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The Pacific thread herring, Opisthonema libertate, is a fishery resource in the eastern tropical Pacific, yet its population dynamics are poorly understood. The aims of this work were to document the metazoan parasite species in O. libertate from the Gulf of California in Mexico, determine latitudinal changes in their infection levels, and assess their potential as biological tags. Six parasitic species were identified: Myosaccium ecaude and Parahemiurus merus digeneans, Cribromazocraes cf. travassosi and Mazocraeoides georgei monogeneans, Pseudoterranova sp. nematodes, and Lepeophtheirus sp. copepods. The monogenean and copepod species are reported for the first time in O. libertate. Many fish were infected with digeneans, and there was a rare occurrence of other parasites. While the prevalence and median intensity of M. ecaude and P. merus significantly varied among sampling localities, a multivariate analysis revealed a distinct separation between some localities; these results suggest that individual fish form several discrete populations. However, the utility of these parasites as biological tags will be further probed because they cannot satisfy all requirements for good biological tags. The present results might be helpful in complementing other techniques to determine the movement and stock structure of O. libertate, albeit with certain limitations.

Variable platyfish, Xiphophorus variatus (Meek, 1904) (Cyprinodontiformes: Poeciliidae) and eastern mosquitofish, Gambusia holbrooki Girard, 1859 (Poeciliidae) from earthen ponds in west central Florida were examined for parasitic infections. At necropsy, we observed myriad nematodes (adults and eggs), which we identified as Huffmanela cf. huffmani, infecting the swim bladder, gonad, and visceral peritoneum. Nucleotide sequences (small subunit ribosomal DNA, 18S) of H. cf. huffmani from variable platyfish and eastern mosquitofish were identical; likewise for newly obtained 18S sequences of Huffmanela huffmani Moravec, 1987 from the swim bladder of red breast sunfish, Lepomis auritus (Linnaeus, 1758) (Centrarchiformes: Centrarchidae) and warmouth, Lepomis gulosus (Cuvier, 1829) from the San Marcos River (type locality for Huffmanela huffmani Moravec, 1987), Texas. The sequences of H. huffmani and H. cf. huffmani differed by 7 (1%) nucleotides. Pathological changes comprised proliferation of the tunica externa of the swim bladder in low-intensity infections in addition to inflammation, proliferation, and tissue necrosis of swim bladder, peritoneum, and gonad in high-intensity infections. The lesion was severe, affecting the cellular constituents of the swim bladder wall and reducing the size of the swim bladder lumen; potentially reducing swim bladder physiological efficiency. The present study is the first record of a freshwater species of Huffmanela Moravec, 1987 from beyond the San Marcos River, first record of a species of Huffmanela from a livebearer, first nucleotide sequences and phylogenetic analysis for Huffmanela, and first evidence that an infection by a species of Huffmanela causes pathological changes that could impact organ function. [ABSTRACT FROM AUTHOR]

In the year 2012 a total of seven individuals (one bull and six cows) of European bison (Bison bonasus) were introduced to a fenced 200 ha area in a forest district (Almindingen, Island Bornholm, Denmark) in the Baltic Sea. In 2017 the herd was supplemented by introduction of another bull. The animals all originated from a population in the Polish Bialowieza forest. Faecal samples were recovered with intervals and subjected to a copro-parasitological investigation (applying egg flotation, sedimentation and Baermann technique). In addition, parasites were sampled during necropsy of animals euthanized or found dead three years after introduction. The animals carried a range of parasite types including trematodes (liver fluke Fasciola and rumen fluke), cestodes (Moniezia), nematodes (Dictyocaulus viviparus, trichurids , and other gastrointestinal nematodes (GIN) including Trichostrongylus axei and Haemonchus contortus). Egg and larval morphology also suggested presence of GIN genera Nematodirus, Ostertagia and Cooperia. The trematodes did not establish a life cycle in the recipient area, as judged by examination of calves born in the new area, but the cestode and several nematode species occurred in these animals. Especially Dictyocaulus viviparus was successfully spread and occurred together with GIN at moderate to high infection intensities at most sampling points. The reproduction among bison in the herd was high during the first few years. The exact birth rate is unknown but up to 24 calves are believed to be born during the ten year study period. Mortality among adults and calves occurred and in early June 2022 the total number of live animals was 11 (seven males, three females, one calf). The possible impact of the parasite infections on the bison health and future wildlife infection status is discussed. [Display omitted] • European bison used for translocation projects may carry parasites. • Translocated parasites species may establish in recipient regions. • Lungworm Dictyocaulus viviparus is persistent in European bison herds. • Gastrointestinal nematodes are spread with translocated bison. • Mortality in bison herds may be associated with high parasite burdens. [ABSTRACT FROM AUTHOR]

Phylogenetically or taxonomically related hosts may harbour similar parasite communities due to phylogenetic conservatism. In addition, host attributes may favour their exposure to parasites. This study aimed to characterize the helminth fauna of sigmodontine rodents in an Atlantic Forest area in northeastern Brazil and determine the pattern of the helminth metacommunity structure. The influence of host attributes and host taxonomy on the metacommunity structure was also investigated. The most abundant helminth species were Raillietina sp. and Hassalstrongylus lauroi. Euryoryzomys russatus was the most infected host species for helminth parasites, as approximately 81% (35/43) of the animals were infected by at least one helminth species. The helminth metacommunity structure was coherent at both the infracommunity and the component community scales, indicating that species responded to the same environmental gradient. A quasi-Clementsian pattern was observed for the infracommunities, indicating the occurrence of compartments of parasite species that were substituted along the environmental gradient, which was formed by host individuals. A quasi-Gleasonian pattern was found at the component community scale, showing random boundary clumping, which is consistent with the individualistic responses of parasite species to each host species. These patterns corroborated the high values of beta-diversity observed, indicating high species turnover among communities at both scales. Host taxonomic distance was the most important variable explaining the patterns of the helminth metacommunity structure. [Display omitted] • This is the first report of the helminth fauna of two sigmodontine rodents. • Rodent hosts had low levels of helminth species sharing among them. • Helminth species responded to the same environmental gradient in the metacommunity. • Helminths formed clusters that were replaced along their hosts at infracommunity scale. • Species showed random responses to one another at component community scale. [ABSTRACT FROM AUTHOR]

