Common Nematode Species Research Articles

First report of the root-knot nematode Meloidogyne enterolobii on sweet potato in Georgia, United States.

Five species of root-knot nematodes (RKN), Meloidogyne spp. (M. haplanaria, M. incognita, M. floridensis, M. javanica, and M. arenaria) were detected in 67% of vegetable-growing regions in Georgia, United States (Marquez et al. 2021a, b; Marquez and Hajihassani 2022a, b). In October 2021, two sweet potato (Ipomoea batatas) samples (FF1 and FF2) collected at harvest from a field located in Tattnall County, Reidsville, GA were received for assessment. Symptoms of RKN damage on storage roots included a veiny appearance, surface cracking, and bumpy yellow to brown colored specks (Fig. 1). The population density of RKN second-stage juveniles (J2) was 148 and 180 J2/100 cm3 of soil for FF1 and FF2 samples, respectively. Genomic DNA was isolated by smashing females (n=10) individually in 20 µL of PCR-grade water, followed by freezing at -20°C overnight and thawing at 95°C for 1 min. Each DNA sample was first analyzed with a duplex PCR method using RKN species-specific primer sets for the most common nematode species: Mi2F4/Mi1R1 (M. incognita) and Far/Rar (M. arenaria) and SEC-1F/SEC-1R (M. incognita) and Fjav/Rjav (M. javanica) (Zijlstra et al. 2000; Hajihassani et al. 2022). Since this method failed to identify the RKN species, DNA samples were amplified with Me-F and Me-R primers, specific for diagnosing M. enterolobii (Long et al. 2006). Species-specific PCR produced a 240 bp DNA fragment for FF1 and FF2 samples (Fig. 2), corresponding to M. enterolobii. RKN species identification was confirmed by DNA sequencing using C2F3/1108 and TRNAH/MRH106 primers (Powers et al. 2018; Stanton et al. 1997). Products of C2F3/1108 (GenBank accessions ON320401 and ON320405) were 100% identical with 100% query coverage to a North Carolina M. enterolobii isolate (MN809527), while TRNAH/MHR106 sequences (ON320402 and ON320406) was 99.4-99.8% identical with 89-91% query coverage to a China isolate (MF467278). Measurements [Mean (range)] of body length of M. enterolobii J2 (BL): 454.0 (411.3-485.1) µm; maximum body width (BW): 15.1 (13.8-17.0) µm; stylet length: 14.3 (12.7-15.2) µm; total BL/greatest BW: 30.1 (28.6-31.4) µm; and BL/head end to posterior end of metacorpus: 7.3 (6.5-8.2) µm. Morphological measurements of J2 were comparable to the original description of M. enterolobii Yang and Eisenback. The host suitability of sweet potato varieties [Covington (susceptible to M. enterolobii), Beauregard (susceptible to intermediate), and Regal (resistant)] to the M. enterolobii isolate was assessed (Rutter et al. 2021). Nematode eggs were extracted from skin/bumps of samples FF1 and FF2 by blending (15 sec) and shaking in a 0.5% NaOCl solution (5 min), followed by washing and centrifugation in a standard sucrose solution. Sweet potato slips were transplanted in 10.8-cm-diam. pots filled with sand and steamed field soil (1:1 v/v), and two days after planting, were inoculated with 10,000 eggs of M. enterolobii (six replicates per plant variety). Plants were maintained in a greenhouse at 25-28°C for 85 days in a completely randomized design. Root galling index (scale of 0 to 5) of 4.4, 4.2, and 0.8 (Fig. 3) and reproduction factor (final egg numbers/initial egg number) of 8.2, 7.5, and 0.01 were obtained for Covington, Beauregard, and Regal, respectively confirming that Covington and Beauregard are susceptible to M. enterolobii while Regal is resistant. Meloidogyne enterolobii has not been reported in GA and this is the first report of the nematode on sweet potato in the state. This RKN species is an emerging pest of economic importance in many crops in the Southern United States (Brito et al. 2004; Rutter et al. 2018; Ye et al. 2013). Development of effective short- and long-term control procedures is urgently needed for managing M. enterolobii.

