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Summary: A survey conducted along the Panjkora river in Bajaur, Khyber Pakhtunkhwa (KPK), Pakistan, identified seven isolates of nematode populations belonging to the Heteroderidae family among the 25 soil and root samples examined. Within these isolates, three were classified as Heterodera avenae , H. filipjevi and H. zeae , while the remaining four were identified as Globodera pallida. The identification of these cyst nematodes involved a combination of morphological and morphometric analyses, complemented by molecular techniques employing newly designed primers to amplify diagnostic regions from any cyst nematode. This study marks the first molecular characterisation of H. avenae , H. zeae and G. pallida in Pakistan and the initial report of H. filipjevi in the country. The mapping of crop-growing regions with sampling points highlights areas at high risk for further pathogen spread. [ABSTRACT FROM AUTHOR]

Recently, the Commission Implementation Regulation (CIR) 2022/1192 was published by the European Union, prescribing regulations on eradication measures for quarantine potato cyst nematodes, including mandated assays for species identification. The CIR 2022/1192 provides a derogation on the use of Beniers et al. (2014) real-time PCR as the validation process was still ongoing. In this study, the validation of a modified version of the Beniers real-time PCR was carried out, following EPPO Standard PM 7/98. Furthermore, the performance was compared to the conventional PCR of Bulman & Marshall (1997) and the Gamel et al. (2017) real-time PCR, both DNA based, which are mandated by CIR 2022/1192. Additionally, the effect of cyst viability was compared with the two real-time PCR assays. The modified Beniers real-time PCR met all validation performance criteria for both target Globodera pallida and G. rostochiensis. The viability assays showed that the DNA based Gamel real-time PCR provided positive results for non-viable, non-infectious cysts, in contrast to the modified RNA based Beniers real-time PCR. Based on the results of this study, the modified Beniers qualifies for the detection and identification of viable Globodera pallida and G. rostochiensis and performs at least equally as well as the other two PCR assays. To encourage the development and improvement of diagnostic protocols, it is suggested that diagnostic laboratories performing official surveys are allowed to use internationally recognized diagnostic protocols when validated in-house according to EPPO standards and accredited by the EU bodies (EPPO, 2021). [ABSTRACT FROM AUTHOR]

Real-time quantitative polymerase chain reaction (qPCR) is used to estimate the population densities of the potato cyst nematodes Globodera pallida Stone and Globodera rostochiensis (Wollenweber) Skarbilovich (Tylenchida: Heteroderidae). Since it is difficult to extract nematode DNA from large amounts of soil (≥ 100 g, enough for quantification of cyst nematodes), cyst isolation is required before DNA extraction. However, when isolating cysts from the soil, various impurities are simultaneously isolated, and separating the cysts from these impurities is laborious. Although previous studies have reported methods for extracting DNA from mixtures of cysts and impurities, it is unclear whether such DNA can be used to estimate nematode densities using qPCR. To examine the effects of impurities on the accuracy of qPCR quantification, we extracted DNA from nematode eggs (G. pallida and G. rostochiensis) mixed with impurities and performed qPCR. The results suggested that the differences in the fields affected the quantification accuracy. Therefore, field-specific standard curves should be set, which are impractical for routine diagnosis. To propose a more practical method, we determined a fixed standard curve for each species and estimated the population densities in field soil samples by qPCR using the standard curves. The estimated population densities significantly correlated with those determined using conventional microscopic inspections. This study revealed that the population densities of G. pallida and G. rostochiensis can be estimated from large amounts of soil, probably only approximately, but efficiently, by qPCR using DNA extracted from mixtures of cysts and impurities. [ABSTRACT FROM AUTHOR]

Potato production faces major challenges from inadequate soil fertility, and nematode infestation, yet synthetic fertilizers and nematicides are costly and harmful to the environment. This study explored the potential of chitin-fortified black soldier fly-composted organic fertilizer (BSFCOF) as a multipurpose organic fertilizer amendment for enhancing potato yield and suppressing potato cyst nematodes (PCN). The BSFCOF was applied at a rate equivalent to 150 kg N ha-1 and fortified with chitin from black soldier fly pupal exuviae at inclusion rates equivalent to 0.5, 1, 2, 3, 4 and 5% chitin. Data were collected on potato growth characteristics, PCN population densities, and soil chemical properties for two growing cycles. Results showed that chitin fortified BSFCOF significantly improved potato growth parameters, chlorophyll concentration, marketable tuber yield and number of marketable tubers. The marketable tuber yield achieved using chitin-fortified BSFCOF was 70 - 362%, and 69 - 238% higher than the values achieved using unfertilized soil during the first and second growing cycles, respectively. Soil amendment with chitin-fortified BSFCOF significantly reduced the number of cysts per 200 g soil-1, number of eggs and J2 per cyst-1, eggs g-1 soil and reproduction rate by 32 - 87%, 9 - 92%, 31-98% and 31 - 98%, respectively. The PCN suppression increased with chitin inclusion rates. There were significantly higher values for soil pH, ammonium nitrogen, nitrate nitrogen, available phosphorus, calcium, magnesium, potassium, and cation exchange capacity in soil amended with BSFCOF compared to unamended soil. This study demonstrates that BSFCOF fortified with 5% chitin is an effective soil enhancer with multiple benefits, including improved soil fertility, potato performance, and effective management of potato cyst nematodes. [ABSTRACT FROM AUTHOR]

