Ecology of the free-living stages of cattle nematodes in the dry season in the Lerma Valley, Salta province, Argentina

The objective of this work was to describe the dynamics of development and survival of the free-living stages of cattle gastrointestinal nematodes (GIN) in fecal matter (FM) and pasture during the dry season in the Lerma Valley, Salta province, northwestern Argentina (NWA) to contribute to GIN management. The climate in the region is characterized by a rainy summer followed by a dry season from middle autumn to early spring. Fecal matter from calves naturally infected with GIN was deposited on three experimental field plots in April, July and October 2019, corresponding to the beginning, middle and end of the dry season, respectively. Each experimental unit consisted of 7 stools of about 800 g and had four repetitions. To determine the development from egg to infective larvae (L3), the first sampling (5 g fecal matter) was performed from the 10th day post-contamination and continued every 3 days until L3 were found. Subsequently, a monthly sampling was made until two consecutive negative results were obtained. Sampling of pasture began three days after the L3 recovery from FM, and continued monthly until two negative results were obtained. The following parameters were evaluated: development time and development rate from egg to L3; permanence time of L3 in feces; time of appearance on pasture; migration rate; and permanence time of L3 on pasture. The main genera of parasites present were Cooperia and Haemonchus. Significant differences were observed in the development time among contamination months (p < 0.001); development time was highest in the July contamination (28 days), with October and April contamination averaging 9 and 10 days, respectively. Development time also showed significant differences (p < 0.01) among contamination months, being highest in October (31.48%). The highest permanence time in fecal matter values were recorded in the July contamination (183 days) and migration rate was highest in the October contamination (42.49%). The highest time of appearance on pasture value was recorded in the July contamination (117 days). Finally, the highest permanence time of L3 in feces values were detected in the October contamination (148 days). The results of this work show that fecal contamination in the NWA region in the dry season would play an epidemiological role in the GIN cycle as a source of infection for the next productive cycle in the rainy season.

Parasitic nematodes of sugarcane - a major productivity impediment and grand challenges in management

Sugarcane is an important cash crop grown in 137 countries, accounting for 80% of global sugar production. It supports the livelihood of over 100 million people and up to 25% of the rural population in some countries. Plant parasitic nematodes are one significant constraint in sugarcane production and can lead to a loss of up to 30% in productivity. Over 300 species of parasitic nematodes have been discovered in sugarcane soil. Due to limited data, potential damage to sugarcane crops caused by parasitic nematodes is often underestimated. The main nematodes present in sugarcane fields are root-lesion (Pratylenchus spp), spiral (Helicotylenchus spp), root-knot (Meloidogyne spp), dagger (Xiphenema spp), stunt (Tylenchorhynchus spp.), ring (Criconemella spp.) and stubby (Paratichodorus spp). Among these, Meloidogyne javanica and Pratylenchus zeae are the most damaging nematode species. Management of nematodes is a challenging task as there are no clear symptoms of their presence, and they often come in multiple species with varying levels of pathogenicity. Moreover, the management options available are not always effective. Integrated nematode management (IMN) is a sustainable strategy for controlling nematode infestations. It involves utilizing all possible methods to suppress the parasitic nematode population in a compatible manner and reduce it below economic threshold levels. This article focuses on the challenges of managing nematodes in sugarcane and highlights the opportunity for implementing a sustainable nematode management strategy.

Evaluating the adverse effects and mechanisms of nanomaterial exposure on longevity of C. elegans: A literature meta-analysis and bioinformatics analysis of multi-transcriptome data

Exposure to large-size particulate air pollution (PM2.5 or PM10) has been reported to increase risks of aging-related diseases and human death, indicating the potential pro-aging effects of airborne nanomaterials with ultra-fine particle size (which have been widely applied in various fields). However, this hypothesis remains inconclusive. Here, a meta-analysis of 99 published literatures collected from electronic databases (PubMed, EMBASE and Cochrane Library; from inception to June 2023) was performed to confirm the effects of nanomaterial exposure on aging-related indicators and molecular mechanisms in model animal C. elegans. The pooled analysis by Stata software showed that compared with the control, nanomaterial exposure significantly shortened the mean lifespan [standardized mean difference (SMD) = -2.30], reduced the survival rate (SMD = -4.57) and increased the death risk (hazard ratio = 1.36) accompanied by upregulation of ced-3, ced-4 and cep-1, while downregulation of ctl-2, ape-1, aak-2 and pmk-1. Furthermore, multi-transcriptome data associated with nanomaterial exposure were retrieved from Gene Expression Omnibus (GSE32521, GSE41486, GSE24847, GSE59470, GSE70509, GSE14932, GSE93187, GSE114881, and GSE122728) and bioinformatics analyses showed that pseudogene prg-2, mRNAs of abu, car-1, gipc-1, gsp-3, kat-1, pod-2, acdh-8, hsp-60 and egrh-2 were downregulated, while R04A9.7 was upregulated after exposure to at least two types of nanomaterials. Resveratrol (abu, hsp-60, pod-2, egrh-2, acdh-8, gsp-3, car-1, kat-1, gipc-1), naringenin (kat-1, egrh-2), coumestrol (egrh-2) or swainsonine/niacin/ferulic acid (R04A9.7) exerted therapeutic effects by reversing the expression levels of target genes. In conclusion, our study demonstrates the necessity to use phytomedicines that target hub genes to delay aging for populations with nanomaterial exposure.

The proof is in the poo-ding: Benefits of the longitudinal molecular surveillance of drug resistance demonstrated in a New South Wales cattle herd

Our understanding of anthelmintic resistance in the gastrointestinal nematodes of Australian cattle relies exclusively on small-scale phenotypic reports utilising traditional faecal egg count reduction tests. This approach is not readily scalable to establish the national prevalence of resistance, nor is it conducive of routine longitudinal surveillance for the emergence of resistance in its early stages. This study introduces the benefits of applying mixed amplicon metabarcoding longitudinally for timely and cost-efficient molecular surveillance of multiple anthelmintic resistance mutations, as they emerge on farms. Using opportunistically collected faecal samples from a cattle herd in central west New South Wales (2019-2023), we detected the early emergence of Haemonchus spp. levamisole-resistant S168T shortly after levamisole introduction, while benzimidazole-resistant allele frequencies remained constant. Additionally, we observed the possible spill-over of resistant Haemonchus contortus from sheep, along with variations in faecal burdens and species diversity influenced by climate stochasticity and host immunity. This study emphasises the power of molecular diagnostics for farm-level anthelmintic resistance management, providing essential evidence to support its integration into routine surveillance programmes.

A phenotypic screen of the Global Health Priority Box identifies an insecticide with anthelmintic activity

BACKGROUND

Infection with parasitic nematodes (helminths), particularly those of the order Strongylida (such as Haemonchus contortus), can cause significant and burdensome diseases in humans and animals. Widespread drug (anthelmintic) resistance in livestock parasites, the absence of vaccines against most of these nematodes, and a lack of new and effective chemical entities on the commercial market demands the discovery of new anthelmintics. In the present study, we searched the Global Health Priority Box (Medicines for Malaria Venture) for new candidates for anthelmintic development.

METHODS

We employed a whole-organism, motility-based phenotypic screening assay to identify compounds from the Global Health Priority Box with activity against larvae of the model parasite H. contortus, and the free-living comparator nematode Caenorhabditis elegans. Hit compounds were further validated via dose-response assays, with lead candidates then assessed for nematocidal activity against H. contortus adult worms, and additionally, for cytotoxic and mitotoxic effects on human hepatoma (HepG2) cells.

RESULTS

The primary screen against H. contortus and C. elegans revealed or reidentified 16 hit compounds; further validation established MMV1794206, otherwise known as 'flufenerim', as a significant inhibitor of H. contortus larval motility (half-maximal inhibitory concentration [IC50] = 18 μM) and development (IC50 = 1.2 μM), H. contortus adult female motility (100% after 12 h of incubation) and C. elegans larval motility (IC50 = 0.22 μM). Further testing on a mammalian cell line (human hepatoma HepG2 cells), however, identified flufenerim to be both cytotoxic (half-maximal cytotoxic concentration [CC50] < 0.7 μM) and mitotoxic (half-maximal mitotoxic concentration [MC50] < 0.7 μM).

CONCLUSIONS

The in vitro efficacy of MMV1794206 against the most pathogenic stages of H. contortus, as well as the free-living C. elegans, suggests the potential for development as a broad-spectrum anthelmintic compound; however, the high toxicity towards mammalian cells presents a significant hindrance. Further work should seek to establish the protein-drug interactions of MMV1794206 in a nematode model, to unravel the mechanism of action, in addition to an advanced structure-activity relationship investigation to optimise anthelmintic activity and eliminate mammalian cell toxicity.

Temporal transcriptome profiling of Pinus densiflora infected with pine wood nematode reveals genetically programmed changes upon pine wilt disease

Pine, an evergreen conifer, is widely distributed worldwide. It is economically, scientifically, and ecologically important. However, pine wilt disease (PWD) induced by the pine wood nematode (PWN) adversely affects pine trees. Many studies have been conducted on PWN and their beetle vectors to prevent the spread of PWD. However, studies providing a comprehensive understanding of the pine tree transcriptome in response to PWN infection are lacking. Here, we performed temporal profiling of the pine tree transcriptome using PWD-infected red pine trees, Pinus densiflora, inoculated with PWN by RNA-sequencing. Our analysis revealed that defense-responsive genes involved in cell wall modification, jasmonic acid signaling, and phenylpropanoid-related processes were significantly enriched 2 weeks after PWD infection. Furthermore, some WRKY-type and MYB-type transcription factors were upregulated 2 weeks after PWD, suggesting that these transcription factors might be responsible for the genome-wide reprogramming of defense-responsive genes in the early PWD stage. Our comprehensive transcriptome analysis will assist in developing PWD resistant pine trees, and identifying genes to diagnose PWD at the early stage of infection, during which large-scale phenotypic changes are absent in PWD-infected pine trees.

Prevalence of gastrointestinal parasitism in pigs of Tripura, India

Pigs breeds are an important livestock species mostly reared by economically lower incomesection of people in India. Within North-Eastern (NE) states, pig husbandry is very much popular hence maintain the livelihood of the rural native population. Gastrointentinal (GI) parasitic infectionisone of the major constraint in profitable pig production in this area. In the present study, the GI parasitism was investigated in 388 pigs in the three districts of Tripura, NE State of India. The examination of faecal samples revealed 61.65% overall prevalence of parasitic infestation, precisely6 GI parasitic species; including 4 nematodes and 2 protozoa, while 46.91% were the mixed infections.Metastrongylus spp. (17.53%), Strongyloids spp. (19.33%),Trichuris spp. (15.98%), Coccidia spp. (12.37%), and Balantidium coli (10.82%), were detected, however, Ascaris spp. was the most prevalentrecording 32.47%. The epidemiological factors including: age, sex, season, breed, area and farming system wise when considered as markers of study showed the highest prevalence of GI parasites in grower(6-12 months) stage, female, monsoon season, non-descript breeds, Khowai district and free range farming system, recorded 71.52%, 67.27%, 65.78%, 65.71%, 64.57%, and 69.44%, respectively. Overall, our study provides a baseline data for further investigation and formulation of strategies for control of GI parasitism in pigs in Tripura.

A QTL on Maize Chromosome 5 is Associated with Root-Knot Nematode Resistance

This study provides the first report of a quantitative trait locus (QTL) in maize (Zea mays) for resistance to the southern root-knot nematode (SRKN) (Meloidogyne incognita). The SRKN can feed on the roots of maize in the U.S. Southern Coastal Plain region and can cause yield losses of 30% or greater in heavily infested fields. Increases in SRKN density in the soil may reduce the yield for subsequently planted susceptible crops. The use of maize hybrids with resistance to SRKN could prevent an increase in SRKN density, yet no genetic regions have been identified that confer host resistance. In this study, a B73 (susceptible) x Ky21 (resistant) S5 recombinant inbred line (RIL) population was phenotyped for total number of eggs (TE) and root weight. This population has been previously genotyped using single nucleotide polymorphisms (SNPs). By utilizing the SNP data with the phenotype data, a single QTL was identified on chromosome 5 that explained 15% of the phenotypic variation (PV) for the number of eggs and 11% of the PV for the number of eggs per g of root (EGR). Plants that were homozygous for the Ky21 allele for the most associated marker PZA03172.3 had fewer eggs and fewer EGR than the plants that were homozygous or heterozygous for the B73 allele. Thus, the first QTL for SRKN resistance in maize has been identified and could be incorporated into maize hybrids.

