BackgroundDispersal is an important nematode behavior. Upon crowding or food depletion, the free living bacteriovorus nematode Caenorhabditis elegans produces stress resistant dispersal larvae, called dauer, which are analogous to second stage juveniles (J2) of plant parasitic Meloidogyne spp. and infective juveniles (IJ)s of entomopathogenic nematodes (EPN), e.g., Steinernema feltiae. Regulation of dispersal behavior has not been thoroughly investigated for C. elegans or any other nematode species. Based on the fact that ascarosides regulate entry in dauer stage as well as multiple behaviors in C. elegans adults including mating, avoidance and aggregation, we hypothesized that ascarosides might also be involved in regulation of dispersal behavior in C. elegans and for other nematodes such as IJ of phylogenetically related EPNs.Methodology/Principal FindingsLiquid chromatography-mass spectrometry analysis of C. elegans dauer conditioned media, which shows strong dispersing activity, revealed four known ascarosides (ascr#2, ascr#3, ascr#8, icas#9). A synthetic blend of these ascarosides at physiologically relevant concentrations dispersed C. elegans dauer in the presence of food and also caused dispersion of IJs of S. feltiae and J2s of plant parasitic Meloidogyne spp. Assay guided fractionation revealed structural analogs as major active components of the S. feltiae (ascr#9) and C. elegans (ascr#2) dispersal blends. Further analysis revealed ascr#9 in all Steinernema spp. and Heterorhabditis spp. infected insect host cadavers.Conclusions/SignificanceAscaroside blends represent evolutionarily conserved, fundamentally important communication systems for nematodes from diverse habitats, and thus may provide sustainable means for control of parasitic nematodes.

SummaryParatylenchus (Gracilacus) straeleni (De Coninck, 1931) Oostenbrink, 1960 was detected for the fi rst time in Turkey. Our studied population was found in the rhizosphere soil of hazelnut orchards in Ordu. Females and males were studied morphologically and morphometrically by light microscopy and molecularly by sequencing the D2-D3 of the 28S rDNA gene. We present here the morphological and molecular characterisation, phylogenetic analysis of examined population and comparison of variability of worldwide known populations of P. straeleni.

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The study was conducted to investigate the status of soil nematode communities in hazelnut orchards in Ordu province, Turkey. Nematodes were identified to genus level and allocated to trophic groups. A total of 50 taxa were found from hazelnut growing areas including 19 plant parasites, 12 bacterivorous, 4 fungivorous, 4 predators and 11 omnivorous. Genera Tylenchus (94.5%), Gracilacus (79.1%) and Helicotylenchus (56.4%) as plant parasites, Acrobeloides (68%) as bacterivores and Aphelenchoides (68.2%) as fungivorous were widespread and found in all districts. The highest abundance of plant parasites was in Kabataş (277 individual/ 100 cm 3 soil) followed by Gölköy (196.6 ind./ 100 cm 3 soil) district. Criconemella, Meloidogyne, Paratylenchus and Pratylenchus were found as important genera by means of the damage potantial on hazelnut as plant parasitic group. The other trophic groups were at desirable level for an healthy soil system.

Essential oils of medicinal and aromatic plants are important and promissing to manage the nematological problems in agriculture. In this study, five of the plants including Origanum onites, Salvia officinalis, Lippia citriodora, Mentha spicata and Mentha longifolia for egg hatching inhibition and four of the plants including Mentha piperita, Foeniculum vulgare, Coriandrum sativum and Ocimum basilicum for juvenile mortality were tested on Meloidogyne hapla under laboratory conditions. The oils were achieved by using water distillation method with a Clevenger apparatus. As the results of egg hatching trial, the highest egg hatching inhibition rate was found as 54% for O. onites. In addition, the other inhibition rates varied as 31.4%, 21.6%, 23.8%, 25.7% for the other plants, S. officinalis, M. longifolia, M. spicata and L. citriodora, respectively. Essential oil of each plant components were determined by gas chromatography (GC). Carvacrol was found as the main component (68.8%) of O. onites followed by Thujone 27.7% for S. officinalis, I-Menthone 76.9% for M. longifolia, Carvone 27.1% for M. spicata and Citral 19.3% for L. citriodora. For the juveile mortality, Mentha piperita showed the highest mortality rate as 93.2% and was followed by F. vulgare 72.9%, C. sativum 69.3% and O. basilicum 64.9%. The main component of the used plants were Carvone 39.3%, Anethole 40.2%, Linalool 81.3% and Linalool 54.6%, respectively.