Potato production faces major challenges from inadequate soil fertility, and nematode infestation, yet synthetic fertilizers and nematicides are costly and harmful to the environment. This study explored the potential of chitin-fortified black soldier fly-composted organic fertilizer (BSFCOF) as a multipurpose organic fertilizer amendment for enhancing potato yield and suppressing potato cyst nematodes (PCN). The BSFCOF was applied at a rate equivalent to 150 kg N ha-1 and fortified with chitin from black soldier fly pupal exuviae at inclusion rates equivalent to 0.5, 1, 2, 3, 4 and 5% chitin. Data were collected on potato growth characteristics, PCN population densities, and soil chemical properties for two growing cycles. Results showed that chitin fortified BSFCOF significantly improved potato growth parameters, chlorophyll concentration, marketable tuber yield and number of marketable tubers. The marketable tuber yield achieved using chitin-fortified BSFCOF was 70 – 362%, and 69 – 238% higher than the values achieved using unfertilized soil during the first and second growing cycles, respectively. Soil amendment with chitin-fortified BSFCOF significantly reduced the number of cysts per 200 g soil-1, number of eggs and J2 per cyst-1, eggs g-1 soil and reproduction rate by 32 – 87%, 9 – 92%, 31– 98% and 31 – 98%, respectively. The PCN suppression increased with chitin inclusion rates. There were significantly higher values for soil pH, ammonium nitrogen, nitrate nitrogen, available phosphorus, calcium, magnesium, potassium, and cation exchange capacity in soil amended with BSFCOF compared to unamended soil. This study demonstrates that BSFCOF fortified with 5% chitin is an effective soil enhancer with multiple benefits, including improved soil fertility, potato performance, and effective management of potato cyst nematodes.

Potato cyst nematodes (PCNs), Globodera rostochiensis and G. pallida, are one of the major pathogens of potato and cause significant losses worldwide. These species, which are on the worldwide quarantine list, can survive in infected areas for more than 20 years. Therefore, these species need to be identified accurately and quickly. Although different molecular methods have been developed for the detection of G. rostochiensis and G. pallida, new techniques are being studied to identify these species. Kompetitive Allele-Specific PCR (KASP) based on single nucleotide polymorphisms (SNP) is a novel molecular technique. This technique is used for marker-assisted selection of genes that confer resistance in plants, for determining genetic variation of pathogens and for species identification. In this study, G. rostochiensis and G. pallida specific KASP primers were developed from the available DNA sequences of all Globodera species retrieved from GenBank. The KASP assay successfully identified the species G. rostochiensis and G. pallida. The developed KASP assays were able to distinguish these species from each other and from other nematode species. Results shown that even one cyst of these species can be sufficient for identification. This is the first study to develop KASP primers to identify PCNs. These assays can be used for accurate and rapid identification PCNs in laboratories. [ABSTRACT FROM AUTHOR]

Potato cyst nematodes (PCN) cause an overall 9% yield loss of total potato production worldwide. Research on sustainable management of PCN is still under progress. Two microbial fermentation products (MFPs) from Alltech, a proprietary blend formulated with a bacterial fermentation media and a Cu component (MFP5075), and a microbial based product (MFP3048), were evaluated against the PCN Globodera rostochiensis. In laboratory tests, effectiveness of the MFPs was recorded in terms of PCN juveniles (J2) hatching from cysts, J2 mortality and their attraction toward potato roots using pluronic gel. Greenhouse trials were conducted to study the effect of the products on PCN infestation in potato plants and a pilot scale experiment was conducted to study the impact of these MFPs on nematode biodiversity in garden soil. All treatments were performed within a concentration range of 0, 0.5, 1, and 2% (v/v) MFP5075 and 2, 6, 10, and 20 g/10 ml (w/v) MFP3048. The attraction assay, juvenile hatching and the PCN infestation in plants results were compared with those in an untreated control and a commercial nematicide (NemguardTM) treatment. After 24 h of treatment with 0.5 and 1% MFP5075, a 13-fold and 43-fold reduction, respectively, relative to J2 survival was recorded compared to that of untreated control. However, no J2 survived at 2% and above concentration of the MFP5075 treatment. Treatment with MFP3048 was effective in causing mortality of J2 only after 48-h. In the attraction assay, a 20-fold and 8-fold reduction in number of J2 attracted toward potato roots was observed, when treated with MFP5075, compared to the untreated and the NemguardTM treatment, respectively. Subsequently, 30–35 PCN cysts were treated with both products dissolved in potato root diffusate and the results were recorded in terms of number of J2 hatched in each treatment after 10 days. No J2 hatched in the MFP5075 treatment, whereas mean numbers (±SE) of 243 ± 11.5, 30 ± 2.5, and 1.3 ± 0.6 J2 were noted in the untreated control, MFP3048, and the NemguardTM treatment, respectively. The treatment with the MFPs compromised the integrity of the unhatched J2, which looked granular, whereas the internal organs of the unhatched J2 could be clearly identified in the untreated control. In plant infestation studies, treatment with MFP3048 and MFP5075 caused 90.6 and 84.9 percent reduction in PCN infestation, respectively, in terms of cysts developed on roots compared to untreated control. Overall, results indicate that the MFPs could potentially provide a promising alternative for sustainable PCN management. [ABSTRACT FROM AUTHOR]