Molecular characterization of a novel Spiruromorpha species in wild Chinese pangolin by mitogenome sequence analysis

Pangolins are susceptible to a variety of gastrointestinal nematodes due to their burrowing lifestyle and feeding habits, and few parasitic nematodes have been reported. Here, a Chinese pangolin with old wounds on its leg and tail was rescued from the Heyuan City, Guangdong Province. The cox1 and SSU rRNA of the worms from the intestine of the Chinese pangolin had the highest sequence identity of 89.58% and 97.95% to the species in the infraorder Spiruromorpha. The complete mitogenome of the worm was further assembled by next-generation sequencing, with a size of 13,708 bp and a GC content of 25.6%. The worm mitogenome had the highest sequence identity of 78.56% to that of Spirocerca lupi, sharing the same gene arrangement with S. lupi and some species in other families under Spiruromorpha. However, the mitogenome between the worm and S. lupi showed differences in codon usage of PCGs, sequences of NCR, and tRNA secondary structures. Phylogenetic analysis showed that the worm mitogenome was clustered with S. lupi in the family Thelaziidae to form a separate branch. However, it is still difficult to identify the worm in the family Thelaziidae because the species in the family Thelaziidae are confused, specifically S. lupi and Thelazia callipaeda in the family Thelaziidae were separated and grouped with species from other families. Thus, the parasitic nematode from the Chinese pangolin may be a novel species in Spiruromorpha and closely related to S. lupi. This study enriches the data on gastrointestinal nematodes in the Chinese pangolin.

Revolutionizing nematode management to achieve global food security goals - An overview

Nematodes are soil-dwelling organisms that inflict substantial damage to crops, resulting in significant declines in agricultural productivity. Consequently, they are recognized as one of the primary contributors to global crop damage, with profound implications for food security. Nematology research assumes a pivotal role in tackling this issue and safeguarding food security. The pursuit of nematology research focused on mitigating nematode-induced crop damage and promoting sustainable agriculture represents a fundamental strategy for enhancing food security. Investment in nematology research is crucial to advance food security objectives by identifying and managing nematode species, developing novel technologies, comprehending nematode ecology, and strengthening the capabilities of researchers and farmers. This endeavor constitutes an indispensable step toward addressing one of the most pressing challenges in achieving global food security and promoting sustainable agricultural practices. Primarily, research endeavors facilitate the identification of nematode species responsible for crop damage, leading to the development of effective management strategies. These strategies encompass the utilization of resistant crop varieties, implementation of cultural practices, biological control, and chemical interventions. Secondly, research efforts contribute to the development of innovative technologies aimed at managing nematode populations, such as gene editing techniques that confer resistance to nematode infestations in crops. Additionally, the exploration of beneficial microbes, such as certain fungi and bacteria, as potential biocontrol agents against nematodes, holds promise. The study of nematode ecology represents a foundational research domain that fosters a deeper comprehension of nematode biology and ecological interactions. This knowledge is instrumental in devising precise and efficacious management strategies.

Cerebral filariasis infection with Litomosoides in Molossus barnesi (Chiroptera: Molossidae) in the Brazilian eastern Amazon, with comments on Molossinema wimsatti Georgi, Georgi, Jiang and Fronguillo, 1987

During bacterial and viral pathogen investigation of 30 specimens of bats captured in periurban forest areas in the city of Belém, Pará, Brazil, a case of cerebral filariasis was observed. In the course of histopathological examination, adult filariae were found in pseudocystic cavities brain of Molossus barnesi (Molossidae) and classified morphologically as Litomosoides by the shape of the spicules-left spicule with a handle longer than the blade; right spicule curved, with a sclerotized heel supporting a dorsal notch; the area rugosa constituted by a ventral band of small longitudinal crests; tail rounded in males; long esophagus with a slightly glandular distal portion; and a muscular bent vagina. All the specimens lack a stoma (buccal capsule). We compared our filarioids with the description of specimens of Molossinema wimsatti. Morphological characteristics of M. wimsatti resemble the genus Litomosoides. Thus, we believe that M. wimsatti is a synonym of L. molossi Esslinger, 1973, and filarioid specimens from material reported by Lichtenfels et al. (Trans Am Micros Soc 100:216-219, 1981) and from de Souto et al. (J. Helminthol 1195:e65, 2021) most probably correspond to Litomosoides. We suggest that the reduction of the buccal capsule may be attributable to the ectopic location. No evidence of tissue responses by the host was observed. This is the first record of Litomosoides infecting brain tissue of Molossus barnesi from Brazil, representing a record of a new host species. More specimens of bats should be examined in order to find filarioids in the brain and verify its taxonomic position using molecular techniques.

A systematic review and meta-analysis on the current status of anthelmintic resistance in equine nematodes: A global perspective

BACKGROUND

The intensive application of anthelmintics in equine has led to considerable resistance in cyathostomins and Parascaris equorum. It has been well documented that benzimidazole (BZ) and pyrantel resistance is widespread in cyathostomins and Parascaris equorum. Since no new classes of anthelmintic have been introduced in the last 40 years, it is critical to be aware of the current risk factors of anthelmintic application to avoid further resistance.

OBJECTIVE

To review the factors affecting the level of anthelmintics resistance in equine around the world, type of anthelmintics, mode of application, dosage, nematode species, and location of anthelmintics application were evaluated and summarized.

DESIGN/PROCEDURE

A systematic review and meta-analyses following the PRISMA Framework were conducted to identify, evaluate, and synthesize primary literature reporting the efficacy of anthelmintic drugs in equines. Information on the bibliographic data, anthelmintic drugs, animals, continents, parasite genera, type of anthelmintics, and dosage was collected. Nonparametric tests (Kruskal-Wallis and Mann-Whitney) were used in SPSS (v.27) to investigate the association between variables. Factors that have a significant impact on efficacy have been subjected to binary logistic regression. Six meta-analyses were conducted in Microsoft Excel (2021) to qualify current resistance issues of the three major anthelmintics classes.

RESULTS

The final database was composed of 60 articles published between 1994 and 2022 with a total of 11835 animals. Anthelmintic class as well as anthelmintic active principle selection did have a significant effect on resistance (P < 0.01), whilst no correlation of the type of anthelmintics, mode of application, and dosage with efficacy were found. Anthelmintics resistance in ascarid was significantly more severe than in strongyle (P < 0.01). Macrocyclic lactone (ML) class and the benzimidazole and probenzimidazole (BP) class have the lowest efficacy against ascarid and strongyle, respectively (67.83% and 69.85%). The effect of location (by continent) also had a significant influence on the resistance of the ML class (P < 0.01). The resistance of the BP class which is the most prevalently applied was demonstrated in all six continents. Binary logistic regression revealed that parasite genera and drug class independently influenced the presence of drug resistance. The forest plots included in this study did not show a significant difference over time.

CONCLUSION

Current evidence indicated that anthelmintics resistance of ML and BP class were common in ascarid and strongyle. A combination of anthelmintics may reduce anthelmintics resistance, but multi-drug resistance may be a concern. Customerised anthelmintics strategy could help reduce resistance.

CHEMOTAXIS RESPONSE OF PHASMARHABDITIS CALIFORNICA (FAMILY: RHABDITIDAE) AND PRISTIONCHUS ENTOMOPHAGUS (FAMILY: NEODIPLOGASTERIDAE) TO THE MUCUS OF FOUR SLUG SPECIES

The chemotaxis responses of soil nematodes have been well studied in bacteriophagic nematodes, plant-parasitic nematodes, entomopathogenic nematodes, and to a lesser extent malacopathogenic nematodes. Free-living stages of parasitic nematodes often use chemotaxis to locate hosts. In this study, we compared the chemotaxis profile of 2 slug-associated nematodes with overlapping host ranges. Phasmarhabditis californica is a facultative parasite that has been shown to express strain-dependent variation in chemoattraction profile. We tested 4 slug species to determine the attraction index of a Canadian strain of Ph. californica and a sympatric necromenic nematode, Pristionchus entomophagus. When tested against a control (distilled water), Ph. californica showed a clear (positive) attraction towards the mucus of slugs Ambigolimax valentianus, Arion rufus, and Arion fasciatus, but not Deroceras reticulatum. However, when given a choice between the mucus of D. reticulatum and Ar. fasciatus in a pairwise test, Ph. californica was strongly attracted to the former. Other pairwise comparisons did not reveal a clear preference for either slug species in the following pairs: D. reticulatum-Ar. rufus, Am. valentianus-Ar. rufus, D. reticulatum-Am. valentianus. The chemotaxis assay for Pr. entomophagus showed an attraction toward D. reticulatum and Ar. fasciatus (tested against controls); the attraction index for Am. valentianus was positive, but this was not statistically significant. In contrast, the attraction index for Ar. rufus was negative, suggesting possible repulsion to the mucus of this slug species. Given that Pr. entomophagus and Ph. californica occupy overlapping habitats, utilize similar hosts, and exhibit similar chemotaxis profiles, there is a potential for direct interaction between these 2 nematodes. Like other members of the genus Pristionchus, Pr. entomophagus may be able to prey upon the co-occurring Ph. californica, such antagonistic interactions could have important implications for the coexistence of these 2 species and Ph. californica in particular as a biocontrol agent against pestiferous slugs.

Sensitivity of Meloidogyne incognita, Fusarium oxysporum f.sp. niveum, and Stagonosporopsis citrulli to succinate dehydrogenase inhibitors used for control of watermelon diseases

Watermelon is affected by diseases such as Fusarium wilt, gummy stem blight, and root-knot nematode. Succinate dehydrogenase inhibitors (SDHIs) with potential fungicide and nematicide activity provide the opportunity to control multiple diseases with one compound. In this study, we aimed to determine the sensitivity of Meloidogyne incognita race 4 (MI4), Fusarium oxysporum f.sp. niveum (FON), and Stagonosporopsis citrulli (SCIT), to existing SDHIs: benzovindiflupyr, fluopyram, cyclobutrifluram, and pydiflumetofen. All SDHIs had fungicidal activity against 19 SCIT isolates in mycelial growth assays, but isolates were most sensitive to pydiflumetofen (median EC50 = 0.41 µg/ml). Most of 50 FON isolates tested were sensitive to cyclobutrifluram for mycelial growth (median EC50 = 4.04 µg/ml) and conidial germination (median EC50 = 0.2 µg/ml) assays but were not sensitive to fluopyram. MI4 was most sensitive to cyclobutrifluram for egg hatch (mean EC50 = 0.0019 µg/ml) and J2 motility (mean EC50 = 1.16 µg/ml) assays but was not sensitive to pydiflumetofen. Significant positive correlations between the sensitivity of SCIT (mycelial growth) and FON (mycelial growth and conidial germination) for cyclobutrifluram and benzovindiflupyr (SCIT r=0.88, FON r =0.7, P< 0.0001) and cyclobutrifluram and pydiflumetofen (SCIT r=0.83, FON r =0.67 and 0.77, P< 0.0001) indicate a potential for cross-resistance between these SDHIs for these fungal pathogens. Overall, results suggest that cyclobutrifluram may be used for managing root-knot nematode, whereas it should be used judiciously for Fusarium wilt of watermelon and gummy stem blight due to the existence of insensitive isolates to the fungicide.