PARASITIC NEMATODE INFECTIONS OF ANURANS FROM A DERIVED SAVANNA BIOTOPE IN EDO STATE, NIGERIA

As part of a broader study to increase the information of parasite infections of anurans from the savanna biotope, an investigation of the nematode parasites of anurans in Agbede, a location in the derived savanna of Edo State, Nigeria was undertaken from August 2007 to July 2008. Anurans were collected at night using the visual acoustic encounter survey (VAES) sampling method, dissected and examined for nematode infections. A total of 329 anurans belonging to sixteen taxa, were examined, of which 235 were infected with an overall prevalence of 71.43%. Seasonal prevalences were 85.63% for wet season and 52.48% for the dry season (p<0.05). Ten nematode species, namely: Amplicaecum africanum, Cosmocerca ornata, Oswaldocruzia hoeplii, Physaloptera sp., Rhabdias africanus, Rhabdias sp., Camallanus dimitrovi, an unidentified oxyurid nematode, Ophidascaris larva, and an unidentified nematode were recovered from the hosts examined. The most common nematode species was Amplicaecum africanum (31.31%), whereas the least common was an unidentified oxyurid nematode (0.30%).Physaloptera sp. is a new record for the anurans of the derived savanna.

First Report of Meloidogyne enterolobii on Cultivated Fenugreek, Trigonella corniculata L. in India

Cultivated fenugreek Trigonella corniculata L, also known as kasuri methi or nagauri paan is a popular spice crop and widely grown in the state of Rajasthan, India. Galls and root-knot nematodes were observed on the roots of T. corniculata collected from Naguar district and its surrounding areas in the state of Rajasthan. The nematode DNA isolated from the sample was subjected to PCR by using species-specific primers for the common root-knot nematode species. Molecular identification confirmed the infestation of Meloidogyne enterolobii on T. corniculata. This is the first report of M. enterolobii infestation on T. corniculata from India.

Revisiting the adequacy of infection criteria recommended in VICH GL 7 for anthelmintic effectiveness studies: Retrospective simulations

Studies conducted to support registration or approval of veterinary anthelmintics generally follow study design recommendations provided by the VICH (International Cooperation on Harmonisation of Technical Requirements for Registration of Veterinary Medicinal Products), “Efficacy of Anthelmintics: General Requirements” (VICH GL7). For dose confirmation studies, VICH GL7 provides recommendations for determining that the control animals had an adequate infection “to permit the appropriate standards of efficacy to be met with acceptable statistical and biological certitude/confidence.” In the simulation studies described in this report, we investigated the performance of one method, the statistical criterion given in Section 4.5 of VICH GL7, for evaluating the adequacy of infection in anthelmintic studies, in combination with the conventional criterion of a minimum of six adequately infected animals. We conducted numerical simulations, based on parasite data from previously conducted dose confirmation studies in dogs and cattle, to investigate how the statistical criterion impacts adequacy of infection determinations when used with the conventional criterion at various sample sizes. Simulation studies in common nematode species in both dogs and cattle indicated that under certain circumstances the statistical criterion can guard against overinterpreting the evaluation of adequacy of infection as sample size is increased. However, the statistical criterion may be overly restrictive for samples with adequate infection but containing multiple zero parasite counts and adding it to the conventional criterion does not provide any additional benefit when the sample contains no zero counts. It is important for investigators designing efficacy studies to understand the potential impact this criterion may have when establishing adequacy of infection criteria in study protocols.