Zoo‐ and phyto‐parasitic nematodes of the order Rhabditida and zooparasites of the subclass Dorylaimia are well known, due largely to their medical, veterinarian and agricultural significance. However, there have been many switches from a free‐living to a symbiotic (including parasitism) mode of existence in the evolutionary trajectories of various nematode clades. Here, we attempt to summarize all known cases of symbioses (from commensalism to true parasitism) between marine nematodes representing nonparasitic taxa and various larger animals, ranging from protists to vertebrates. Most cases are of nematodes relating to dwelling on crustaceans (ectocommensalism) or living in the body cavity and internal organs of various invertebrates (endoparasitism or parasitoidism). Ectocommensal species may differ from their free‐living relatives in their longer filiform bodies and enlarged ventral and caudal glands, which may be interpreted as adaptations for the purpose of fixation on the body surface of a motile host. Endoparasitic species are characterized by deep anatomical modification, including rudimentation of the alimentary tract and hypertrophy of reproductive organs. Unlike terrestrial and limnetic invertebrates, marine invertebrates have almost no intestinal nematode dwellers. The evolutionary trajectories of nematode dwellers of marine and nonmarine invertebrates are compared. [ABSTRACT FROM AUTHOR]

The ecosystem formed by the marine flowering plant Posidonia oceanica is a biodiversity reservoir and provides many ecosystem services in coastal Mediterranean regions. Marine meiofauna is also a major component of that biodiversity, and its study can be useful in addressing both theoretical and applied questions in ecology, evolution, and conservation. We review the meiofaunal diversity in the meadow ecosystem of P. oceanica by combining a literature review and a case study. First, we gathered records of 672 species from 71 published studies, as well as unpublished sources, highlighting 4 species exclusive to this ecosystem. Eighteen of those studies quantified the spatial and temporal changes in species composition, highlighting habitat‐specific assemblages that fluctuate following the annual changes experienced by these meadows. Hydrodynamics, habitat complexity, and food availability, all three inherently linked to the seagrass phenology, are recognized in the literature as the main factors shaping the complex distribution patterns of meiofauna in the meadows. These drivers have been identified mainly in studies of Copepoda and Nematoda, and their effect may depend ultimately on species‐specific preferences. Second, we tested the generality of these observations using marine mites as a model group, showing that similar ecological preferences might be found in other less abundant meiofaunal groups. Overall, our study highlights the high diversity of meiofauna in meadows of P. oceanica compared with algae and sessile macrofauna associated with this seagrass and shows the complexity of the interactions and habitat use by meiofauna associated with the seagrass. [ABSTRACT FROM AUTHOR]

The intensification of dredging and infilling activities in lagoons and on coral reefs are common practices in the Maldivian archipelago, and these activities alter the biodiversity of the bioconstructors and the functioning of the ecosystem. The alteration of environmental factors can also affect inconspicuous fauna, such as free-living nematodes. The implications of a reduction in biodiversity may transcend decreased taxonomic diversity, resulting in changes in functional diversity and redundancy; however, how the environmental conditions and human pressure affects the functionality of nematodes in Maldivian coral degradation zones (CDZs) remain poorly understood. In this paper, we examined changes in the taxonomic and functional diversity and the functional redundancy in nematode communities regarding the geographic location (atolls with various levels of human pressure), the exposure and topography of the reef (lagoon and ocean), the slope of the reef, and the depth. The functional diversity and redundancy were evaluated by considering two main biological traits of nematodes: i) the trophic strategy, and ii) the life strategy. The extremely high number of nematode genera observed in the Maldives is supported by the high complexity of the carbonate sediments. The reef exposure and depth were the most relevant environmental factors that influenced the taxonomic and functional diversity. The functional diversity, according to the trophic strategies, mirrored the taxonomic diversity because the adaptive plasticity of nematode buccal cavity structures is closely associated with the high biodiversity of the phylum. The high abundance of k-strategists in ocean reefs may indicate a higher ecological quality when compared to lagoon reefs; however, the absence of significant differences in life strategy functional diversity and functional redundancy indicates that a recovery process is underway. Analyses of nematode communities should be combined with standard investigations of reef bioconstructors during monitoring activities to assess the vulnerability of CDZ systems to future disturbances and facilitate the adoption of the most appropriate preventative actions. [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbons (PAHs) are an important group of organic pollutants present in all parts of the environment, affecting ecosystems and human health. PAHs, which have a strong affinity for organic carbon, are found in large quantities in soil, which is one of the most important sinks for these contaminants. Their impact on the soil biotic compartments depends on a number of different factors in combination with PAH behaviour and can be assessed using soil monitoring. Soil fauna have already shown excellent properties for biomonitoring of contaminants with most promising indicator frameworks based on nematodes, which are involved in essential processes in this environment. Nematodes respond to PAHs at multiple levels, including molecular, individual and community levels. At the molecular level, this is associated with activation of metabolic pathways for xenobiotics and increased demand for energy and resources. At the individual level, this is reflected in the slowing down of various physiological processes, which has consequences at the individual and community level for sensitive taxa. In this review, the toxicity and the direct and indirect effects of PAHs on soil nematode communities are discussed. It also considers the perspectives and challenges in assessing the toxicity of PAHs and their indication using soil nematodes. [ABSTRACT FROM AUTHOR]

