Parasites Of Birds Research Articles

Citizen scientists mapping the United Kingdom's and Republic of Ireland's flat flies (louse flies) (Diptera: Hippoboscidae) reveal a vector's range shift.

Changes in climate may cause changes in the ranges, phenology and interactions of insects with other species and lead parasites to switch host species. A study of louse (flat) flies in the United Kingdom, Republic of Ireland and Isle of Man, in which licensed bird ringers acting as citizen scientists collected ectoparasites that left birds during ringing, showed recent range shifts of several species. The Common or Bird Louse Fly Ornithomya avicularia (Linnaeus, 1758), a vector of Haemoproteus sp. and trypanosomes, has undergone a major northwards range expansion of over 300 km in the United Kingdom (UK) since the 1960s. The Finch Louse Fly Ornithomya fringillina (Curtis, 1836) has also expanded its range over 300 km northwards and 400 km westwards into the Island of Ireland, and the Swallow Louse Fly Ornithomya biloba (Dufour, 1827) is now established in Wales and Southern England. The Grouse Louse Fly Ornithomya chloropus (Bergroth, 1901) has undergone a range contraction at lower altitudes and on the southern edge of its range. Other species of louse fly were detected: Crataerina pallida (Latreille, 1812), Stenepteryx hirundinis (Linnaeus, 1758), Pseudolynchia garzettae (Rondani, 1879) and Icosta minor (Bigot, 1858). Some generalist species have shifted their phenology, whereas the more specialist nest parasites of migrant birds have not, as the arrival and breeding dates of their hosts have not changed. The range changes of the generalist species of these ectoparasites may have implications for bird health, especially if they switch to new host species as their ranges shift.

Redefining the spliceosomal introns of the sexually transmitted parasite Trichomonas vaginalis and its close relatives in columbid birds.

Trichomonas vaginalis infects the urogenital tract of men and women and causes the sexually transmitted infection trichomoniasis. Since the publication of its draft genome in 2007, the genome has drawn attention for several reasons, including its unusually large size, massive expansion of gene families, and high repeat content. The fragmented nature of the draft assembly made it challenging to obtain accurate metrics of features, such as spliceosomal introns. The number of introns identified varied over the years, ranging from 41 when first characterized in 2005, to 32 in 2018 when the repertoire was revised. In both cases, the results suggested that more introns could be present in the genome. In this study, we exploited our new T. vaginalis G3 chromosome-scale assembly and annotation and high-coverage transcriptome datasets to provide a definitive analysis of the complete repertoire of spliceosomal introns in the species. We developed a custom pipeline that distinguishes true splicing events from chimeric alignments by utilizing the extended motifs required by the splicing machinery and experimentally verified the results using transcript evidence. We identified a total of 63 active introns and 34 putative "inactive" intron sequences in T. vaginalis, enabling an analysis of their length distribution, extended consensus motifs, intron phase distribution (including an unexpected expansion of UTR introns), and functional annotation. Notably, we found that the shortest intron in T. vaginalis, at only 23 nucleotides in size, is one of the shortest introns known to date. We tested our pipeline on a chromosome-scale assembly of the bird parasite Trichomonas stableri, the closest known relative to T. vaginalis. Our results revealed some conservation of the main features (total intron count, sequence, length distribution, and motifs) of these two closely related species, although differences in their functional annotation and duplication suggest more specialized splicing machinery in T. vaginalis.

Population structure of Clinostomum complanatum (Trematoda: Digenea) with new data on haplotype diversity of flukes from Slovakia and Italy.

