Parasite Species Composition Research Articles

Fauna of parasite of cyprinids and percoids in the reservoirs of the Moscow Canal

The purpose of the research is determination of the species composition of parasites of cyprinid and percoid fish in the reservoirs of the Moscow Canal.Materials and methods. In 2019–2020, parasitological material was collected in the spring, summer and autumn from percoid (the pike perch and European perch) and cyprinid fish (the bream, silver bream, roach, rudd and sabrefish) aged 2 to 7 years from the reservoirs of the Moscow Canal (Ikshinsky, Pestovsky, Pyalovsky and Klyazminsky Reservoirs) by the methods generally accepted in ichthyo-parasitology. To quantify the fish infection rate, we used the incidence or prevalence of infection, the intensity of infection, and the mean amplitude of the intensity of infection. We used Kabiosh index (K) to assess the species diversity of parasites. Results and discussion. The parasitological analysis results of percoids and cyprinids from the reservoirs of the Moscow Canal are presented. 34 parasite species were found in fish, which belong to nine taxonomic groups: Microsporidia, Myxosporea, Monogenea, Cestoda, Trematoda, Nematoda, Acanthocephala, Hirudinea, Crustacea. The largest number of species belongs to trematodes, the rest, taxa (mixo- and microsporidia, cestodes, nematodes, acanthocephalans, leeches and parasitic crustaceans), are represented singly. We calculated the species diversity ratio (R) of fish parasites in the reservoirs, which ranged from 0.335 to 0.575, which indicates the fauna similarity from 50 to 75%. The greatest similarity in the parasite fauna was found in the roach (R = 0.168–0.447), the least in the European perch (R = 0.447–1.0). We have identified the dominant species that are found in more than 20% of the studied fish and determine the “core” of the parasitic fauna, which included 4 parasite species of epizootic and 1 parasite species of epidemiological significance.

Field Survey on the Status of Internal Parasites in Young Calves on Farms in Eastern Slovakia

Abstract The objective of this study was to evaluate the species composition of protozoan and helminth parasites of young calves on farms in eastern Slovakia. Faecal samples from calves were analysed using the floatation technique, McMaster Methods and stained slide method for Cryptosporidium spp. From 105 samples analysed, nine samples (8.6 %) were suspected to be positive for Cryptosporidium spp. The results gathered from this study displayed that 64.8 % of calves were infected with some species of parasite at the moment of sampling. The highest prevalence of infection was with Eimeria spp. with 56.2 % of calves infected being positive for this. OPG (oocysts per gram) values for Eimeria spp. observed in this study ranged from 100 to 75,200. The lowest prevalence was found to be from Giardia duodenalis and Trichostrongylidae family equally 0.95 %. All faecal samples had nematode egg counts below 50 EPG (eggs per gram).

Associative parasitoses of the gastrointestinal tract of horses and assessment of anti-parasitic drugs efficiency

Invasive diseases of horses are an urgent problem in the horse breeding industry of the Republic of Belarus, as well as in the near and far abroad countries. The main role among the parasitic pathology is occupied by helminths of the small and large intestine, as well as larvae of gasterophilus. In associative course, they are the cause of significant economic losses associated with the growth and development of sick young animals, reduced performance, endurance of animals, increased susceptibility to other diseases, and even the death of animals. Planned therapeutic and preventive measures using broad-spectrum anthelmintics is a priority measure to reduce economic damage in development of the horse breeding industry. The paper provides data on spread of parasitoses of gastrointestinal tract in horses in the Republic of Belarus during period of 2004-2020. The paper presents the species composition of horse parasites localized in the stomach, small and large intestines. Data on extensiveness and intensity of invasions of horses by parasitocenosis of digestive tract in terms of age are presented. Therapeutic efficiency of antiparasitic drugs of various pharmacological groups in mono- and polyinfestations of gastrointestinal tract of horses are studied. High extensibility of Avermectin series preparations (Avermectin paste 1 %, Rivertin 1 %) has been determined for nematodes of gastrointestinal tract of horses and gastrointestinal disease. High efficiency has been obtained from a new complex antiparasitic preparation for horses “Prazimax” in mono- and polyinfestations caused by parasites of gastrointestinal tract, including nematodes of the small and large intestines, larvae of gasterophilus and Anoplocephala perfoliata cestodes. Data on spread of associative course of parasitocenoses of the digestive tract of horses, age and seasonal dynamics will allow veterinary specialists to make timely diagnosis, conduct differential diagnostics, determine the optimal timing of diagnostic, therapeutic and preventive treatments, taking into account the specifics of parasitocenosis.

