Journal of nematology最新文献

In nematology research, hypothesis testing is a fundamental method and is typically supported by statistical significance (e.g., P-value <0.05). However, our review of recent publications in nematology reveals frequent issues, including unjustified sample size and unclear reporting of statistical methods, which undermines the validity and reproducibility of the results. To address these issues, we recommend researchers to conduct a priori power analyses to estimate adequate sample sizes and report key descriptive statistics (e.g., effect size). These practices not only strengthen the reliability of research, but can also help answer a central question for investigators: How many samples are needed to detect a "truly" statistically significant difference in an experiment?

Chrysodeixis includens is a major soybean pest in the southern United States and has developed resistance to many insecticides. Entomopathogenic nematodes (EPNs) are potential alternative control tools. Above ground EPN applications are limited by environmental stresses; thus, we evaluated adjuvants to improve the performance of Steinernema carpocapsae. Laboratory assays showed that Xanthan & Tween enhanced EPN efficacy at 24 hr post application across all four exposure durations, whereas Barricade did not improve efficacy at the 1 hr exposure compared with EPNs without adjuvants. At 72 hr post application, adjuvant treatments achieved >90% mortality beginning at the 4 hr exposure duration, whereas EPNs without adjuvants reached >90% only at 24 hr. Greenhouse trials indicated efficacy improvements with Xanthan & Tween under some conditions, whereas Barricade did not. Optimization tests demonstrated that adding Tween to Barricade significantly improved EPN performance. Both Xanthan & Tween and Barricade & Tween reduced nematode sedimentation. Overall, adjuvant enhanced formulations increased EPN efficacy and stability, supporting their potential as a biological management tool for C. includens.

Tylenchulus semipenetrans, a destructive root-parasitic nematode, causes slow decline and significant yield losses worldwide in citrus. Developing resistant cultivars/rootstocks remains an important strategy for the sustainable management of plant-parasitic nematodes in integrated pest management (IPM) systems. Controlling the citrus nematode is challenging due to its wide host range and high adaptability. Although commonly used, chemical nematicides increase production costs and pose risks to human health and the environment. In this study, we separately evaluated the response of five commonly used citrus rootstocks, Citrus paradisi (M.) × Poncirus trifoliata (L.) Raf. (Citromelo), P. trifoliata (L.) Raf. (Poncirus), Citrus jambhiri Lush (Rough lemon), C. volkameriana Ten. & Pasq. (Volkamer lemon), and Citrus aurantium L. (Sour orange), to T. semipenetrans infection. In parallel, we evaluated the biocontrol potential of two bacterial strains, Bacillus safensis Q.en and Pseudomonas chlororaphis P.en, on the susceptible 'Sour Orange'. The results showed that T. semipenetrans exhibited the highest reproduction on 'Volkamer lemon' (275 females/g root and 1,150 second-stage juveniles [J2s]/200 g soil), whereas 'Citromelo' showed the strongest resistance (8 females/g root and 220 J2s/200 g soil). Application of the bacterial agents to 'Sour Orange' significantly reduced the number of females on roots and juveniles in the soil, while also improving plant growth parameters compared to untreated controls. Our findings demonstrate the individual potential of using resistant rootstocks or biocontrol agents as economical, effective, and environmentally safe components for managing T. semipenetrans. The resistant genotypes identified may also be useful in future breeding programs.

Meloidogyne chitwoodi, commonly known as the Columbia root-knot nematode (CRKN), is a major threat to potato production in the Pacific Northwest (Idaho, Oregon, and Washington) of the United States. The nematode damages both roots and tubers, significantly lowering tuber market value. In Washington and Oregon's Columbia Basin, the two main M. chitwoodi populations are race 1 and a pathotype of race 1 known as Roza. While resistance to race 1 is present in the potato breeding line PA99N82-4, this resistance is ineffective against Roza. To assess virulence differences, both populations were tested on Arabidopsis thaliana and tomato roots. Results showed that Roza was more virulent on these two susceptible hosts. Furthermore, infection assays on tomatoes carrying the Mi-1.2 resistance gene revealed that both populations can overcome this resistance, indicating that Mi-1.2 does not confer protection against either M. chitwoodi race 1 or Roza.

Nematode sampling was conducted to identify ring and needle nematodes in forests of central and northern Greece. Two species of the genus Xenocriconemella, X. iberica and X. paraiberica, and three species of Longidorus, L. aetnaeus, L. intermedius, and L. iranicus, were identified based on integrative taxonomy. To our knowledge, this is the first report of X. iberica and X. paraiberica in Greece, and the first time these species have been documented outside the Iberian Peninsula. Similarly, L. aetnaeus and L. intermedius are reported from Greece for the first time. This study expands the known geographic distribution of Xenocriconemella and Longidorus species in Greece and the broader Mediterranean Basin. Molecular characterization confirms that two morphologically distinct species, L. intermedius and L. piceicola, despite differences in lip region width, odontostyle and body lengths, exhibit high similarity in the D2-D3 expansion segments of 28S and internal transcribed spacer 1 (ITS1) rDNA regions. This close molecular affinity underscores the need for further investigation using additional nuclear (e.g., hsp90) and mitochondrial (e.g., COI) markers to clarify the extent of genetic divergence between these two needle nematode species.