The fluke Clinostomum complanatum, a parasite of piscivorous birds, but also reptiles and rarely mammals, has established several foci in the western Palaearctic regions. Previous studies pointed out the complicated taxonomy of the genus, but broader population genetic analysis of C. complanatum has not yet been carried out. The aim of this study was to determine the structure, intraspecific variability, and diversity of mitochondrial cox1 haplotypes of C. complanatum from different localities in Slovakia (Danube floodplain forests) and Italy (Emilia-Romagna and Tuscany), as well as to evaluate the interrelationships among populations from Europe, the Middle East, and North Africa. The genetic structure of C. complanatum from Slovakia and Italy was represented by a great number of haplotypes, showing stable populations with high intraspecific diversity. The haplotypes of samples from other localities (Romania, Turkey, Egypt, and Iran) showed possible gene flow among the populations from Central Europe down to the Mediterranean region, North Africa, and the Middle East. The genetic homogeneity of these samples can be linked to the distribution and migratory routes of the definitive hosts, aquatic piscivorous birds, mainly herons and cormorants, that spread parasite eggs among the continents.

Intensity of <em>Haemoproteus</em> spp. blood infection differs between wild birds captured using different trapping methods

Infection with haemoparasites (Haemosporida spp.) is common within wild birds’ populations and has been associated with adverse effects on birds’ fitness and life performance. Existing literature suggests a hypothesis that birds infected with haemosporidians and exhibiting high parasitemia levels may demonstrate reduced activity, potentially leading to their underrepresentation in captures which use stationary traps, such as mist nets. However, there are limited studies demonstrating this phenomenon in wild birds. To study the possible under representation of highly parasitized birds, captured with commonly used stationary mist nets, we compared parasitemia levels of haemosporidian parasites in wild birds captured during spring migration using both actively startling of birds and birds trapped passively into the mist nets. Utilizing cumulative link mixed models, we assessed the influence of trapping methods on parasitemia scores, controlling for factors such as species identity, season progression, and migration distance. Our dataset comprised 1815 individuals of 60 species, including 142 actively captured and 1673 passively captured ones. Although the number of infected individuals was higher in passively caught birds (24 % in active vs 43 % in passive), the study revealed a significant difference between infected birds within two capture methods: despite challenges in balancing sample sizes, and trapping dates, the findings affirm the underestimation of birds having high parasitemia levels with prevalent mist net techniques. We highlight the importance of considering potential biases in trapping methods when studying haemosporidian parasites in avian hosts during migration.

Description of a new Ornithomya Latreille, 1802 (Diptera: Hippoboscidae) species with a key to all species of this genus

The family Hippoboscidae Samouelle, 1819 includes approximately 213 species. The genus Ornithomya Latreille, 1802 (Diptera: Hippoboscidae) is one of the largest louse fly genera and now includes 31 species. These flies are parasites of different small birds from the order Passeriformes. Many of them specifically prefer swallows as hosts. Swallows have a wide beak, short legs, dense plumage and poor preening abilities. They feed in flight and therefore do not associate insects in their nests with food. A new species of the genus Ornithomya, O. delichoni sp. nov., is described. A female of O. delichoni sp. nov. was collected in the Spassk district of Primorskiy Territory (Far East, Russia) from western house martin. The new species differs from other Ornithomya species from this region in its combined length of the head and thorax, eye width, number of large setae on the scutellum, and arrangement of microtrichia on the wings. The new species is named after the bird from which the fly was collected. An updated key for 32 species of the genus Ornithomya, including the new one, is provided. These key is based on the following morphological features: head and thorax length combined, wing length, number of scutellum and mesonotum setae, ratio of sections of costal vein between junctions of R1 and R2+3 and between junctions of R2+3 and R4+5 and arrangement of wing microtrichia. Additionally, known data on the hosts and distribution of the Ornithomya species are provided.

Expanding the known haemosporidian parasite diversity in Eurasian Bluethroat (Luscinia svecica) subspecies through amplicon sequencing