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SummaryThis study was conducted to determine the suppressiveness of obligat parasite P. penetrans against the peanut root-knot nematode Meloidogyne arenaria race 1 in vegetable growing site and to find out whether the field site have infested with other root-knot nematode species, causing the suppression to break down. The study were carried out at four vegetable crops grown sites tomato Lycopersicon lycopersicum cv. Bella Rosa, cucumber Cucumis sativus L. cv. Cobra, okra Abelmoschus (=Hibiscus) esculentus (L.) Moench cv. Clemson Spineless and squash Cucurbita pepo L. cv. Golden Summer at the Plant Science Research and Education Unit-Citra, University of Florida, US. The field site was arranged in a split plot design with eight replicates. To determine the effect of 1,3-dichloropropene (1,3-D) on P. penetrans, the split plot was fumigated with 1,3-D (Telone II)at dose of 112 L/ha.. Plant and soil samples were collected from each plot at harvest time. The percentages of M. arenaria race 1 infective juvenile (J2) with endospores attached ranged from 40%to 10%.. Only a very low incidence of M. incognita was extracted from tomato roots galls.. The results indicate that P. penetrans is likely to be one of the important effective agent in the nematode suppression and the reduction M. arenaria race 1 damage.. ÖzetBu çalışmanın amacı, obligat parazit olan Pasteuria penetrans bakterisinin sebze yetiştirilen alanlarda kök-ur nematodu Meloidogyne arenaria ırk 1'e karşı baskınlığını ortaya çıkarmak, bu baskınlığın etkisinin kırılmasına neden olan diğer kök-ur nematod türlerinin alanda bulunup bulunmadığını tespit etmektir. Bu amaçla 2011 yılının Mart ayında, daha önceden P. penetrans bulaştırılmış ve M. arenaria race 1'e karşı baskın olduğu bilinen Florida Üniversitesi'nin araştırma arazisinde, domates Lycopersicon lycopersicum cv. Bella Rosa, salatalık Cucumis sativus L. cv. Cobra, bamya Abelmoschus (=Hibiscus) esculentus (L.) cv. Clemson Spineless ve kabak Cucurbita pepo L. cv. Golden Summer gibi dört farklı sebze çeşidi yetiştirilmeye başlanmıştır. Çalışma bölünmüş parseller deneme deseninde 8 tekerrürlü olarak yürütülmüştür. Her bir sebze çeşidi için biri ilaçlı diğeri ilaçsız olacak şekilde parseller hazırlanmıştır. Ilaçlı parseller 112 lt/ha oranında 1,3-dichloropropene (1,3-D) (Telone II) ile ilaçlanmıştır. Tüm deneme parsellerinden hasat sonunda bitki kökleri ve toprak örnekleri alınarak inceleme yapılmıştır. Alınan toprak örneklerinden elde edilen M. arenaria ırk 1 juvenillerinin P. penetrans'ın endosporları ile bulaşıklık oranı en yüksek %40 olarak kimyasal uygulanmış kabak parselinde, en düşük endospor bulaşıklık oranı ise kimyasal uygulanmayan bamya parselinde yaklaşık %10 olarak gözlenmiştir. Deneme alanlarında yetiştirilen sebzelerden yalnızca domates bitkisi köklerinde çok düşük oranda diğer nematode türlerinden M. incognita tespit edilmiştir. Çalışmadan elde edilen sonuçlar, sebzelerde M. arenaria race 1 tarafından meydana gelen zararın azaltılmasında ve bu nematodun baskı altında tutulmasında P. penetrans'...

Swiss Chard (Beta vulgaris subsp. cicla) is a vegetable crops growing in different regions of the world for variying purposes. Root-knot nematodes (Meloidogyne spp.) seem the potantial pest group on Swiss Chard according to the reported species from other countries. In this investigation, the root knot nematode (RKN) extracted from the root of Swiss Chard was identified as M. arenaria by using different primer sets (TRNAH-MRH106 and MORF-MTHIS) targeting the large sub-unit ribosomal DNA (lrDNA) and the intergenic spacer (IGS) of rDNA of mitochondrial (mtDNA). Furthermore, the restriction enzymes (HinfI and MnlI) for the fragments given by TRNAH-MRH106 primer set was also used for restriction and digestion. Finally, species-specific SCAR primers (Far/Rar) were performed to validation of the identification results. M. arenaria is considered as an important species among the major root knot nematodes in the world. In this context, the Swiss Chard as an intercroped, small-scale produced or randomly dispersed commodity must be observed as the potantial host for the nematode. This is especially important in case of any change for long term professional production planning in the same area for more valuable agricultural commodity.