Parasite Communities Research Articles

The prevalence of gastrointestinal nematodes in sheep (Ovisaries) in the central and south-eastern regions of Ukraine

The article investigates into the species composition of agents causing gastrointestinal tract nematodes in sheep. It determines the forms of nematodes communities. For this purpose, 710 sheep were examined, 79.58% of which were infected. The fauna of nematodes was represented by 15 species of helminths from 12 genera: Bunostomum, Oesophagostomum, Nematodirus, Chabertia, Cooperia, Trichostrongylus, Ostertagia, Haemonchus, Тrichuris, Aonchotheca, Strongyloides, and Skrjabinema. The indicators of infestation intensity in sheep ranged from 1 to 93 specimens per animal, and the abundance index ranged from 0.01 to 16.96 specimens per animal. The most common nematodes are H. contortus (prevalence, 61.97%), O. circumcincta (59.58%), T. colubriformis (57.35%), Т. оvis (55.21%), N. spathiger (49.01%), Oe. venulosum (42.54%), S. ovis (41.13%), Ch. оvina (36.76%), and T. skrjabini (26.34%). Gastrointestinal nematodes in the body of 99.12% of the infected sheep proceeded as parasitic communities. Most frequently, coinvasions were represented by parasitic communities which consisted of five (prevalence, 14.51%), six (19.44%), or seven (15.92%) species. The study revealed 361 varieties of mixed coinvasions. The most frequent comembers were H. contortus, O. circumcincta, T. colubriformis, Т. оvis, N. spathiger, S. ovis, and Ch. оvina. The data obtained provide an opportunity to increase the effectiveness of measures to combat and prevent gastrointestinal tract nematodes in sheep farms.

Comparative analysis of the helminth fauna of Dasypus hybridus and Chaetophractus villosus (Xenarthra: Cingulata) in the Pampas region, Argentina

Abstract Chaetophractus villosus and Dasypus hybridus are the most widespread and abundant armadillos inhabiting the Pampas grasslands. Studies on the parasitic fauna from an ecological perspective are scarce in both species. We describe and compare the component communities of C. villosus and D. hybridus in the Pampas ecoregion of Argentina and analyse if the composition and structure of the parasitic communities of these host species reveal trophic behaviour and/or habitat use. In the population of C. villosus 10 species of helminths were found, namely Ancylostoma caninum, Aspidodera fasciata, Aspidodera scoleciformis, Mazzia bialata, Moennigia celinae, Orihelia anticlava, Strongyloides sp., Trichohelix tuberculata (Nematoda) and Mathevotaenia sp. (Cestoda), whereas in the population of D. hybridus four species were found, A. fasciata, Delicata abbai, Pterygodermatites chaetophracti and Strongyloides sp. Only A. fasciata and Strongyloides sp. were present in both species. Prevalences and intensities were similar in Strongyloides sp. In A. fasciata, however, there were differences regarding mean intensity. Diversity was higher in C. villosus than in D. hybridus. The differences may be related to the diet, behaviour, evolutionary histories or immune response of the species studied. A combination of several of these factors would possibly influence the composition of their parasitic fauna.

Disentangling the beta-diversity in anuran parasite communities.

There is great heterogeneity in parasite communities among hosts, understanding the nature and drivers of such variations is still a great scientific quest. Here, we analyse the variation in parasite communities by addressing the following questions: (i) What is the beta-diversity component (nestedness or turnover) that most contributes to beta diversity in parasite communities among anuran species? (ii) Does the beta diversity of parasite communities follow a non-random pattern? (iii) Is the dissimilarity in composition of parasite communities related to the phylogenetic or functional dissimilarity among hosts? We found that turnover in parasite assemblages was the main component of beta diversity, but the variation observed both in the total beta diversity and in its components did not differ from the respective null models. The dissimilarity among parasite communities was not related to the phylogenetic species variability or functional dissimilarity among anuran species for most localities. In short, our findings may indicate a process of resource tracking by the parasite species, in which the resource may not necessarily be conserved phylogenetically in their hosts.