Potato cyst nematodes (PCN) cause an overall 9% yield loss of total potato production worldwide. Research on sustainable management of PCN is still under progress. Two microbial fermentation products (MFPs) from Alltech, a proprietary blend formulated with a bacterial fermentation media and a Cu component (MFP5075), and a microbial based product (MFP3048), were evaluated against the PCN Globodera rostochiensis. In laboratory tests, effectiveness of the MFPs was recorded in terms of PCN juveniles (J2) hatching from cysts, J2 mortality and their attraction toward potato roots using pluronic gel. Greenhouse trials were conducted to study the effect of the products on PCN infestation in potato plants and a pilot scale experiment was conducted to study the impact of these MFPs on nematode biodiversity in garden soil. All treatments were performed within a concentration range of 0, 0.5, 1, and 2% (v/v) MFP5075 and 2, 6, 10, and 20 g/10 ml (w/v) MFP3048. The attraction assay, juvenile hatching and the PCN infestation in plants results were compared with those in an untreated control and a commercial nematicide (Nemguard™) treatment. After 24 h of treatment with 0.5 and 1% MFP5075, a 13-fold and 43-fold reduction, respectively, relative to J2 survival was recorded compared to that of untreated control. However, no J2 survived at 2% and above concentration of the MFP5075 treatment. Treatment with MFP3048 was effective in causing mortality of J2 only after 48-h. In the attraction assay, a 20-fold and 8-fold reduction in number of J2 attracted toward potato roots was observed, when treated with MFP5075, compared to the untreated and the Nemguard™ treatment, respectively. Subsequently, 30–35 PCN cysts were treated with both products dissolved in potato root diffusate and the results were recorded in terms of number of J2 hatched in each treatment after 10 days. No J2 hatched in the MFP5075 treatment, whereas mean numbers (±SE) of 243 ± 11.5, 30 ± 2.5, and 1.3 ± 0.6 J2 were noted in the untreated control, MFP3048, and the Nemguard™ treatment, respectively. The treatment with the MFPs compromised the integrity of the unhatched J2, which looked granular, whereas the internal organs of the unhatched J2 could be clearly identified in the untreated control. In plant infestation studies, treatment with MFP3048 and MFP5075 caused 90.6 and 84.9 percent reduction in PCN infestation, respectively, in terms of cysts developed on roots compared to untreated control. Overall, results indicate that the MFPs could potentially provide a promising alternative for sustainable PCN management.

[Display omitted] • Tests niche similarity of two potato cyst nematode species with fuzzy logic. • Integrated dataset improved model accuracy, mitigating data deficiency. • Comprehensive model comparison supported a better performance. • One tool for detecting and controlling two potato cyst nematode species together. Global potato trade has resulted in the spread of potato cyst nematodes (PCNs) worldwide, which causes significant agricultural and economic loss. Predicting the potential habitats and risk regions for PCNs is critical for management and biosecurity strategies. However, building such prediction models is challenged by the uncertainty of the occurrence data. This research aimed to mitigate the effect of the deficiency of data and build a reliable prediction model of PCNs. The model proposed a combination of fuzzy logic and Maxent modelling enabling the forecasting of the integrated distribution of PCNs. Firstly, the niche similarity between two PCN species was tested by a fuzzy generalised linear model. Then, an integrated dataset was employed to calibrate and evaluate the Maxent model. Results showed that the model constructed on the integrated dataset possessed higher accuracy (Boyce index 0.917) compared to that of individual datasets. After verifying the prediction with the recent incursions in China, the prediction was in accord with actual presence records, which provided further evidence to prove the accuracy of this model. The prediction illustrated that 39% of the land surface in China was suitable for PCNs. The high-risk regions occupied more than half of the cultivated lands, including 66% of the potato-producing areas. In conclusion, the proposed modelling procedure with an integrated dataset can provide an informative reference for countries facing the uncertainty of PCNs' occurrence to conduct an adequate risk assessment. The integrated prediction result can support policymakers in simultaneously managing both PCN species. [ABSTRACT FROM AUTHOR]

Cyst nematodes of the species Globodera rostochiensis and G. pallida are devastating parasites of the potato crop. Early detection of cyst nematodes in the field is critical for adopting an appropriate management strategy. A specific and sensitive loop-mediated isothermal amplification (LAMP) assay using four oligonucleotide primers has been developed to amplify the internal transcribed spacer region (ITS) of ribosomal DNA of potato cyst nematode G. rostochiensis. The PCN-LAMP reaction could be completed within 75 min at 68 °C followed by termination at 85 °C for 7 min. The primers exhibited specificity for G. rostochiensis and did not detect any other tested genera of plant parasitic or entomopathogenic nematodes. LAMP reaction was highly sensitive, suitable for crude genomic DNA and could successfully detect G. rostochiensis DNA up to femtogram quantity. This assay is rapid, cost effective and requires minimal instrumentation. It will facilitate the detection of G. rostochiensis at field and point-of-care labs and help in the interception of infested plant material/soil samples at quarantine stations independent of a professional nematologist. [ABSTRACT FROM AUTHOR]

Taxonomy: Phylum Nematoda; class Chromadorea; order Rhabditida; suborder Tylenchina; infraorder Tylenchomorpha; superfamily Tylenchoidea; family Heteroderidae; subfamily Heteroderinae; Genus Globodera. Biology: Potato cyst nematodes (PCN) are biotrophic, sedentary endoparasitic nematodes. Invasive (second) stage juveniles (J2) hatch from eggs in response to the presence of host root exudates and subsequently locate and invade the host. The nematodes induce the formation of a large, multinucleate syncytium in host roots, formed by fusion of up to 300 root cell protoplasts. The nematodes rely on this single syncytium for the nutrients required to develop through a further three moults to the adult male or female stage. This extended period of biotrophy—between 4 and 6 weeks in total—is almost unparalleled in plant–pathogen interactions. Females remain at the root while adult males revert to the vermiform body plan of the J2 and leave the root to locate and fertilize the female nematodes. The female body forms a cyst that contains the next generation of eggs. Host range: The host range of PCN is limited to plants of the Solanaceae family. While the most economically important hosts are potato (Solanum tuberosum), tomato (Solanum lycopersicum), and aubergine (Solanum melongena), over 170 species of Solanaceae are thought to be potential hosts for PCN (Sullivan et al., 2007). Disease symptoms: Symptoms are similar to those associated with nutrient deficiency, such as stunted growth, yellowing of leaves and reduced yields. This absence of specific symptoms reduces awareness of the disease among growers. Disease control: Resistance genes (where available in suitable cultivars), application of nematicides, crop rotation. Great effort is put into reducing the spread of PCN through quarantine measures and use of certified seed stocks. Useful websites: Genomic information for PCN is accessible through WormBase ParaSite. [ABSTRACT FROM AUTHOR]