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Purpose: We aimed to describe the helminth fauna associated with two sympatric congeneric treefrogs species (Boana multifasciata and Boana raniceps) from a highland marsh in northeastern Brazil. In addition, we investigate the body size influence on parasitological descriptors in these treefrogs, in which we expected that larger frogs would have greater abundance and richness helminths too, and no differences with respect to helminth composition once both hosts are exposed to similar environmental conditions. Methods: We collected anurans during the rainy season from 11 January to 09 February 2019, using visual and auditory searches in breeding environments. We analysed the presence of ectoparasites under an epidermis, oral cavity, and endoparasites present in the organs. Using a Linear mixed-effects model we tested the relationship between the host body size (length and weight) and helminths abundance and richness. In addition, we used the ANOSIM R test to investigate the differences between the hosts with respect to helminth composition. Results: We recorded 37 individuals (15 specimens of B. multifasciata and 22 of B. raniceps), in which 89.1% of them were infected by at least one helminth species. We found 355 helminths from 12 taxa parasitizing the two treefrogs, but just three parasite taxa were common to both species. All identified helminth species found in B. multifasciata are new records and four are new records for B. raniceps. In addition, we present the first record of Cosmocerca paraguayensis in Brazil. We found no support for the hypothesis that larger frogs tend to be more parasitized, at least for congeneric species, and sympatric hosts species have similar helminth composition. We also present a compilation of helminths occurring in treefrogs belonging to the Boana genus in South American, increasing our knowledge of the parasitic diversity of Neotropical anurans. Conclusion: Our results suggest a lack of knowledge about helminth fauna associated with amphibians even for common and widely distributed species, such as Boana spp., and demonstrate the need to deepen our knowledge about host parasitic relationships, especially in the Neotropical region. [ABSTRACT FROM AUTHOR]

The predominant landscape of the Atlantic Forest of the Brazilian state of Rio de Janeiro is made up of forest fragments surrounded by a matrix of modified habitat, which may influence the occurrence and distribution of host species and their parasites in comparison with the original continuous forest. The present study describes the structure, composition, and diversity of the helminth community found in rodents in two areas of an open matrix of different status of conservation. The abundance, intensity, and prevalence were calculated for each helminth species in rodent species. The influence of biotic and abiotic factors on the abundance and prevalence of the helminth species was also investigated. Community structure was analyzed based on the beta diversity and a bipartite network. Nine helminth species were recovered from Akodon cursor, Necromys lasiurus and Mus musculus, with the greatest helminth species richness being recorded in A. cursor (S = 8), followed by N. lasiurus (S = 6), and M. musculus (S = 3). Only three of the helminths recorded in A. cursor had been recorded previously in this rodent in the Atlantic Forest, where 12 different helminths have been recorded, so that the other five are new occurrences for this rodent. All the helminth species of N. lasiurus had been reported previously in this rodent in the Cerrado and Caatinga regions. Mus musculus was infected with the same helminths as the local fauna. Host species and locality were the most important factors influencing helminth abundance and prevalence. Beta-diversity was high for infracommunities indicating more substitutions of helminth species than losses among individuals. Three helminths species were shared by the three host species. The reduced beta-diversity observed in the component communities was consistent with the overlap observed in the helminth fauna of the host species.

Abstract Background Nematodes are a widespread and diverse group comprising free-living and parasitic species, some of which have major detrimental effects on crops, animals, and human health. Genomic comparisons of nematodes may help reveal the genetic bases for the evolution of parasitic lifestyles. Fatty acid and retinol-binding proteins (FARs) are thought to be unique to nematodes and play essential roles in their development, reproduction, infection, and possibly parasitism through promoting the uptake, transport, and distribution of lipid and retinol. However, the evolution of FAR family proteins across the phylum Nematoda remains elusive. Results We report here the evolutionary relationship of the FAR gene family across nematodes. No FAR was found in Trichocephalida species and Romanomermis culicivorax from Clade I, and FAR could be found in species from Clades III, IV, and V. FAR proteins are conserved in Clade III species and separated into three clusters. Tandem duplications and high divergence events lead to variable richness and low homology of FARs in Steinernema of Clade IVa, Strongyloides of Clade IVb, and intestinal parasitic nematodes from Clades Vc and Ve. Moreover, different richness and sequence variations of FARs in pine wood, root-knot, stem, and cyst nematodes might be determined by reproduction mode or parasitism. However, murine lungworm Angiostrongylus and bovine lungworm Dictyocaulus viviparus from Clade Vd have only 3–4 orthologs of FAR. RNA-seq data showed that far genes, especially far-1 and far-2, were highly expressed in most nematodes. Angiostrongylus cantonensis FAR-1 and FAR-3 have low sequence homology and distinct ligand-binding properties, leading to differences in the cavity volume of proteins. These data indicate that FAR proteins diverged early and experienced low selective pressure to form genus-level diversity. The far genes are present in endophyte or root-colonized bacteria of Streptomyces, Kitasatospora sp., Bacillus subtilis, and Lysobacter, suggesting that bacterial far genes might be derived from plant-parasitic nematodes by horizontal gene transfer. Conclusions Data from these comparative analyses have provided insights into genus-level diversity of FAR proteins in the phylum Nematoda. FAR diversification provides a glimpse into the complicated evolution history across free-living and parasitic nematodes.