Species composition of parasites Rana temporaria Linnaeus, 1758 (Amphibia: Ranidae) in the vicinity of the Visim State Nature Biosphere Reserve

The purpose of the research is to study the parasite fauna of the common frog (Rana temporaria Linnaeus, 1758) inhabiting the vicinity of the Visim Nature Biosphere Reserve.Materials and methods. The species composition, dominance structure and endoparasite infection of 32 individuals of R. temporaria caught along the banks of the upper reaches of the Sulem Riverwere assessed according to the following indicators: the prevalence and intensity of infection and abundance index.Results and discussion. The species composition of parasites in a common frog from the vicinity of the Visim Nature Biosphere Reserve is presented for the first time. Five species of macroparasites have been identified, classified as Nematoda: Oswaldocruzia filiformis (Goeze, 1782), Neoraillietnema praeputiale (Skrjabin, 1916), Cosmocerca ornata (Dujardin, 1845), Rhabdias bufonis (Schrank, 1788) and as Platyhelminthes: Haplometra cylindracea (Zeder, 1800). One species of endosymbiotic protozoa of Chromista, Opalina ranarum was recorded (Purkinje et Valentin, 1835). The prevalence of the infection of common frogs by helminths reaches 100%, the abundance index is 11.06, and protozoa is 93.8% and 62.16, respectively. Nematodes O. filiformis (the prevalence of infection 96.9%, and abundance index 7.97) and R. bufonis (the prevalence of infection 46.9%, abundance index 2.28) predominate. It was shown that nematode N. praeputiale was not found in the parasitocenosis of immature amphibians, and trematode H. cylindracea was not found in adult animals. The proportion of O. filiformis and C. ornata increases with age in common frogs. It was found that the animals of the July population are infected with nematode R. bufonis largely. Regardless of the age of R. temporaria, the probability of colonization by O. ranarum in spring will be higher.

Sheep nemabiome diversity and its response to anthelmintic treatment in Swedish sheep herds

BackgroundA novel way to study the species composition and diversity of nematode parasites in livestock is to perform deep sequencing on composite samples containing a mixture of different species. Herein we describe for the first time the nematode community structures (nemabiomes) inhabiting Swedish sheep and how these are/were affected by host age and recent anthelmintic treatments.MethodsA total of 158 fecal samples were collected (n = 35 in 2007 and n = 123 in 2013–2016) and cultured from groups of sheep on 61 commercial farms in the south-central part of the country where most animals are grazed. Among the samples, 2 × 44 (56%) were paired collections from the same groups pre- and post-treatment with anthelmintics such as macrocyclic lactones, benzimidazoles or levamisole. Samples were analyzed for their nemabiome using the PacBio platform followed by bioinformatic sequence analysis with SCATA. Species richness and diversity were calculated and analyzed in R.ResultsNematode ITS2 sequences were found in all larval culture samples except two, even though the fecal egg counts were below the McMaster threshold in 20 samples. Sequencing yielded, on average, 1008 sequences per sample. In total, 16 operational taxonomical units (OTU), all with ≥ 98 % identity to sequences in the NCBI database, were recognized. The OTUs found represented nematode species of which ten are commonly associated with sheep. Multiple species were identified in all pre-anthelmintic treatment larval culture samples. No effects on nematode diversity were found in relation to host age. On the other hand, recent anthelmintic treatment lowered species richness, especially after use of ivermectin and albendazole. Interestingly, despite zero egg counts after use of levamisole, these samples still contained nematode DNA and especially H. contortus.ConclusionsOur findings provide evidence that nemabiome analysis combined with diversity index analysis provides an objective methodology in the study of the efficacy of anthelmintic treatment as both high and low abundant species were detected.Graphical

