestris) ont eteetudiees en fonction de leur infestation par des especes du genre Bursaphelenchus. Entre 2001 et 2004, 217 arbres presentant une defoliation plus ou moins marquee ont ete examines dans differentes sites du Valais. 40% des pins sylvestres fortement affaiblis ou deja deperis etaient infestes par des especes de Bursaphelenchus. Pour ces arbres, une relation etroite a pu etre etablie entre l'attaque par Bursaphelenchus et le bleuissement du bois. Cinq especes de Bursaphelenchus ont ete identifiees a l'aide de methodes morphologiques et biomoleculaires: B. vallesianus, B. mucronatus, B. sexdentati, B. leoni et B. silvestris. Les especes les plus frequentes etaient B. vallesianus et B. mucronatus, que l'on a pu determiner respectivement dans 75% et 20% de l'ensemble des arbres contamines par Bursaphelenchus. C'est seulement recemment que B. vallesianus a ete decrit comme nouvelle espece faisant partie du groupe de B. sexdentati (Braasch et al. 2004).

Zusammenfassung

Kiefernbestande (Pinus sylvestris) wurden hinsichtlich ihres Befalls mit Bursaphelenchus-Arten untersucht. Insgesamt 217 Baume mit unterschiedlich ausgepragter Kronenverlichtung wurden zwischen 2001 and 2004 an verschiedenen Standorten im Wallis beprobt. 40% der stark geschwachten oder bereits abgestorbenen Kiefern waren mit Bursaphelenchus-Arten befallen. In diesen Baumen wurde eine enge Beziehung zwischen dem Bursaphelenchus-Befall und der Holz-Blaue gefunden. Funf Bursaphelenchus-Arten wurden mittels morphologischer und molekularbiologischer Methoden identifiziert: B. vallesianus, B. mucronatus, B. sexdentati, B. leoni und B. silvestris. Die haufigsten Arten waren B. vallesianus und B. mucronatus, die in 75% bzw. 20% aller mit Bursaphelenchus kontaminierten Baume festzustellen waren. B. vallesianus wurde erst kurzlich als neue Art innerhalb der B. sexdentati Gruppe beschrieben (Braasch et al. 2004). Obwohl Nematoden der Gattung Bursaphelenchus in vielen der abgestorbenen oder stark geschwachten Kiefern nachgewiesen wurden, muss deren Rolle beim Fohrensterben in weiteren Studien geklart werden.

Helen Braasch

Papers

First report of Bursaphelenchus xylophilus in Portugal and in Europe

ITS-RFLP patterns for differentiation of 26 Bursaphelenchus species (Nematoda: Parasitaphelenchidae) and observations on their distribution

ITS-RFLP analysis, an efficient tool for differentiation of Bursaphelenchus species

Identification of Bursaphelenchus species (Nematoda, Aphelenchoididae) on the basis of amplified ribosomal DNA (ITS-RFLP)

Occurrence of Bursaphelenchus species in declining Pinus sylvestris in a dry Alpine valley in Switzerland