Integrated management of root-knot nematode (Meloidogyne spp.) in Florida tomatoes combining host resistance and nematicides

Host resistance governed by the Mi gene is available in many commercial tomato cultivars, and is effective against the most common tropical root-knot nematode species (Meloidogyne incognita, M. javanica and M. arenaria). The resistance has some drawbacks like the lack of activity against other common root-knot nematode species like M. hapla and M. enterolobii, the widespread emergence of resistance-breaking races of M. incognita, and the reported heat sensitivity of the Mi gene. In Florida, many tomato fields often also harbour soilborne pathogens and weeds, such as nutsedge, together with root-knot nematodes. Therefore, most tomato fields in Florida are fumigated, and nematode-resistant tomato cultivars are rarely planted. Two field trials were conducted during fall 2017 and spring 2018 to evaluate the potential of Mi-tomato cultivars in Florida, with or without additional use of a soil fumigant and/or nematicide. Root-knot severity in both seasons was significantly reduced in cultivars having Mi (Sanibel, Skyway, and Tasti Lee + Mi), as compared to the cultivar without Mi (FL 47). Fumigation with chloropicrin at 225 kg/ha and nematicides (fluensulfone in fall and fluazaindolizine in spring) also significantly reduced nematode damage. This was mostly noted for the cv. FL 47, and mostly during the fall growing season, when early nematode pressure was higher. End-of-season root-knot nematode soil populations were significantly lower with Mi cultivars. Chloropicrin on the other hand tended to increase end-of-season root-knot soil populations. No breakdown of resistance due to high soil temperature (>30 °C) was observed. Soil fumigation significantly increased fruit yield, especially in fall (95% increase) and to a lesser extent in spring (14.5% increase), and mostly so for cv. FL 47 and cv. Sanibel. Overall, cv. Sanibel produced the highest fruit yields.

Nematodes associated with terrestrial slugs in the Edmonton region of Alberta, Canada.

A survey of nematodes associated with terrestrial slugs was conducted in residential gardens, nurseries, greenhouses and agricultural sites located in and around Edmonton, Alberta, Canada. A total of 2406 slugs were collected from 82 sites. Slugs were decapitated and cadavers were incubated for two weeks, with emerging nematodes removed and processed for identification. Nematodes were identified using molecular sequence data for the 18S ribosomal DNA. Nematodes were recovered from 20 of the 82 sites surveyed, with 24.4% of the slugs infected with nematodes. A total of seven nematodes were identified to species level, including Caenorhabditis elegans, Panagrolaimus papillosus, Pellioditis typica, Pelodera pseudoteres, Rhabditella axei, Rhabditoides inermiformis and Phasmarhabditis californica. An additional four specimens were identified to genus level, including Oscheius sp. (9), Pristionchus sp., Rhabditis sp. and Rhabditophanes sp. (1). The two most common nematode species were C. elegans and P. pseudoteres. The facultative parasite, P. californica, was recovered from a single Arion rufus specimen, collected from a seasonal nursery. To our knowledge, this study represents the first survey of slug-associated nematodes in Canada.

First report of Meloidogyne javanica on Ginger and Turmeric in the United States.