Interannual and spatial variation in the parasite communities of Pacific sierra Scomberomorus sierra (Jordan et Starks) on Mexico's Pacific coast

The parasite communities of predatory fish can be species rich and diverse, making them effective models for studying the factors influencing temporal and spatial variation in these communities. Over a ten-year period an initial study was done on the metazoan parasite communities of Scomberomorus sierra (Jordan et Starks) from four locations on the south-central Pacific coast of Mexico. Twenty-four metazoan parasite taxa were identified from 674 S. sierra specimens: three species of Monogenea, eight Digenea, one Cestoda, one Acanthocephala, four Nematoda, five Copepoda, and two Isopoda. The parasite communities were characterised by high ectoparasite species richness, with monogeneans and some didymozoid species being numerically dominant. Community structure and species composition varied between locations, seasons and sampling years. Similarity between the component parasite communities was generally low, despite the occurrence of a distinctive set of host-specialist parasites. Interannual or local variations in some biotic and abiotic environmental factors are possible causes of the observed variations in the structure and species composition of the parasite community of S. sierra. Ecological factors were therefore considered to have more influence than phylogenetic aspects (host phylogeny) on parasite community structure.

Parasites of an Arctic scavenger; the wolverine (Gulo gulo).

Parasites are fundamental components within all ecosystems, shaping interaction webs, host population dynamics and behaviour. Despite this, baseline data is lacking to understand the parasite ecology of many Arctic species, including the wolverine (Gulogulo), a top Arctic predator and scavenger. Here, we combined traditional count methods (i.e. adult helminth recovery, where taxonomy was confirmed by molecular identification) with 18S rRNA high-throughput sequencing to document the wolverine parasite community. Further, we investigated whether the abundance of parasites detected using traditional methods were associated with host metadata, latitude, and longitude (ranging from the northern limit of the boreal forest to the low Arctic and Arctic tundra in Nunavut, Canada). Adult parasites in intestinal contents were identified as Baylisascaris devosi in 72% (n = 39) of wolverines and Taenia spp. in 22% (n = 12), of which specimens from 2 wolverines were identified as T. twitchelli based on COX1 sequence. 18S rRNA high-throughput sequencing on DNA extracted from faeces detected additional parasites, including a pseudophyllid cestode (Diplogonoporus spp. or Diphyllobothrium spp.), two metastrongyloid lungworms (Angiostrongylus spp. or Aelurostrongylus spp., and Crenosoma spp.), an ascarid nematode (Ascaris spp. or Toxocara spp.), a Trichinella spp. nematode, and the protozoan Sarcocystis spp., though each at a prevalence less than 13% (n = 7). The abundance of B. devosi significantly decreased with latitude (slope = -0.68; R2 = 0.17; P = 0.004), suggesting a northerly limit in distribution. We describe B. devosi and T. twitchelli in Canadian wolverines for the first time since 1978, and extend the recorded geographic distribution of these parasites ca 2000 km to the East and into the tundra ecosystem. Our findings illustrate the value of molecular methods in support of traditional methods, encouraging additional work to improve the advancement of molecular screening for parasites.

Helminth diversity in Pimelodus blochii Valenciennes, 1840 (Osteichthyes: Pimelodidae) in two Amazon Rivers

Structure of the helminth community and analyses of helminth population parameters of Pimelodus blochii collected in the Xapuri River in comparison with those in the Acre River were evaluated. Eight adult helminth species were found parasitizing P. blochii in the Acre River: the nematodes Orientatractis moraveci, Rondonia rondoni, Philometroides acreanensis, Cucullanus (Cucculanus) pinai pinai, Procamallanus (Spirocamallanus) pimelodus, Rhadochona acuminata, and Brasilnema sp., and the trematode Dadaytrema oxycephala. For Xapuri’s fishes, nine helminth species were found: the nematodes O. moraveci, R. rondoni, C. (C.) pinai pinai, Procamallanus (Spirocamallanus) rarus, P. (S.) pimelodus, R. acuminata, Brasilnema sp., and Cystidicolidae gen. sp., and the trematode D. oxycephala. Nematode and Acanthocephala larvae were also reported. Helminth abundance, prevalence, and diversity were influenced by seasonality and locality (river). The helminth parasites from Acre’s fishes formed a subset of the helminth community of the Xapuri’s. The results indicate an influence of the environmental characteristics of the rivers on the helminth community structure and diversity. This is the first study of the parasite community of P. blochii in the Xapuri River. The paretheses of (Spirocamallanus) and (S.) should not be in italics all along the text and tables.

