Comparison of the Galleria baiting technique and a direct extraction method for recovering Steinernema (Nematoda: Rhabditida) infective-stage juveniles from soil

Forty soil samples from forests and other biotopes in Germany and the Czech Republic were studied for the presence of entomopathogenic nematodes using the Galleria bait method at the same time as a sieving-decanting method for direct extraction of infective-stage juveniles. Five Steinernema species were recovered from the samples from Germany and four species from the samples from Czechia. All five species were recovered with both methods, but the baiting technique was generally less effective and mixtures of species were frequently undetected. The direct extraction method provided quantitative estimates of infective-stage juvenile density but no information on their infectivity or on morphological characters of adults, and nematode cultures could not be established.     

Report on the 42nd joint meeting of the DPG-working group Nematology and the working group “free living nematodes”

Journal of Plant Diseases and Protection -     

Über neue Wirtspflanzen der BlattälchenAphelenchoides fragariae undA. ritzemabosi,mit Bemerkungen zu den Wirtspflanzenkreisen beider Nematodenarten

Zusammenfassung Bei Untersuchungen, die an mehreren Orten im bayerischen Gebiet durchgeführt wurden, konntenAphelenchoides fragariae undA. ritzemabosi an zahlreichen Pflanzen als Parasiten festgestellt werden. FürA. fragariae wurden 46, fürA. ritzemabosi 31 vermutlich noch unbekannte Wirtspflanzen gefunden. Insgesamt sind damit vomA. fragariae mindestens 256, vonA. ritzemabosi mindestens 160 Wirtsarten bekannt. Eine Zusammenstellung s?mtlicher Wirtspflanzenfamilien beider Blatt?lchenarten mit Anzahl der zugeh?rigen anf?lligen Pflanzenarten la?t eine Bevorzugung bestimmter Pflanzenfamilien und-gattungen erkennen.A. fragariae bef?llt vorwiegend Farne, Liliaceen, Ranunculaceen, Primulaceen, wogegen A. riB emabosi vor allem die Compositen bevorzugt. Welche Faktoren die Wirtswahl und das unterschiedliche Verhalten beider Blatt?lchenarten bestimmen, ist noch weitgehend ungekl?rt. Die Auspr?gung der Befallssymptome h?ngt im Wesentlichen von Bau- und Reaktionsweise der befallenen Pflanzenteile ab und ist zwischen beidenAphelenchoides-Arten nicht wesentlich verschieden.     

Pflanzenparasitische Nematoden als Beute der Wurzelmilbe Rhizoglyphus echinopus (Acarina,Tyroglyphidae)

Plant-parasitic nematodes as a prey of the bulb mite Rhizoglyphus echinopus (Acarina, Tyroglyphidae In feeding experiments the bulb mite,Rhizoglyphus echinophus, was found to feed on the following plant-parasitic nematodes:Aphelenchoides ritzemabosi, Ditylenchus dipsaci, D. destructor, Heterodera avenae, Longidorus elongatus andXiphinema index. Moreover,Fusarium mycelium tobacco leaves and enchytraeids served as a diet. Small nematodes were completely devoured, large species bit into pieces and sucked out. WhiteHeterodera females were ingested with their egg contents, whereas brown cysts were only attacked after a hesitation. It is suggested that the polyphagous mite may constitute a regulator of nematode populations under certain conditions.      

Molecular Diagnostics, Taxonomy, and Phylogeny of the Stem Nematode Ditylenchus dipsaci Species Complex Based on the Sequences of the Internal Transcribed Spacer-rDNA

ABSTRACT The stem nematode Ditylenchus dipsaci is of great economic importance worldwide as a parasite of agricultural crops and horticultural plants. The internal transcribed spacer (ITS) of rDNA from 23 populations of the D. dipsaci complex from various host plants were amplified and sequenced. Seven previously studied populations were also included in the study. The phylogenetic analysis of the full ITS and ITS2 sequence alignments using minimum evolution, maximum parsimony, and Bayesian inference under the complex model of DNA evolution revealed trees with two main clades: (i) D. dipsaci sensu stricto with diploid chromosome numbers and comprising most isolates from agricultural, ornamental, and several wild plants, and (ii) Ditylenchus spp. with polyploid chromosome numbers, reproductively isolated from diploid populations, and subdivided into six subclades ("giant race" from Vicia faba, Ditylenchus species parasitizing various Asteraceae, and a Ditylenchus sp. from Plantago maritima). Using the energy minimization approach and comparative sequence analysis, it has been found that the secondary structure of ditylenchid ITS2 is organized in three main domains. The importance of knowledge on the RNA structure for phylogenetic analysis is discussed. Conventional polymerase chain reaction (PCR) and real-time PCR with SYBR green dye I with a species specific primer have been developed for detection and quantification of D. dipsaci sensu stricto Validation tests revealed a rather high correlation between real numbers of fourth-stage juveniles of the stem nematodes in a sample and expected numbers detected by real-time PCR. Problems of accuracy of quantification are discussed.     

Distribution of Cereal and Grass Cyst Nematodes in the Federal Republic of Germany1

A survey of cereal and grass cyst nematodes in the Federal Republic of Germany revealed that Heterodera avenae is the most widely distributed heteroderid species and common mainly in areas with light sandy soils and intensive cereal cultivation. The so-called ≪race 3 ≫ was recovered several times, and other populations differing morphologically from ≪ typical ≫ H. avenae were found. H. hordecalis, H. bifenestra, H. mani, H. iri and Punctodera punctata were also recovered in many parts of the country. In arable soils these species constituted only 7 % of all records of cereal and grass cyst nematodes, whereas they prevailed in grassland, forests and other habitats, where they amounted to almost 80 % of the records. 93 % of all H. avenae records came from agricultural soils, but only 21 % of the records of the five other species. H. hordecalis and H. bifenestra are obviously of no economic importance in FRG.     

Species Identification of European Cereal and Grass Cyst Nematodes by Larval Characters1

Second-stage juveniles of heteroderid species often present more reliable diagnostic characters than cysts. For identification of European cereal and grass cyst nematodes, size and position of the phasmids, swelling of the cuticle behind the lip region, expression of the lateral fields, shape and size of the stylet knobs and measurements of, for example, the tail and the hyaline tail portion are useful. A key presented, based on larval characters, allows identification of seven European cereal and grass cyst nematode species and their distinction from other European heteroderids not reproducing on Gramineae. Species identification is often difficult in the Heterodera avenae/H. mani complex and evidence exists that additional species are present within this group.