• Solanum sisymbriifolium is a resistant trap crop for both the species of potato cyst nematodes and able to reduce more than 97% of the nematode populations in next season of potato crop. • Comparing with the antagonistic crops, the trap crop, S. sisymbriifolium was found to minimize populations of both the species of potato cyst nematodes in two successive seasons. • Potato cyst nematodes can be managed effectively by growing of the trap crop, S. sisymbriifolium one season before the potato crop. The potato cyst nematodes are the most wilful and difficult to manage pests of potato crop. Due to the regulatory considerations and potential risk involved in environmental and health hazards, the options for controlling this nematode are becoming increasingly limited. Among the available management options, trap and antagonistic crops offer viable alternative for controlling PCN species. Therefore the present experiments were conducted to determine the effect of locally available nematode trap crop, Solanum sisymbriifolium and antagonistic crops against potato cyst nematodes. Initially, S. sisymbriifolium was evaluated for its trap crop potential against PCN and the results showed that S. sisymbriifolium acts as a resistant crop for both the species of PCN, as no females were observed on the roots of the trap crop up to the end of the crop season. In addition to this, in the subsequent season negligible populations of PCN females with improved plant growth parameters were observed in susceptible potato cv. Kufri Jyoti. In another experiment, its efficiency was compared with antagonistic crop species viz., Tagetes patula (marigold), Allium sativum (garlic) and Brassica juncea (mustard) on the population decline of PCN. From the study, it was observed that minimum populations of both the species of PCN (0.6 and 33.4 female's plant−1 respectively) were supported in two succeeding seasons of susceptible potato cultivar where S. sisymbriifolium was grown in the preceding season which was followed by marigold, garlic and mustard-based sequences. Therefore, S. sisymbriifolium can be used as a potential trap crop for the management of PCN; however, future studies on its suitability in field conditions are required for its effective utilization under field condition for the management of this nematode. [ABSTRACT FROM AUTHOR]

Plant-parasitic nematodes often interact with their host plants via chemical compounds for successful invasion. In cyst nematodes, hatching requires chemicals known as hatching factors that are released from host roots. Previous studies succeeded in identifying and synthesizing solanoeclepin A (SEA) as a host-derived hatching factor for Globodera rostochiensis (Wollenweber) Behrens and Globodera pallida (Stone) Behrens (Tylenchida: Heteroderidae). However, no published data were available about the hatching response of Globodera species, other than G. rostochiensis, toward SEA. In this study, we tested the hatching responses of G. rostochiensis, G. pallida, Globodera ellingtonae Handoo, Carta, Skantar, and Chitwood, Globodera tabacum (Lownsbery and Lownsbery) Behrens, and Globodera artemisiae (Eroshenko and Kasachenko) Behrens (Tylenchida: Heteroderidae) toward SEA by exposing eggs of each species to 0.001, 0.01, 0.1, 1, 10, and 100 ppb of SEA and observing their hatching response. SEA stimulated the hatching of Solanaceae-parasitic Globodera species (G. rostochiensis, G. pallida, G. ellingtonae, and G. tabacum). The optimal concentration of SEA for hatching was 0.01–10 ppb. However, the hatching activity of G. pallida and G. ellingtonae was lower than that of G. rostochiensis and G. tabacum. SEA showed no effects on G. artemisiae which is parasitic to Artemisiae plants. [ABSTRACT FROM AUTHOR]

As a severe danger to potato plants, potato cyst nematodes (PCNs) are regulated quarantine pests in many countries. Adhering soils to potato or other tuber crops provoke the uncontrolled spread of the pest after their industrial processing. The disinfection of soil tares to inactivate PCNs is therefore compulsory. In the present study, we test whether the viability and formation of PCN cysts are suppressed after treatment with γ and β irradiation. In a first experiment, nematode cysts were treated with γ or β irradiation without soil matrix to determine the minimum dose parameters in a range between 0–12 kGy. Subsequently, two representative soils that included cysts were irradiated. Irradiation effects on PCN viability and the formation of new cysts were evaluated via hatching tests and bioassays with susceptible potato plants, respectively. In addition, maize seedling growth was tested in irradiated soil tares. We found that next to γ also, β irradiation suppressed the hatch of PCN juveniles and its formation of cysts when placed in soil tares. The growth of maize seedlings was not impaired in irradiated soils compared to control soils. Both γ and β irradiation treatment offer an organism group selective and effective phytosanitary measures to disinfect soil tares from PCNs.