Monitoring haemosporidian parasites in birds is essential to comprehend the dynamics of avian malaria, a disease that significantly affects bird populations worldwide. This study concentrated on the prevalence and diversity of haemosporidian parasites in 198 specimens from two subspecies of the Eurasian bluethroat (Luscinia svecica), aiming to explore the genetic diversity and species richness of haemosporidian fauna across the host populations. By utilizing next-generation amplicon high-throughput sequencing (NGS), we observed a marked increase in the detection of haemosporidian diversity, revealing cryptic variants and species previously unidentified by Sanger sequencing. A high prevalence of Plasmodium was seen in all studied sites, accompanied by a less frequent Leucocytozoon infection in the red-spotted subspecies and minimal occurrence of Haemoproteus. Both previously known and new, low prevalence cryptic variants were detected, underscoring the complexity of haemosporidian infections in avian hosts. The use of species delimitation tools provided a detailed understanding of haemosporidian species diversity, their coexistence within hosts, and their phylogenetic relationships. Despite the varying ecological characteristics of the study sites, no significant difference in haemosporidian alpha diversity among populations was found. However, significant differences in beta diversity were identified, suggesting that habitat characteristics and geographic distance influence parasite distribution. These findings highlight the importance of advanced molecular techniques in revealing the hidden diversity of parasites, offering valuable insights into the ecology and evolution of haemosporidian infections. Given the threatened status of one of the host’s populations, knowledge on local diversity of haemosporidian parasites also has implications for possible conservation strategies.

Copromicroscopic Diagnosis and Prevalence of Parasitic Infections in Animals in Sitio Ibayo, San Mateo, Rizal, Philippines: Establishing a Sentinel Study for Zoonotic Disease Surveillance.

This study investigates the prevalence and intensity of parasitic infections in animal fecal samples collected from Sitio Ibayo, San Mateo, Rizal, Philippines, a suburban community considered a potential sentinel site for zoonotic disease surveillance. Using cross-sectional sampling, 132 animal fecal samples were collected in the area exhaustively. Samples were processed through direct smear with saline solution and Lugol's iodine and flotation technique using mini- and fill-FLOTAC. Microscopy was conducted, and the photomicrographs were analyzed to identify the parasite. This study revealed an overall prevalence of parasitic infection of 50.67%. The prevalence was 100% in birds, cats, doves, and a rabbit, whereas dogs showed a high prevalence of 68.75%, followed by ducks at 66.67% and humans at 44.44%. Notably, the parasitic infection among ruminants was low, including zero in cows. Farm animals such as pigs and chickens have 53.8% and 42.9% prevalence, respectively. The co-infection was seen as 24 (18.18%) samples had two types of parasites, 12 (9.09%) had three types of parasites, three (2.27%) had four types of parasites, and one (0.76%) had five types of parasites. A total of 17 genera/species of parasites were found, including those belonging to the phylum Nematoda, phylum Platyhelminthes, and phylum Protozoa. Intensity analysis of infections demonstrated high intensity ofCapillariaspp. infections among 50% of the sampled birds andEimeriaspp. among 20% of the sampled geese, with most parasitic infections in the other categories at low intensity. This study highlights the burden of parasitic infections among various animal groups in Sitio Ibayo. The prevalence and co-infections in companion animals, farm animals, and humans were notable. The high prevalence of parasites in dogs, cats, and birds underscores their potential role in maintaining and dispersing parasitic infections within the ecosystem. The predominance of low-intensity infections suggests that while immediate health impacts may be minimal for some hosts, multi-parasite infections raise concerns for ecosystem health and zoonotic transmission. Targeted interventions using the One Health approach, including improved hygiene practices, deworming programs, and public awareness campaigns, are needed to mitigate the spread of parasitic diseases in this community.

A new blood parasite of the accentor birds: description, molecular characterization, phylogenetic relationships and distribution.