The production of environmentally friendly livestock products is currently receiving much attention, especially in the European Union. The problem of monitoring the quality and safety of meat and milk in modern conditions is relevant not only for Ukraine but also for the world community. The scientific substantiation of the methods of research on meat for sale subject to invasive diseases is especially important, as the product may pose risks to the consumer. One of the criteria for assessing the welfare of a herd is the prevalence of helminthiases in cattle. Ruminant parasitoses in Ukraine have always been and remain a separate, often significant, problem for veterinary specialists. Helminths have evolved to use a wide range of ecological niches. In this study, we tried to quantify the prevalence of helminthiases among ruminants (cattle, sheep and goats) in Ukraine. The relevant studies were searched for in the online databases. The meta-analysis included 15 publications from January 2015 to December 2020 which reported the spread of parasites in Ukraine. The research results show that the infestation of ruminants with gastrointestinal helminths on the territory of Ukraine is 56.7%. Egger’s regression test revealed no significant publication bias. During the period of pastured farming, stable parasitocenoses are formed in the body of ruminants. The parasitoses are caused by helminths (gastrointestinal strongyles, liver flukes, paramphistomas, dicrocelia). They are recorded in monoinvasions or mixed invasions. Ruminants, according to helminthological examination in different climatic zones, are constantly infested with trematodes. In Ukraine, the presence of three species of flukes has been confirmed in ruminants: Fasciola hepatica, Dicrocoelium dendriticum and Paramphistomum cervi. Parasitization by those species negatively affects the profitability of dairy farming. Trematodes cause significant economic losses: reduced milk productivity of cows, reduced live weight gain of young animals, negative impact on reproduction. At the same time, fascioliasis is socially significant and dangerous to humans. According to the analyzed literature sources, two types of cestodes have been registered in Ukraine: Moniezia benedeni and M. expansa. The epizootic situation regarding nematodes is just as fraught. That is the most numerous group of helminths, their fauna is represented by the following species: Strongyloides papillosus, Nematodirus spathiger, Bunostomum spp., Oesophagostomum radiatum, Haemonchus contortus, Toxocara vitulorum, Trichuris skrjabini, T. ovis and T. globulosa. It is proven that in cattle parasitocenoses are recorded more often than monoinvasions. The highest rates of prevalence of infection were observed when polyinvasion included gastrointestinal strongyles, namely from the order Strongylida. Strongyloides papillosus is the most common taxonomic representative, while Fasciola hepatica has the lowest prevalence of infection, especially in sheep. Updated data on helminthiasis will expand the screening strategy to maintain the health of farm ruminants and reduce economic losses.

In 2018, human anisakiasis caused by the ingestion of the skipjack tuna Katsuwonus pelamis occurred frequently in Japan. This may be attributable to a heavy infection of A. simplex (s.s.) in the host's muscle tissue. In this study, we investigate infection levels of anisakid L3 larvae in skipjack tuna captured in Japanese waters afterward (2019–2020) to contribute to predict and prevent the outbreak of human anisakiasis. A total of 476 larvae were detected from 78 out of 85 skipjack tuna captured at 14 stations of the Pacific and East China Sea. The present parasitological survey suggests that infection levels in 2019–2020 were low, comparing that in 2018; in total only seven larvae were found from the host's muscle tissue. The collected larvae were identified by molecular methods to Anisakis berlandi , A. pegreffii , A. simplex (s.s.), A. typica and Skrjabinisakis physeteris (s.l.). Not only larvae of A. simplex (s.s.) but also those of A. berlandi were found from the muscle tissue and thus the latter species may also be a causative agent of human anisakiasis. In addition, this study confirmed the geographic distribution pattern that A. simplex (s.s.) is abundant in the Pacific, while A. pegreffii is dominant in the East China Sea. Our results contribute to understanding the risk of food poisoning and stock delimitation of host animals. [Display omitted] • Anisakid larvae of Japanese skipjack tuna were investigated in 2019–2020. • A few larvae parasitized the host's muscle tissue investigated. • Not only Anisakis simplex (s.s.) but also A. berlandi was detected from the muscle tissue. [ABSTRACT FROM AUTHOR]

Entomopathogenic nematodes (EPNs) are insect parasites used as biological control agents. Free-living infective juveniles (IJs) of EPNs employ host-seeking behaviors to locate suitable hosts for infection. We found that EPNs can differentiate between naïve and infected hosts, and that host attractiveness changes over time in a species-specific manner. We used solid-phase microextraction and gas chromatography/mass spectrometry to identify volatile chemical cues that may relay information about a potential host's infection status and resource availability. Among the chemicals identified from the headspace of infected hosts, 3-Methyl-2-buten-1-ol (prenol) and 3-Hydroxy-2-butanone (AMC) were selected for further behavioral assays due to their temporal correlation with the behavioral changes of IJs towards the infected hosts. Both compounds were repulsive to IJs of Steinernema glaseri and S. riobrave in a dose-dependent manner when applied on an agar substrate. Furthermore, the repulsive effects of prenol were maintained when co-presented with the uninfected host odors, overriding attraction to uninfected hosts. Prenol was attractive to dauers of some free-living nematodes and insect larvae. These data suggest that host-associated chemical cues may have several implications in EPN biology, not only as signals for avoidance and dispersal of conspecifics, but also as attractants for new potential hosts.

The beet cyst nematode Heterodera schachtii causes major yield losses in sugar beet. Understanding the interaction between H. schachtii and its host plant is important for developing a sustainable management system. Nematode effectors play a crucial role in initializing and sustaining successful parasitism. In our study, we identified a gene (Hs-Tyr) encoding a tyrosinase functional domain (PF00264). We describe Hs-Tyr as a novel nematode effector. Hs-Tyr is localized in the nematode esophageal gland. Up-regulation of its expression coincided with the parasitic developmental stages of the nematode. Silencing Hs-Tyr by RNA interference made the treated nematodes less virulent. When RNAi-treated nematodes succeeded in infecting the plant, developing females and their associated syncytial nurse cells were significantly smaller than in control plants. Ectopically expressing the Hs-Tyr effector in Arabidopsis increased plant susceptibility to H. schachtii, but not to the root-knot nematode Meloidogyne incognita. Interestingly, Hs-Tyr in the plant promoted plant growth and changed the root architecture. Additionally, the expression of Hs-Tyr in Arabidopsis caused changes in the homeostasis of several plant hormones especially auxin and the ethylene precursor aminocyclopropane-carboxylic acid.

Wolbachia is an intracellular endosymbiont infecting most arthropod and some filarial nematode species that is vertically transmitted through the maternal lineage. Due to this primary mechanism of transmission, most studies have focused on Wolbachia interactions with the host germline. However, over the last decade many studies have emerged highlighting the prominence of Wolbachia in somatic tissues, implicating somatic tissue tropism as an important aspect of the life history of this endosymbiont. Here, we review our current understanding of Wolbachia-host interactions at both the cellular and organismal level, with a focus on Wolbachia in somatic tissues.