Structure activity relationship and target prediction for ABX464 analogues in Caenorhabditis elegans

Global challenges with treatment failures and/or widespread resistance in parasitic worms against commercially available anthelmintics lend impetus to the development of new anthelmintics with novel mechanism(s) of action. The free-living nematode Caenorhabditis elegans is an important model organism used for drug discovery, including the screening and structure-activity investigation of new compounds, and target deconvolution. Previously, we conducted a whole-organism phenotypic screen of the 'Pandemic Response Box' (from Medicines for Malaria Venture, MMV) and identified a hit compound, called ABX464, with activity against C. elegans and a related, parasitic nematode, Haemonchus contortus. Here, we tested a series of 44 synthesized analogues to explore the pharmacophore of activity on C. elegans and revealed five compounds whose potency was similar or greater than that of ABX464, but which were not toxic to human hepatoma (HepG2) cells. Subsequently, we employed thermal proteome profiling (TPP), protein structure prediction and an in silico-docking algorithm to predict ABX464-target candidates. Taken together, the findings from this study contribute significantly to the early-stage drug discovery of a new nematocide based on ABX464. Future work is aimed at validating the ABX464-protein interactions identified here, and at assessing ABX464 and associated analogues against a panel of parasitic nematodes, towards developing a new anthelmintic with a mechanism of action that is distinct from any of the compounds currently-available commercially.

The root-lesion nematode, Pratylenchus penetrans, affects early growth and physiology of grafted M.9, G.41 and G.935 apple rootstocks similarly under field microplot conditions

The root-lesion nematode, Pratylenchus penetrans, is a ubiquitous parasite of roots of temperate fruit trees. It affects early growth of trees replanted into former orchard sites where populations have built up, and may contribute to decline complexes of older trees. Most British Columbia, Canada apple acreage is planted with M.9 rootstock, but growers are increasingly considering Geneva-series rootstocks such as G.41 and G.935. Among these rootstocks, responses to P. penetrans, specifically, are poorly known. To compare the resistance and tolerance to P. penetrans of G.41, G.935 and M.9 rootstocks ('Ambrosia' scion), a field microplot experiment was established in spring of 2020 at the Summerland Research and Development Centre. The experimental design was a 2 x 3 factorial combination of: P. penetrans inoculation (+/-) and rootstock (G.41, G.935, M.9), with 20 replicate microplots of each of the six treatment combinations arranged in a randomized complete block design. The P. penetrans inoculum was 5400 nematodes per microplot (54 P. penetrans L-1 soil), which is below commonly accepted damage thresholds. Though P. penetrans population densities were lower for the G.41 rootstock by the end of the 2021 growing season, the effects of P. penetrans were similar among rootstocks. In the establishment year (2020), P. penetrans caused significant reductions in aboveground growth. In 2021, shoot growth and root weight were reduced by P. penetrans. The nematode also reduced rates of leaf gas exchange and stem water potential. These data suggest that while G.41 and G.935 may have other horticultural benefits over M.9, they are equally susceptible to P. penetrans at the early stages of tree growth.

Enhancing reniform nematode management in sweetpotato by complementing host-plant resistance with non-fumigant nematicides

The reniform nematode (Rotylenchulus reniformis Linford and Oliveira) adversely impacts the quality and quantity of sweetpotato storage roots. Management of R. reniformis in sweetpotato remains a challenge because host plant resistance is not available, fumigants are detrimental to the environment and health, and crop rotation is not effective. We screened a core set of 24 sweetpotato plant introductions (PIs) against R. reniformis. Four PIs were resistant and 10 were moderately resistant to R. reniformis suggesting these PIs can serve as sources of resistance for sweetpotato resistance breeding programs. PI 595869, PI 153907, and PI 599386 suppressed 83% to 89% egg production relative to the susceptible control 'Beauregard', and these PIs were employed in subsequent experiments to determine if their efficacy against R. reniformis can be further increased by applying non-fumigant nematicides oxamyl, fluopyram and fluensulfone. A 34% to 93% suppression of nematode reproduction was achieved by the application of non-fumigant nematicides, with oxamyl providing the best suppression followed by fluopyram and fluensulfone. Although sweetpotato cultivars resistant to R. reniformis are currently not available and there is a need for the development of safer yet highly effective non-fumigant nematicides, results from the current study suggest that complementing host plant resistance with non-fumigant nematicides can serve as an important tool for effective and sustainable nematode management.

A mixed amplicon metabarcoding and sequencing approach for surveillance of drug resistance to levamisole and benzimidazole in Haemonchus spp

Anthelmintic-resistant parasitic nematodes present a significant threat to sustainable livestock production worldwide. The ability to detect the emergence of anthelmintic resistance at an early stage, and therefore determine which drugs remain most effective, is crucial for minimising production losses. Despite many years of research into the molecular basis of anthelmintic resistance, no molecular-based tools are commercially available for the diagnosis of resistance as it emerges in field settings. We describe a mixed deep amplicon sequencing approach to determine the frequency of the levamisole (LEV)-resistant single nucleotide polymorphism (SNP) within arc-8 exon 4 (S168T) in Haemonchus spp., coupled with benzimidazole (BZ)-resistant SNPs within β-tubulin isotype-1 and the internal transcribed spacer-2 (ITS-2) nemabiome. This constitutes the first known multi-drug and multi-species molecular diagnostic developed for helminths of veterinary importance. Of the ovine, bovine, caprine and camelid Australian field isolates we tested, S168T was detected in the majority of Haemonchus spp. populations from sheep and goats, but rarely at a frequency greater than 16%; an arbitrary threshold we set based on whole genome sequencing (WGS) of LEV-resistant Haemonchus contortus GWBII. Overall, BZ resistance was far more prevalent in Haemonchus spp. than LEV resistance, confirming that LEV is still an effective anthelmintic class for small ruminants in New South Wales, Australia. The mixed amplicon metabarcoding approach described herein paves the way towards the use of large scale sequencing as a surveillance technology in the field, the results of which can be translated into evidence-based recommendations for the livestock sector.

Investigations on Microbes Attached to the Cuticle of Phytonematodes

Nematodes form various associations with soil microbiome. Experimental studies on nematode-attached microbes can improve mechanistic understanding of these associations and lead to new discoveries relevant for the field of nematode biocontrol. Microbial attachment to the surface of phytonematodes is very specific and influenced by a multitude of factors, including the designation of nematodes and microbes, environmental and biological factors in soil, time of incubation, and the ratio and evolutionary trajectories between nematodes and microbes. Here, we describe how the classical nematological and microbiological techniques can be coupled with the advanced molecular tools to study the microbial attachment to phytonematodes in soil. We focus on the characterization of nematode-attached microbes using classical microbiological approaches and high-throughput amplicon sequencing and on the effects of nematode-attached microbes on plant defense responses.

Clarifying the functional role of serotonin in Meloidogyne graminicola host plant parasitism by immunolocalization and RNA interference

Serotonin (5-hydroxytryptamine, 5-HT) is an essential neurotransmitter involved in regulating various behaviors in plant-parasitic nematodes (PPNs), including locomotion, egg laying, feeding, and mating. However, the functional role of serotonin in root-knot nematode invasion of host plants and the molecular mechanisms underlying feeding behavior remain poorly understood. In this study, we tested the effects of exogenous serotonin and the pharmacological compounds fluoxetine and methiothepin on the feeding behaviors of Meloidogyne graminicola. Our results suggested that M. graminicola possesses an endogenous serotonin signaling pathway and that serotonin plays a crucial role in modulating feeding behaviors in M. graminicola second stage juveniles (J2). We also identified and cloned the serotonin synthesis enzyme tryptophan hydroxylase (Mg-tph-1) in M. graminicola and investigated the role of endogenous serotonin by generating RNA interference nematodes in Mg-tph-1. As a result, silencing Mg-tph-1 substantially reduced nematode invasion, development, and reproduction. According to the immunostaining results, we speculated that these serotonin immunoreactive cells near the nerve ring in M. graminicola are likely homologous to Caenorhabditis elegans ADFs, NSMs, and RIH serotonergic neurons. Furthermore, we investigated the impact of phytoserotonin on nematode invasion and development in rice by overexpressing OsTDC-3 or supplementing rice plants with tryptamine and found that an increase in phytoserotonin increases nematode pathogenicity. Overall, our study provides insights into the essential role of serotonin in M. graminicola host plant parasitism and proposes that the serotonergic signaling pathway could be a potential target for controlling PPNs.

Wheat rhizosphere-derived bacteria protect soybean from soilborne diseases

Soybean [Glycine max (L.) Merr.] is an important oilseed crop with a high economic value. However, three damaging soybean diseases, soybean cyst nematode (SCN; Heterodera glycines Ichinohe), Sclerotinia stem rot caused by the fungus Sclerotinia sclerotiorum (Lid.) de Bary, and soybean root rot caused by Fusarium spp., are major constraints to soybean production in the Great Plains. Current disease management options, including resistant or tolerant varieties, fungicides, nematicides, and agricultural practices (crop rotation and tillage), have limited efficacy for these pathogens or have adverse effects on the ecosystem. Microbes with antagonistic activity are a promising option to control soybean diseases with the advantage of being environmentally friendly and sustainable. In this study, 61 bacterial strains isolated from wheat rhizospheres were used to examine their antagonistic abilities against three soybean pathogens. Six bacterial strains significantly inhibited the growth of Fusarium graminearum in the dual-culture assay. These bacterial strains were identified as Chryseobacterium ginsengisoli, C. indologenes, Pseudomonas poae, two Pseudomonas spp., and Delftia acidovorans by 16S rRNA gene sequencing. Moreover, C. ginsengisoli, C. indologenes, and P. poae significantly increased the mortality of SCN second-stage juveniles (J2) and two Pseudomonas spp. inhibited the growth of S. sclerotiorum in vitro. Further growth chamber tests found that C. ginsengisoli and C. indologenes reduced soybean Fusarium root rot disease. C. ginsengisoli and P. poae dramatically decreased SCN egg number on SCN susceptible soybean "Williams 82". Two Pseudomonas spp. protected soybean plants from leaf damage and collapse after being infected by S. sclerotiorum. These bacteria exhibit versatile antagonistic potential. This work lays the foundation for further research on the field control of soybean pathogens.

New species of Serpinema (Nematoda: Camallanidae) from the scorpion mud turtle Kinosternon scorpioides (Testudines: Kinosternidae) from eastern Amazon, Brazil

The genus Serpinema Yeh, 1960 allocates parasitic nematodes of freshwater turtles distributed across the Oriental, Neotropical, and Palearctic regions. Five of 10 valid species of the genus Serpinema occur in the Neotropical region, and three have been recorded parasitizing Kinosternon scorpioides Linnaeus, 1766. In the present work, we describe a new species of Serpinema, a gastrointestinal parasite of K. scorpioides from the Brazilian Amazon, using light and scanning electron microscopy. Serpinema pelliculatus n. sp. differs from other species of the genus by the number and distribution of caudal papillae and spicule morphology. The new species is the seventh recorded for the Neotropical region.