Ginger (Zingiber officinale L.) and turmeric (Curcuma longa L.) are two her baceous perennial plant species with rhizomes that are commonly used for flavoring or medicinal purposes. In January 2018, stunting and poorly developed root systems typically associated with plant-parasitic nematode infection were observed on organically grown edible ginger and turmeric in a hoop house in Wheeler County, Georgia. Examination of soil and root samples from symptomatic plants revealed the presence of high populations of root-knot nematodes (Meloidogyne spp.). The second-stage juveniles (J2s) were extracted from soil samples as described by Jenkins (1964). Nematode counts were 285 and 155 J2s per 100 cm3 soil in the areas planted with ginger and turmeric, respectively. Nematode eggs were recovered from infected root systems using the bleach (1%) and blending method (Hussey and Barker, 1973). Examination of the root samples showed the presence of 840 and 320 eggs per g of roots in ginger and turmeric, respectively. Primary diagnosis of the Meloidogyne specimens was done by comparing morphological features observed in the J2s (n = 10) and perineal pattern of females (n = 11) based on the description given by Eisenback and Triantaphyllou (1991) and were tentatively identified as M. javanica (Treub, 1885; Chitwood, 1949). For species identification, DNA sequencing was performed using multiple markers located in 18S ribosomal RNA and 5.8S internal transcribed spacer 1 regions, (18S + ITS) (GenBank Accession No. MK390613), 28S domain 2 and 3 (28S D2/D3) (MK385596), cytochrome oxidase subunit I (COI) (MK391558), and subunit II and 16S (COII + 16S) (MK391557) of mitochondrial DNA following methods as described in Ye et al. (2015). PCR assays by species-specific primers were also conducted to confirm species identity as described by Zijlstra et al. (2000).The blast search results of DNA sequences of 18S + ITS, 28S (D2/D3), COI and COII + 16S revealed the best match as M. javanica, M. incognita (Kofoid and White, 1912; Chitwood, 1949) and M. arenaria (Neal, 1889; Chitwood, 1949) with 99–100% identity. These genes are highly conserved across these three most common root-knot nematode species. However, results of PCR assays by species-specific primers were only positive for M. javanica using primers Fjav/Rjav, but negative for M. incognita by Finc/Rinc and M. arenaria by Far/Rar as described by Zijlstra et al. (2000). Based on morphological characteristics and molecular analyses, the root-knot nematodes infecting ginger and turmeric were identified as M. javanica. After confirmation of the nematode species, a test was conducted in the greenhouse to assess the pathogenicity of the nematode on ginger and turmeric. Five seedlings per plant species (cultivars unknown) were grown in 15 cm-diam plastic pots containing equal parts of pasteurized field soil and sand, and then inoculated with 2,000 eggs of M. javanica. The egg suspension was added into three holes around the base of each seedling. Non-inoculated seedlings (n2 = 25) were used as controls. Plants were arranged in completely randomized design and grown at 25 ± 3 °C for 10 weeks. At the termination of the experiment, small galls were noticed on the roots of the inoculated seedlings of both ginger and turmeric. No galls were observed on the roots of non-inoculated plants. Egg were extracted from the galled roots (Hussey and Barker, 1973) yielding an average of 1040 ± 96 and 732 ± 54 eggs per g of root of ginger and turmeric, respectively. On ginger, the nematode produced large numbers of galls and egg masses on both primary and secondary (feeder) roots, but the galls produced on turmeric were often observed only on primary roots (Fig. 1). No symptoms of root-knot nematode infestation including galls or water-soaked lesions were observed on the outer surface of rhizomes of both ginger and turmeric. However, the size of rhizomes in the M. javanica-infested areas was visibly smaller than that in non-infested areas (Fig. 2). A similar reduction in the growth of turmeric rhizomes was also observed. Meloidogyne incognita has been commonly reported as a nematode pest of ginger (Myers et al., 2017) and turmeric (Hall et al., 2017) in the USA and both M. incognita and M. javanica are known to cause damage on these plant hosts (Ray et al., 1995; Singh and Gupta, 2011). To the best of our knowledge, this is the first report of M. javanica on ginger and turmeric in the USA.

Morphological and molecular characterisation of Spirinia antipodea Leduc n. sp. (Nematoda: Desmodoridae), a cryptic species related to S. parasitifera, from the coast of New Zealand

SummarySpirinia parasitiferais a common nematode species recorded from coastal habitats of the White, North and Barents Seas, the Northwest Atlantic, the Maldives and Australia, and exhibits a high degree of variability in some morphological characters. For these reasons it has been suggested thatS. parasitiferais a species complex comprised of several distinct but potentially cryptic species. However, no study has yet combined molecular and morphological approaches to verify this assertion. Here, we describeS. antipodean. sp., a species morphologically very similar toS. parasitifera, from the coast of New Zealand.Spirinia antipodean. sp. differs from the original description ofS. parasitiferaas well as subsequent descriptions by other authors in at least one body dimension, but no single trait differs consistently between the New Zealand specimens and all descriptions ofS. parasitifera. Phylogenetic analyses showed that the new species is distinct from other species of the genus, includingS. parasitiferaspecimens sampled near the type locality. TheS. antipodean. sp. SSU sequence differed from otherSpiriniasequence by 2.1-5.3%, whilst D2-D3 of LSU sequences differed by 12.5-18.9%. The consensus SSU tree also recovered three distinctS. parasitiferaclades, which provides support for the existence of a species complex. Because it is not possible to determine whether the variability in morphological characters observed among descriptions ofS. parasitiferais intra- or interspecific, and therefore to determine which trait can reliably be used to differentiate betweenS. antipodean. sp. andS. parasitifera, the new species is best differentiated fromS. parasitiferaand other closely related species based on SSU sequences rather than morphological characters.