ГОДОВАЯ ИЗМЕНЧИВОСТЬ ПАРАЗИТОВ ACIPENSER RUTHENUS MARSIGLII В НИЖНЕМ ТЕЧЕНИИ ИРТЫША

The article gives the analysis of infestation of Siberian sterlet Acipenser ruthenus marsiglii by parasites in the Lower Irtysh within 2017 to 2019. The annual changes in the species composition of parasites and in quantitative indicators of the fish infestation were revealed. In 2017 there were found 10 species of parasites, of which 4 were specific: Trypanoplasma acipenseris, Haemogregarina acipenseris, Acrolichanus auriculatum, Capillospirura ovotrichuria; in 2018 - 11 species, of which 6 were specific: T. acipenseris, H. acipenseris, Sphaerospora colomani, A. auriculatum, Truttaedacnitis clitellarius, Capillospirura itrichura; in 2019 - 7 species of parasites, of which 4 were specific: T. acipenseris, H. acipenseris, S. colomani, A. auriculatum. Of the broadly specific parasites, 6 species have been recorded: Trichodina acuta, Trichodina nigra, Trichodina sp., Diplostomum chromatophorum, Piscicola geometra, Unionidae gen. sp. In Siberian starlet blood there were registered T. acipenseris and H. acipenseris in all years of research. An increased extensiveness of invasion by these parasites was established. A significant decrease in infection with A. auriculatum trematode was found. The nematode C. ovotrichuria was recorded in sterlet only in 2017 and 2018. High values of infestation with Trichodina acuta, Trichodina nigra, Trichodina sp.were recorded. Myxosporidium Sphaerospora colomani was first recorded in the Ob-Irtysh basin. It has been suggested that the annual changes in the species composition of sterlet parasites are associated with the direct impact of the temperature regime and fluctuations in the level of the Irtysh basin

Розробка комплексної схеми боротьби з іксодовими кліщами

In the context of globalization, climate changing and the spread of tick-borne diseases, the control of ixodid ticks is becoming increasingly important. The uncontrolled use of chemicals to limit the harmful effects of ticks has led to the development of acaricide resistance of ticks, as is observed with most pest control chemicals. There are many reasons for lack of success in the control of ticks and the diseases they transmit. The tick ecology is problematic and has not yet been fully explored. It is believed that effective methods of tick control require the development of integrated methods. The development of a program for the control of ectoparasites is required to take into account seasonality, species composition of parasites, features of biological development. The purpose of our study was to create an effective way of elimination of the ticks in the environment. During 2019, the research was conducted in the Khmelnytsky region. As a result of the preliminary parasitological examination, natural biotopes of Dermacentor reticulatus ticks were found. In natural conditions, the treatment was carried out to eliminate ticks in the environment. Three plots, two test plots, and a control plot were identified for the research. At the first tested plot, the efficiency of chemical treatment with Tsiflur-Kombi after 24 hours of the application was 92.6%, at the second site - 100%. The highest efficacy was obtained in the two groups on day 7 after administration and continued for 35 days. During this period, no ticks were detected in the test plots. During the whole period, the average number of ticks per plot - 26 individuals was observed on the control plot. The acaricide Tsiflur-combi has shown high effectiveness in controlling of ixodid ticks at a concentration of 0.2% and 0.5% for five weeks in natural biotopes. The duration of the repellent and acaricidal effect on ticks after treatment with the Tsiflur-combi preparation was 35 days. It is recommended that prophylactic application be carried out every 4 weeks, but it’s necessary to take into account the region's acarological indicators. An effective and safe way to eliminate ticks in the environment has been developed. Synthetic pyrethroids have a long residual acaricidal effect on different surfaces, and when used in small quantities, do not pose a risk to mammals.