Haemoproteus bobricklefsi sp. nov. (Haemosporida, Haemoproteidae) was found in the dunnock Prunella modularis and represents the first blood parasite described in accentor birds of the Prunellidae. The description is based on the morphology of blood stages and includes information about a barcoding segment of the mitochondrial cytochrome b gene (lineage hDUNNO01) and the full mitochondrial genome, which can be used for identification and diagnosis of this infection. The new parasite can be readily distinguished from described species of haemoproteids parasitizing passeriform birds due to markedly variable position of nuclei in advanced and fully grown macrogametocytes. Illustrations of blood stages of the new species are given, and phylogenetic analyses based on partial mitochondrial cytochrome b gene sequences and the full mitochondrial genome identified the closely related lineages. DNA haplotype networks showed that transmission occurs in Europe and North America. This parasite was found in the dunnock in Europe and several species of the Passerellidae in North America. It is probably of Holarctic distribution, with the highest reported prevalence in the UK. The parasite distribution seems to be geographically patchy, with preference for areas of relatively cool climates. Phylogenetic analysis suggests that H. bobricklefsi sp. nov. belongs to the Parahaemoproteus subgenus and is probably transmitted by biting midges belonging to Culicoides (Ceratopogonidae). The available data on molecular occurrence indicate that this pathogen is prone to abortive development, so worth attention in regard of consequences for bird health.

Unravelling the diversity of Posthodiplostomum Dubois, 1936 (Trematoda: Diplostomidae) in fish-eating birds from the Neotropical region of Mexico, with the description of a new species.

Adults of the genus Posthodiplostomum, Dubois, 1936 are parasites of fish-eating birds, mainly of the family Ardeidae, and are globally distributed. The genus currently comprises 35 species, although recent molecular evidence has shown that the diversity of the genus is underestimated since several candidate species have been recognized. In the Neotropical region of Mexico, at least 6 Posthodiplostomum lineages have been detected with metacercaria stages recovered from unrelated fish hosts. Here, we obtained adult specimens of Posthodiplostomum from 6 fish-eating birds representing 2 families (Butorides virescens, Ardea herodias, Nycticorax nycticorax, Tigrisoma mexicanum – Ardeidae, and Rynchops niger and Leucophaeus atricilla – Lariidae) from 4 localities in southern Mexico. Specimens were sequenced for 2 nuclear (28S and ITS1–5.8S–ITS2) and 1 mitochondrial (cox1) molecular marker. Phylogenetic analyses allowed us to link metacercariae and adult specimens and recognized a lineage, which was described morphologically. The new species can be distinguished from its congeners by its prosoma morphology and body size; this is the first described species in the Neotropical region of Mexico. Additionally, new host and locality records for P. macrocotyle and P. pricei are presented, expanding their geographical distribution range in the Americas.

Platyhelminthes of common buzzard (Buteo buteo): Checklist of species in Europe and new parasite-host associations in Romania

BackgroundPlatyhelminthes are common parasites of diurnal birds of prey, including common buzzard (Buteo buteo). They are widely distributed in Europe. Despite the extensive study of flatworms across the continent, this study represents the first report for Romania and extends the biogeographic knowledge of Platyhelminthes in diurnal raptors. It also identifies common buzzards as a new host of Parastrigea flexilis in Europe. Materials and methodsBetween 2017 and 2020, 63 common buzzards (Buteo buteo) found road killed or dead due to other causes were collected from Romania. All specimens were necropsied and examined for internal helminths, which were preserved in ethanol for molecular identification and formaldehyde for morphological identification. ResultsSpecies identified included Cestoda: Cladotaenia globifera (33.3%) and five species of Trematoda: Neodiplostomum attenuatum (12.7%), Strigea falconis (6.4%), Parastrigea flexilis (3.2%), Neodiplostomum spathoides (3.2%) and Brachylaima fuscata (1.6%). ConclusionsThis study provides new data about diversity, phylogenetics and geographical distribution of Platyhelminthes parasitizing Buteo buteo in Romania. To our best knowledge, it identifies B. buteo as a new host of Parastrigea flexilis and reports the first genetic sequence of Neodiplostomum spathoides.