Potato cyst nematodes (PCNs), Globodera rostochiensis (Woll.) and G. pallida (Stone), are globally important pests of potato prevalent in the Nilgiri area of South India. PCNs were first intercepted from North India at Shimla, Himachal Pradesh (HP) in 2010. Subsequent surveys in the hilly areas of North India have revealed the occurrence of PCNs in several districts of HP, Uttarakhand and Jammu & Kashmir, despite domestic quarantine against this nematode. High populations of PCN were mainly encountered in the Potato Seed Multiplication Farms that supply seed potato to farmers. Here, a hypothesis on the dissemination of PCNs within India is proposed [ABSTRACT FROM AUTHOR]

Summary: Globodera presently contains 13 valid and three as yet undescribed species. Three species, G. rostochiensis , G. pallida and G. ellingtonae , the potato cyst nematodes (PCN), cause significant economic losses on potatoes around the world. In our study we provide comprehensive phylogenetic analyses of 455 ITS rRNA, 219 COI and 164 cytb gene sequences of 11 valid and two undescribed species of Globodera using Bayesian inference, maximum likelihood and statistical parsimony. New 205 COI , 116 cytb and 21 ITS rRNA gene sequences were obtained from 148 populations of these species collected from 23 countries. The phylogenetic analysis revealed that Globodera displayed two main clades in the trees: i) Globodera from South and North America parasitising plants from Solanaceae; and ii) Globodera from Africa, Europe, Asia and New Zealand parasitising plants from Asteraceae and other families. Based on the results of phylogeographical analysis and age estimation of clades with a molecular clock approach, it is hypothesised that Globodera species originated and diversified from several centres of speciation located in mountain regions and then dispersed across the world from these regions during the Pleistocene. High genetic diversity of Bolivian populations of G. rostochiensis was observed for both mtDNA genes. Analysis of phylogenetic relationships of G. pallida and G. rostochiensis populations revealed incongruence in topology between networks inferred from mtDNA genes, which might be an indication of possible recombination and selective introgression events through gene flow between previously isolated populations. This puts some limitations on the use of the mtDNA marker as universal DNA barcoding identifier for PCN. Globodera bravoae syn. n. is proposed as a junior synonym of G. mexicana. [ABSTRACT FROM AUTHOR]

The potato cyst nematode Globodera pallida is a globally regulated potato pest. It was detected for the first time in the United States in the state of Idaho in 2006, and as of February 2019, the infestation is limited to 1,326 hectares. G. pallida is a specialized obligate sedentary endoparasite that can survive in the soil for up to 30 years in the absence of its potato host. In highly infested fields, the nematode can reduce tuber yields up to 80% and is spread mainly through the movement of soil, tubers, or farm equipment. The objectives of this study were to describe the spatiotemporal pattern of G. pallida in infested fields and model its dispersal patterns in southeastern Idaho. We used geostatistical tools and simulation models for precise mapping and to describe the relationships between G. pallida incidence and the spatial configurations. We found that the nematode is spatially clustered and prevalent around edges of fields, and its dispersal pattern followed the direction of cultivation. We found that the absence of potato in an infested field significantly reduced the number of cysts sampled each year subsequent to the initial delimitation sampling in 2007. Phytosanitary measures prohibiting the growth of potato contributed to stopping nematode reproduction, and the use of chemical fumigants and biofumigant cover crops contributed to a significant reduction in egg viability. We observed a process of a nonlinear decline in the prevalence of cysts as the distance separation from the primary infestation focus increased. A power law model was used to fit G. pallida dispersal capabilities. This study contributed to describing G. pallida infestation for Idaho. The goal of this study is to provide information on the spatial pattern and landscape ecology of G. pallida in Idaho for policy makers, industry, and researchers as well as facilitate common understandings on the challenges and opportunities for controlling this pest in Idaho. [ABSTRACT FROM AUTHOR]

Summary: Population-level genetic tools to study the epidemiology of potato cyst nematodes (PCN) are needed to evaluate their adaptive potential and validate management strategies. The effector gene vap1 is essential in early infection by PCN. We expected high allelic variation due to diversifying selection. A technique was developed specifically to amplify vap1 fragments of PCN, and electrophoretically separate variants in a denaturing gradient (DGGE). Sequenced gene variants differed in intron as well as exon regions. Siblings were more similar in vap1 pattern than juveniles from different cysts. Nearly all juveniles analysed had unique patterns with up to ten or five vap1 variants for Globodera pallida or G. rostochiensis , respectively. Patterns differed significantly among populations, with similarities increasing from between-species, within-species to within-pathotype comparisons. In conclusion, the method is suitable to determine the similarity of heterogeneous PCN populations for studies on their temporal change and spread. [ABSTRACT FROM AUTHOR]

Summary: Globodera pallida infestation on potato is responsible for huge yield losses globally. Screening of potato germplasm for resistance to the nematode at the early stages of a breeding programme can significantly enhance resistance-based management. This study assessed the suitability of tissue culture (TC)-derived potato plants as screening material for resistance to G. pallida. Reproduction of the nematode on TC plants was similar to the reproduction on tuber- and eye-plug-derived plants. The pot volume, inoculum density and inoculation time had a significant effect on the reproduction. A positive correlation was found between the mean number of white females on the root surface and the final number of nematode cysts after extraction. Resistance ranking using TC plants and the tubers yielded comparable results, thus justifying the use of TC in the screening process. Tissue culture plants have the potential of speeding up the screening process and reducing resource requirements, thus lowering breeding cost. [ABSTRACT FROM AUTHOR]

Selection for virulence of Globodera pallida on potato cultivars was studied for four generations under controlled conditions. The reproduction rate (Pf/Pi) of a mixed Pa2/3 population increased by a factor of 61 during rearing on the partially resistant potato cv. Darwina compared to rearing on the susceptible cv. Irene. This was a result of selection for virulence on cv. Darwina, and achieving the Hardy–Weinberg equilibrium on cv. Irene. Increased virulence also significantly raised the reproduction rate on several other Solanum genotypes. These changes could be explained reasonably well by the monogenic inheritance of a virulence factor breaking the Grp1 locus. The virulence changes were probably mainly evoked by this gene only, inherited from S. vernei 1‐3 or S. vernei 24/20. The Grp1 locus has probably provided the differential S. vernei hybrid (VTn)2 62‐33‐3 with its resistance to the Pa2 group and not to the Pa3 group. Alternation of cultivars did not halt selection if the cultivars highly differentiated between the Pa2 and Pa3 populations. Only when alternation was with cultivars that harboured a different resistance gene against Pa3 was selection for virulence delayed. Differences in virulence levels (i.e. reproduction rates) within the nematode population determined the rate of selection, not the resistance level itself. Selection of a Pa3 population for three generations on cv. Karakter not only increased the reproduction rate on cv. Karakter itself by a factor 4.2, but also raised the reproduction on other potato genotypes. A simple monogenic model could explain these changes in virulence. [ABSTRACT FROM AUTHOR]