Lack of population genetic structure in the marine nematodes Ptycholaimellus pandispiculatus and Terschellingia longicaudata in beaches of the Persian Gulf, Iran

AbstractWe investigated genetic diversity and population genetic structure of two common benthic nematode species, Ptycholaimellus pandispiculatus and Terschellingia longicaudata, from sandy beaches in the area of Bandar Abbas (Iran), Persian Gulf. Based upon partial mitochondrial cytochrome oxidase c subunit 1 (COI) gene data, 17 and two haplotypes were found for P. pandispiculatus and Te. longicaudata, respectively. Analysis of molecular variance did not reveal a significant population genetic structure for either species. The absence of genetic structuring indicates substantial dispersal and gene flow in our study area. To assess the species structure of Te. longicaudata at a larger geographic scale, we compared 18S rDNA and COI sequences from Iran and the Scheldt Estuary in The Netherlands to ascertain whether they truly belong to the same species. Our data confirmed previous studies that Te. longicaudata likely constitutes a complex of multiple cryptic species, with one of these species having a (near) cosmopolitan distribution.

Helminth parasites of the lesser great cormorant Phalacrocorax carbo sinensis from two nesting regions in the Czech Republic.

Parasitological examinations of 102 specimens of the lesser great cormorant Phalacrocorax carbo sinensis (Blumenbach) from two nesting regions in the Czech Republic (South Bohemia and South Moravia) were carried out at the Institute of Parasitology, Czech Academy of Sciences (previously the Czechoslovak Academy of Sciences) in the years 1987-1992. In them, a total of 19 species of helminth parasites was found, including Trematoda (11 species), Cestoda (2), Nematoda (4) and Acanthocephala (2), which can be divided into three main groups regarding their host specificity: parasites specific for cormorants (Phalacrocorax spp.) (37%), those parasitic mainly in cormorants (16%) and non-specific parasites (47%). Of the 19 species recorded, 100% were found in South Moravia, but only 47% of these 19 species in South Bohemia. The higher number of helminth species in cormorants from South Moravia and a higher proportion of non-specific species may be associated with the presence of the large Nové Mlýny water reservoir, in addition to better ecological and environmental conditions in this warmer region. Scanning electron microscopical examination of three common nematode species parasitising cormorants, Contracaecum rudolphii Hartwich, 1964, Desmidocercella incognita Solonitsin, 1932 and Syncuaria squamata (von Linstow, 1883), revealed some taxonomically important, previously unreported morphological features, such as the cephalic structures, numbers and distribution of male caudal papillae or the shapes of spicules.

Morphological, Biometrical, Biochemical, and Molecular Characterization of the Coffee Root-Knot Nematode Meloidogyne megadora

Meloidogyne megadora infects coffee trees, an economically important crop worldwide. The accurate identification of M. megadora is essential for the development of preventive measures to avoid the dispersion of this pathogen and establishment of efficient and sustainable integrated pest management programs. One M. megadora isolate was studied by biometrical, biochemical, and molecular characteristics (random amplified polymorphic DNA [RAPD] and PCR of internal transcribed spacer [ITS] region). Biometrical characteristics of M. megadora females, males, and second-stage juveniles were similar to the original description. Biochemical studies revealed a unique enzyme pattern for M. megadora esterases (Me3) that allowed for species differentiation. Three RAPD primers (OPG-4, OPG-5, and OPG-6) produced specific bands to all Meloidogyne spp. studied: M. megadora, M. arenaria, M. incognita, and M. javanica. Molecular analysis of the ITS region resulted in an amplification product of 700 bp. The phylogenetic relationship between M. megadora and several Meloidogyne spp. sequences was analyzed, revealing that M. megadora clearly differs from the most common root-knot nematode species. Based on the studies conducted, isozyme analysis remains a useful and efficient methodology for M. megadora identification when females are available. Further studies will be needed to convert the M. megadora differential DNA fragment obtained by RAPD and develop a species-specific sequence-characterized amplified region PCR assay for its diagnosis based on second-stage juveniles.

