Nieuwe wortelknobbelaaltjes en opvallende waarnemingen in Europa

Update met toelichting van nieuwe wortelknobbelaaltjes, die gevonden zijn na afronding van een taxonomische studie naar de soortstatus van de in Europa gevonden Meloidogyne soorte

Plantenparasitaire nematoden en golfvelden

Over schimmels en insecten, als belagers van grassen en golfvelden, is relatief veel bekend. Minder bekend zijn nematoden ofwel aaltjes. Vanuit met name Ierland en het Verenigd Koninkrijk, golflanden bij uitstek, worden de laatste jaren regelmatig problemen gemeld met slecht groeiend gras op golfbanen veroorzaakt door nematoden. Vooral de greens laten veel schade zien

Nematoden : op zoek naar alternatieve bestrijding

Dit artikel gaat in op de schadelijke nematoden (aaltjes) en geeft een overzicht van recente bevindingen over de alternatieve bestrijding van schadelijke aaltjes

Meloidogyne duytsi n. sp. (Nematoda : Heteroderidae), a root-knot nematode from Dutch coastal foredunes

Un nématode galligène, #Meloidogyne duytsi n. sp., parasitant #Elymus farctus (Viv.) Melderis croissant sur les avant-dunes côtières hollandaises, est décrit et illustré. Cette nouvelle espèce est caractérisée par : femelle ayant un stylet long de 13,3 micromètres, légèrement incurvé dorasalement, boutons basaux grands et transversalement ovoïdes, bien séparés de la hampe ; empreinte périnéale asymétrique avec arche dorsale relativement basse, stries épaisses et lignes latérales indistinctes ; queue pointue. Mâle : région céphalique haute et séparée du reste du corps ; disque labial légèrement proéminent ; secteurs latéraux labiaux réduits ; queue conique à extrémité arrondie. Juvéniles de deuxième stade : longueur moyenne de 424 mircomètres ; hémizonide antéieur au pore excréteur ; queue longue de 70,4 micromètres, effilée, légèrement incurvée ventralement à partie hylaine terminale distincte et longue de 11,3 micromètres. Un profil nouveau pour la malate deshydrogénase et une bande estérasique de type lent ont été détectés. #M. duytsi n. sp. a également été collecté en mélange avec #M. maritima Jepson, 1987 sur #Ammophila areanaria$ (L.) Link. (Résumé d'auteur

The effects of swing-leg retraction on running performance: analysis, simulation, and experiment

Using simple running models, researchers have argued that swing-leg retraction can improve running robot performance. In this paper, we investigate whether this holds for a more realistic simulation model validated against a physical running robot. We find that swing-leg retraction can improve stability and disturbance rejection. Alternatively, swing-leg retraction can simultaneously reduce touchdown forces, slipping likelihood, and impact energy losses. Surprisingly, swing-leg retraction barely affected net energetic efficiency. The retraction rates at which these effects are the greatest are strongly model-dependent, suggesting that robot designers cannot always rely on simplified models to accurately predict such complex behaviors

Technological advancements and their importance for nematode identification

Nematodes represent a species-rich and morphologically diverse group of metazoans known to inhabit both aquatic and terrestrial environments. Their role as biological indicators and as key players in nutrient cycling has been well documented. Some plant-parasitic species are also known to cause significant losses to crop production. In spite of this, there still exists a huge gap in our knowledge of their diversity due to the enormity of time and expertise often involved in characterising species using phenotypic features. Molecular methodology provides useful means of complementing the limited number of reliable diagnostic characters available for morphology-based identification. We discuss herein some of the limitations of traditional taxonomy and how molecular methodologies, especially the use of high-throughput sequencing, have assisted in carrying out large-scale nematode community studies and characterisation of phytonematodes through rapid identification of multiple taxa. We also provide brief descriptions of some the current and almost-outdated high-throughput sequencing platforms and their applications in both plant nematology and soil ecology

Integrative taxonomy of root-knot nematodes reveals multiple independent origins of mitotic parthenogenesis

Open Access JournalDuring sampling of several Coffea arabica plantations in Tanzania severe root galling, caused by a root-knot nematode was observed. From pure cultures, morphology and morphometrics of juveniles and females matched perfectly with Meloidogyne africana, whereas morphology of the males matched identically with those of Meloidogyne decalineata. Based on their Cox1 sequence, however, the recovered juveniles, females and males were confirmed to belong to the same species, creating a taxonomic conundrum. Adding further to this puzzle, re-examination of M. oteifae type material showed insufficient morphological evidence to maintain its status as a separate species. Consequently, M. decalineata and M. oteifae are synonymized with M. africana, which is herewith redescribed based on results of light and scanning electron microscopy, ribosomal and mitochondrial DNA sequences, isozyme electrophoresis, along with bionomic and cytogenetic features. Multi-gene phylogenetic analysis placed M. africana outside of the three major clades, together with M. coffeicola, M. ichinohei and M. camelliae. This phylogenetic position was confirmed by several morphological features, including cellular structure of the spermatheca, egg mass position, perineal pattern and head shape. Moreover, M. africana was found to be a polyphagous species, demonstrating that "early-branching" Meloidogyne spp. are not as oligophagous as had previously been assumed. Cytogenetic information indicates M. africana (2n = 21) and M. ardenensis (2n = 51-54) to be a triploid mitotic parthenogenetic species, revealing at least four independent origins of mitotic parthenogenesis within the genus Meloidogyne. Furthermore, M. mali (n = 12) was found to reproduce by amphimixis, indicating that amphimictic species with a limited number of chromosomes are widespread in the genus, potentially reflecting the ancestral state of the genus. The wide variation in chromosome numbers and associated changes in reproduction modes indicate that cytogenetic evolution played a crucial role in the speciation of root-knot nematodes and plant-parasitic nematodes in general

Aaltjesschade in gras : een onderschat probleem?

Schade aan golfbanen en sportvelden wordt in Nederland vaak toegeschreven aan gebrekkige bemesting, schimmelaantasting of vreterij door emelten of andere insecten. Er wordt niet direct gedacht aan schade door aaltjes. In ons land is onderzoek naar schadelijke aaltjes, ofwel nematoden, niet standaard voor de aanleg van golfbanen, gazons of sportvelden. In tegenstelling tot landen met veel golfbanen en sportvelden zoals Engeland en de Verenigde Staten. In grondmonsters uit slecht groeiende plekken van golfbanen werden in deze landen diverse schadelijke aaltjessoorten gevonde