Common cuckoo eggs are more resistant to puncture by the host

The puncture resistance hypothesis suggests that thick-shelled eggs of parasitic birds can resist puncture-ejection by the host. However, few experiments have yet been conducted to test this hypothesis in terms of natural host behavior (e.g., pecking at foreign eggs). To explore whether the eggshells of common cuckoos (Cuculus canorus) are resistant to puncture-ejection by their common hosts, Oriental reed warblers (Acrocephalus orientalis), we designed experiments to investigate if and how breeding Oriental reed warblers peck at foreign eggs that includes common cuckoo, Oriental reed warbler and budgerigar (Melopsittacus undulatus) eggs. The results showed that, given the same frequency of egg pecking, the probability of eggshell breakage was 87.5% for eggs of the Oriental reed warbler and 0% for eggs of the common cuckoo, with a significant difference (P = 0.001, Fisher's exact test). Our study shows clearly that common cuckoos' eggshells are less susceptible to puncture-ejection than those of Oriental reed warblers and budgerigars. This indicates that the eggshells of common cuckoos can resist host Oriental reed warblers' puncture-ejection, supporting the puncture resistance hypothesis.

Diversity and Interactions between Picobiine Mites and Starlings.

The subfamily Picobiinae (Acariformes: Syringophilidae) comprises obligate and permanent parasites of birds found exclusively in the quills of contour feathers. We studied associations of picobiine mites with birds of the family Sturnidae (Aves: Passeriformes) across the Palaearctic, Afrotropical, Oriental, and Oceanian zoogeographical regions. Among the 414 examined bird individuals belonging to 44 species (35.2% of all sturnids), 103 individuals from 24 species (54.5% of examined species) were parasitised by quill mites. The diversity of mites was represented by five species, including one newly described, Picobia malayi Patan and Skoracki sp. n. Statistical analysis of the Picobiinae-Sturnidae bipartite network demonstrated a low connectance value (Con = 0.20) and high modularity, with significant differences in the H2' specialisation index compared to null model values. The network structure, characterised by four distinct modules, highlighted the specificity and limited host range of the Picobiinae-Sturnidae associations. The distribution of Picobia species among starlings was congruent with the phylogeny of their hosts, with different mites parasitising specific clades of starlings. Additionally, the findings suggest that the social and breeding behaviours of starlings influence quite a high prevalence. Finally, our studies support the validity of museum collections to study these parasitic interactions.

Survey of gastrointestinal coccidian parasites of pet birds in Tehran

ABSTRACT Birds of various families and genera comprise a notable proportion of veterinary clients in veterinary practice. Regarding the scarcity of information on avian coccidia in pet birds, this study was designed to investigate and identify the diversity of gastrointestinal coccidian protozoa in caged pet birds. Accordingly, droppings samples were collected in 2.5% potassium dichromate and examined for the presence of oocysts by wet smear and by flotation with the saturated salt solution. Detected oocysts were further morphologically specified. Special Modified Ziehl-Neelsen stain was used for the detection of Cryptosporidium spp. oocysts. Out of the 145 droppings that were collected for parasitological investigations, it was discovered that a Japanese quail (Coturnix japonica) had a Cryptosporidium sp. infection (1/145: 0.7%). Additionally, Isospora spp. was found in a common mynah and a canary (2/145: 1.4%), while Eimeria sp. was detected in a canary (1/145: 0.7%). Studied birds were clinically normal and no signs of intestinal infection were observed. The oocysts are described morphologically in detail and compared with the available data. Periodic faecal examination should be recommended for monitoring intestinal parasites in pet birds both from a public health perspective for Cryptosporidium and for avian host health in the case of non-zoonotic parasites. Additionally, the identification of parasite/host species composition will enhance our understanding of species diversity and the variety of hosts that coccidian parasites are capable of infecting.

Haemosporidian intensity and nestlings' life-history along an urban-to-rural gradient