Factors likely to influence the adoption of targeted selective treatment strategies by sheep farmers in Western Australia

The investigation aimed to assess factors affecting the uptake of novel targeted selective treatment (TST) strategies by sheep farmers in Western Australia where the most common nematode species present were Teladosagia circumcincta, Trichostrongylus spp. and Nematodirus spp. (“scour worms”). The study used a questionnaire format with questions concentrated on current worm control practices and farmers’ current understanding and adoption of putative TST strategies. Participants represented a range of environments (derived from four farming regions) and sheep management situations, and it is therefore likely that the results of this investigation will apply in other locations where scour worms predominate. Sixty-five percent of participants were aware of the TST concept and 25% had implemented it in some form. The awareness of the TST approach was greatest where sheep farmers were concerned about anthelmintic resistance, where tools such as worm egg counts and faecal worm egg count resistance tests were employed, and where professional advisers were consulted regarding worm control. Respondents that sought advice chiefly from rural merchandise retailers were considerably less (0.1–0.6 times) likely to be aware of these management tools or to be aware of TST approaches. The findings indicated that the adoption of TST strategies will require greater use of professional advisers for worm control advice by sheep farmers, and that advisers are conversant with TST concepts.

Opossum Nematodiasis: Diagnosis and Treatment of Stomach, Intestine, and Lung Nematodes in the Virginia Opossum (Didelphis virginiana)

Internal parasitic infections are common in the Virginia opossum (Didelphis virginiana). More than 50 different species of nematodes have been identified from the genus Didelphis. Of them, 3 can cause significant illness to native opossums in Southern California, 2 gastrointestinal nematodes and 1 pulmonary nematode. This article provides an overview of the life cycles, methods for identification, pathologic findings, diagnostic tests, clinical signs, and options for treating these common nematode species.

Differences in time until dispersal between cryptic species of a marine nematode species complex.

Co-occurrence of closely related species may be achieved in environments with fluctuating dynamics, where competitively inferior species can avoid competition through dispersal. Here we present an experiment in which we compared active dispersal abilities (time until first dispersal, number and gender of dispersive adults, and nematode densities at time of dispersal) in Litoditis marina, a common bacterivorous nematode species complex comprising four often co-occurring cryptic species, Pm I, II, III, and IV, as a function of salinity and food distribution. The experiment was conducted in microcosms consisting of an inoculation plate, connection tube, and dispersal plate. Results show species-specific dispersal abilities with Pm I dispersing almost one week later than Pm III. The number of dispersive adults at time of first dispersal was species-specific, with one dispersive female in Pm I and Pm III and a higher, gender-balanced, number in Pm II and Pm IV. Food distribution affected dispersal: in absence of food in the inoculation plate, all species dispersed after ca four days. When food was available Pm I dispersed later, and at the same time and densities irrespective of food conditions in the dispersal plate (food vs no food), suggesting density-dependent dispersal. Pm III dispersed faster and at a lower population density. Salinity affected dispersal, with slower dispersal at higher salinity. These results suggest that active dispersal in Litoditis marina is common, density-dependent, and with species, gender- and environment-specific dispersal abilities. These differences can lead to differential responses under suboptimal conditions and may help to explain temporary coexistence at local scales.