The distribution and host range of Thecaphora melandrii, with first records for Britain

SummaryThecaphora melandrii (Syd.) Vánky & M.Lutz infects species in the Caryophyllacaeae forming sori with spore balls in the floral organs. We report new finds from Britain, supported by phylogenetic analysis, that confirm its occurrence on Silene uniflora Roth. We review published and web accessible records and note the relatively few records of this smut, its sparse distribution, confined to Europe but scattered predominantly from central to eastern Europe. Analysis of the rDNA ITS and 28S sequences demonstrates little variability among specimens, even those parasitising different host genera, which suggests that the species has evolved relatively recently. Some Microbotryum species infect the same host plants, and we found two species, M. lagerheimii Denchev and M. silenes-inflatae (DC. ex Liro) G.Deml & Oberw., in the same locations as T. melandrii, identified by morphology and molecular phylogenetic analysis. These species may form a stable multi-species community of parasites of Silene uniflora.

Harrison's rule scales up to entire parasite assemblages but is determined by environmental factors.

Harrison's rule states that parasite body size and the body size of their hosts tend to be positively correlated. After it was proposed a century ago, a number of studies have investigated this trend, but the support level has varied greatly between parasite/host associations. Moreover, while the rule has been tested at the individual species level, we still lack knowledge on whether Harrison's rule holds at the scale of parasite and host communities. Here, we mapped flea (parasites) and rodent (hosts) body sizes across Mongolia and asked whether Harrison's rule holds for parasite/host assemblages (i.e. whether a parasite's average body size in a locality is positively correlated with its host's average body size). In addition, we attempted to disentangle complex relationships between flea size, host size and environmental factors by testing alternative hypotheses for the determinants of fleas' body size variation. We gathered occurrence data for fleas and rodents from 2,370 sites across Mongolia, constructed incidence matrices for both taxa and calculated the average body sizes of fleas and their hosts over half-degree cells. Then, we applied a path analysis, accounting for spatial autocorrelation, trying to disentangle the drivers of the correlation between parasite and host body sizes. We found a strong positive correlation between average flea and host size across assemblages. Surprisingly though, we found that environmental factors simultaneously affected the body sizes of both fleas and hosts in the same direction, leading to a most likely deceptive correlation between parasite and host size across assemblages. We suggest that environmental factors may, to a great extent, reflect the environmental conditions inside the hosts' burrows where fleas develop and attain their adult body size, thus influencing their larval growth. Similarly, rodent body size is strongly influenced by air temperature, in the direction predicted by Bergmann's rule. If our findings are valid in other host-parasite associations, this may explain the dissenting results of both support and lack thereof for Harrison's rule.

High parasite diversity in the amphipod Gammarus lacustris in a subarctic lake.

Amphipods are often key species in aquatic food webs due to their functional roles in the ecosystem and as intermediate hosts for trophically transmitted parasites. Amphipods can also host many parasite species, yet few studies address the entire parasite community of a gammarid population, precluding a more dynamic understanding of the food web. We set out to identify and quantify the parasite community of Gammarus lacustris to understand the contributions of the amphipod and its parasites to the Takvatn food web. We identified seven parasite taxa: a direct life cycle gregarine, Rotundula sp., and larval stages of two digenean trematode genera, two cestodes, one nematode, and one acanthocephalan. The larval parasites use either birds or fishes as final hosts. Bird parasites predominated, with trematode Plagiorchis sp. having the highest prevalence (69%) and mean abundance (2.7). Fish parasites were also common, including trematodes Crepidostomum spp., nematode Cystidicola farionis, and cestode Cyathocephalus truncatus (prevalences 13, 6, and 3%, respectively). Five parasites depend entirely on G. lacustris to complete their life cycle. At least 11.4% of the overall parasite diversity in the lake was dependent on G. lacustris, and 16% of the helminth diversity required or used the amphipod in their life cycles. These dependencies reveal that in addition to being a key prey item in subarctic lakes, G. lacustris is also an important host for maintaining parasite diversity in such ecosystems.