Urban areas, i.e. dense housing and reduced green spaces, can significantly impact avian health, through altering land use and increasing biotic and abiotic stress. This study assessed the association of urbanization on haemosporidian infections, vectors, immune response, and body condition in Parus major nestlings, across four classes of urbanization along an urban-to-rural gradient in Vienna, Austria. Contrary to our expectations, vector abundance remained consistent across the gradient, while an increase in leukocyte count is positively associated with total parasite intensity. We found that nestlings in more urbanized areas exhibited higher parasite intensity and altered immune response, as evidenced by variations in the heterophil to lymphocyte ratio and leukocyte counts. Culicidae female vectors were associated with nestlings’ total parasites, scaled mass index, and industrial units. Nestlings in highly developed areas had higher infection rates than those in forests, suggesting increased exposure to infections. However, there was no clear relationship between total female vectors and total parasites. The level of urbanization negatively affected nestling body condition, with a decrease in fat deposits from forested to highly urbanized areas. Our findings highlight the complex interplay between urbanization, vector-borne parasite transmission, and host immune response, emphasizing the need for comprehensive urban planning to improve wildlife health and guarantee ecosystem functioning. Understanding how urbanization affects bird immunity and parasite infections is critical for adapting urban landscapes for wildlife health and ecosystem integrity.

Untangling the “Renicola somateria” (Digenea, Renicolidae) Muddle: Actual Number of Species and Their Distribution and Transmission in the Holarctic

Renicolids are parasites of aquatic birds. Their species identification based on morphological characters is problematic. Here, we revised the composition of Renicola spp. parasitising anatids in nearshore areas of northern seas using integrated morphological and molecular data. We redescribed Renicola somateria and verified the diagnosis of R. mediovitellata. We established that the first intermediate host (FIH) of R. somateria is the mollusc Buccinum undatum, while the FIHs of R. mediovitellata are Nucella spp. molluscs. We described the intramolluscan stages of both species. Renicola somateria and R. mediovitellata formed a separate clade in the molecular trees of the Renicolidae. This finding confirms the existence of three main phylogenetic branches of renicolids, differing in the structure of adults, type of cercariae, and host range. Molecular data demonstrated an amphiboreal distribution of both R. somateria and R. mediovitellata. The former is represented by a single population in Europe and the North Pacific, while the latter forms separate populations in these regions. This may be because R. somateria actually uses not only B. undatum but also some other buccinid species with similar circum-Arctic ranges as the FIH. We discuss the roles played in the formation of digenean ranges by the vagility of the definitive host, the lifespan of the adults, and the distribution of the FIH.

Avian nematode parasites of some wild birds of Bangladesh

Avian nematode parasites of some wild birds of Bangladesh

Urban house finches are more resistant to the effects of artificial light at night

Rapid urbanization of habitats alters the physical, chemical, auditory, and photic environments of human and wild animal inhabitants. One of the most widespread transformations is caused by artificial light at night (ALAN), but it is not clear the extent to which individuals acclimate to such rapid environmental change. Here, we tested the hypothesis that urban birds show increased resistance to harmful behavioral, parasitological, and physiological effects of ALAN. We captured house finches (Haemorhous mexicanus), a bird that commonly inhabits cities and their natural surroundings, from two urban and two rural sites in Phoenix, Arizona, USA, which differ by both degree of urbanization and by multiple orders of magnitude in ALAN intensity, and placed them in a common garden laboratory setting. We exposed half of the birds from each habitat type to ecologically relevant levels of night lighting during the subjective night and found that, while ALAN exposure reduced sleep in both urban and rural birds, ALAN-exposed urban birds were able to sleep longer than ALAN-exposed rural birds. We also found that ALAN exposure increased the proliferation rate of an intestinal coccidian parasite (Isospora spp.) in both urban and rural birds, but that the rate of proliferation was lower in urban relative to rural birds. We found that night lighting suppressed titers of feather corticosterone in rural but not urban birds, suggesting that light impairs HPA function through chronic stress or suppression of its circadian rhythmicity, and that urban birds were again resistant to this effect. Mediation analyses show that the effect of ALAN exposure in rural birds was significantly sleep-mediated for feather corticosterone but not coccidiosis, suggesting a diversity of mechanisms by which ALAN alters physiology. We contribute further evidence that animals from night-lit habitats can develop resistance to ALAN and its detrimental effects.