Plant parasitic nematodes associated with vegetable growing greenhouses in Southeastern Anatolia Region, Turkey

In this study, plant parasitic nematodes determined in greenhouses of vegetables growing in some provinces of the Southeastern Anatolia Region (Batman, Diyarbakir, Mardin, Siirt and Ažanliurfa) were examined faunistically and taxonomically. Nematode species obtained from soil and root samples were measured and identified by preparing their permanent preparations. The descriptions, synonyms, possible variations, distribution, habitats and literature records of each species are presented in this study. As a result of the study, totally, 18 species belonging to 10 genera of 7 families of superfamilies, Tylenchoidea, Hoplolaimoidea and Anguinoidea of suborder, Tylenchina were determined. This was first recorded since there was no literature record regarding the nematodes in greenhouses of vegetables growing in The Southeastern Anatolia Region. The most common nematode species in this study are Ditylenchus destructor Thorne (54.54%),Pratylenchoides alkani Yuksel (42.42%), Geocenamus brevidens Allen (Siddiqi) (24.24%), Pratylenchus thornei Sher and Allen (21.21%) and Boleodorus thyllactus Thorne (18.0%), respectively. Key words: Southeastern Anatolia Region, Turkey, plant parasitic nematodes, nematafauna, vegetable, greenhouse.

Effects of Using Chemical-Free Root-Knot Nematode (Meloidogyne Incognita) Control Methods on the Occurrence of Blossom-End Rot in Pepper

Pepper takes up the largest growing area among forced vegetables in Hungary. The most significant abiotic disease problem of this plant is blossom-end rot (BER), which can cause substantial yield losses. The uptake of calcium by plants from the soil may be negatively affected by many factors such as root-knot nematodes feeding on the roots. The nematodes then impede water and nutri- ent transport. In Hungary, Meloidogyne incognita is the most common root-knot nematode species in greenhouses. The use of resistant cultivars is undoubtedly the most successful control method of root-knot nematodes in warm climates. Growing of resistant pepper cultivars, and grafting onto resistant rootstocks offer alternative, environmentally friendly ways of control. The main objective of this study was to investigate the effect of both growing resistant pepper cultivars and using resistant rootstocks on the occurrence of fruit showing symptoms of BER. Research was carried out in a plastic tunnel with soil which was heavily infested with M. incognita. Roots of the non-resistant cultivars were moderately damaged by the pest at the end of the vegetation period. After grafting these cultivars onto two different resistant rootstocks, symptoms of damage caused by M. incognita were not observed on the rootstocks. There was a negligible number of galls appearing on the roots of the resistant cultivar Cinema F1. Due to the resistance properties and other characteristics of the newly bred Cinema F1, fruit of this cultivar rarely show symptoms of calcium deficiency. In most cases, there was less fruit with BER symptoms in plants grafted onto rootstocks Robusto F1 or Snooker F1. The results showed a reduction in the extent of damage caused by the root-knot nematode, and there were other beneficial effects of the rootstocks on the scions. The occurrence of fruit showing symptoms of BER was reduced.

Responses of Seashore Paspalum Cultivars to Sting and Spiral Nematodes

ABSTRACTSting (Belonolaimus longicaudatus Rau) and spiral (Helicotylenchus spp.) nematodes are among the most common and damaging nematode species found on seashore paspalum (Paspalum vaginatum Swartz) in Florida. Restriction and cancellation of nematicides on turfgrass have accelerated the development of more environmentally friendly nematode management strategies. Use of nematode‐tolerant or ‐resistant cultivars is the practice with the least ecological impact on nontargeted species. The objective of this study was to identify the nematode tolerance or resistance of commercial seashore paspalum cultivars. Seven cultivars were tested under greenhouse conditions in two sequential trials. The cultivars were grown in sand‐filled plastic conetainers and inoculated with 50 sting nematodes or 500 spiral nematodes conetainer−1. Nematode and root samples were collected 90 d after nematode inoculation. All seashore paspalum cultivars supported the reproduction of sting nematode, with a reproduction rate of 2.7‐ to 9.5‐fold in the two trials. Population densities of the spiral nematode H. pseudorobustus (Steiner, 1914) Golden, 1956 declined on all cultivars. Seashore paspalum cultivars showed differences in root length reductions caused by nematodes. ‘Salam’, ‘SeaDwarf’, and ‘SeaIsle Supreme’ were most tolerant to sting nematode, and ‘SeaSpray’ and ‘SeaIsle 2000’ were most tolerant to spiral nematode. No cultivar was tolerant to both nematode species.