Morphological and molecular studies were conducted to characterize the specific identity of 36 isolates of potato cyst nematodes (PCNs) recovered from soil samples collected in several potato producing areas of Algeria. Morphometric data revealed that 44% of isolates contained Globodera pallida alone, 28% contained Globodera rostochiensis alone and 28% mixtures of the two species. Morphometric values of cysts and second-stage juveniles were generally distributed with slight differences in the expected ranges for both Globodera species. Inter- and intraspecific morphometric variability in nematode isolates was noted. Molecular analysis using conventional multiplex PCR with species-specific primers and TaqMan real-time PCR confirmed the morphological identification. In addition, the distribution of both potato cyst nematode species throughout various parts of the country was investigated. In the central areas, the isolates of G. pallida alone dominate, whereas isolates of G. rostochiensis alone are more frequent in the southern areas. In the eastern regions, mixed isolates are more representative. Most isolates examined in the western areas are mixtures of the two species or G. rostochiensis alone. Comparatively, G. pallida remains the most widely distributed species in its geographic range. This study confirms the presence of two PCN species, G. pallida and G. rostochiensis, in Algeria and provides additional information on their biogeographic distribution.

The potato cyst nematode (PCN) Globodera rostochiensis is a plant parasite of potato classified into a group of quarantine organisms causing high economic losses worldwide. Due to the long persistence of the parasite in soil, cysts harbor numerous bacteria whose presence can lead to cyst death and population decline. The cysts of G. rostochiensis found in two potato fields were used as a source of bacteria. The universal procedure was applied to extract DNA from bacteria which was then sequenced with 16S primers. The aims of the study were to identify bacterial microbiota associated with the PCN populations and to infer their phylogenetic relationships based on the maximum likelihood and Bayesian phylogeny of the 16S sequences. In addition, the impact of the most significant climate and edaphic factors on bacterial diversity were evaluated. Regarding the higher taxonomy, our results indicate that the prevalent bacterial classes were Bacilli, Actinobacteria and Alphaproteobacteria. Phylogenetic analyses clustered Brevibacterium frigoritolerans within the family Bacillaceae, confirming its recent reclassification. Long-term climate factors, such as air temperature, insolation hours, humidity and precipitation, as well as the content of soil organic matter, affected the bacterial diversity. The ability of cyst nematodes to persist in soil for a long time qualifies them as a significant natural source to explore the soil bacterial microbiota.

Background and aims: This study was undertaken to evaluate the effects of Solanum sisymbriifolium cvs Melody, Pion, Sharp, Sis 4004 and Sis 6001 on potato cyst nematode (PCN), Globodera spp., populations in the field in Portugal, to improve crop protection systems based on trap crops. Methods: Two PCN infested fields (Bolho and Barcouço) were selected. Solanum sisymbriifolium root exudates effects on PCN hatching were evaluated by in vitro assays and their susceptibility/resistance to PCN was assessed. Field trials were performed during 2 years using the following rotation: S. tuberosum cv. Désirée followed by S. sisymbriifolium. Results: Solanum sisymbriifolium root exudates promoted hatching of second-stage juveniles (J2). The cultivars tested were resistant to both species of PCN. In both fields, all cultivars had the same behaviour with no statistically significant differences. Conclusions: As S. sisymbriifolium cultivars were resistant to G. rostochiensis and G. pallida populations in Portugal, they can be included in crop rotations and are potential candidates to incorporate in management programs against PCN. Although there were no statistical differences it seems that fallow could be the best strategy to reduce PCN populations faster and this avoids the introduction of an exotic plant that could become a problem. [ABSTRACT FROM AUTHOR]

Considering the growing trade of seed potato, reliable diagnostic protocols are required for the detection of regulated nematode species. In this study, a specific and sensitive multiplex Taqman-based real-time PCR method was developed in order to detect and identify Globodera pallida, G. rostochiensis and Heterodera schachtii. The newly designed primers and probes enabled the detection of all the target populations tested and with no cross-reaction for closely related non-target species (55 populations tested). The limit of detection (LOD) was one juvenile for G. rostochiensis and G. pallida and five juveniles for H. schachtii. For monitoring potato cyst nematodes, this analytical tool would extend the number of cyst investigated as five juveniles can be detected among 50 cysts in a sample. Furthermore, this multiplex assay detects DNA of the three targeted species in template DNA obtained directly from float material after nematode extraction from soil. [ABSTRACT FROM AUTHOR]

Quarantine species such as potato cyst nematodes Globodera rostochiensis and G. pallida are present in Serbia since 1999 and 2005, respectively. These nematodes are sibling species and their morphological identification is complex due to their morphometric overlap. The cysts from the localities of Kladnica, Šanac, Gojna Gora and Milatovići were grown on susceptible potato varieties and their morphological differences have been discussed. To avoid ambiguities in species morphological designation a duplex PCR method was chosen for a rapid and accurate species identification. The whole procedure, from DNA extraction to DNA isolation, can be performed in a single day. .