Plant parasitic nematode communities associated with the crop banana (Musa spp.) at Attappady Tribal hill area, India

Attappady is a region of immense biological importance comes under the Nilgiri Biosphere Reserve area of India at Palakkad district. Biodiversity study of this hill area has great importance in conservative science. Except a national range study for nematode fauna of banana (Musa spp.) in Indian banana fields, a detailed survey of this agriculturally and environmentally important area has not reported till now. The diversity analysis of plant parasitic nematodes was done with samples taken from rhizosphere soil and roots of banana at this area. Comparing with the reported nationwide study the present study newly reported the presence of Aphelenchus spp., Dorylaimoides spp., Hoplolaimus spp., Rotylenchulus spp., Tylenchorynchus spp. and Tylenchus spp. from the crop banana other than the already reported one’s such as Helicotylenchus spp., Meloidogyne spp., Pratylenchus spp. and Radopholus spp. The analysis of nematode genera in different banana cultivars such as Musa × paradisiaca L. (AAB) ‘Nendran’, Musa acuminata Colla (AAA) ‘Robusta’, Musa acuminata Colla (AA) ‘Kadali’ and Musa × paradisiaca L. (Mysore AAB) ‘Poovan’ revealed differences in the reaction to attack between genotypes, and that the cultivar ‘Nendran’ was the most susceptible one to plant parasitic nematodes.

Parasitoids, Nematodes, and Protists in Populations of Striped Cucumber Beetle (Coleoptera: Chrysomelidae).

The striped cucumber beetle, Acalymma vittatum (Fabricius), is an important pest of cucurbit production in the eastern United States, where most commercial producers rely on insecticides to control this pest species. Biological control provides an alternative to insecticide use, but for A. vittatum, top-down control has not been well developed. In the northeastern United States, two parasitoid species, Celatoria setosa (Coquillett) (Diptera: Tachinidae) and Centistes diabroticae (Gahan) (Hymenoptera: Braconidae) have been reported from A. vittatum, but their distribution is poorly known. To determine whether these parasitoid species are attacking A. vittatum in Pennsylvania and the amount of mortality they provide, we characterized the parasitoid dynamics in two distinct efforts. First, we reared parasitoids from beetles captured at two research farms. Second, we focused on one of these farms and dissected beetles to quantify both parasitoid and parasite species attacking A. vittatum. Both efforts confirmed Cl. setosa and Cn. diabroticae, and parasitism rates varied widely between locations and among years (4-60%). Unexpectedly, our dissections revealed that a potentially undescribed nematode species (Howardula sp.) as the most common parasite in the community. We also discovered gregarine protists. Despite being smaller than females, males were more commonly attacked by parasitic species, but we detected no relationship between the size of beetles and abundance of parasitic species in A. vittatum. This work provides a baseline understanding of the parasitoid and parasite community attacking A. vittatum and advances opportunities for conservation biological control using these natural-enemy species.

Parasite intensity drives fetal development and sex allocation in a wild ungulate

An understanding of the mechanisms influencing prenatal characteristics is fundamental to comprehend the role of ecological and evolutionary processes behind survival and reproductive success in animals. Although the negative influence of parasites on host fitness is undisputable, we know very little about how parasitic infection in reproductive females might influence prenatal factors such as fetal development and sex allocation. Using an archival collection of Dall’s sheep (Ovis dalli dalli), a capital breeder that depends on its body reserves to overcome the arctic winter, we investigated the direct and indirect impacts of the parasite community on fetal development and sex allocation. Using partial least squares modelling, we observed a negative effect of parasite community on fetal development, driven primarily by the nematode Marshallagia marshalli. Principal component analysis demonstrated that mothers with low parasite burden and in good body condition were more likely to have female versus male fetuses. This association was primarily driven by the indirect effect of M. marshalli on ewe body condition. Refining our knowledge of the direct and indirect impact that parasite communities can have on reproduction in mammals is critical for understanding the effects of infectious diseases on wildlife populations. This can be particularly relevant for species living in ecosystems sensitive to the effects of global climate change.