First report of root-knot nematode, Meloidogyne javaniva, infecting Stachys byzantina on São Paulo, Brazil

Stachys byzantina belongs to the Labiatae and is known by the names "peixinho-da-horta" (Brazil) and "lamb's ear" (USA). Its importance is associated with its medicinal properties (Bahadori et al. 2020) and nutritional aspects (Milião et al. 2022). Root-knot nematodes cause severe damage to plants and suppress production. In January 2021, plants of S. byzantina in the municipality of Jaboticabal (21°14'38.7"S, 48°17'10.6"W) showed symptoms of reduced growth, yellowed leaves and the presence of galls in the roots. Initially, samples of roots from a S. byzantina were analyzed at the Nematology Laboratory (LabNema/UNESP), Jaboticabal, Brazil, estimating 20,000 eggs and juveniles of Meloidogyne sp. in 10 g of roots. To confirm the host ability of the species, a pathogenicity test was performed using Koch's postulate. For this purpose, the test was conducted in a greenhouse where 3,000 eggs and second-stage juveniles (J2) were inoculated onto three plants (n=3) of S. byzantina. After 90 days, the inoculated plants showed the same symptoms as those observed in the field. No symptom or nematode was detected in the uninoculated plant (control). Nematodes were extracted from the roots of inoculated plants and quantified. The perineal pattern of females (n=10) (Netscher and Taylor, 1974) and the labial region of males (n=10) (Eisenback and Hirschmann, 1981) were analyzed and compared with the morphological characteristics of the original description of the species (Chitwood, 1949). For analysis based on esterase isozyme phenotype, the α-method of Esbenshade and Triantaphyllou (1990) was used, and females (n=7) were examined. To confirm identification, whole genomic DNA from an adult female (n=1) was extracted using the Qiagen DNeasy® Blood & Tissue Kit and this sample was used for both genetic sequencing and the sequence-characterized amplified region techniques (SCAR). PCR amplifications were performed for the 18s rRNA gene using primers 988F and 1912R from Holterman et al (2006). Our sequence was deposited in GenBank (NCBI) under the identifier OP422209. Finally, species-specific SCAR primers (Fjav/Rjav, Me-F/Me-R, and Finc-F/Finc-R) designed by Zijlstra (2000) were used to identify Meloidogyne spp. Koch's postulate analysis yielded the following results: (n=1) 9,280 eggs and J2 (Reproduction factor, RF = 33.09); (n=2) 111,720 eggs and J2 (RF = 37.24); (n=3) 59,700 eggs and J2 (RF = 19.9) (RF mean = 30.08). The following characteristics were observed in the perineal region of females: Low and rounded trapezoidal dorsal arch with two distinct lateral lines clearly separating the dorsal and ventral arch regions, similar to the morphological features of the species description by Chitwood (1949). Males had a convex labial plate with a non-raised labial disk joining the submedial labia, a non-rugged labial region, the basal tubercles were usually wider than high, and a rounded tail tip (Eisenback and Hirschmann 1981). The α-esterase enzyme profile showed the J3 phenotype typical of M. javanica (Rm [×100] = 46.0, 54.5, and 58.9). The 18s rRNA sequences grouped Meloidogyne sp. with species such as M. enterolobii, M. incognita, and M. javanica. A DNA fragment of about 700 bp was amplified with Mj (Fjav/Rjav) primers, but not with Me (Me-F/Me-R) and Mi (Finc-F/Finc-R) primers, which confirmed the identification of M. javanica. Accurate identification and characterization of the occurrence of new hosts of M. javanica will allow us to determine the range and geographic distribution of the species. This is the first report on the occurrence of M. javanica on S. byzantina in Brazil. This report is important so that management strategies can be applied to prevent the spread of the pest to other areas.

Botanicals against some important nematodal diseases: Ascariasis and hookworm infections

Ascariasis and intestinal parasitic nematodes are the leading cause of mass mortality infecting many people across the globe. In light of the various deleterious side effects of modern chemical-based allopathic drugs, our preferences have currently shifted towards the use of traditional plant-based drugs or botanicals for treating diseases. The defensive propensities in the botanicals against parasites have probably evolved during their co-habitation with parasites, humans and plants in nature and hence their combative interference in one another's defensive mechanisms has occurred naturally ultimately being very effective in treating diseases. This article broadly outlines the utility of plant-based compounds or botanicals prepared from various medicinal herbs that have the potential to be developed as effective therapies against the important parasites causing ascariasis and intestinal hookworm infections leading to ascariasis & infections and thereby human mortality, wherein allopathic treatments are less effective and causes enormous side-effects.

A fecal egg count reduction test in grazing beef steers using topical pioneer and generic eprinomectin and fenbendazole oral suspension

Many generic anthelmintics are commercially available; however, little information exists regarding product effectiveness compared to pioneer brands. The objective of this study was to compare the effectiveness of a generic eprinomectin to the pioneer eprinomectin, as well as to fenbendazole and fenbendazole in combination with the pioneer eprinomectin in grazing beef steers via a fecal egg count reduction test. Forty naturally infected steers were allocated into five treatment groups based on ranked fecal egg counts: 1. pioneer eprinomectin (Eprinex®, topical), 2. generic eprinomectin (Eprizero®, topical), 3. fenbendazole (Safeguard® 0.5% oral suspension), 4. combination of pioneer eprinomectin topical and fenbendazole oral suspension, 5. negative control. Fecal samples were collected on days -14, 0, 14, and 29. Data were analyzed using the MIXED procedure of SAS 9.4. Neither the pioneer nor the generic eprinomectin groups reached a 90% fecal egg count reduction (FECR) throughout the study with reductions of 50% and 11% for pioneer eprinomectin and 79% and - 5% for generic eprinomectin at days 14 and 29 post-treatment, respectively. Both the fenbendazole and combination groups showed 98% and 99% FECR, respectively, at 14 days post-treatment; these reductions dropped slightly at day 29 post-treatment to 94% and 89%, respectively. Primarily Cooperia punctata, Cooperia oncophora and Ostertagia ostertagi larvae were recovered from the coprocultures across all treatment groups. Interestingly, the proportions of C. punctata and C. oncophora essentially demonstrated a post-treatment reversal in the both the fenbendazole and combination treatment groups when comparing days 0 and 29, demonstrating prepatency period differences or a fenbendazole treatment effect.

Cercopithifilaria spp. of dogs: little known but prevalent filarioids beneath the skin

Filarioids of the genus Cercopithifilaria are little studied, yet widespread parasites, that are relatively unique in being one of the very few nematodes transmitted by hard ticks. These filarioids live in the subcutis while microfilariae are found in the dermis. Definitive hosts include domestic dogs as well as a wide range of vertebrates, such as ruminants, non-human primates, murids, marsupials, porcupines, viverrids, bears and lagomorphs. The genus Cercopithifilaria contains three taxa (i.e. C. bainae, C. grassii and a yet undescribed species, namely Cercopithifilaria sp. II) that are known to infect dogs worldwide, with their occurrence overlapping the distribution of the main tick vector, Rhipicephalus sanguineus sensu lato. In recent decades, more attention has focused on these filarioids since they have been associated with clinical signs of infection, such as dermatitis, chronic polyarthritis and cutaneous cysts, and possibly with facilitating infections caused by other tick-borne pathogens. Nevertheless, these parasites remain largely underdiagnosed in clinical practice due to the lack of awareness of veterinary practitioners and to major obstacles to their diagnosis. In this review, we have assessed currently available data on Cercopithifilaria spp. infecting dogs worldwide and discussed the biological, clinical and epidemiological aspects of these filarioids, with the overall aim to gain a better understanding of their potential role in skin diseases.

First report of four rare strongylid species infecting endangered Przewalski's horses (Equus ferus przewalskii) in Xinjiang, China

BACKGROUND

The Przewalski's horse (Equus ferus przewalskii) is the only surviving wild horse species in the world. A significant population of Przewalski's horses resides in Xinjiang, China. Parasitosis poses a considerable threat to the conservation of this endangered species. Yet, there is limited information on the nematode parasites that infect these species. To deepen our understanding of parasitic fauna affecting wild horses, we identified the intestinal nematodes of Przewalski's horses in Xinjiang and added new barcode sequences to a public database.

METHODS

Between 2018 and 2021, nematodes were collected from 104 dewormed Przewalski's horses in Xinjiang. Each nematode was morphologically identified to the species level, and selected species underwent DNA extraction. The extracted DNA was used for molecular identification through the internal transcribed spacer 2 (ITS2) genetic marker.

RESULTS

A total of 3758 strongylids were identified. To the best of our knowledge, this is the first study to identify four specific parasitic nematodes (Oesophagodontus robustus, Bidentostomum ivashkini, Skrjabinodentus caragandicus, Petrovinema skrjabini) and to obtain the ITS2 genetic marker for P. skrjabini.

CONCLUSIONS

The ITS2 genetic marker for P. skrjabini enriches our understanding of the genetic characteristics of this species and expands the body of knowledge on parasitic nematodes. Our findings extend the known host range of four strongylid species, thereby improving our understanding of the relationship between Przewalski's horses and strongylids. This, in turn, aids in the enhanced conservation of this endangered species. This study introduces new instances of parasitic infections in wild animals and offers the DNA sequence of P. skrjabini as a valuable resource for molecular techniques in nematode diagnosis among wildlife.

Development and Validation of a Resistance Management Model for the Soybean Cyst Nematode, Heterodera glycines

Plant-parasitic nematodes are a key yield limiting pest of crops around the world. Deployment of plant resistance genes are an important management tactic for many economically important plant-parasitic nematodes. The selection for virulence in nematode populations is a major threat to the effectiveness of resistance gene-based management. Little research has gone into resistance management modelling despite the importance of both plant-parasitic nematodes and resistance genes for their management. In this paper we report on a cyst nematode resistance management model created to explore the factors which are most important for determining the durability of resistance genes to this important family of plant-parasitic nematodes. The relative dominance of virulence expression, the level of inbreeding, and the number of generations per cropping season were the most important factors in predicting resistance gene durability. Aspects of cyst nematode biology that reduce the number of generations per season for a portion of the population had a much smaller effect on the durability of resistance genes. These factors included delayed hatching within a season and early dormancy. The accuracy and utility of the model was tested using the soybean cyst nematode (SCN) rhg1-mediated resistance system. The model accurately predicted the rate at which virulence to the rhg1b resistance gene developed in Iowa over a two-decade period. The model suggested resistance gene pyramids as the most durable management solution for SCN with multiple possible avenues to obtain acceptable efficacy and durability.

The Bacterial Gq Signal Transduction Inhibitor FR900359 Impairs Soil-Associated Nematodes

The cyclic depsipeptide FR900359 (FR) is derived from the soil bacterium Chromobacterium vaccinii and known to bind Gq proteins of mammals and insects, thereby abolishing the signal transduction of their Gq protein-coupled receptors, a process that leads to severe physiological consequences. Due to their highly conserved structure, Gq family of proteins are a superior ecological target for FR producing organisms, resulting in a defense towards a broad range of harmful organisms. Here, we focus on the question whether bacteria like C. vaccinii are important factors in soil in that their secondary metabolites impair, e.g., plant harming organisms like nematodes. We prove that the Gq inhibitor FR is produced under soil-like conditions. Furthermore, FR inhibits heterologously expressed Gαq proteins of the nematodes Caenorhabditis elegans and Heterodera schachtii in the micromolar range. Additionally, in vivo experiments with C. elegans and the plant parasitic cyst nematode H. schachtii demonstrated that FR reduces locomotion of C. elegans and H. schachtii. Finally, egg-laying of C. elegans and hatching of juvenile stage 2 of H. schachtii from its cysts is inhibited by FR, suggesting that FR might reduce nematode dispersion and proliferation. This study supports the idea that C. vaccinii and its excreted metabolome in the soil might contribute to an ecological equilibrium, maintaining and establishing the successful growth of plants.

Two in vitro anthelmintic assays of four Paraguayan medicinal plants for proof of concept of the role of polyphenols in their biological activities and LC-HRMS analysis

ETHNOPHARMACOLOGICAL RELEVANCE

Gastrointestinal nematodes (GIN) control in small ruminants has relied on the systematic use of synthetic anthelmintics (AH), their effectiveness has been progressively decreasing due to the rise and diffusion of anthelmintic resistances. The most prevalent genera affecting small ruminants were Haemonchus spp., and Trichostrongylus spp. The investigation of new anthelmintics in plants is a highly studied option, especially when it is linked to ethnobotanical knowledge and phenolic compounds.

THE AIMS OF OUR STUDY

Four medicinal plants mentioned in traditional medicine were selected to evaluate their anthelmintic proprieties at different stages of the life cycle of GIN, namely: Kyllinga odorata Valh., Cassia occidentalis L., Artemisia absinthium L, and Verbena litoralis Kunth and to explore the role of polyphenols in the AH activity.

MATERIALS AND METHODS

To evaluate the anthelmintic activity in this study, two models of GIN species, namely Haemonchus contortus (Hc) and Trichostrongylus colubriformis (Tc) were selected and tested on two in vitro assays: 1) Larval Exsheathment Inhibition Assay (LEIA) and, 2) Egg Hatch Assay (EHA). To explore the role of tannins and polyphenols in AH activity by comparing the effects of LEIA and EHA with or without polyvinylpolypyrrolidone (PVPP) and to characterize the phytochemical composition of the most active plants using ultra-high performance liquid chromatography (UHPLC) coupled with high-resolution mass spectrometry (HRMS).