Parasite communities of striped bonito Sarda orientalis (Pisces: Scombridae) on the Pacific coast of Mexico

ABSTRACT The parasite communities of marine fish in the tropical Pacific remain poorly studied. We did an initial study of the metazoan parasite communities of striped bonito Sarda orientalis from the Pacific coast of Mexico. Two hundred thirty individuals from two locations were collected between April 2017 and March 2018. Twenty-two metazoan parasite taxa (20 helminths and two Crustacea) were identified: one species of Monogenea, twelve of Digenea, one of Acanthocephala, two of Cestoda, four of Nematoda, one of Copepoda, and one of Isopoda. Didymozoid digeneans (six species) were the most frequent and abundant parasite species at both sampling locations. Parasite species richness at the component community level was similar in both locations (16–17 species). However, parasite community structure and species composition varied between them. Local fluctuations in some biotic (e.g. host feeding behaviour and body size) and abiotic environmental factors were probably responsible for these variations.

Impacts of ontogenetic dietary shifts on the food-transmitted intestinal parasite communities of two lake salmonids.

Ontogenetic dietary shifts are common in fish and often impact trophically transmitted parasite communities. How parasite species composition and relative abundances change among size classes, and at what rate these changes occur, is rarely examined. Hosts with a broad trophic niche are potentially exposed to a large variety of parasite species. The degree of ontogenetic changes in parasite species composition versus changes in parasite abundance should suggestively differ between thropically generalist and specialist host species. In the present study, we explore ontogenetic dietary shifts and their impact on species composition and relative abundance of intestinal parasites in two sympatric salmonid fish species, Arctic charr (Salvelinus alpinus) and brown trout (Salmo trutta) caught in the littoral habitat of a subarctic lake. Our results highlight a close interplay between ontogenetic dietary niche shifts and alterations in the acquisition of trophically transmitted parasites, leading to host-specific differences in the component community of parasites. Ontogenetic changes in the intestinal parasite community related to dietary niche shifts were distinct but less pronounced in Arctic charr than in brown trout due to a broader and more consistent dietary niche of the former and an ontogenetic shift toward piscivory in the latter. At the component community level, changes in parasite assemblages of both host species were driven by a faster increase in the heterogeneity of parasite relative abundance than in the compositional heterogeneity, a pattern that partly may be related to a rather species-poor parasite community of this subarctic study system. Separating compositional heterogeneity from heterogeneity in relative parasite abundance is important to understand how size-dependent variability shapes parasite communities of host populations.

Метазойные паразиты сибирской плотвы Rutilus rutilus lacustris (Pallas) реки Тобол

The article describes the problems of the Ob-Irtysh basin (the Tyumen region), which is a natural focus of opisthorchosis. Localized in the bile ducts of the liver, the pathogen of opisthorchosis poses a risk to the human body. Parasitic community of Siberian roach inhabiting the Tobol Riverwas studied in the autumn period of its life cycle. There were examined 24 fish species of different sexes at the age of 0+ to 4+. There was registered the roach invasion by 9 species of para-sites belonging to 6 systematic groups: Monogenea - 2, Cestoda - 1, Trematoda - 4, Nematoda - 1, Bivalvia - 1, Copepoda - 1. Parasitization of gills by monogeny Dactylogyrus crucifer with inva-sive extensiveness of 83.3% and Paradiplozoon homoion homoion with invasive extensiveness of 16.7% has been stated. Diplostomum chromatophorum parasitizes in the lens of the eye, in total 18 of the examined fish are invaded. Opisthorchis felineus was found in muscles with invasive exten-siveness of 29.2%. Immature specimens of Sphaerostoma bramae were found in the intestines of nine fish examined. Mesentery of 4 fish species and liver of 1fish species examined are affected by Raphidascaris acus at a larval stage. The dominant parasite in the study is Rhipidocotyle campanula. Trematode at the metacercaria stage was found on the gills and fins, the overall infection rate comes to 70.8%. Also, Ergasilus sieboldi parasitizes on the gills and fins of the examined roach species. Depletion of the species composition of parasites is observed in the autumn period of the roach life cycle.

Helminths of Fedorov's lumpsucker Eumicrotremus fedorovi Mandrytsa, 1991 (Actinopterygii: Cyclopteridae) in the Simushir Island area (Pacific Ocean).