Over one billion people worldwide are infected with parasitic nematodes. Many parasitic nematodes actively search for hosts to infect using volatile chemical cues, so understanding the olfactory signals that drive host seeking may elucidate new pathways for preventing infections. The free-living nematode Caenorhabditis elegans is a powerful model for parasitic nematodes: because sensory neuroanatomy is conserved across nematode species, an understanding of the microcircuits that mediate olfaction in C. elegans may inform studies of olfaction in parasitic nematodes. Here we review circuit mechanisms that allow C. elegans to respond to odorants, gases, and pheromones. We also highlight work on the olfactory behaviors of parasitic nematodes that lays the groundwork for future studies of their olfactory microcircuits.

Abstract During a survey of the helminth fauna of characiform fishes from the Tocantins River, Brazil, 185 fish specimens from 22 species were studied. Twelve species of Nematoda and nine species of Digenea were collected. Some of these helminth species were reported for the first time in their hosts, thus representing new host records: Procamallanus (Spirocamallanus) sp. in Bivibranchia notata, Brycon pesu, Chalceus macrolepidotus, Hemiodus microlepis and Hemiodus unimaculatus; Procamallanus (Spirocamallanus) inopinatus in Triportheus elongatus; Goezia sp. (larva) in Boulengerella cuvieri; Rhabdochona acuminata in Brycon pesu and Triportheus trifurcatus; Raphidascaris sp. (larva) in Caenotropus labyrinthicus; Cosmoxynema vianai in Cyphocharax gouldingi; Rondonia rondoni in Leporinus fasciatus and Mylesinus paucisquamatus; Klossinemella iheringi in Mylesinus paucisquamatus; Cucullanidae gen. sp. in Myloplus rubripinnis; Rhabdochona sp. in Triportheus elongatus; Alphamphistoma sp. in Myleus setiger; Chalcinotrema sp. in Cyphocharax gouldingi; Pacudistoma guianense in Hemiodus unimaculatus and Myleus torquatus; Pseudocladorchis cylindricus in Hemiodus unimaculatus; Dadaytrema oxycephala in Mylesinus paucisquamatus; Travassosinia dilatata in Myloplus asterias; and Genarchella genarchella in Raphiodon vulpinus. Studies identifying new hosts and new localities for parasites have contributed to the knowledge of local biodiversity. A list of previous records of helminths included in the present study, providing hosts, localities, and references, is presented here.

Gastrointestinal parasitic worm infection is one of the most common disease agents found in Bali cattle. The large number of eggs found, indicates the prevalence of nematodiasis in a region. This study aims to calculate the prevalence and analyze the relationship of the degree of infection with risk factors for the incidence of gastrointestinal nematodiasis in Bali cattle in Kupang Regency. This study uses acrosssectional study with simple random sampling and the number of samples taken is 171 samples. Microscopic examination of faecal samples uses the McMaster method to identify gastrointestinal nematode eggs based on their type. Data analysis uses the Chi-Square test to determine the relationship ofthe significance of risk factors. Based on the results of research, Strongyle type nematodes have a prevalence value of 46.78%. Age and sex did not show an influence on infection risk.

The intensification of dredging and infilling activities in lagoons and on coral reefs are common practices in the Maldivian archipelago, and these activities alter the biodiversity of the bioconstructors and the functioning of the ecosystem. The alteration of environmental factors can also affect inconspicuous fauna, such as free-living nematodes. The implications of a reduction in biodiversity may transcend decreased taxonomic diversity, resulting in changes in functional diversity and redundancy; however, how the environmental conditions and human pressure affects the functionality of nematodes in Maldivian coral degradation zones (CDZs) remain poorly understood. In this paper, we examined changes in the taxonomic and functional diversity and the functional redundancy in nematode communities regarding the geographic location (atolls with various levels of human pressure), the exposure and topography of the reef (lagoon and ocean), the slope of the reef, and the depth. The functional diversity and redundancy were evaluated by considering two main biological traits of nematodes: i) the trophic strategy, and ii) the life strategy. The extremely high number of nematode genera observed in the Maldives is supported by the high complexity of the carbonate sediments. The reef exposure and depth were the most relevant environmental factors that influenced the taxonomic and functional diversity. The functional diversity, according to the trophic strategies, mirrored the taxonomic diversity because the adaptive plasticity of nematode buccal cavity structures is closely associated with the high biodiversity of the phylum. The high abundance of k-strategists in ocean reefs may indicate a higher ecological quality when compared to lagoon reefs; however, the absence of significant differences in life strategy functional diversity and functional redundancy indicates that a recovery process is underway. Analyses of nematode communities should be combined with standard investigations of reef bioconstructors during monitoring activities to assess the vulnerability of CDZ systems to future disturbances and facilitate the adoption of the most appropriate preventative actions.

Abstract Although the common opossum, Didelphis marsupialis (Didelphimorphia: Didelphidae) is a species widely distributed in South America, knowledge about their helminth parasites and helminth community structure is scarce. The aims of this study were to describe the species composition and analyze the structure of the helminth community of the common opossum in an area of the Amazonian Arc in northern Mato Grosso. The helminths were recovered, counted, and identified in 32 individuals. Overall, 10,198 specimens were categorized into 9 helminths taxa (seven nematodes, one cestode, and one acanthocephalan). The most abundant species were Aspidodera raillieti, Viannaia hamata, and Travassostrongylus orloffi. No statistically significant differences in helminth abundance and prevalence were observed between host sexes. However, young hosts had higher abundance and prevalence of Didelphonema longispiculata, whereas Oligacanthorhynchus microcephalus had higher abundance and prevalence in adult hosts. This was the first study to analyze the helminth fauna and helminth community structure of D. marsupialis in the Amazonian Arc. This is the first report of the presence of A. raillieti, D. longispiculata, T. orloffi, T. minuta, V. hamata, and O. microcephalus in the state of Mato Grosso, Brazil.