Parasite infection reflects host genetic diversity among non-native populations of pumpkinseed sunfish in Europe

Species introductions often coincide with loss of genetic diversity and natural enemies. Anthropogenic translocation of the North-American pumpkinseed Lepomis gibbosus (L., 1758) (Centrarchidae) and its further spread have resulted in recent species establishment in most European countries. This study determines genetic differentiation of non-native European pumpkinseed populations and identifies how their genetic structure relates to the distribution and abundance of parasite species. Microsatellite analysis indicated presence of three genetic lineages, which were well supported by discriminant analysis based on parasite abundance data. The first lineage clustered pumpkinseed populations from northern and southern France and showed high allelic richness, heterozygosity and parasite richness. The second included populations along the “Southern invasion corridor” connecting the rivers Rhine, Main and Danube. The fish exhibited low to high genetic and parasite diversity and generally high parasite abundance. The third lineage clustered populations with low genetic and parasite diversity, located in Portuguese reservoirs and water bodies along the upper Elbe. Parasite species richness was significantly associated with host microsatellite heterozygosity and allelic richness, a trend partially affected by richness of North-American parasites. Furthermore, our results indicate that parasite community composition may serve as a useful biological tool to discriminate non-native fish populations and their inter-relationships.

The use of ITS-2 rDNA nemabiome metabarcoding to enhance anthelmintic resistance diagnosis and surveillance of ovine gastrointestinal nematodes

(300 words)A lack of quantitative information on the species composition of parasite communities present in fecal samples is a major limiting factor for the sensitivity, accuracy and interpretation of the diagnostic tests commonly used to assess anthelmintic efficacy and resistance. In this paper, we investigate the ability of ITS-2 rDNA nemabiome metabarcoding to enhance fecal egg count reduction testing by providing information on the effect of drug treatments on individual parasite species. Application of ITS-2 rDNA nemabiome metabarcoding to fecal samples from ewes from over 90 flocks across western Canada revealed high gastrointestinal nematode infection intensities in many flocks with Haemonchus contortus being the most abundant species followed by Teladorsagia circumcincta and then Trichostrongylus colubriformis. Integration of ITS-2 rDNA nemabiome metabarcoding with pre- and post-treatment fecal egg counting revealed consistently poor efficacy of producer-applied ivermectin and benzimidazole treatments against H. contortus, but much better efficacy against T. circumcincta and T. colubriformis, except for in a small number of flocks. Integration of nemabiome ITS-2 rDNA metabarcoding with Fecal Egg Count Reduction Tests (FECRT), undertaken on farm visits, confirmed that ivermectin and fenbendazole resistance is widespread in H. contortus but is currently less common in T. circumcincta and T. colubriformis in western Canada. FECRT/nemabiome testing did not detect moxidectin resistance in any GIN species but suggested the early emergence of levamisole resistance specifically in T. circumcincta. It also revealed that although poor efficacy to closantel was relatively common, based on total fecal egg counts, this was due to its narrow spectrum of activity rather than the emergence of anthelmintic resistance. This study illustrates the value of ITS-2 rDNA nemabiome metabarcoding to improve fecal egg count resistance testing, perform large-scale anthelmintic resistance surveillance and direct more targeted rational anthelmintic use.