Fedorov's lumpsucker, Eumicrotremus fedorovi Mandrytsa, 1991, is native to the Kuril Islands area. Two sets of 69 and 30 adult specimens of E. fedorovi caught on the continental shelf and slope of Simushir Island in the Pacific Ocean were dissected and studied for macroparasites. The studied specimens were heavily infected with plerocercoids of Nybelinia surmenicola and Ascarophis pacifica. For the first time, 15 parasite taxa were recorded for E. fedorovi. None of the parasites found are solely specific to the E. fedorovi or to the representatives of the family Cyclopteridae. The infection of E. fedorovi could be dramatically different in different parts of the Simushir Island area in terms of parasite species composition and intensity of infection.

Geographic and ontogenetic variations in parasite communities of intertidal fish species from the south-eastern Pacific coast

Parasite composition can be affected by physiological and ecological changes during host ontogeny. Intertidal fish do not travel long distances and live in the same area throughout their lifetimes, meaning that parasite communities can differ across geographic ranges. The objective of this study was to analyse the parasite communities of three fish species (Hypsoblennius sordidus, Helcogrammoides cunninghami and Scartichthys viridis) collected from the Chilean coast. The composition of parasite species was compared among host ontogenetic stages (larvae, juveniles and mature fish) and geographic areas. A total of 184 larval, 252 juveniles and 217 mature individuals were collected in the northern area (c. 24°S), and 186 larval, 192 juveniles and 112 mature individuals from the central area (c. 33°S). Ectoparasites were most prevalent in fish from the central area, whereas endoparasites were most prevalent in the northern area. The parasite species richness varied significantly between geographical areas for H. sordidus and H. cunninghami, but the parasite composition varied significantly between geographical areas for all fish species analysed. Therefore, the geographical area was the most important factor determining the parasite composition of intertidal fish species. The absence of endoparasites in fish larvae and the increased infestation in juvenile and mature fish may be explained by the shift in habitat from the water column to intertidal pools where prey abundance and availability are higher. On the other hand, hydrographic barriers affecting prey distributions may also offer an explanation as to the differences in parasite composition.

Biological drivers of individual-based anuran-parasite networks under contrasting environmental conditions.

Understanding the mechanisms driving host-parasite interactions has important ecological and epidemiological implications. Traditionally, most studies dealing with host-parasite interaction networks have focused on species relationship patterns, and intra-population variation in such networks has been widely overlooked. In this study, we tested whether the composition of parasite communities of five anuran species (Leptodactylus chaquensis, Leptodactylus fuscus, Leptodactylus podicipinus, Pseudis paradoxa and Pithecopus azureus) vary across a pasture pond and a natural reserve site in south-eastern Pantanal, Brazil. We analysed the structure of individual-based networks of these five anuran species, assessed the species roles in the networks and the contribution of host species and body size to interaction strength in the networks, and tested if network ecological attributes varied between the two sites. We observed a total of 17 parasite morphospecies in 151 individual anurans and found that the abundance of parasite species tends to vary, with host species being the main filter driving parasite community structure. The composition of core parasite species remained similar between study sites, and network structure (i.e. parasite richness, interaction diversity, specialization, nestedness and modularity) did not change between pasture and natural reserve. Individual traits of hosts influenced network descriptors since larger hosts presented greater interaction strength independent of the study site. In short, we found that the occurrence of highly connected parasite taxa in both the pasture and the reserve sites may have promoted similarity in network structures, and host body size was the best predictor of associations with parasites in both study sites.

Interannual variation in the metazoan parasite communities of bigeye trevally Caranx sexfasciatus (Pisces, Carangidae).