The potato cyst nematode Globodera rostochiensis is one of the most serious pests of potato in Slovenia. Precise nematode identification and knowledge about potato cultivars, which are most suitable for growing in the Slovenian climate conditions and most resistant to G. rostochiensis, are necessary to develop an effective integrated pest control. Here we report the results of the influence of G. rostochiensis pathotype Ro1/4 on the yield of different potato cultivars: the susceptible cultivar Desiree, the resistant cultivars White Lady, Miranda, Aladin, Sante and Adora, and the clone KIS 94-1/5-14. The yield of cv. White Lady was the highest and that of susceptible cv. Desiree the lowest. The influence of several resistant and one susceptible potato cultivars on population dynamics of G. rostochiensis was also determined. The total number of cysts/100 cm3 and the number of eggs and juveniles per cyst increased in the susceptible cv. Desiree and decreased in the resistant cultivars White Lady, Sante and Adora.

Potato cyst nematodes are a major threat to potato production worldwide. In 2006, the isolation of the golden nematode,Globodera rostochiensis, in Quebec, Canada, led to the establishment of a quarantine area and the initiation of a research programme for the sustainable management of this regulated pest. In this study, the field efficacy of crop rotations and soil amendments was assessed in microplots for their potential to reduce populations ofG. rostochiensisin the quarantine area. Crop rotation with a resistant potato cultivar was very effective in decreasing the population density ofG. rostochiensisin soil. A single year with a cultivar carrying the H1 resistance gene reduced nematode populations by 62–95%. After 3 consecutive years of cropping to resistant potato, the number of viable eggs was zero in several microplots, and the overall population reduction was around 95%. Natural population decline with the cultivation of a non-host crop such as corn was around 30% per year. Trap cropping also showed reducedG. rostochiensispopulations with results similar to the resistant cultivar. Sticky nightshade could not be established under Quebec’s climatic conditions and therefore was not a viable alternative for managing golden nematode in Quebec. Soil amendment with high rates of urea provided some reduction in populations but was not an economically viable option for managing potato cyst nematodes. Chicken manure and pig slurry did not provide a significant reduction ofG. rostochiensisunder Quebec field conditions. [ABSTRACT FROM PUBLISHER]

Potato cyst nematodes (PCN) are pests of phytosanitary quarantine with high economic implication on potato production and commercialization. Both nematode species Globodera pallida and G. rostochiensis have the origin in Peru and evolved with the potato dissemination all over the world during the last two centuries. G. rostochiensis was recorded in Romania for the first time in 1984 and starting with 2007 all the country is under phytosanitary quarantine for both species. The analysis of the official potato management programme reveals that there are no measures in place to address abiotic (dry wind, run off water) and biotic factors (i.e. sheep and goat transhumance and boars movement in arable land) as well as climate change impact. The interview of 122 city halls in Sibiu and Braov counties revealed the constant presence of boars into arable land as well as of sheep and goat movement or transhumance that is positively correlated with the presence of both nematode species in soil. The article renders the need to integrate scientific achievements regarding potato resistance, environmental factors impact and new agricultural practices into the current potato management programme. [ABSTRACT FROM AUTHOR]

Potato cyst nematodes (PCN) are the big problem in worldwide planting of potatoes and another Solanaceous plants. Identification of individual pathotypes according to international scheme is very demanding but a very important part of the phytosanitary process to control these pests. Molecular genetic identification of different plant and animal species or individuals is a very interesting way at the present time and let's hope that it will be important in future. This report presents results of the RAPD study of nine different real PCN populations. There were five Globodera rostochiensis populations and four G. pallida populations. Pathotypes Ro2, Ro2/3, Ro4, Ro5, Pa2 and Pa3 were from European populations; population Ro1 and X were of Czech provenance. Genetics variable of these populations was described by a set of six decameric primers (OPA 07, OPG 03, OPG 05, OPG 08, OPG 10 and OPG 13). Genetic dissimilarity was by Gel Manager for Windows evaluated. Detectable differences behind all populations were found and the dendrogram was compiled. The unknown population X was sorted into group of Globodera pallida species subgroup of Pa2 consequently.

Relationships between soil temperatures and the potato cyst nematode (PCN) life cycle and population multiplication were investigated to understand the risks to potato crops from PCN in relation to increasing soil temperatures associated with climate change, and to support development of the United Kingdom Potato Council`s PCN management model. The initial (hatching) part of the PCN life cycle was examined for both Globodera rostochiensis and G. pallida over a range of temperatures, and the responses are then considered in relation to actual soil temperatures during the potato growing season in different sites in the United Kingdom. Hatching was stimulated by potato root diffusate over a temperature range from 5–29ºC and was monitored for 5 weeks. The greatest cumulative percentage hatch of second stage juveniles (J2) occurred between 15 and 27ºC for G. rostochiensis and 13–25ºC for G. pallida. Globodera rostochiensis hatched more quickly and had a delayed hatch at ≥25ºC while G. pallida was more efficient at these higher temperatures. From these observations, it is likely that climate change, and associated increases in soil temperatures, will result in increased rates and amounts of hatching for both species, leading to increased population levels on susceptible hosts and damage to potato crops. Currently, regions of the United Kingdom with warm soil temperatures are also expected to have high levels of hatching of PCN, and therefore greater multiplication resulting in greater challenges in the management of these nematodes in infested land.