Is Host Selection by Mosquitoes Driving Vector Specificity of Parasites? A Review on the Avian Malaria Model

Parasites and hosts are in a complex evolutionary arm race where host compatibility represents a key obstacle for successful infections. The degree of parasite specialization on a host varies along a continuum: on one end, extreme specialist parasites may be restricted to a single host species, and on the other, generalist parasites are able to infect a diverse set of hosts. Multiple intrinsic factors associated to the host, such as their immune system and physiological condition, can contribute to the evolution of host specificity of parasites and have been well-studied and documented in vertebrates. In contrast, vector specificity of parasites has been largely overlooked, especially in natural conditions. While a few studies suggested that insect vectors do not play an important role in shaping the parasite community structure since they may feed widely from the bird community, current studies have demonstrated the importance of vector feeding behaviour on transmission dynamics for several vector-borne pathogens. Here, we provide a review on the specialization of avian Plasmodium in vectors, emphasizing the necessity to study simultaneously the three players to further understand how host choice by the vectors might influence the distribution of parasites in the wild. In addition, we suggest specific research directions making use of both empirical data gathered in the field and controlled experiments on vector host‐feeding preferences

Stable Isotopes and Parasites Indicate Feeding Ecology in Florida, USA, Wading Birds

We assessed δ13C and δ15N profiles and endoparasite community composition in Great Egrets (Ardea alba), Great Blue Herons (A. herodias), and White Ibis (Eudocimus albus) from four wildlife rescue centers (two mainland, two on islands in the Florida Keys) in south Florida, USA to elucidate feeding ecology. We detected among-species differences for δ15N but not δ13C and noted decreased δ13C enrichment in Great Egrets and Great Blue Herons (but not White Ibis) from these centers. Parasite component community and infracommunity species richness were higher in Great Egrets and Great Blue Herons relative to White Ibis, and higher in birds of the same species from mainland centers. Multivariate analysis of parasite infracommunity structure detected co-occurring clusters of parasite taxa characteristic of Great Egrets and Great Blue Herons on the one part, and of White Ibis on the other; mainland Great Egrets and Great Blue Herons had similar parasite communities and clustered separately from conspecifics from the islands. We detected a significant (negative) correlation of infracommunity species richness with δ13C but not δ15N. Lastly, parasite infracommunity Bray-Curtis similarity correlated significantly with stable isotope Euclidean distances. We conclude that the two approaches converge towards similar outcomes, providing complementary and consilient information on host feeding ecology.

Associations between pharmaceutical contaminants, parasite load and health status in brown trout exposed to sewage effluent in a small stream

Owing to their widespread use, pharmaceuticals have become important pollutants of the aquatic environment. Pharmaceuticals and parasites can affect the immunity, physiology and behaviour of target organisms, both singly and through interaction. In this study, we related pharmaceutical concentration, parasite infection and condition in brown trout (Salmo trutta m. fario) collected at localities upstream and downstream of a sewage treatment plant (STP). The sites were separated by a weir preventing fish migration. Pharmaceutical number and concentrations differed significantly between sites. Antibiotics and antidepressants were found at the highest concentrations at both localities. Though fish condition and overall parasite abundance did not differ between sites, there was a significant difference in parasite community composition. A higher abundance of monogenean ectoparasites, along with a lower abundance of endoparasites, was observed at the downstream locality. The adverse effect of pharmaceutical load on ecto- and endoparasitic species on brown trout was further confirmed at the individual level using multivariate analysis. Both the number and concentration of pharmaceuticals in fish tissues reflected their high incidence in the environment, confirming the ability of trout to bioaccumulate pharmaceuticals. This could have important consequences on fish health, particularly in small streams where STP effluent represents a high proportion of stream flow.

Facilitative priority effects drive parasite assembly under coinfection.