Parasite communities in Caranx sexfasciatus were characterized and analyzed to determine any interannual variations in structure and/or species composition. In total, 422 C. sexfasciatus were collected from Acapulco Bay, Mexico, between May 2016 and March 2019. Thirty-two taxa of metazoan parasites were identified: five Monogenea, thirteen Digenea, one Acanthocephala, one Cestoda, three Nematoda, seven Copepoda, and two Isopoda. Monogeneans were the most frequent and abundant parasite species in all sampling years. Parasite species richness at the component community level varied significantly from 8 (May 2016) to 25 (March 2019) and was similar to previous reports for other species of Carangidae. The component communities and infracommunities in C. sexfasciatus were characterized by low parasite species numbers, low diversity, and dominance of a single species (the monogenean Neomicrocotyle pacifica). Parasite community structure and species composition varied between sampling years and climatic seasons. Seasonal or local fluctuations in some biotic and abiotic environmental factors probably explain these variations.

Hiện trạng nhiễm ký sinh trùng ở cá tra (Pangasianodon hypophthalmus) giai đoạn ương giống

The study was conducted to determine the current status of parasitic infection in three nursing stages (larval, fry and fingerling stages) of striped catfish (Pangasianodon hypophthalmus). A total of 857 fish (302 samples of larval stage, 218 samples of fry stage and 337 samples of fingerling stage) were sampled from 20 nursery ponds (9 ponds in rainy season and 11 ponds in dry season). The parasitic composition and the infection rate from different nursing stage of fish were examined. Results showed that nine parasite genera (Cryptobia, Trichodina, Balantidium, Apiosoma, Epistylis, Myxobolus, Henneguya, Dactylogyrus, and Gyrodactylus) were found in striped catfish at nursing stage. Besides, cysts of some parasites were identified as Myxozoans, metacercariae of trematodes, larval nematodes and parasitic copepods. Parasitic infection rate was higher in the dry season than the rainy season. In which, the infection rate in dry season was observed at the rate of 56.6%-73.3% in larvae, 50%-100% in fry, 73%-85.7% in fingerlings. The infection rate in the rainy season was observed at the rate of 15%-57.3% in larvae, 40%-100% in fry, 25%-90.3% in fingerlings. In particular, Trichodina, Apiosoma, Epistylis, Myxozoa, Myxobolus, Henneguya spores are commonly found on skin and gills of fish in both dry and rainy seasons. The trend in prevalence and species composition of parasites observed in this study may reflect the specific time of nursing stage to apply interventions in order to reduce the pathogenic impact of the parasites.

Первые данные о двустворчатых миксоспоридиях кефалевых рыб залива Нячанг (Вьетнам)

Кефалевые рыбы являются объектом промысла во Вьетнаме; некоторых из них разводят на рисовых чеках. Интенсивное развитие в этой стране марикультуры рыб, а также большая доля гидробионтов в рационе населения требуют знаний не только о видовом составе паразитов, но и об их жизненных циклах, патогенности, медицинском и эпизоотологическом значении. Фауна морских миксоспоридий в этом районе изучена крайне слабо. В пресноводных видах Вьетнама известно 36 видов и 10 не идентифицированных до вида миксоспоридий; в морских рыбах найдено 7 видов и 9 не определённых до вида Myxosporea. В марте — апреле 2018 г. в заливе Нячанг (Вьетнам, Восточное море) на предмет обнаружения миксоспоридий методом неполного паразитологического вскрытия исследовали 71 экз. рыб 7 видов из сем. Mugilidae (4 экз. Chelon planiceps, 25 экз. Valamugil speigleri, 10 экз. V. formosae, 1 экз. Planiliza subviridis, 19 экз. Paramugil parmatus, 9 экз. Mugil cephalus, 3 экз. Moolgarda seheli). Все органы просматривали под бинокуляром Olympus SZ61 при увеличении от ×15 до ×25. Мазки из тканей различных органов рыб исследовали на микроскопе Olympus CKX53 с фазовым контрастом при увеличении ×400 и на микроскопе Olympus CX41 с цифровой камерой Olympus SC50 и фазовым контрастом при увеличении ×800. Миксоспоридий фиксировали в глицерин-желатине по общепринятой методике. Промеры паразитов базировались на 20 спорах Myxobolus spinacurvatura, 25 спорах Sphaerospora dicentrarchi и 10 спорах Henneguya sp. Все промеры выполнены по стандартной методике. Для оценки численности паразитов использованы показатели экстенсивности и интенсивности инвазии. Получены первые сведения о миксоспоридиях отр. Bivalvulida кефалевых рыб залива Нячанг: найдены Myxobolus spinacurvatura в жёлчном пузыре и кишечнике у 78 % лобана M. cephalus при интенсивности инвазии, составляющей единичные споры в мазке из жёлчного пузыря и 5–11 цист в кишечнике; Sphaerospora dicentrarchi в жёлчном пузыре у 5 % черноплавничных хелонов Paramugil parmatus, 12 % Valamugil speigleri, 20 % V. formosae и 56 % Mugil cephalus при интенсивности инвазии, составляющей единичные споры в мазке; Henneguya sp. в жёлчном пузыре 8 % V. speigleri и 10 % V. formosae при интенсивности инвазии, составляющей единицы, десятки спор в мазке. Сделаны описания обнаруженных видов. Указано их распространение в других регионах Мирового океана. S. dicentrarchi — новый вид в фауне Восточного моря и Вьетнама. Он был найден не только в известном для него в других регионах M. cephalus, но и в новых хозяевах — P. parmatus, V. speigleri и V. formosae. Myxobolus spinacurvatura впервые констатирован в заливе Нячанг. Myxobolus spinacurvatura и Sphaerospora dicentrarchi известны от лобана в бассейне не только Тихого, но и Атлантического океана, поэтому предполагается, с учётом связи этих водоёмов в глубокой древности, наличие у каждого из данных паразитов в прошлом единого большого ареала, который затем был разорван вследствие мощных геологических преобразований нашей планеты.