Changes in Plant Species Richness Induce Functional Shifts in Soil Nematode Communities in Experimental Grassland

BackgroundChanges in plant diversity may induce distinct changes in soil food web structure and accompanying soil feedbacks to plants. However, knowledge of the long-term consequences of plant community simplification for soil animal food webs and functioning is scarce. Nematodes, the most abundant and diverse soil Metazoa, represent the complexity of soil food webs as they comprise all major trophic groups and allow calculation of a number of functional indices.Methodology/Principal FindingsWe studied the functional composition of nematode communities three and five years after establishment of a grassland plant diversity experiment (Jena Experiment). In response to plant community simplification common nematode species disappeared and pronounced functional shifts in community structure occurred. The relevance of the fungal energy channel was higher in spring 2007 than in autumn 2005, particularly in species-rich plant assemblages. This resulted in a significant positive relationship between plant species richness and the ratio of fungal-to-bacterial feeders. Moreover, the density of predators increased significantly with plant diversity after five years, pointing to increased soil food web complexity in species-rich plant assemblages. Remarkably, in complex plant communities the nematode community shifted in favour of microbivores and predators, thereby reducing the relative abundance of plant feeders after five years.Conclusions/SignificanceThe results suggest that species-poor plant assemblages may suffer from nematode communities detrimental to plants, whereas species-rich plant assemblages support a higher proportion of microbivorous nematodes stimulating nutrient cycling and hence plant performance; i.e. effects of nematodes on plants may switch from negative to positive. Overall, food web complexity is likely to decrease in response to plant community simplification and results of this study suggest that this results mainly from the loss of common species which likely alter plant – nematode interactions.

Facing the threat of equine parasitic disease

Horses worldwide are exposed to a complex mixture of intestinal parasitic helminths. When burdens are high, these parasites can seriously compromise health and welfare. Some helminth species have an extremely high prevalence and are difficult to control, not least because there is a limited understanding of their most basic biology. Furthermore, levels of resistance to some of the commonly used anthelmintics are widespread and increasing. The cyathostomins are the most common nematode species affecting equids worldwide. Within this group of parasites are more than 50 different species. Until recent research activities, little was known about the contribution that individual species make to clinical disease, parasite epidemiology and anthelmintic resistance. This review describes some of the recent research advances in the understanding of cyathostomins in these areas. As part of the research effort, molecular tools were developed to facilitate identification of the non-parasitic stages of cyathostomins. These tools have proved invaluable in the investigation of the relative contributions that individual species make to the pathology and epidemiology of mixed infections. At the more applied level, research has also progressed in the development of a diagnostic test that will allow numbers of cyathostomin encysted larvae to be estimated. This test utilises cyathostomin-specific serum antibody responses as markers of infection. As anthelmintic resistance will be the major constraint on parasite control in future, researchers are actively investigating mechanisms of drug resistance and how to improve the detection of resistance in the field. Recent developments in these areas are also outlined.

Severe infection of adult dogs with helminths in Hunan Province, China poses significant public health concerns

The prevalence of helminths in adult dogs was investigated in Hunan Province, the People's Republic of China between June 2006 and December 2007. A total of 438 adult farm dogs slaughtered in local abattoirs from 9 representative administrative regions in Hunan Province were examined for the presence of helminths using a helminthological approach. All collected worms were counted and identified to species according to existing keys and descriptions. A total of 11 helminth species were found in the dogs, and they represented 2 phyla, 3 classes, 6 families and 8 genera. All dogs were infected by more than one helminth species. Clonorchis sinensis (29.4%) was the only trematode species found, Dipylidium caninum (42.3%) was the most common cestode species, and Toxocara canis (45.2%) the most common nematode species. 6 of the 11 dog helminths are also transmissible to humans (i.e., zoonotic), and can cause severe clinical human diseases, posing significant public health threats. The results of the present investigation have implications for the ongoing control of helminth infections in dogs and humans in Hunan Province, China.