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Steinau an der Straße, Germany

Iqbal M.,Ghent University | Ehlers R.-U.,E nema GmbH | Waeyenberge L.,Belgium Institute for Agricultural and Fisheries Research
Nematology | Year: 2016

Entomopathogenic nematodes belong to the families of Steinernematidae and Heterorhabditidae. They are obligate and lethal parasites of insects that can provide effective control of some important pests of commercial crops. A total of 53 isolates of EPN were molecularly characterised (ITS region-based) in the present study. Most of the studied isolates belong to the Steinernema genus and only few isolates belong to the Heterorhabditis genus. The phylogenetic relations of Steinernema and Heterorhabditis species were analysed by utilising the maximum likelihood method. In the Steinernema phylogenetic tree, 99 isolates formed five major, moderately or highly reinforced clades: clade I: affine-intermedium group; clade II: carpocapsae-siamkayai-tami-scapterisci; clade III: bicornutum-riobrave-thermophilum; clade IV: glaseri-arenarium-karii-longicaudum; and clade V: feltiae-schliemanni-kushidaikraussei- oregonense. The BLAST analysis of the ITS region of the rDNA of the steinernematid isolate PAL10 showed a rather low similarity of 93% with S. vulcanicum (accession number: GU929442), supporting the possible designation of a new species. In the Heterorhabditis phylogenetic tree, 25 isolates formed three main clades: clade I: bacteriophora-argentinensis-hepialius; clade II: baujardi-sonorensis-amazonensis; and clade III: indica-brevicaudis-hawaiiensis. All five studied isolates of Heterorhabditis were identified as H. indica and H. bacteriophora. In both phylogenetic trees, the intra-specific variability level was different among clades for some species. The description of the new species (PAL10 isolate) would need further morphometric characterisation, morphologically identification and cross-breeding studies. © Koninklijke Brill NV, Leiden, 2016. Source

Honnens H.,University of Kiel | Assheuer T.,University of Kiel | Ehlers R.-U.,University of Kiel | Ehlers R.-U.,E nema GmbH
Aquaculture International | Year: 2014

The nematode Panagrolaimus sp. (strain NFS-24-5) may have potential as a live food organism for larvae of several marine species. It can be mass-produced in liquid culture and is desiccation tolerant enabling long-term storage and transportation. Nematodes lack the essential fatty acid docosahexaenoic acid (DHA), so this investigation examined an enrichment procedure by incubating nematodes in S.presso® (INVE Aquaculture, Belgium), a commercial enrichment product. Mass-produced nematodes from liquid cultures on yeast cells were cleaned and then exposed to concentrations of 0.1-3 % S.presso® for 24 h at 200,000 nematodes ml-1. Nematode viability was >90 % after the treatment. Following enrichment percentage, total lipid ranged from 23.6 to 33.3 % of nematode dry matter, and nematodes incubated in 3 % S.presso® had a significantly higher lipid percentage than untreated controls. Enrichment was successful in increasing the percentage of DHA, and a maximum value of 5.8 % of total fatty acids was achieved. The results of enrichment of Panagrolaimus sp. (strain NFS-24-5) following treatment with 3 % S.presso® should promote the carrying out of feeding trials to test the efficacy of the nematodes as a live food for larval marine fish and crustaceans. © 2013 Springer Science+Business Media Dordrecht. Source

Peters A.,E nema GmbH
Applied Microbiology and Biotechnology | Year: 2013

While nematodes are most commonly known for their negative impact on plants, animals, and humans, there are a number of species which are commercially explored. This review highlights some of the most important success stories for the application of nematodes. They are used as bioindicators in ecological and toxicity studies, as model organisms for elucidating fundamental biological questions and for high throughput screening of drugs. Besides these indirect uses, direct applications include the use of Beddingia siricidicola against a major forest pest and the commercialization of Steinernema, Heterorhabditis, and Phasmarhabditis as biological pest control products. New directions for the commercialization of nematodes are the use as living food, specifically loaded with essential nutrients for various fish and shrimp larvae. Even human parasites or closely related species have been successfully used for curing autoimmune disorders and are currently in the process of being developed as drugs. With the striving development of life sciences, we are likely to see more applications for nematodes in the future. A prerequisite is that we continue to explore the vast number of yet undiscovered nematode species. © 2013 Springer-Verlag Berlin Heidelberg. Source

Nimkingrat P.,University of Kiel | Strauch O.,University of Kiel | Ehlers R.-U.,University of Kiel | Ehlers R.-U.,E nema GmbH
Biocontrol Science and Technology | Year: 2013

Shelf life of biological control products based on the entomopathogenic nematode Steinernema feltiae is rather limited. In order to prolong shelf life, the metabolism of nematodes during storage must be reduced, either by low temperature or by means of desiccation of the third stage dauer juveniles (DJs). Tolerance to desiccation is limited in S. feltiae. Their tolerance can be increased by an adaptation to moderate desiccation conditions. The objective of this study was to screen for tolerant strains among wild type populations of S. feltiae, hybridise most tolerant strains and further improve desiccation tolerance by subjection of the hybrid strain to genetic selection. Dehydrating conditions, measured as water activity (aw-values), were produced by treating DJs with different concentrations of the polymer polyethylene glycol 600. Significant variation was recorded among 24 S. feltiae strains. The mean tolerated water activity survived by 50% of the population (WA50) ranged from 0.78 to 0.93 when nematodes were not adapted to desiccation stress and from 0.66 to 0.88 when preadapted to desiccation stress. The six most desiccation tolerant strains of non-adapted and adapted nematode populations were crossed. Preadapted tolerance of hybrids was superior to the tolerance of parental strains, whereas non-adapted tolerance was not increased. The most tolerant hybrid had a WA50 when preadapted of 0.67 and 0.86 when not adapted. The tolerance was lost after few reproductive cycles in the insect Galleria mellonella but was recovered again after six selection cycles with exposure to increasing stress conditions. Virulence and reproduction potential was not negatively affected by the selection. Stabilisation of the selection progress will be a major challenge to enable commercial exploitation of the genetic improvement. © 2013 Taylor & Francis. Source

Honnens H.,University of Kiel | Ehlers R.-U.,E nema GmbH
Nematology | Year: 2013

Free-living nematodes have potential to be used as live food for early life stages of several species in marine aquaculture. Panagrolaimus sp. displays several favourable characteristics for this application. The present study proved the feasibility of propagation in monoxenic liquid culture on Saccharomyces cerevisiae. The development of yeast cell density, nematode numbers and size distribution was assessed daily for 15 days. After a lag phase of 4 days the inoculated first-stage juveniles started development to adults. Yields in terms of nematode number as well as biomass were highly variable. The maximum number of nematodes varied from 45 000 to 238 000 ml-1 and maximum biomass from 49 to 143 g l-1. Information on size, dry and wet weight of the nematodes is provided. The size spectrum of Panagrolaimus sp. individuals ranged from 176 × 8 μm to 1377 × 61 μm and 8.15 to 3202.39 ng wet weight. Water content of the nematodes was 71.7 ± 2.5%, so dry weight per individual was 2.31-905.95 ng. Differentiation of juvenile stages by body length was not possible. Based on comparison of dry weight per individual the Panagrolaimus sp. might be used as a substitute for rotifers, a commonly used live food organism. © 2013 Koninklijke Brill NV, Leiden. Source

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