Trematode parasites associated with amphibians from a rice field in the northeastern Argentina

In altered environments, such as agricultural lands, studies of amphibian parasites can provide helpful information about the food web structure, parasite species abundance and composition, and environmental stress. Here, we investigate the parasitic digeneans in three amphibian families (Leptodactylidae, Bufonidae and Hylidae) in a rice field (30 ha) from Corrientes Province, Argentina. A total of 171 amphibian specimens were collected between March 2017 and February 2018. Amphibian trematode parasites in this area included 18 species, with dominance of common species. The trematode fauna was characterized by only one species (Choledocystus vitellinophillum) with high prevalence (>50%). The dominant adult species corresponded to Catadiscus propinquus for most of the hosts (80%), and when only larval trematodes were analyzed, the dominant metacercariae in most hosts (60%) were strigeids larvae. Of the total trematode individuals (n = 278), 57% corresponded to metacercariae that complete their life cycles mainly in birds. The amphibians Leptodactylus chaquensis and Lysapsus limellus presented high species richness. This is related to the microhabitats occupied by these hosts as well as with the biology of their parasites. Infection of all the trematode taxa for which larvae and adults were examined occurs through a sequence of trophic relationships. Finally, the results expand the knowledge of the biodiversity and ecology of parasite helminths in amphibians from agricultural landscapes; furthermore, this information is a fundamental baseline to quantify the loss of biodiversity and assess the health of the ecosystem.

Hosts and environment overshadow spatial distance as drivers of bat fly species composition in the Neotropics

AbstractAimDetermine the relative influence of geographical distance, environmental differences, and host species composition on the similarity of bat fly species composition.LocationNeotropics.TaxonBats (Chiroptera: Phyllostomidae) and bat flies (Diptera: Streblidae).MethodsAbundance data on bats and ectoparasites were obtained from published studies. The relative influences of environmental variation (annual precipitation, temperature seasonality, elevation, and NDVI), host species composition, and geographic distance on parasite community composition were analysed with Generalized Dissimilarity Modelling and variance partitioning. Additionally, we evaluated the influence of these environmental variables and geographic distance on host species composition.ResultsOur model explains 45.3% of the variance in the dissimilarity of bat fly species. Host species composition had the most significant influence on bat fly species composition across communities, followed by environmental effects. Variance partitioning showed that host species composition explained 14.9% and environmental characteristics explained 10.3% of the variance in bat fly species dissimilarity. Geographical distance alone had a negligible effect as it accounted for only 0.007% of the variance in bat fly species composition. Host species composition was mainly influenced by geographic distance (18.0%) and secondarily by environmental variables (9.8%). The most important environmental variables influencing parasite and host species composition were annual precipitation and temperature seasonality, respectively.Main ConclusionsThe lack of relationship between geographical distance and bat fly species composition may reflect either the high mobility or the high dispersal capacity of bat flies, or a combination of these. Alternatively, it could reflect a taxonomic artefact. Environmental differences seem to directly affect bat flies, as opposed to affecting them indirectly through their impact on the hosts. Our results support the fundamental role that host species composition plays in determining the species composition of highly host‐specific parasites. However, we argue that host specificity is not the only trait impacting ectoparasite species composition.