Trichuris vulpis and Toxocara canis are worldwide parasitic nematodes affecting dogs and mammals of the Canine family. Due to the special structure of the shells, the eggs of these geohelminths can maintain their viability in soil, sand, water and the environment for a long time. The study involved young (6–12 months old) and adult (1.5–8.0 years old) dogs affected by co-infection of T. vulpis + T. canis; the control group consisted of dewormed healthy animals of the same age. Parasitological examination of dogs' faeces was performed using a "Counting Chamber for Ovoscopic Researches"; morphological parameters, indicators of nutrient metabolism, mineral metabolism and activity of enzymatic systems were determined in blood and serum. According to the results of parasitological research on the dogs, it was found that young animals are more prone to toxocarosis, and adults – trichurosis. The co-infection of nematodes T. vulpis + T. canis in dogs develops several changes in haematological parameters: a significant decrease in erythrocytes, haemoglobin, MCV, MCH, and haematocrit, leukocytosis with basophils and eosinophilia in young infected animals; and eosinophilia and basophilia (15.9 times) in adults, compared with healthy dogs of the same age. Among the changes in serum biochemical parameters, young infected dogs showed a decrease in the concentration of total protein and albumin content, an increase in the content of "acute phase" proteins (α-1, α-2 and β-globulins), an increase in cholesterol and total bilirubin; in adult infected dogs, a decrease in albumin content, an increase in the content of α-1, α-2, and β-globulins, an increase in the concentration of cholesterol and total bilirubin, a decrease in the concentration of urea in comparison with healthy animals were determined. Also, among the indicators of mineral metabolism, a decrease in the concentration of calcium and magnesium in the serum was found in young infected dogs. Among the changes in the enzyme metabolism in the serum of infected dogs, there was an increase in the activity of all studied enzymes in animals of both research groups: ALT, AST, α-amylase, GGT and ALP. Thus, co-infection with nematodes T. vulpis + T. canis has a complex pathogenic effect on the body of dogs of all ages, which manifested itself in multiple changes in haematological parameters. In the future, the authors’ team plan to develop comprehensive measures to combat nematode infections in different living conditions of dogs, taking into account the results of the current research.

Introduction: Strongyloides venezuelensis is a nematode whose natural host is rats. It is used as a model for the investigation of human strongyloidiasis caused by S. stercoralis. The latter is a neglected tropical disease in Ecuador where there are no specific plans to mitigate this parasitic illness. Objective: To evaluate the stages of S. venezuelensis in an experimental life cycle using Wistar rats. Materials and methods: Male Wistar rats were used to replicate the natural biological cycle of S. venezuelensis and describe its morphometric characteristics, as well as its parasitic development. Furthermore, the production of eggs per gram of feces was quantified using two diagnostic techniques and assessment of parasite load: Kato-Katz and qPCR. Results: Viable larval stages (L1, L2, L3) could be obtained up to 96 hours through fecal culture. Parthenogenetic females were established in the duodenum on the fifth day postinfection. Fertile eggs were observed in the intestinal tissue and fresh feces where the production peak occurred on the 8th. day post-infection. Unlike Kato-Katz, qPCR detected parasitic DNA on days not typically reported. Conclusions: The larval migration of S. venezuelensis within the murine host in an experimental environment was equivalent to that described in its natural biological cycle. The Kato-Katz quantitative technique showed to be quick and low-cost, but the qPCR had greater diagnostic precision. This experimental life cycle can be used as a tool for the study of strongyloidiasis or other similar nematodiasis.

Abstract As social insects, ants represent extremely interaction-rich biological systems shaped by tightly integrated social structures and constant mutual exchange with a multitude of internal and external environmental factors. Due to this high level of ecological interconnection, ant colonies can harbour a diverse array of parasites and pathogens, many of which are known to interfere with the delicate processes of ontogeny and caste differentiation and induce phenotypic changes in their hosts. Despite their often striking nature, parasite-induced changes to host development and morphology have hitherto been largely overlooked in the context of ecological evolutionary developmental biology (EcoEvoDevo). Parasitogenic morphologies in ants can, however, serve as “natural experiments” that may shed light on mechanisms and pathways relevant to host development, plasticity or robustness under environmental perturbations, colony-level effects and caste evolution. By assessing case studies of parasites causing morphological changes in their ant hosts, from the eighteenth century to current research, this review article presents a first overview of relevant host and parasite taxa. Hypotheses about the underlying developmental and evolutionary mechanisms, and open questions for further research are discussed. This will contribute towards highlighting the importance of parasites of social insects for both biological theory and empirical research and facilitate future interdisciplinary work at the interface of myrmecology, parasitology, and the EcoEvoDevo framework.

Objective:This study aimed to evaluate the efficacy of eprinomectin, moxidectin and fenbendazole for treating Dentostomella translucida infections in naturally infected Mongolian gerbils (Meriones unguiculatus).Methods:A total of 28 gerbils were placed in individually numbered cages to determine the individual animal parasite load. Eggs per gram (EPG) counts were used to estimate the efficacy of the drugs. The day before the anthelmintic administration was denoted as day 0, and the EPG counts were determined by the McMaster technique from the stool removed from the cage bottom on days 7, 14, 21 and 28. The animals were assigned to one of four treatment groups according to their day 0 EPG counts. The orally administered drugs in the treatment groups were eprinomectin (15 mg/kg), moxidectin (0.4 mg/kg) and fenbendazole (12 mg/kg) for groups 1-3, respectively. The fourth group served as the control (without any drug administration).Results:Treatment efficacy was evaluated based on weekly EPG counts. The values decreased to zero in the fenbendazole group at 4 weeks of follow-up after treatment, and no parasite was found in any of the repeated examinations. The eprinomectin and moxidectin groups exhibited a fluctuating EPG state on both individual and group basis.Conclusion:D. translucida, which is known as the specific parasite of gerbils, can easily affect other members of the animal colony; thus, the control of its presence in gerbil breeding units is necessary. Therefore, the reported effective drug treatments are important for the fight against the investigated parasitic infection.