RESULTS

C. occidentalis exhibited the highest activity on LEIA (EC₅₀ = 250.42-41.80 μg/mL) and A. absinthium on egg hatching processes (EC₅₀ = 121.70-137.34 μg/mL) in both species of GIN. The inhibition in the development of eggs was from 67.70% to 96.36% on H. contortus, and from 78.87% to 99.65% on T. colubriformis. At the maximal dose, Additionally, it was observed that the AH on eggs varies according to the GIN species: on H. contortus the extracts tested blocked the formation of larvae Ovicidal Effect (% higher OE) and on T. colubriformis they blocked the appearance of L1 larvae, Larvae Failing Eclosion (% higher LFE). After PVPP, a reduction in AH activity on LEIA and EHA was noted, especially with C. occidentalis (87.20-67.00% of larvae exsheathment, (p < 0.05) and 40.51-24.96% of egg hatching, (p > 0.05) of both parasite species. Nine putative features were identified using HRMS and MS/MS after addition of PVPP.

CONCLUSIONS

The present study demonstrated that C. occidentalis, A. absinthium, and K. odorata, which parts have been traditionally used as medicinal plants are a valuable source of active compounds with anthelmintic activity. The medicinal use of these plants against GIN parasites was proven by in vitro analysis. Therefore exploration of the secondary metabolites of these plant extracts and testing of isolated fractions of active compounds under in vivo experiments are planned and represent a specific challenge for alternative drug research. Regarding the PVPP, in this study we hypotheses about the standard doses it was not able to completely absorb the polyphenols of extracts of K. odorata, C. occidentalis, and A. absinthium, which would lead to more studies to evaluate the role of this product in the absorption of phenolic compounds.

Demographic, environmental and physiological predictors of gastrointestinal parasites in urban raccoons

Raccoons are host to diverse gastrointestinal parasites, but little is known about the ecology of these parasites in terms of their interactions with each other during coinfections, their interactions with host physiology and environmental factors, and their impact on raccoon health and survival. As a first step, we investigated the patterns of parasite infection and their demographic distribution in an urban-suburban population of raccoons trapped in the summers and autumns of 2018 and 2019. We collected faecal samples, demographic data, morphometric measurements, and blood smears, and used GPS data to classify trapping location by land cover type. Faecal floats were performed to detect and quantify gastrointestinal nematode eggs and coccidia oocysts, and white blood cell differentials were performed on blood smears to characterise white blood cell distributions. Data were analysed cross-sectionally and, where possible, longitudinally, using generalised linear models. Overall, 62.6% of sampled raccoons were infected with gastrointestinal nematodes, and 82.2% were infected with gastrointestinal coccidia. We analysed predictors of infection status and faecal egg count for three different morphotypes of nematode-Baylisascaris, strongyle, and capillariid nematodes-and found that infection status and egg count varied with Year, Month, Age class, Land cover, and coinfection status, though the significance of these predictors varied between nematode types. Gastrointestinal coccidia prevalence varied with Year, Month, Age class, strongyle infection status, and capillariid infection status. Coccidia oocyst counts were lower in adults and in October, but higher in females and in raccoons trapped in areas with natural land cover; furthermore, coccidia oocysts were positively associated with capillariid faecal egg counts. We found no evidence that gastrointestinal parasites influenced raccoon body condition or overwinter mortality, and so conclude that raccoons, though harbouring diverse and abundant gastrointestinal parasites, may be relatively tolerant of these parasites.

Secondary metabolites related to the resistance of Psidium spp. against the nematode Meloidogyneenterolobii

The guava tree (Psidium guajava) is a tropical species native to South America and is recognized as the 11th most economically important fruit tree in Brazil. However, the presence of the nematode Meloidogyne enterolobii and the fungus Fusarium solani in the roots of guava plants leads to the development of root galls, causing significant damage. In contrast, the species P. guineense and P. cattleianum have been identified as resistant and immune to the nematode, respectively. In this study, the researchers aimed to compare the metabolomic profiles of infected and uninfected roots of P. guajava, P. cattleianum, and P. guineense using mass spectrometry coupled with liquid chromatography (LC-MS). The goal was to identify secondary metabolites that could potentially be utilized as biochemical resources for nematode control. The findings of the study demonstrated that the plant metabolism of all three species undergoes alterations in response to the phytopathogen inoculation. By employing molecular networks, the researchers identified that the secondary metabolites affected by the infection, whether produced or suppressed, are primarily of a polar chemical nature. Further analysis of the database confirmed the polar nature of the regulated substances after infection, specifically hydrolysable tannins and lignans in P. guineense and P. cattleianum. Interestingly, a group of non-polar substances belonging to the terpene class was also identified in the resistant and immune species. This suggests that these terpenes may act as inhibitors of M. enterolobii, working as repellents or as molecules that can reduce oxidative stress during the infection process, thus enhancing the guava resistance to the nematode. Overall, this study provides valuable insights into the metabolic alterations occurring in different Psidium spp. in response to M. enterolobii infection. The identification of specific secondary metabolites, particularly terpenes, opens up new possibilities for developing effective strategies to control the nematode and enhance guava resistance.

Soil nematode assemblages respond to interacting environmental changes

Multi-factor experiments suggest that interactions among environmental changes commonly influence biodiversity and community composition. However, most field experiments manipulate only single factors. Soil food webs are critical to ecosystem health and may be particularly sensitive to interactions among environmental changes that include soil warming, eutrophication, and altered precipitation. Here, we asked how environmental changes interacted to alter soil nematode communities in a northern Chihuahuan Desert grassland. Factorial manipulations of nitrogen, winter rainfall, and nighttime warming matched predictions for regional environmental change. Warming reduced nematode diversity by 25% and genus-level richness by 32%, but declines dissipated with additional winter rain, suggesting that warming effects occurred via drying. Interactions between precipitation and nitrogen also altered nematode community composition, but only weakly affected total nematode abundance, indicating that most change involved reordering of species abundances. Specifically, under ambient precipitation, nitrogen fertilizer reduced bacterivores by 68% and herbivores by 73%, but did not affect fungivores. In contrast, under winter rain addition, nitrogen fertilization increased bacterivores by 95%, did not affect herbivores, and doubled fungivore abundance. Rain can reduce soil nitrogen availability and increase turnover in the microbial loop, potentially promoting the recovery of nematode populations overwhelmed by nitrogen eutrophication. Nematode communities were not tightly coupled to plant community composition and may instead track microbes, including biocrusts or decomposers. Our results highlight the importance of interactions among environmental change stressors for shaping the composition and function of soil food webs in drylands.

Pattern and repeatability of ascarid-specific antigen excretion through chicken faeces, and the diagnostic accuracy of coproantigen measurements as compared with McMaster egg counts and plasma and egg yolk antibody measurements in laying hens

BACKGROUND

A coproantigen enzyme-linked immunosorbent assay (ELISA) has recently been proposed for detecting ascarid infections in chickens. The excretion pattern of ascarid antigens through chicken faeces and the consistency of measurements over the course of infections are currently unknown. This study evaluates the pattern and repeatability of worm antigen per gram of faeces (APG) and compares the diagnostic performance of the coproantigen ELISA with a plasma and egg yolk antibody ELISA and McMaster faecal egg counts (M-FEC) at different weeks post-infection (wpi).

METHODS

Faecal, blood and egg yolk samples were collected from laying hens that were orally infected with a mix of Ascaridia galli and Heterakis gallinarum eggs (N = 108) or kept as uninfected controls (N = 71). Measurements including (a) APG using a coproantigen ELISA, (b) eggs per gram of faeces (EPG) using the McMaster technique and (c) ascarid-specific IgY in plasma and in egg yolks using an ascarid-specific antibody ELISA) were performed between wpi 2 and 18.

RESULTS

Time-dependent significant differences in APG between infected and non-infected laying hens were quantified. At wpi 2 (t₍₁₆₄₎ = 0.66, P = 1.00) and 4 (t₍₁₆₄₎ = -3.09, P = 0.094) no significant differences were observed between the groups, whereas infected hens had significantly higher levels of APG than controls by wpi 6 (t₍₁₆₄₎ =  -6.74, P < 0.001). As indicated by a high overall repeatability estimate of 0.91 (CI = 0.89-0.93), APG could be measured consistently from the same individual. Compared to McMaster and antibody ELISA, coproantigen ELISA showed the highest overall diagnostic performance (area under curve, AUC = 0.93), although the differences were time-dependent. From wpi 6 to 18 coproantigen ELISA had an AUC > 0.95, while plasma IgY ELISA showed the highest diagnostic performance in wpi 2 (AUC = 0.95). M-FEC had the highest correlation with total worm burden, while APG had highest correlations with weights and lengths of A. galli.

CONCLUSION

Ascarid antigen excretion through chicken faeces can be measured with high accuracy and repeatability using a coproantigen ELISA. The antigen excretion increases over time, and is associated with worm maturation, particularly with the size of A. galli. Our results suggest the necessity of complementary use of different diagnostic tools for a more accurate diagnosis of infections.

Nematostatic activity of isoprenylated guanidine alkaloids from Pterogyne nitens and their interaction with acetylcholinesterase

Although new nematicides have appeared, the demand for new products less toxic and more efficient for the control of plant-parasitic nematodes are still high. Consequently, studies on natural secondary metabolites from plants, to develop new nematicides, have increased. In this work, nineteen extracts from eleven Brazilian plant species were screened for activity against Meloidogyne incognita. Among them, the extracts of Piterogyne nitens showed a potent nematostatic activity. The alkaloid fraction obtained from the ethanol extract of leaves of P. nitens was more active than the coming extract. Due to the promising activity from the alkaloid fraction, three isoprenylated guanidine alkaloids isolated from this fraction, galegine (1), pterogynidine (2), and pterogynine (3) were tested, showing similar activity to the alkaloid fraction, which was comparable to that of the positive control Temik at 250 μg/mL. At lower concentrations (125-50 μg/mL), compound 2 showed to be the most active one. As several nematicides act through inhibition of acetylcholinesterase (AChE), the guanidine alkaloids were also employed in two in vitro AChE assays. In both cases, compound 2 was more active than compounds 1 and 3. Its activity was considered moderated compared to the control (physostigmine). Compound 2 was selected for an in silico study with the electric eel (Electrophorus electricus) AChE, showing to bind mostly to the same site of physostigmine in the AChEs, pointing out that this could be the mechanism of action for this compound. These results suggested that the guanidine alkaloids 1,2 and 3 from P. nitens are promising for the development of new products to control M. incognita, especially guanidine 2, and encourage new investigations to confirm the mechanism of action, as well as to determine the structure-activity relationship of the guanidine alkaloids.

Nematode's morphometric shifts related to changing environmental conditions in the Mekong estuaries Ba Lai and Ham Luong, Vietnam

Damming has been reported to give many short-term benefits for local people but also to result in long-term negative impacts on the aquatic ecosystem. The ecological impact of the Ba Lai dam was studied by investigating environmental differences and the response of associated aquatic nematode communities (structure and morphometric characteristics) in both downstream and upstream sections of its estuary in comparison to an adjacent dam-free estuary Ham Luong, both belonging to the Mekong delta in Vietnam. Depleted dissolved oxygen, elevated methane and sulfide concentrations and increased accumulation of contaminants, including total suspended solid, heavy metals, and nutrients in the dammed estuary and its upstream section, indicated an impact of the dam on the environment. The dammed estuary showed differences in the nematode communities inhabiting the subtidal sediments from the reference estuary such as a higher nematode individual biomass with smaller length/width ratio as a consequence of the larger body width. The absence of long/thin nematodes in the dammed estuary, but high abundance of a slender nematode morphotype, a group with a higher efficiency of obtaining dissolved oxygen as a consequence of their comparatively large surface/volume ratio, might represent an adaptation of those communities to live in poor oxygen condition. In the dammed estuary, the small L/W ratio of nematode communities was potentially driven by the interaction effects of enrichment of both total suspended solid and ammonium linked to dissolved oxygen depletion. These findings support the potential use of nematode communities as bioindicators in ecological quality assessment although plausible; it is not possible to ascertain if only the dam causes the changes in the nematode communities.