Factors linked to interannual variation in the metazoan parasite communities of black skipjack, Euthynnus lineatus (Pisces: Scombridae)

AbstractMarine parasite communities can exhibit temporal and spatial changes in response to seasonal and local variations in several biotic and abiotic environmental factors. Limited attention has been given to the influence of abiotic factors, so their effects on parasite community structure remain unclear. A total of 496 specimens of Euthynnus lineatus were collected over a 7‐year period (2012–2018) from Acapulco Bay, Mexico. Their parasite communities were analyzed to determine if they experience interannual variations due to local biotic and abiotic factors. Thirty‐three metazoan parasite species were recovered and identified: four species of Monogenea (adults); 16 of Digenea (one larvae and 15 adults); two of Acanthocephala (adults); two of Cestoda (larvae); three of Nematoda (two larvae and one adult); and six of Crustacea (three Copepoda, and three Isopoda). Species richness was greatest among the digeneans, which represented 48% of the total species recovered, followed by the crustaceans (19% of total species). Species richness at the component community level (14–24 species) was similar to reported richness in other small tuna species. The component communities and infracommunities of E. lineatus exhibited a similar pattern: high species richness and diversity, and numerical dominance by a single species, mainly by one of the didymozoids Allopseudocolocyntotrema claviforme or Pseudocolocyntotrema yaito. Parasite community structure and species composition varied among sampling years. Variations were possibly caused by a combination of abiotic and biotic factors which generated notable changes in the infection levels of several component species during the study period. These communities may therefore be unpredictable in terms of structure and species composition, as has been suggested for other communities of marine parasites.

THE PARASITE FAUNA OF COREGONIDS FROM LOWER OB TRIBUTARIES AND THE KHATANGA RIVER

A comparative analysis was carried out investigating the parasite faunas of coregonids (humpback whitefish, peled, least cisco, and tugun) from the Lower Ob Ural tributaries (Rivers Synya, Voykar, Severnaya Sos'va, Sob, Shchuch'ya) and from the Khatanga River. Surveys revealed 48 parasite species, most with a complex life cycle (29 helminth species and 3 myxosporidian species whose development involves benthic organisms). Semi-anadromous whitefish spawning in Lower Ob tributaries were shown to have a poorer species composition of parasites (13-16 species) compared to land-locked whitefish from the Khatanga (23 species). The parasite fauna of semi-anadromous peled from the Lower Ob had the most diverse species composition among the rest of coregonids, with relatively high similarity between the rivers Voykar and Synya, while that of the S. Sos'va River stood apart. Resident ecotypes of peled from the rivers Shchuch'ya and Khatanga were similar in the species composition of their parasites in spite of the substantially different geographical locations of the catchments. Least cisco within the Lower Ob basin (Rivers Voykar and Sob) featured a high similarity of the parasite species composition, which was, however, very different from that in least cisco from the Khatanga. Some freshwater parasites (infusorians, monogeneans, trematodes and leeches) apparently get lost in the brackish waters of Khatangsky Bay, while the crustacean Coregonicola orientalis is introduced into the river during the spawning run. The parasite fauna of tugun was the richest in the Khatanga (17 species), relatively poor in the Sob (5) and Shchuch'ya (6 species), and generally reflected the features of the fish ecology in each specific river.