Abstract Background Nematodes of the family Cosmocercidae (Ascaridomorpha: Cosmocercoidea) are mainly parasitic in the digestive tract of various amphibians and reptiles worldwide. However, our knowledge of the molecular phylogeny of the Cosmocercidae is still far from comprehensive. The phylogenetic relationships between Cosmocercidae and the other two families, Atractidae and Kathlaniidae, in the superfamily Cosmocercoidea are still under debate. Moreover, the systematic position of some genera within Cosmocercidae remains unclear. Methods Nematodes collected from Polypedates megacephalus (Hallowell) (Anura: Rhacophoridae) were identified using morphological (light and scanning electron microscopy) and molecular methods [sequencing the small ribosomal DNA (18S), internal transcribed spacer 1 (ITS-1), large ribosomal DNA (28S) and mitochondrial cytochrome c oxidase subunit 1 (cox1) target regions]. Phylogenetic analyses of cosmocercoid nematodes using 18S + 28S sequence data were performed to clarify the phylogenetic relationships of the Cosmocercidae, Atractidae and Kathlaniidae in the Cosmocercoidea and the systematic position of the genus Aplectana in Cosmocercidae. Results Morphological and genetic evidence supported the hypothesis that the nematode specimens collected from P. megacephalus represent a new species of Aplectana (Cosmocercoidea: Cosmocercidae). Our phylogenetic results revealed that the Cosmocercidae is a monophyletic group, but not the basal group in Cosmocercoidea as in the traditional classification. The Kathlaniidae is a paraphyletic group because the subfamily Cruziinae within Kathlaniidae (including only the genus Cruzia) formed a seperate lineage. Phylogenetic analyses also showed that the genus Aplectana has a closer relationship to the genus Cosmocerca in Cosmocercidae. Conclusions Our phylogenetic results suggested that the subfamily Cruziinae should be moved from the hitherto-defined family Kathlaniidae and elevated as a separate family, and the genus Cosmocerca is closely related to the genus Aplectana in the family Cosmocercidae. The present study provided a basic molecular phylogenetic framework for the superfamily Cosmocercoidea based on 18S + 28S sequence data for the first time to our knowledge. Moreover, a new species, A. xishuangbannaensis n. sp., was described using integrative approach. Graphical abstract

With over 300 terrestrial and aquatic mammalian species, Iran is considered a country with an ample mastofauna. Although many studies have assessed the distribution of gastrointestinal helminth parasites in animals and humans in Iran, lungworms have not received adequate attention. Following a previous article in which we reviewed the diversity and prevalence of lungworm infections in pastoral and wild ruminants of Iran, this report compiles the available scientific information about the occurrence of lungworms in non-ruminant mammals and humans from 1980 to 2022 to provide insights into the epidemiology of these infections. International and national scientific databases were searched, and twenty-six articles in peer-reviewed journals, one conference paper, and one D.V.M. thesis were included in the study. In total, 10 species belonging to seven genera, including Dictyocaulus, Deraiophoronema, Protostrongylus, Crenosoma, Eucoleus, Aelurostrongylus, and Metastrongylus, were reported in the respiratory tract or feces of humans, domestic animals (i.e., camels, equids, dogs, and cats), and wildlife species (i.e., hedgehogs, wild boars, and hares). Most of the studies (22/28) were performed using post-mortem examinations. The overall prevalence of respiratory nematode infection varied according to animal species in camels (14.83%), equids (13.31%), dogs (5%), wild boars (45.66%), hedgehogs (42.57%), and hares (1.6%). In addition, pulmonary capillariasis caused by Eucoleus aerophilus was reported in a 9 year old child. The prevalence of lungworm species in domestic camels, equids, and dogs, combined with a lack of labeled anthelmintic products, supports the need to improve our understanding of these important nematode parasites and inform the development of sustainable control strategies. From a zoo and wildlife medicine point of view, there is a shortage of information about the presence and prevalence of lungworm infections in the majority of mammalian species, pending epidemiological studies that integrate classical parasitology and molecular methods.

A new spirurid nematode, Protospirura canariensis n. sp., a parasite of the black rat Rattus rattus Linnaeus, 1758 (Rodentia: Muridae), in El Hierro Island (Canary Archipelago, Spain), was described by means of light (LM) and scanning electron microscopy (SEM). The most discriminating characteristics between the new species and the remaining species of the genus Protospirura were observed to be the following: (a) the number of tooth-like outgrowths in the sub-median and lateral lobes of the pseudolabia, both in males and females (2 and 4, respectively); (b) the size of the right and left spicules in males (643–715 µm and 309–412 µm, respectively); and (c) the numbers and arrangements of the cloacal papillae in males. The new species has a total of 17 cloacal papillae (4 large and pedunculated pairs of precloacal papillae, an unpaired precloacal papilla and 4 pairs of postcloacal papillae). The arrangement of the postcloacal papillae are as follows: the first pair are large, pedunculated and placed near the posterior edge of cloaca; the three remaining postcloacal pairs are grouped and located near the posterior tip. In the latter group, the papillae in the first pair are large and pedunculated. The parasitized hosts and their geographical distributions were also useful criteria in distinguishing P. canariensis n. sp. from the remaining species of the genus Protospirura. In addition, the cytochrome c oxidase subunit I (cox1) sequence of the new species was obtained and compared with the available data of related species.