Host individuals are often coinfected with diverse parasite assemblages, resulting in complex interactions among parasites within hosts. Within hosts, priority effects occur when the infection sequence alters the outcome of interactions among parasites. Yet, the role of host immunity in this process remains poorly understood. We hypothesized that the host response to the first infection could generate priority effects among parasites, altering the assembly of later-arriving strains during epidemics. We tested this by infecting sentinel host genotypes of Plantago lanceolata with strains of the fungal parasite Podosphaera plantaginis and measuring susceptibility to subsequent infection during experimental and natural epidemics. In these experiments, prior infection by one strain often increased susceptibility to other strains, and these facilitative priority effects altered the structure of parasite assemblages, but this effect depended on host genotype, host population and parasite genotype. Thus, host genotype, spatial structure and priority effects among strains all independently altered parasite assembly. Using a fine-scale survey and sampling of infections on wild hosts in several populations, we then identified a signal of facilitative priority effects, which altered parasite assembly during natural epidemics. Together, these results provide evidence that within-host priority effects of early-arriving strains can drive parasite assembly, with implications for how strain diversity is spatially and temporally distributed during epidemics.

Humic-acid-driven escape from eye parasites revealed by RNA-seq and target-specific metabarcoding

BackgroundNext generation sequencing (NGS) technologies are extensively used to dissect the molecular mechanisms of host-parasite interactions in human pathogens. However, ecological studies have yet to fully exploit the power of NGS as a rich source for formulating and testing new hypotheses.MethodsWe studied Eurasian perch (Perca fluviatilis) and its eye parasite (Trematoda, Diplostomidae) communities in 14 lakes that differed in humic content in order to explore host-parasite-environment interactions. We hypothesised that high humic content along with low pH would decrease the abundance of the intermediate hosts (gastropods), thus limiting the occurrence of diplostomid parasites in humic lakes. This hypothesis was initially invoked by whole eye RNA-seq data analysis and subsequently tested using PCR-based detection and a novel targeted metabarcoding approach.ResultsWhole eye transcriptome results revealed overexpression of immune-related genes and the presence of eye parasite sequences in RNA-seq data obtained from perch living in clear-water lakes. Both PCR-based and targeted-metabarcoding approach showed that perch from humic lakes were completely free from diplostomid parasites, while the prevalence of eye flukes in clear-water lakes that contain low amounts of humic substances was close to 100%, with the majority of NGS reads assigned to Tylodelphys clavata.ConclusionsHigh intraspecific diversity of T. clavata indicates that massively parallel sequencing of naturally pooled samples represents an efficient and powerful strategy for shedding light on cryptic diversity of eye parasites. Our results demonstrate that perch populations in clear-water lakes experience contrasting eye parasite pressure compared to those from humic lakes, which is reflected by prevalent differences in the expression of immune-related genes in the eye. This study highlights the utility of NGS to discover novel host-parasite-environment interactions and provide unprecedented power to characterize the molecular diversity of cryptic parasites.

Data from monogenean and endohelminth communities in twospot livebearer Pseudoxiphophorus bimaculatus (Teleostei: Poeciliidae) populations in a neotropical river.

The data presented in this article are related to the research article entitled “Competition from sea to mountain: interactions and aggregation in low diversity monogenean and endohelminth communities in twospot livebearer Pseudoxiphophorus bimaculatus (Teleostei: Poeciliidae) populations in a neotropical river.” accepted for publication in Ecology and Evolution. The data describes the communities of helminth parasites in 11 populations of a small poeciliid freshwater fish Pseudoxiphophorus bimaculatus (Heckel, 1848) sampled along the La Antigua river basin in Veracruz, Mexico. We examined 19 P bimaculatus from one locality, 21 from another locality, and 20 from each of the other nine locations sampled in June 2016. A total of 220 individual fish were examined, and in this paper we provide the data for 18 helminth parasite taxa recorded from them. The material in this Data paper comprised the raw data on the abundance, i.e. the number of helminth individuals of each of 18 taxa found in each one individual of P. bimaculatus from each of 11 localities. The data set is contained in a single text-table including one matrix containing each of the 220 host P. bimaculatus examined from 11 localities (lines). Measures for each host P. bimaculatus include total length, standard length, maximum deep and sex, documented for everyone fish examined, plus data of the number of individual helminth of each taxa collected by each examined fish are placed in the columns. These data might be used to examine spatial distribution of helminth parasite taxa. These data might be reused to examine the spatial variation in community structure of helminth parasites of freshwater fish. This kind of data could be used to provide an assessment of human environmental impacts, or for public awareness of conservation objectives.