First Report of Stunt Nematode, Tylenchorhynchus zeae, on Corn in Republic of Korea

Corn (Zea mays), one of the major food sources it contains rich in fiber and many vitamins, is one of the most widely consumed cereal grains in Republic of Korea. A survey of plant-parasitic nematodes (PPNs) was carried out in corn fields in Goesan, Republic of Korea from August in 2021. PPNs were extracted from the corn roots and soil using modified Baermann funnel methods and were identified using morphological and molecular analyses. Among the roots and soil samples of 21 fields, 5 fields (23.8%) were infected with stunt nematodes. Tylenchorhynchus zeae was originally described in India from soil around corn and is reported to dwarf plants, yellow leaves (Sethi and Swarup, 1968). Morphologically, characteristics of females were very similar to T. zeae with cylindrical body and slightly ventrally arcuated after fixation. Lip region slightly offset from body with four annuli. Stylet with anteriorly flattened knobs, the vulva was located in the center of the body, didelphic-amphidelphic reproductive system and tail conoid, tail terminus with obtuse smooth, with four incisures areolated throughout body. Bodies of males were similar to females but with shaper tails, with relatively strong bursa and spicules (Fig. S1). The morphology of Korean populations was in agreement with the described populations of India and China (Alvani et al., 2017; Xu et al., 2020). Measurements and micrographs with the light-microscope (DM5000; Leica[Germany]) and camera (DFC450; Leica[Germany]) were taken from females (n=10) for mean, standard deviation and range of body length: 553.2 ± 41.2 (492.7-643.6) µm, maximum body width: 19.4 ± 1.0 (17.6-21.0) µm, stylet length: 18.1 ± 0.4 (17.5-18.7) µm, percent of distance from anterior end to vulva / body length: 58.5 ± 1.3 (56.1-60.9), tail length: 31.7 ± 1.2 (30.3-34.0) µm, and distance of anterior to excretory pore: 96.5 ± 1.8 (94.1-99.4) µm. In addition, PCR was performed for the 28S rDNA D2-D3 segments using the primers D2A and D3B, and ITS region with the primers TW81 and AB28. The newly obtained sequences were submitted to GenBank database under accession numbers ON909086, ON909087 and ON909088 of 28S rDNA D2-D3 segments, and ON909123, ON909124 and ON909125 of ITS region. The resulting 28S rDNA D2-D3 segment sequences were 100% identical to KJ461565 and the BLASTn search of the ITS region sequences was most similar to T. zeae (KJ461599), which is the species isolated from corn in Spain. The identities of ITS region sequences on these populations were 99.89% (893/894), with no insertions/deletions. The phylogenetic relationships of the population strongly support T. zeae (Fig. S2). Phylogenetic relation analysis based on the two genes was constructed using PAUP version 4.0 and MrBayes 3.1.2 programs. To confirm pathogenicity, a modified version of Koch's postulates was conducted in the greenhouse by inoculating 100 females and males onto each of five pots of seedling corn (cv. Daehakchal) filled with the sterilized sandy soil and maintained for 60 days at 25℃ under the conditions. Tylenchorhynchus zeae reproduction factor was 2.21 ± 0.37 was observed at the end of the trial in soil on pots. The stunted and swollen roots and dwarfed and yellowing leaf shoots symptoms in the greenhouse pots trial were confirmed the same as those typical damage symptoms. To the best of our knowledge, this is the first report of T. zeae in Republic of Korea. The host range of T. zeae includes some economic crops such as cabbage, cauliflower, grapevine, and olive (Chen at al., 2007; Handoo et al., 2014). It is necessary to investigate the damage to economic crops in the Republic of Korea to this nematode.

Biochemical and physiological effects of multigenerational exposure to spheric polystyrene microplastics in Caenorhabditis elegans

Although studies have already shown the effects of exposure to microplastics (MP) in different species, the effects over generations in these individuals remain poorly understood. Therefore, the present study aimed to evaluate the effect of polystyrene MP (spherical, 1 μm) on the responses of the free-living nematode Caenorhabditis elegans in a multigenerational approach over five subsequent generations. MP concentrations of both 5 and 50 μg/L induced a detoxification response, increasing glutathione S-transferase (GST) activity and inducing the generation of reactive oxygen species (ROS) and lipid peroxidation (TBARS). MP also demonstrated the ability to accumulate in the animal's body during the 96 h of each generational exposure, and possibly, this constant interaction was the main reason for the decreased response in physiological parameters as in the exploratory behavior (body bending) of nematodes, and in the reproduction, being this last parameter most negatively affected during the five exposed generations, with a reduction of almost 50% in the last generation. These results emphasize the importance of multigenerational approaches, highlighting their advantage in the assessment of environmental contaminants.

Reproductive toxicity of enrofloxacin in Caenorhabditis elegans involves oxidative stress-induced cell apoptosis

Fluoroquinolone antibiotics (FQs) that persist and bioaccumulate in the environment have aroused people's great concern. Here, we studied the adverse effects of FQs in soil animals of Caenorhabditis elegans via food-chronically exposure. The result shows C. elegans exposed to FQs exhibited reproductive toxicity with small-brood size and low-egg hatchability. To study the underlying mechanism, we conduct a deep investigation of enrofloxacin (ENR), one of the most frequently detected FQs, on nematodes which is one of commonly used animal indicator of soil sustainability. The concentration-effect curves simulated by the Hill model showed that the half effect concentrations (EC₅₀) of ENR were (494.3 ± 272.9) µmol/kg and (107.4 ± 30.9) µmol/kg for the brood size and the hatchability, respectively. Differential gene expression between the control and the ENR-exposure group enriched with the oxidative stress and cell apoptosis pathways. The results together with the enzyme activity in oxidative stress and the cell corpses suggested that ENR-induced reproductive toxicity was related to germ cell apoptosis under oxidative stress. The risk quotients of some soil and livestock samples were calculated based on the threshold value of EC₁₀ for the egg hatchability (2.65 µmol/kg). The results indicated that there was possible reproductive toxicity on the nematodes in certain agricultural soils for the FQs. This study suggested that chronic exposure to FQs at certain levels in environment would induce reproductive toxicity to the nematodes and might reduce the soil sustainability, alarming the environment risks of antibiotics abuse.

Advancing the knowledge of the nematode Echinocephalus pseudouncinatus (Gnathostomatidae, Spirurida): morphological and molecular identification, new host, and host specificity in two coexisting pen shells (Bivalvia: Pinnidae)

The life cycle of Echinocephalus pseudouncinatus has not been described in detail to date, as is also the case of other species in the genus. This study contributes to the information available about the life history of the genus, particularly E. pseudouncinatus, by (1) using molecular techniques (small subunit rRNA gene [SSU rRNA] sequences) to identify larvae of this species; (2) describing the most conspicuous morphological characteristics that distinguish the species by scanning electron microscopy; (3) describing histological characteristics of the internal anatomy of larvae and the lesions caused by them in the gonads of hosts; (4) reporting new host and reporting evidence of host specificity of E. pseudouncinatus between two species of edible pen shells coexisting in the northern Pacific of Mexico; and (5) analyzing the frequency of infested gonads by host sex, size, and gonadal development stage. The molecular analysis confirmed the morphological and histological diagnosis of E. pseudouncinatus larvae infesting gonads of Atrina maura and Pinna rugosa in Ojo de Liebre and San Ignacio lagoons. The morphological characterization of larvae provides internal details of the cephalic bulb (including rows of hooks and ballonets), neural chord, and cell types of the body wall. Histopathological findings such as degenerated and atretic gametes and the displacement of gonadal tissue in hosts infested with E. pseudouncinatus larvae are discussed in terms of temperature anomalies caused by the "Godzilla El Niño." The frequency of infestation increased with shell length and gonadal development in A. maura, with a higher infestation frequency in females versus males observed at both study sites. Our findings expand the list of hosts of E. pseudouncinatus, which was previously unknown as a parasite of P. rugosa. In P. rugosa, infestation frequencies are noticeably lower (<1%) compared with those observed in A. maura (>30%) at both study sites, suggesting host-specific requirements or preferences in E. pseudouncinatus larvae.

Relationship between faecal egg count and health status in Nguni goats reared on semi-arid rangelands

Gastrointestinal parasitism is a major constraint to goat productivity, particularly in resource-limited production systems. The objective of the study was to determine the relationship between faecal egg count and the health status of different classes of Nguni goats. Body condition score (BCS), packed cell volume (PCV), FAMACHA score, and faecal egg count (FEC) were measured in 120 goats of different classes (weaners, does and bucks) across seasons. The identified gastrointestinal nematodes (GIN) were Strongyloides (30 %), Haemonchus contortus (28 %), Trichostrongylus sp. (23 %), Oesophagostomum sp. (17 %) and Ostertagia (2 %), which showed higher prevalence at the hot-wet season compared to other seasons. An interaction (P<0.05) between class and season on BCS was observed. Lower PCV were observed in weaners (24.6 ± 0.79) in the post-rainy season, whereas does 27.4 ± 0.86 and bucks (29.3±1.03) had the highest PCV in the same season. Higher FAMACHA scores were observed in the hot seasons for all goat classes, while lower in the cool-dry season. Linear relationships between FAMACHA scores and FEC were observed in all seasons. The rate of change in FAMACHA score was higher in the post-rainy season (P<0.01) than in other seasons as FEC increased in weaners and does. Bucks had a higher rate of change in FAMACHA in the hot-wet season (P<0.0001) as FEC increased. The rate of BCS decline was higher in the post-rainy season in weaners and does (P<0.01) and bucks (P<0.05) than in other seasons. The decline in PCV was faster during the wet than in the dry seasons. It can be concluded that class and season affected BCS, FAMACHA, and PCV. A linear relationship between FEC and FAMACHA score suggests that FAMACHA could be a good indicator of GIN burden.