The distribution of economically significant plant-parasitic nematodes in pulse crops in the Canadian Prairies is relatively unknown. Reports suggested that Ditylenchus dipsaci in yellow pea export was likely the nonquarantine species D. weischeri, a Canada thistle (Cirsium arvense) parasite. To determine if D. dipsaci is found in pulse plants and understand nematode distribution in the Canadian Prairies, a survey was conducted in commercial yellow pea, lentil and chickpea fields in Alberta, Saskatchewan, and Manitoba. Samples of pulse and thistle plants (flowers or pods, stems and leaves) and soil were collected from 94 fields. Nematodes were identified by morphological features and molecular analyses (species-specific PCR, PCR-RFLP, and sequencing of the partial 18S, 28S and ITS of the rDNA gene). High densities of plant-parasitic nematodes - Pratylenchus, Paratylenchus, Helicotylenchus and Telotylenchinae - were found in several fields. Ditylenchus weischeri, a parasite of thistles and not pulse crops, was recovered from 20 fields across Alberta, Saskatchewan and Manitoba; D. dipsaci was found in pods of one yellow pea field in Manitoba. These results confirm the high prevalence of D. weischeri on creeping thistle in pulse fields and the near absence of the quarantine pest D. dipsaci.

Xiphinema baliense sp. nov., a member of the X. americanum-group, brevicolle-subgroup, was recovered from the rhizosphere of native vegetation in Bali, Indonesia. Females of the new species are characterized by a moderately long body (2.0-2.4 mm), having a lip region offset by a shallow depression, well-developed odontostyle (106-118 μm), didelphic-amphidelphic equally developed reproductive branches, vulva at 52-55% of body length and a conoid tail (24-31 μm), dorsally convex, ventrally flat with a widely rounded tip. Males were not observed. The alpha-numeric identification codes for the new species are: A5, B23, C2, D2, E3, F-, G2, H2, I2. The new species was morphologically compared with relevant tentative cryptic species in the aforementioned subgroup, including X. brevicolle, X. himalayense, X. paramonovi, X. primum, X. parabrevicolle, and X. purpureum. Molecular data derived from the D2-D3 expansion segments of 28S rRNA, ITS1, partial 18S rRNA, and COI genes were used to reconstruct the phylogenetic relationships of X. baliense sp. nov. with related species within the X. americanum-group using the Bayesian approach, and the resulting topologies were discussed.

Mesocriconema xenoplax and Pratylenchus penetrans are important plant parasitic nematodes of cherry trees, but little is known of how soil and water management practices affect the buildup of either species in cherry orchards. A split-plot field experiment was initiated in 2014 to compare five soil treatments (untreated control, preplant fumigated, compost, bark chip mulch, compost+bark chip mulch) under drip and microsprinkler irrigation. Plant-parasitic nematode populations were monitored through 2023. The population of M. xenoplax was initially detected in only 3% of the 60 plots whereas P. penetrans was initially present in all plots. By 2023, M. xenoplax were detected in 70% of plots with maximum population density among plots of 834 M. xenoplax 100 cm^-1 soil. Mesocriconema xenoplax became more abundant in compost plots and fumigated plots than in untreated plots, and more abundant under drip than microsprinkler irrigation. In contrast, P. penetrans were least abundant in compost plots and less abundant under drip than microsprinkler irrigation. The opposing responses of these two nematode species illustrate tradeoffs in pest pressures that can occur with changes in orchard soil and water management practices, obscuring effects of either species on tree growth.

Pellioditis koreana n. sp. was recovered from cadavers of Protaetia brevitarsis seulensis larvae and is herein characterized using morphometric and DNA barcode data. P. koreana n. sp. is characterized by its lateral fields with four lines, anterior part of the pharynx longer than posterior part, hemizonid prominent, located adjacent to the middle or posterior part of isthmus, excretory pore located anterior to basal bulb or within the anterior part of basal bulb, tail cupola-shaped, with angular sides, with a slender spike, phasmids prominent, papilla-like, flanking the cupola part, male tail region with nine pairs of genital papillae with a 1 + (1 + 1) + 2 + 1 + 3 pattern, spicules 48.0-70.5 μm long, gubernaculum less than half of spicule length long, dauer juvenile with a long tail, and tapering to a filiform posterior end. The phylogenetic relationships were reconstructed using 18S-, 28S-, and ITS-rRNA gene sequences. The phylogenies showed that P. koreana n. sp. is a sister species to P. zhejiangensis. This species represents the first record of an entomo-parasitic relationship within this predominantly gastropod-parasitic genus.

Papaya (Carica papaya L.) is an increasingly important fruit crop in Burkina Faso; however, its production is constrained by plant-parasitic nematodes, whose diversity and impact remain poorly documented. A survey of papaya orchards across 9 production regions identified 10 nematode genera, with Rotylenchulus, Helicotylenchus, Meloidogyne, Scutellonema, and Pratylenchus as the most frequent and abundant. Regional patterns indicated that Meloidogyne, Rotylenchulus, Helicotylenchus, and Scutellonema were widespread, and the High-Basins region harbored the richest nematode diversity. Papaya monocultures presented significantly higher nematode densities than intercropped systems, while banana and eggplant associations reduced populations. Meloidogyne and Rotylenchulus populations were influenced by climatic factors, with frequencies positively correlated with temperature and negatively with rainfall and humidity. Molecular characterization confirmed the widespread presence of Meloidogyne javanica and identified Rotylenchulus reniformis 0type A in papaya orchards. This study provided the first comprehensive description of nematode distribution in papaya systems, offering valuable insights for developing targeted nematode management strategies in Burkina Faso.