In 2006, the golden cyst nematode, Globodera rostochiensis, was discovered in the province of Quebec, Canada. We report here the life cycle of G. rostochiensis under the climatic conditions of southwestern Quebec. Only one full generation was completed per year under these latitudes. On susceptible potato cv. Snowden, G. rostochiensis needed a minimum of 579 growing degree units (GDU) (base 5.9°C) to complete its life cycle and the first mature cysts were observed 42 to 63 days after planting (DAP). In soil, second-stage juveniles (J2) were first observed 14 to 21 DAP, whereas both white females on roots and males in soil appeared synchronously after 35 to 42 days. The duration of the life cycle was affected by temperature but not by soil type. A second wave of hatching systematically occurred later in the season and a second generation of males was observed during the 2011 growth season. No complete second cycle was observed before plant senescence. Climate change and later maturing cultivars/crops could allow the development of a full second generation in the future. [ABSTRACT FROM AUTHOR]

In the Canary Islands, a number of old Andean potato introductions have been maintained by farmers and are cultivated there since the sixteenth century. Genetic resistance is an inexpensive way to control the main pests and diseases of potato and avoids the use of phytochemicals or other costly protective measures. In this study, we have analysed eight Solanum tuberosum subsp. andigena and S. tuberosum subsp. tuberosum accessions, representing old potato varieties from Tenerife Island, for their resistance levels to Phytophthora infestans, Globodera rostochiensis, Globodera pallida and Pectobacterium atrosepticum. New resistance sources against P. infestans in leaves and P. atrosepticum were found, as well as partial resistance to both nematode species. The results suggest the potential exploitation of the cultivar Venezolana Negra in breeding programmes in order to improve pest and disease resistance of potato. [ABSTRACT FROM AUTHOR]

Sewage sludge is a significant fertilizer that is generally suitable for usage in agriculture. Depending on the origin of the sewage sludge, it can be contaminated with various animal, human or plant pathogens. Based on literature data, current sewage sludge treatments were analyzed regarding their effectiveness on the inactivation of relevant pathogens of potatoes and the associated risk of their dissemination when sewage sludge is used in agriculture. According to the available literature it has to be concluded, that treatments usually applied in Germany will not be sufficient for complete inactivation of robust phytopathogens. This refers mainly to pathogens of potato that are listed in Directive 2000/29/EC, especially Synchytrium endobioticum, the agent for potato wart disease. Therefore, risky waste waters, e.g. from potato processing industries, should not be introduced in municipal waste waters or sewage sludge produced from such risky waste water should not be used in agriculture, to avoid the possible dissemination of such phytopathogens. [ABSTRACT FROM AUTHOR]

Relationships between soil temperatures and the potato cyst nematode (PCN) life cycle and population multiplication were investigated to understand the risks to potato crops from PCN in relation to increasing soil temperatures associated with climate change, and to support development of the United Kingdom Potato Council's PCN management model. The initial (hatching) part of the PCN life cycle was examined for both Globodera rostochiensis and G. pallida over a range of temperatures, and the responses are then considered in relation to actual soil temperatures during the potato growing season in different sites in the United Kingdom. Hatching was stimulated by potato root diffusate over a temperature range from 5-29°C and was monitored for 5 weeks. The greatest cumulative percentage hatch of second stage juveniles (J2) occurred between 15 and 27°C for G. rostochiensis and 13-25°C for G. pallida. Globodera rostochiensis hatched more quickly and had a delayed hatch at ≥25°C while G. pallida was more efficient at these higher temperatures. From these observations, it is likely that climate change, and associated increases in soil temperatures, will result in increased rates and amounts of hatching for both species, leading to increased population levels on susceptible hosts and damage to potato crops. Currently, regions of the United Kingdom with warm soil temperatures are also expected to have high levels of hatching of PCN, and therefore greater multiplication resulting in greater challenges in the management of these nematodes in infested land. [ABSTRACT FROM AUTHOR]

The general opinion about the introduction of potato in Europe is the one regarding the direction from South America to Spain and subsequent distribution to other continents. Some historical data point out an alternative road. The potato spread from its place of origin to other continents in the light of parasite-host relationship, relying on nematode molecular data, is discussed in the present work. Biogeographic history of potato cyst nematode populations from different continents is in congruence with historical records. [ABSTRACT FROM AUTHOR]

A series of proficiency tests on potato cyst nematode (PCN; n = 29) and free-living stages of Meloidogyne and Pratylenchus (n = 23) were investigated to determine the accuracy and precision of the nematode counts and to gain insights into possible trends and potential improvements. In each test, each participating laboratory received ten samples of soil collected from naturally infested fields and well mixed before distribution. The variance between the counts from the ten samples, estimated per test and laboratory, was constant for PCN cysts and free-living stages of Meloidogyne spp. and Pratylenchus spp. during the period monitored. However, during the initial years, the variance between the samples showed a downward trend for PCN living juveniles. The variance between the laboratories, estimated per test, was constant for PCN cysts over the period 1994-2010. For PCN living juveniles the variance between laboratory means declined from 1994-2000 and from 2000 it was more or less constant, which coincided with the introduction of a well-described new methodology. For Meloidogyne spp. and Pratylenchus spp., from 1998-2005 the variance between laboratory means was more or less constant or increased. From 2006, all participating laboratories incubated the organic matter and the variance between the laboratories was stable and below the levels observed during 2003-2005. After discarding data from initial years with unstable variances of the nematode counts, a meta-analysis was carried out on the remaining data using HGLMs to model the mean and variance of the counts simultaneously. The within-laboratory variance for the ten samples and the interaction variance of test and laboratory were estimated and combined to percentage coefficient of variation (%CV) per laboratory. For PCN cysts, %CV per laboratory ranged from 12.6 to 41.6 and for PCN juveniles in sandy soil from 24.4 to 67.4 and in loamy soil from 37.9 to 102.0. For Meloidogyne spp., %CV ranged from 53.2 to 84.4 and for Pratylenchus spp. from 24.3 to 90.6. The quality of a proficiency test is largely defined by random distribution of the nematodes over the samples allocated, statistical analysis of the data and communication of the results to participating laboratories. This study provides insights into the accuracy and precision at laboratories in recent years and the effect of concerted actions during the period in which the proficiency tests were conducted. [ABSTRACT FROM AUTHOR]