Nutria (or coypu, Myocastor coypus), is a semi-aquatic rodent that is native to South America and has been introduced almost all over the world since the end of the 19th century. In Europe, this rodent is considered an invasive species. In this report, we analyzed nutria fecal samples in a small coastal wetland of Central Italy, using different techniques (fresh smear, direct immunofluorescence, Baermann technique, flotation, ethyl acetate sedimentation) to obtain an arrangement of eukaryote endoparasites (Protozoa and Helminths) and compare them with data available in the literature for both Italy and worldwide. We recorded five taxa, with a dominant occurrence (>70%) of nematodes of the genus Strongyloides. Moreover, we reported for the first time in nutria a bronchopulmonary strongyle nematode (Muellerius vel. Angiostrongylus) and, for the first time in Italy, protozoans of the genus Cryptosporidium. Since nutria co-occurs with humans and domestic animals in the study area, we highlighted possible sanitary and management implications.

Background: A central question in parasitology is why parasites mature and reproduce in some host species but not in others. Yet, a better understanding of the inability of parasites to complete their life cycles in less suitable hosts may hold clues for their control. To shed light on the molecular basis of parasite (non-)maturation, we analyzed transcriptomes of thorny-headed worms (Acanthocephala: Pomphorhynchus laevis), and compared developmentally arrested worms excised from European eel (Anguilla anguilla) to developmentally unrestricted worms from barbel (Barbus barbus). Results: Based on 20 RNA-Seq datasets, we demonstrate that transcriptomic profiles are more similar between P. laevis males and females from eel than between their counterparts from barbel. Impairment of sexual phenotype development was reflected in gene ontology enrichment analyses of genes having differential transcript abundances. Genes having reproduction- and energy-related annotations were found to be affected by parasitizing either eel or barbel. According to this, the molecular machinery of male and female acanthocephalans from the eel is less tailored to reproduction and more to coping with the less suitable environment provided by this host. The pattern was reversed in their counterparts from the definitive host, barbel. Conclusions: Comparative analysis of transcriptomes of developmentally arrested and reproducing parasites elucidates the challenges parasites encounter in hosts which are unsuitable for maturation and reproduction. By studying a gonochoric species, we were also able to highlight sex-specific traits. In fact, transcriptomic evidence for energy shortage in female acanthocephalans associates with their larger body size. Thus, energy metabolism and glycolysis should be promising targets for the treatment of acanthocephaliasis. Although inherently enabling a higher resolution in heterosexuals, the comparison of parasites from definitive hosts and less suitable hosts, in which the parasites merely survive, should be applicable to hermaphroditic helminths. This may open new perspectives in the control of other helminth pathogens of humans and livestock. [ABSTRACT FROM AUTHOR]

Three new species of free-living nematodes were discovered in the central basin of the South China Sea and are described here as Elzalia longicaudata sp. nov., Minolaimus distalamphidus sp. nov. and Setoplectus minor sp. nov. Elzalia longicaudata sp. nov. is characterised by a longer tail and longer buccal cavity relative to other members of the genus; presence of a circle of four cervical setae; spicules slender and long, which curve as the body bends; and simple gubernaculum with only one section of dorsal apophysis. Minolaimus distalamphidus sp. nov. can be distinguished from congeners by the male having lateral differentiation with six longitudinal rows of large dots; multispiral amphideal fovea with 8.5 turns; pharynx cylindrical without bulb; spicules slightly arcuate; gubernaculum rod-like without apophysis; about 17 sucker-shaped precloacal supplements; and tail conical with long filiform posterior portion. Setoplectus minor sp. nov. differs from its congeners by small body size, anterior third of pharyngeal region attenuated; cephalic setae 2 µm long; amphidial aperture circular or oval; tail elongated conical; male with a single papilliform precloacal supplement. Updated identification keys for species of the three genera are also given. [ABSTRACT FROM AUTHOR]

The current study was designed for analysis of the pattern of the nucleotide sequence of the tissue DNA isolates based on the ITS2,28SrDNA gene by the traditional polymerase chain reaction. All amplicons were well suited for the prepared primer with size 873 bp . and identical ratio ranged 87.2- 98% of the same species, as included a high similarity of the isolates taken camels in Iran and Iraq related to Parabronema skrjabini . Phylogenic tree inferred the degree of relatedness between 28SrDNA sequences deposited in the international nucleotide bank sequence database (NCBI). The sequence of Parabronema skrjabini was recorded in the Genbank under accession number MT742154.1. [ABSTRACT FROM AUTHOR]

Soil invertebrates are members of terrestrial ecosystems, contributing to the processing of organic matter, resulting in carbon and nutrient cycling that is essential for continuous productivity. By linking species delineations, morphological traits and measured or inferred functional roles, we demonstrate a method for functional identification of soil faunal assemblages based on molecular information. Here we align the genetic inter‐relatedness and functional trait expression in nematodes and springtails. Nematodes were assigned feeding guild, plant parasitic feeding type and coloniser‐persister (c‐p) value, with springtail sequences assigned to soil vertical stratification level, soil moisture preference and a selection of morphological traits. We found that both nematode and springtail feeding preferences show significant phylogenetic clustering. In contrast, greater dispersal was found amongst nematode coloniser‐persister (c‐p) values and springtail soil vertical stratification level and moisture preferences. Minimum patristic (p) distances between species supported the clustering amongst nematode feeding guilds, with plant feeders being separated from all other guilds by at least p = 0.99. Distances between endoparasitic, ectoparasitic and sedentary plant parasitic nematodes were also distinct with minimal distances of p = 0.35–0.72 between parasitic types. Springtail stratification level and soil moisture preferences showed greater dispersion across phylogenies, with negligible between‐group minimum patristic distances. However, nematode c‐p values and springtail moisture preference alignments indicate some genetic conservation at the genus level. These results indicate how ecosystems can direct trait conservation beyond that of environmental stimuli. Being able to assign functional traits to novel sequences will allow individual species' likely contribution to ecosystem functioning to be inferred without the need for exact taxonomic identification. More broadly, such information can advance our understanding of the evolution of soil faunal traits and the contribution of diverse soil assemblages to functional soil systems, particularly those with a high proportion of undescribed species. [ABSTRACT FROM AUTHOR]