First Report of the Root-Knot Nematode Meloidogyne luci on Tomato in Serbia

Root-knot nematode (RKN) Meloidogyne luci Carneiro, Correa, Almeida, Gomes, Deimi, Castagnone-Sereno, and Karssen, 2014 was described from Brazil, Chile and Iran, parasitizing in various crops (Carneiro et al. 2014). It was later also described from Slovenia, Italy, Greece, Portugal, Turkey and Guatemala (review in Gerič Stare et al. 2017). It is considered an extremely damaging pest as it has a wide host range and infects numerous higher plants, including monocotyledons and dicotyledons as well as herbaceous and woody plants. This species was included in the European Plant Protection Organisation Alert List of harmful organisms. In Europe, M. luci has been detected in both greenhouse and field agricultural production (review in Gerič Stare et al. 2017). Furthermore, M. luci has been shown to survive winter in the field under continental and sub-Mediterranean climatic conditions (Strajnar et al. 2011). In August 2021, an official survey for quarantine RKN in Serbia (Province Vojvodina) revealed in a greenhouse in the village of Lugovo (43043'32,562; 19008'55,168), near Sombor, yellowing, stunning and extensive root galls on tomato (Solanum lycopersicum L.) cultivar Diva F1 caused by an unknown Meloidogyne sp. (Fig. 1). As correct identification is essential for effective pest management program, the next step was to identify the nematode species. Morphological characterization performed on freshly isolated females revealed perineal patterns similar to M. incognita (Kofoid and White, 1919) Chitwood, 1949. The shape was oval to squarish with the dorsal arch rounded to moderately high and without shoulders. The dorsal striae were wavy and continuous. The ventral striae were smooth and the lateral lines were weakly demarcated. The perivulval region was without striae (Fig. 2). The female stylet was robust with well-developed knobs and the stylet cone slightly curved dorsally. Although morphological characters was very variable, the nematode was suspected as M. luci based on comparison with originally described M. luci and M. luci populations from Slovenia, Greece and Turkey. Identification was achieved with subsequent species-specific PCR and sequence analysis. The nematode was determined to belong to the tropical RKN group and the M. ethiopica group using two PCR reactions as described by Gerič Stare et al. (2019) (Figs. 3 and 4). Identification was confirmed by species-specific PCR of M. luci as described by Maleita et al. (2021), and a band of approximately 770 bp was obtained (Fig. 5). In addition, the identification was confirmed by sequence analyses. The region of mtDNA was amplified with primers C2F3 and 1108 (Powers and Harris 1993), cloned, sequenced (acc. no. OQ211107), and compared to other Meloidogyne spp. sequences from the Genbank. The determined sequence is 100% identical to an unidentified Meloidogyne sp. from Serbia, while the next highest scores are sequences of M. luci from Slovenia, Greece and Iran, all of which have 99.94% sequence identity. In phylogenetic tree, all M. luci sequences including the sequence from Serbia belong to a single clade. Egg masses isolated from infected tomato roots were used to establish a nematode culture in greenhouse and they caused typical root galls on cultivar Maraton of tomato. The galling index assessed 110 days-post-inoculation was in the range 4-5 according to the scoring scheme (1-10) for field evaluation of RKN infestations (Zeck 1971). To our knowledge, this is the first report of M. luci in Serbia. The authors hypothesize that climate change and higher temperatures could lead to much greater spread and damage to various agricultural crops in the field by M. luci in the future. National surveillance program for RKN in Serbia continued in 2022 and 2023. A management program to control the spread and damage from M. luci will be implemented in Serbia in 2023. Acknowledgments: This work was financially supported by the Serbian Plant Protection Directorate of MAFWM in the frame of Program of Measures in Plant Health in 2021, the Slovenian Research Agency in the frame of Research Programme Agrobiodiversity (P4-0072) and the Ministry of Agriculture, Forestry and Food of the Republic of Slovenia in the frame of Expert work in the field of plant protection (C2337).

First Report of Root-Knot Nematode (Meloidogyne incognita) on Dioscorea opposita in Henan Province, China

Dioscorea opposita is an annual twining plant in China that is used for consumption and medicinal purposes. The planting area of D. opposita is near 500,000 hectares in China, mainly in Shangdong, Hebei, Henan, Jiangxi and Yunnan provinces. In August 2021, we observed that some D. opposita plants grew poorly with smaller and chlorotic leaves in Changyuan (35°8'12"N; 114°43'52"E), Henan Province, China. Galls with hook-shaped roots and tuber damage were also observed, typical of root-knot nematode. Thirty tubers were randomly collected and 60% were infested with root-knot nematodes. During a disease survey in Changyuan, the incidences of root-knot nematode damage were 31.5%, 21%, and 18% in three fields (0.33, 0.67, and 4 ha, respectively) at harvest. The average tuber length of infected plants was decreased by 65.8%, and the average weight was decreased by 70.1% compared to the healthy plants. Males, females, second-stage juveniles (J2s), and eggs were extracted from individual diseased tubers from the three fields for morphological identification. Females were white, pear-shaped with a projecting neck. Males showed a trapezoidal labial region with prominent stylet knobs, including a high head cap which had a stepped outline and was centrally concave in lateral view. Morphological measurements are described in the supplementary material. All data and descriptions conformed to the morphological characteristics of Meloidogyne incognita. Genomic DNA was extracted from J2s (n=9) using PCR lysis buffer, and used for PCR amplification of the sequence characterized amplified region (SCAR) markers specific for M. incognita. Two pairs of the SCAR primers, Mi-F/Mi-R, and Inc-K14-F/Inc-K14-R, were used to diagnose whether these nematodes from D. opposita were M. incognita (Meng et al. 2004; Randig et al. 2002). The PCR produced expected amplification products of 955 and 399 bp, confirming the nematode to be M. incognita. Primers specific for M. arenaria (Far/Rar) and M. javanica (Fjav/Rjav) were used but failed to amplify fragments (Randig et al. 2002; Zijlstra et al. 2000). The obtained PCR fragments were sequenced and deposited in GenBank (accession no. OQ420602.1, OQ427638.1). They showed 99.9 and 100% identity to the available GenBank M. incognita sequence (accession no. MK410954.1, ON861825.1), respectively. A pathogenicity test was conducted in greenhouse conditions. Bulbils of D. opposita were sown in the pots filled with 2,000 ml of autoclaved soil mixture (loamy soil/sand, 1:1). One month later, 15 seedlings (five to six leaf stage) were inoculated with 1,000 M. incognita J2s individually. Five plants without nematode inoculation were used as the control. Two months after inoculation, all of the inoculated roots had galling symptoms similar to those observed in the field, and 100% of root system tissues had galls. The root gall index was ~6 according to a 0 to 10 RKN damage rating scale (Poudyal et al. 2005). No symptoms were found on the control plants. The nematodes were reisolated from root tissue and identified. M. incognita has a broad host range in many species of economic importance including Salvia miltiorrhiza (Wen et al. 2023), Ipomoea batatas (Maleita et al. 2022), and Zea mays (López-Robles et al. 2013). So far, M. incognita has been reported in D. alata and D. rotundata in Africa (Onkendi et al. 2014). To our best knowledge, this is the first record of M. incognita on D. opposita in Henan Province, China. With the increased planting area of D. opposita in China, root-knot nematodes are becoming more serious and reducing tuber production, with yield losses more than 60%. This identification is a preliminary step in developing effective disease management schemes. Declaration of interest The authors declare no conflict of interest. Funding This work was financially supported by the Key Scientific Research Projects of Higher Education Institutions of Henan Province (21A180013), China Agriculture Research System (CARS-21), The Zhongyuan high level talents special support plan-Science and Technology Innovation Leading Talents (224200510011) and Science and Technology Research Project of Henan Province (222102310211). References López-Robles, J., et al. 2013. Plant Dis. 97:694. https://doi.org/10.1094/PDIS-07-12-0674-PDN. Maleita, C., et al. 2022. Plant Dis. 106:2536. https://doi.org/10.1094/PDIS-12-21-2680-PDN. Meng, Q. P., et al. 2004. Acta Phytopathol. Sinica 34:204. https://doi.org/10.13926/j.cnki.apps.2004.03.003. Onkendi, E. M., et al. 2014. Plant Pathol. 63:727. https://doi.org/10.1111/ppa.12202. Poudyal, D. S., et al. 2005. Australas. Plant Pathol. 34:181. https://doi.org/10.1071/AP05011. Randig, O., et al. 2002. Genome 45:862. https://doi.org/10.1139/g02-054. Wen, Y., et al. 2023. Plant Dis. Accepted. https://doi.org/10.1094/PDIS-05-22-0997-PDN. Zijlstra, C., et al. 2000. Nematology 2:847. https://doi.org/10.1163/156854100750112798.

Meiosis-mediated reproductive toxicity by fenitrothion in Caenorhabditis elegans from metabolomic perspective

Fenitrothion (FNT), an organophosphorus insecticide, is widely detected in the living environment. The reproductive and endocrine toxicity of FNT to biological communities has been ever reported, but potential mechanism and reproductive toxicity dose effect remain unclear. In our study, we constructed Caenorhabditis elegans model to analyze the reproductive toxicity mechanism of FNT based on metabolomics and evaluated its reproductive toxicity dose effect using benchmark dose (BMD)method. Our results showed that FNT exposure significantly reduced brood size, number of germ cells, and delayed gonadal development in nematodes. Non-targeted metabolomics revealed that FNT exposure caused significant metabolic disturbances in nematodes, leading to a significant reduction in the synthesis of cortisol and melatonin, and the latter played a mediating role in the effects of FNT on number of germ cells. We further found that the levels of these two hormones were significantly negative correlated with the expression of the androgen receptor nhr-69 and affected the meiosis of germ cells by regulating the nhr-69/ fbf-1/2 /gld-3 /fog-1/3 pathway. Meanwhile, the study found the BMDL10s for N2 and him-5 mutant were 0.411 μg/L by number of germ cells and 0.396 μg/L by number of germ cells in the meiotic zone, respectively, providing a more protective reference dose for ecological risk assessment of FNT. This study suggested that FNT can affect androgen receptor expression by inhibiting cortisol and melatonin secretion, which further mediate the meiotic pathway to affect sperm formation and exert reproductive toxicity, and provides a basis for setting reproductive toxicity limits for FNT.

First Report of the Root-Lesion Nematode (Pratylenchus thornei Sher and Allen, 1953) Parasitizing Oats in Gansu Province, China

Oat (Avena sativa L.) is a vital cereal crop and serves as food, feed, and industrial material for many commercial growers. The presence of root-lesion nematodes (RLN; Pratylenchus spp.) in oat-cultivated areas of China is alarming because RLNs display an endo-migratory life cycle and rank third among the most damaging nematode pests (Jones et al. 2013). Their penetration and feeding cause necrotic lesions on the roots, which further dispose plants to other soilborne pathogens resulting in extensive root rots (LaMondia, 2003). In China, it has been reported that P. thornei harmed sugarcane and wheat. (Fang et al 1994; Fan et al. 2020), However, there are no reports on the damage of P. thornei to oat. In June 2021, a survey of one oat field, exhibiting poorly developed plants reduced till number and distinct lesions on roots was conducted in Dingxi city, Gansu province, China (N 35°56', E 104°60'). Thirteen soil and root samples were collected from symptomatic plants (cultivar: Jizhangyan No.5). Nematodes were extracted from root and soil samples using the modified Baermann funnel method (Hooper, 1986). Twelve samples tested positive for the presence of RLN with population densities ranging from 3 to 25 juveniles and females/100 g of soil and 2 to 32/g of root. No males were detected. Twenty females from the twelve positive samples were selected at random and examined morphologically for species-level identification (Figure 1A-J). The female bodies were slender, almost straight or ventrally curved after heat relaxation (Figure 1A), labial region continuous with the rest of the body and bears three faint lip annuli. The stylets were short and stout with well-developed basal knobs (Figure 1C, G). The pharyngeal and reproductive components were typical of pratylenchid nematodes (Figure 1B). Tail region cylindrical, straight or curved ventrally, having variable terminus viz., broad, bluntly rounded or truncate, with no striations around terminus (Figure 1H-J). The diagnostic morphometrics of adult females were as follows: body length 591.4 ± 20.1 μm (466.6 to 742.7 μm), body width 22.5 ± 0.5 μm (20.1 to 26.2 μm), distance from anterior end to excretory pore 88.4 ± 3.5 μm (75.7 to 99.7 μm), stylet length 16.8 ± 0.2 μm (15.2 to 18.7 μm), and tail length 33.7 ± 1.3 μm (25.5 to 43.2 μm). De man's morphometric parameters were a: 26.3 ± 0.8 (19.8 to 31.1), b: 5.7 ± 0.2 (4.7 to 7.0), c: 17.9 ± 0.8 (12.9 to 23.7), c': 2.3 ± 0.1 (1.7 to 2.8) and V value was 77.8 % ± 1.2 (67.3 to 86.6 %). The morphological and morphometric characteristics of our detected population is consistent with Loof's 1960 description of P. thornei Sher and Allen, 1953 (Table 1). For molecular analysis, five females from the twelve positive samples were selected at random for molecular analysis. DNA was extracted from single females according to the method of Wang et al. (2011). The ITS region was amplified by primer pair 18S/26S (Vrain et al., 1992) and the D2/D3 expansion region of the 28S rDNA was amplified by primer pair D2A/D3B (Castillo et al., 2003). High quality PCR products of accurate fragment length were sent to the Tsingke Biological Technology (Xian, China) for sequencing. The ITS sequences (813 bp-817 bp, GenBank OP902282, OP902284, OP902287, OP902288 and OP902289) of Gansu population showed 99.26%-100% sequence identity with P. thornei reported from Italy (FR692299, FR692303 and FR692304) (Figure 2). The 28S sequences (738 bp-764 bp, GenBank OM278343, OP217988, OP218403, OP218404 and OP218567) showed 100% identity with P. thornei populations reported from Belgium (KY828302), the USA (OK490327) and Iran (JX261960) (Figure 3). Morphological and molecular data of the Gansu population obtained in this study supported its identification as P. thornei. The endo-migratory association of the host-nematode relationship was confirmed by observing nematodes inside the roots using acid fuchsin root staining (Wu et al. 2014) (Figure 4). Oat (cultivar: Jizhangyan No.5) seeds were sown in pots containing 500 g of naturally infested soil (an average of 12 P. thornei /100g of soil); autoclaved soil was used as a control. Fifty seeds were directly sown in pots (20 × 16 cm), with three replicates. Plants were maintained in an incubator at 28 ± 1°C (12 h/12 h light/dark). Results indicated that plants inoculated obviously grew poorly with some lesions on roots and P. thornei numbers in them increased 16 times both in soil (50.7 ± 9.6 nematodes/100g) and roots (708.0 ± 8.7 nematodes in the entire root system). No P. thornei was found in the control soil and roots (Figure 5). Morphological and molecular characteristics of specimens isolated from oat symptomatic roots (n = 10) were identical to P. thornei. The losses caused by P. thornei are still unknown, and considering Pratylenchus spp. are commercially important nematode, the more investigations on oats should be made in the future. As of yet, RLNs were not reported from any oat-cultivated areas of China. To our knowledge, this is the first report of P. thornei parasitizing oats in the Gansu province of China.

