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

The contribution of two funds of identity interventions to well-being related student outcomes in primary education

Drawing on students' ‘funds of identity’ is supposed to contribute to more equitable educational outcomes, both in terms of achievement and well-being-related outcomes. However, it is not obvious how teachers can uncover and use students' funds of identity (FoI) and little is known about the actual effects of an approach based on funds of identity theory. This study investigates the (perceived) effects on students' engagement, motivation for learning, school well-being, social initiative and self-efficacy of two different interventions in which four primary school teachers tried to uncover and use their students' FoI (N = 31). A mixed methods design was used. Observations were conducted before, during and after the FoI-interventions, teachers filled in questionnaires and semi-structured interviews were conducted with teachers and students. In order to track how the intervention was enacted, logbooks of teachers were collected. The quantitative results showed significant improvement of students' engagement and social initiative during the FoI-interventions, which was confirmed by the observations. In the interviews and logbooks teachers and students reported positive effects of the interventions on students' engagement, motivation for learning, school well-being and self-efficacy. The interventions from this study can serve as examples for other schools

Morphological and molecular characterisation of Scutellonema species from yam (Dioscorea spp.) and a key to the species of the genus

The yam nematode, Scutellonema bradys, is a major threat to yam (Dioscorea spp.) production across yam-growing regions. In West Africa, this species cohabits with many morphologically similar congeners and, consequently, its accurate diagnosis is essential for control and for monitoring its movement. In the present study, 46 Scutellonema populations collected from yam rhizosphere and yam tubers in different agro-ecological zones in Ghana and Nigeria were characterised by their morphological features and by sequencing of the D2-D3 region of the 28S rDNA gene and the mitochondrial COI genes. Molecular phylogeny, molecular species delimitation and morphology revealed S. bradys, S. cavenessi, S. clathricaudatum and three undescribed species from yam rhizosphere. Only S. bradys was identified from yam tuber tissue, however. For barcoding and identifying Scutellonema spp., the most suitable marker used was the COI gene. Additionally, 99 new Scutellonema sequences were generated using populations obtained also from banana, carrot, maize and tomato, including the first for S. paralabiatum and S. clathricaudatum, enabling the development of a dichotomous key for identification of Scutellonema spp. The implications of these results are discussed

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

Aanvullend waardplantenonderzoek van Meloidogyne fallax Karssen, 1996

De wortelknobbelaaltjes Meloidogyne chitwoodi en M.fallax staan op de quarantainelijsten van de EU en de EPPO.De levenswijze van deze nematoden, hun potentiële schade en hun schaarse verspreiding in Europa waren aanleiding voor de quarantaine status. Beide nematoden zijn in Nederland aanwezig. Voor enkele gewassen is waardplantgeschiktheid voor M. chitiwoodi bekend, maar ontbreekt die van M.fallax. Om de uitbrekende gegevens aan te vullen is een aantal gewassen getoetst op hun waardplantgeschikthei