A population of an unknown species of Ditylenchus was recovered from the rhizosphere of pistachio (Pistacia vera L.) in Gonabad county, Razavi Khorasan province, Iran. The new species, Ditylenchus behradi n. sp., is characterized by females with a body length of 801–932 µm, lateral fields with six incisures, a slender stylet 8.1–9.2 µm long, an elliptical median pharyngeal bulb with a distinct valve, the secretory-excretory pore located 95.8–108.7 µm from the anterior end, an elongated to pyriform basal pharyngeal bulb with a short overlap over the intestine, a relatively short post-vulval uterine sac (21.5–27.1 µm), and a tail 54.0–78.4 µm long with a bluntly rounded to occasionally pointed terminus. Males possess arcuate spicules 17.1–19.8 µm long. Morphological and morphometric comparisons demonstrated that the new species is most similar to Ditylenchus baoqingensis, Ditylenchus israelensis, Ditylenchus triformis, Ditylenchus valveus, and Ditylenchus zeae, but differs from these species by a unique combination of diagnostic characters. Molecular characterization was performed using partial sequences of the small subunit and the D2–D3 expansion segments of the large subunit ribosomal DNA, as well as the internal transcribed spacer region. Phylogenetic analyses using Bayesian inference consistently placed the new species within the group of Ditylenchus-like taxa, distinct from the recently established genera Ditylenchoides and Paraditylenchus, and supported its recognition as a new species. In all phylogenetic trees, D. behradi n. sp. formed an independent lineage closely related to D. israelensis and D. valveus. The present study expands the current knowledge of Ditylenchus diversity in Iran and further demonstrates the value of integrative taxonomy for species delimitation within Anguinidae.
The core soil samples collected from annual bluegrass at a golf course in Oakridge Country Club, Utah, USA were submitted for identification in July 2024. A high number of Helicotylenchus sp., Mesocriconema sp. females, and Meloidogyne sp. juveniles were recovered from the samples using the rapid centrifugal-flotation and mist chamber extraction methods. They were examined by morphological observation and morphometric measurements under light microscopy, and by analysis of sequences from multiple molecular markers, including the ribosomal DNA 18S, 28S, and ITS. Morphological characteristics and morphometrics, as well as BlastN comparisons with other population sequences of respective nematodes from GenBank, were consistent with identification as Helicotylenchus microlobus, Mesocriconema nebraskense, and Meloidogyne naasi. Phylogenetic trees inferred from rDNA18S, 28S, and ITS sequences all separated the Utah population into a strongly supported clade with other respective isolates of H. microlobus, Mesocriconema nebraskense, and Meloidogyne naasi. This study first comprehensively reports morphological and molecular characterization of H. microlobus, Mesocriconema nebraskense and Meloidogyne naasi from turfgrass in Utah, USA.
Dragon fruit (Selenicereus undatus) is a commercially important tropical fruit widely cultivated in Southeast Asia. During a nematode disease survey in Danzhou County, Hainan Province, China, cyst nematodes were recovered from the rhizosphere soil and roots of dragon fruit plants exhibiting poor growth. Morphological and morphometric analyses of cysts and second-stage juveniles matched the original and subsequent descriptions of Cactodera cacti. Molecular characterization, based on sequences of the ITS rRNA, the D2–D3 expansion segments of 28S rRNA, and the mitochondrial cytochrome c oxidase I (COI) gene, confirmed the species identity as C. cacti. Phylogenetic analysis using the Neighbor-Joining method revealed that this population clustered closely with known C. cacti populations from the USA, Vietnam, and Taiwan, China. A pathogenicity test on dragon fruit seedlings yielded a reproduction factor (Rf) of 11.6, indicating high pathogenicity. This is the first report of C. cacti infecting dragon fruit in Hainan, highlighting a potential threat to regional dragon fruit production.
Soil and root samples were collected from 189 citrus orchards in Fars Province, Iran, during summer to early autumn 2018 to assess the spatial distribution and biotype identity of Tylenchulus semipenetrans. This study also evaluated the applicability of Geographic Information Systems (GIS)-based spatial modeling for predicting nematode distribution. A stratified field survey was conducted across major citrus-producing regions, and nematode densities were determined using the tray extraction method. Overall, 67.7% of orchards were infested, with 32.3% nematode-free, 11.6% having low (1-800 nematodes/100 cm3 soil), 20.6% moderate (800-3,600 nematodes), and 35.4% high (>3,600 nematodes) population densities. To evaluate biotype identity, 19 representative populations were inoculated onto sour orange, trifoliate orange, grapevine, and olive under greenhouse conditions. All populations reproduced on citrus but failed to reproduce on trifoliate orange and had minimal reproduction on olive and grapevine, consistent with the Mediterranean biotype. In a subset of 46 orchards in Jahrom County, soil physicochemical properties were analyzed and related to nematode density using GIS and Random Forest modeling. Spatial interpolation and predictive mapping were conducted using ArcGIS. The Random Forest model explained 82.6% of the variation in nematode density (R 2 = 0.826), with soil pH identified as the most important predictor, followed by silt and sand content, whereas clay content and calcium carbonate had lower importance. These results demonstrate the widespread distribution of T. semipenetrans in Fars Province and the utility of GIS and machine learning for identifying environmental drivers of nematode abundance and supporting spatially targeted management strategies.
Plant-parasitic nematodes such as soybean cyst nematodes (SCNs) (Heterodera glycines) and root-knot nematodes (Meloidogyne spp.) pose a significant threat to global soybean productivity. This study evaluated the multimodal biocontrol potential of 'Candidatus Pseudomonas auctus' JDE115, a soybean nodule-derived bacterium known for its plant growth-promoting properties. Greenhouse-based pot and split-root assays showed that JDE115 not only significantly improved soybean growth and nodulation but also suppressed SCN reproduction by over 90% locally and 85% systemically, indicating both direct antagonism and possibly induced systemic resistance. Volatile profiling using solid-phase microextraction gas chromatography-mass spectrometry identified dimethyl disulfide and 1-undecene as distinctive volatile organic compounds produced by JDE115. Bioassays with free-living nematodes demonstrated that 1-undecene elicits strong avoidance behavior and causes rapid mortality in nematodes in the absence of direct contact. Furthermore, a colorimetric picrate assay confirmed substantial hydrogen cyanide production by the bacterium. Additional tests revealed that JDE115 inhibits egg hatching and causes juvenile mortality through a combination of chemical toxicity and enzymatic degradation. Collectively, these findings establish JDE115 as a multifunctional plant growth-promoting rhizobacterium with potential nematicidal activity and broad biocontrol potential, underscoring its value as a next-generation microbial tool for integrated nematode management in soybean cultivation. To our knowledge, this is the first report demonstrating combined volatile-mediated and systemic suppression of SCN by a nodule-derived Pseudomonas.