Into the large ears: otitis externa associated with nematodes, mites, and bacteria in Asian elephants (Elephas maximus)

BACKGROUND

The Asian elephant (Elephas maximus), which is an endangered species, harbors several parasites. Among the ectoparasites that it harbors, ear mites of the genus Loxanoetus have the potential to cause external otitis, an inflammation that may also be associated with the presence of other microorganisms. We assessed the relationships between ear mites, nematodes, yeast, bacterial rods, and cocci sampled from the ears of captive Asian elephants in Thailand. In addition, we discuss the possibility that dust-bathing behavior may be triggered by ear mite infestation, and that this in turn may lead to contamination of the ears with soil microorganisms.

METHODS

Legally owned captive Asian elephants (n = 64) were sampled. Ear swabs were individually collected from both ears and microscopically examined for the presence of mites, nematodes, yeast, bacterial rods, cocci, and host cells. Mites and nematodes were identified to species level using morphological and molecular methods.

RESULTS

Loxanoetus lenae mites were present in 43.8% (n = 28/64) of the animals (19 animals with mites in one ear and nine animals with mites in both ears). Nematodes of the genus Panagrolaimus were detected in 23.4% (n = 15/64) of the animals (10 with nematodes in one ear and five with nematodes in both ears). In adult elephants (Fisher's exact test, P = 0.0278) and female elephants (Fisher's exact test, P = 0.0107), the presence of nematodes in both ears was significantly associated with the presence of mites. In addition, higher categorical burdens of nematodes were also significantly associated with the presence of mites (Fisher's exact test, P = 0.0234) and epithelial cells (Fisher's exact test, P = 0.0108), and marginally significantly associated with bacterial cocci (Fisher's exact test, P = 0.0499).

CONCLUSIONS

The presence of L. lenae mites in the ear canals of the Asian elephants was significantly associated with the occurrence of other microorganisms, such as soil nematodes, bacteria and yeasts. The presence of mites in their ears may increase the dust-bathing behavior of elephants which, if confirmed, represents a further paradigmatic example of a parasitic infestation affecting animal behavior.

Carbohydrate larval antigen (CarLA IgA) responses to mixed species nematode infection in pasture grazed Angora goats

The genetics of indicator traits for resistance of Angora goats to gastrointestinal nematode parasite infections, and their relationships with productivity traits, were investigated on a commercial mixed-enterprise farm in the eastern North Island of New Zealand. Faecal egg counts (FEC), specific Immunoglobulin A (IgA) and Immunoglobulin G (IgG) antibody titres against carbohydrate larval antigen (CarLA) in saliva, live weight and fleece weights were recorded from 278 goats of 19-20 months of age, run as four separate mobs (breeding bucks, castrated males (wethers), or 2 groups of breeding does). Summary statistics showed the mobs differed significantly in liveweight, log_e (FEC+50), log_e (IgA) and log_e (IgG). Genetic parameters were estimated using an animal model with repeated records where appropriate, after adjusting for the different contemporary animal groups, using the restricted maximum likelihood (REML) package. Heritability estimates from repeated measures were 0.19 ± 0.16 for FEC, 0.28 ± 0.16 for CarLA specific IgA and 0.23 ± 0.15 for CarLA specific IgG. The CarLA specific IgA response was negatively genetically correlated with FEC (-0.99 ± 0.31) suggesting that it could be used as a selection tool for breeding resistant animals. Although the genetic and phenotypic correlations between CarLA IgA and IgG were high and significant, the analysis between log_e (FEC+50) and log_e CarLA IgG did not converge. Further, both FEC and CarLA IgA showed significant and favourable genetic correlations with live weight. In contrast, CarLA IgG showed an unfavourable phenotypic correlation with liveweight. While this is only a preliminary study, the results do suggest that the immunoassay measuring salivary CarLA IgA response may have utility as a selection tool for parasite resistance in some breeds of goats.

Pratylenchus zeae a causative agent of Corn Root Rot in Jiangsu Province of China

Corn (Zea mays L.) plays an important role in China's cash crops, not only as food, but a vital raw material for animal husbandry and industry (Li et al. 2022). Pratylenchus zeae is one of the most damaging root-lesion nematodes (RLN) that can result in decreased yield and quality of crops (Liu et al. 2017). In September 2020, five root/soil samples were collected from the rhizosphere of corn (cv. Zhengdan 958), which had weak growth and root brown lesions in Chenzhou Village, Taolin Town, Donghai County, Lianyungang City, Jiangsu Province of China. Nematodes were extracted from the collected samples using the modified Baermann funnel method (Hooper et al. 2005). RLN were found in all samples, an average of 46 RLN per gram of root and 138 RLN per 100 cm3 of soil. The obtained RLN females were sterilized with 0.3% streptomycin sulfate and then inoculated on each carrot disks individually to obtain the purified population. RLN were examined by morphological and molecular characteristics to confirm the species indentification. The main morphological measurements of adult (n = 15) included body length = 524.7 μm (mean) ± 15.1 (standard deviation) (range = 490.7 to 543.6 μm), stylet = 15.2 μm ± 0.8 (14.2 to 16.8 μm), tail length = 30.3 μm ± 2.5 (26.3 to 35.3 μm), a = 25.6 ± 1.3 (24.4 to 29.3), b = 5.3 ± 0.3 (4.7 to 5.8), c = 17.4 ± 1.4 (14.9 to 19.3), two annules on the lip region. No males were found in the specimens. The morphological characters of this population are consistent with the description of P. zeae (Castillo and Vovlas, 2007). Furthermore, DNA was extracted from individual nematodes. The primers of TW81/AB28 and D2A/D3B (Subbotin et al. 2006) were used to amplified the rDNA-ITS region and rDNA 28S D2-D3 region, respectively. The purified PCR products were ligated into One step ZTOPO-Blunt/TA vector and transformed to Escherichia coli strain DH5α, and then sequenced by Sunya Biotechnology Co., Ltd (Henan, China). The obtained seqences were submitted to NCBI. The rDNA-ITS sequences (669 bp, GenBank Accession No: OP456372 and OP466367) exhibited 95.0% to 97.1% of identity with P. zeae sequences (KU198980 and KU198975). The obtained D2-D3 region of the 28S rDNA sequences (782 bp, OP441397 and OP448675) exhibited 99.7% to 100% identity with P. zeae sequences (EU130893 and KY424269). Consequently, both morphological and molecular data confirmed the identity of P. zeae. To further confirm reproduction on corn, single corn seeds (cv. Zhengdan 958) were sown in eight 2-liter pots filled with 1.8-liter of sterilized soil in greenhouse at 28°C. About 15 days after sowing, each pot with one corn plant with the same growth status was selected to inoculate with 1,000 mixed stage nematodes of P. zeae , Eight pots of uninoculated corn plants were used as controls. After 60 days, the inoculated plants were harvested and brown lesions were observed on roots. No symptoms and nematodes was detected in the control. An average number of RLN per pot was 3,752 in soil and 1,183 in roots were extracted, the reproduction factor (final population/initial population) was 4.94, indicating that P. zeae infects and reproduces well on this corn cultivar. P. zeae has only been reported on corn in Guangxi Province, southern in China(Fang et al. 1994). To our knowledge, this is the fist report of P. zeae infecting corn in Jiangsu Province, eastern in China. As P. zeae can cause great damage to corn, necessary measures should be taken to prevent the spread of P. zeae to other areas.

Intestinal roundworm infection in organic and alternative swine farms in the USA

Swine parasites are a challenge for organic and alternative pig farmers and represent suboptimal animal health because use of chemical prophylaxis is not recommended. There is no comprehensive study of how prevalent gastrointestinal parasites are in organic or alternative pig farms across the USA. This study investigates prevalence, abundance, and intensity measures for three intestinal roundworm parasites (Ascaris suum, Oesophagostomum spp. and Trichuris suis) on organic and alternative swine farms by quantifying their eggs in pig feces, pastured soil, and bedding. Nine farms raising pigs in bedded facilities across four states (Iowa, Minnesota, Pennsylvania, and Wisconsin) were sampled, and analysis of parasite egg counts from feces indicate that 88.9%, 55.5%, and 44.4% of farms were infected with A. suum, Oesophagostomum spp. and T. suis, respectively. Prevalence, mean abundance, and mean intensity of eggs per gram (EPG) in feces for A. suum and T. suis were higher in growing and finishing pigs, whereas they were higher for Oesophagostomum spp. in finishing pigs and sows. Prevalence and abundance with A. suum eggs in feces were higher in organic certified farms, whereas abundance of Oesophagostomum spp. and T. suis was lower than those in alternative farms. Fewer eggs were recovered from soils than bedding samples, but their presence in both substrates confirmed that dispersal stages occur in farms. Overall, our results indicate that intestinal parasite infection across organic and alternative swine farms in the USA is common, and not surprising given that few options to control infection within organic regulations are available.

Baseline Narcosis for the Glass-Vial 96-h Growth Inhibition of the Nematode C. elegans and Its Use for Identifying Electrophilic and Pro-Electrophilic Toxicity

The nematode Caenorhabditis elegans has been widely used as a model organism for assessing chemical toxicity. So far, however, a respective baseline narcosis reference has been lacking to predict narcosis-level toxicity and to identify excess-toxic compounds and associated mechanisms of action. Employing 22 organic narcotics that cover 7.2 units of their log K_ow (octanol/water partition coefficient) from -1.20 to 6.03, a baseline narcosis model has been derived for a glass-vial 96-h growth inhibition test with C. elegans, both without and with correction for compound loss through volatilization and sorption. The resultant effective concentrations yielding 50% growth inhibition, EC₅₀, vary by 6.4 log units from 5.04 · 10^-1 to 1.90 · 10^-7 mol/L (exposure-corrected). Application of the new model is illustrated through sensing the toxicity enhancement (T_e) of four Michael-acceptor carbonyls driven by their reactive mode of action. Moreover, narcosis-level predicted vs experimental EC₅₀ of two α,β-unsaturated alcohols demonstrate the biotransformation capability of C. elegans regarding ADH (alcohol dehydrogenase). The discussion includes narcosis-level and excess-toxicity doses (critical body burdens) as well as chemical activities A₅₀ (at the EC₅₀) as compared to fish, daphnids, ciliates, bacteria, zebrafish embryo, and cell lines. Overall, the presently introduced model for predicting C. elegans baseline narcosis enables generating respective pre-test expectations, enriches experimental results by mechanistic information, and may complement 3Rs (reduce, refine, replace) test batteries through its ADH metabolic capacity.