New insights into the relationship of parasitic quill mites and birds: Picobia species in Asian and New World Barbets

Quill mites are obligatory parasites of birds, widely distributed among their hosts. For the first time, we examined birds from two small, phylogenetically closely related piciform families, Megalaimidae (New World Barbets) and Capitonidae (Asian Barbets), for infestation by parasitic mites of the subfamily Picobiinae (Acariformes: Syringophilidae). Birds of the family Megalaimidae were infested by two new species of the genus Picobia: Picobia insolita Skoracki, Sikora & Unsoeld n. sp. collected from Caloramphus hayii in Indonesia, and Picobia paraheeri Skoracki, Sikora & Unsoeld n. sp. found on nine bird species of the genus Psilopogon, including P. zeylanicus in Sri Lanka, P. asiaticus in India, P. virens in China, P. franklini and P. lineatus both in Nepal, and P. corvinus, P. rafflesii, P. chrysopogon, P. pyrolophus, all in Indonesia. Within the Capitonidae family, a single quill mite species, Rafapicobia olszanowskii Skoracki et al. 2020, was found infesting two species of the genus Capito, i.e. C. maculicoronatus in Panama and C. niger in Surinam and Guyana, and these two Asian Barbet species are new hosts for this quill mite species. Our further analysis of picobiine mite records associated with the entire order of Piciformes revealed a correlation between the mites’ distribution patterns and the phylogeny of piciform birds. This significant congruence suggests a close evolutionary relationship between picobiine mites and their avian hosts. http://zoobank.org/urn:lsid:zoobank.org:pub:F9DEB980-6481-4229-A071-52AC9FF69879 http://zoobank.org/urn:lsid:zoobank.org:act:6B4F98EB-D166-4DBF-B26F-49F4B22903A8 http://zoobank.org/urn:lsid:zoobank.org:act:98140DAC-5C53-438B-85A6-1FBA52D178D0

Morphological and molecular data on acuariid nematodes in European great cormorants (Phalacrocorax carbo sinensis) and pygmy cormorants (Microcarbo pygmaeus)

The family Acuariidae is a speciose group of parasitic nematodes, infecting mostly birds as definitive hosts. This study focused on the characterization of two species of acuariids, collected in two different species of piscivorous birds, the European great cormorant Phalacrocorax carbo sinensis from Italy, and the pygmy cormorant Microcarbo pygmaeus from Israel. Parasites were analyzed using light and scanning electron microscopy and by amplification and sequencing of the 28S rDNA. The results of morphological and molecular analyses showed that Ph. carbo sinensis was infected by the acuariid Syncuaria squamata (12 females) and Cosmocephalus obvelatus (1 female), whereas M. pygmaeus was infected by C. obvelatus (2 males, 12 females). The present results provide new data on the distribution of acuariid parasites of piscivorous birds, the first report of Acuariidae in Israel, and the first molecular data on S. squamata and C. obvelatus, which will be useful in future epidemiological and phylogenetic studies of these widely distributed, but less molecularly studied parasites.

"Isolation by Gentes with Asymmetric Migration" shapes the genetic structure of the common cuckoo in China.

Amid coevolutionary arms races between brood parasitic birds and their diverse host species, the formation of host-specific races, or gentes, has drawn significant research focus. Nevertheless, numerous questions about gentes evolutionary patterns persist. Here, we investigated the potential for gentes evolution across multiple common cuckoo (Cuculus canorus) populations parasitizing diverse host species in China. Using maternal (mitochondrial and W-linked DNA) and biparental (autosomal and Z-linked DNA) markers, we found consistent clustering of cuckoo gentes (rather than geographical populations) into distinct clades in matrilineal gene trees, indicating robust differentiation. In contrast, biparental markers indicated intermixing of all gentes, suggesting asymmetric gene flow regardless of geography. Unlike the mitonuclear discordance commonly resulting from incomplete lineage sorting, adaptive introgression, or demographic disparities, the observed pattern in brood parasitic cuckoos might reflect biased host preferences between sexes. We hereby present the "Isolation by Gentes with Asymmetric Migration" model. According to this model, the maternal line differentiation of the common cuckoo in China is potentially driven by host preferences in females, whereas males maintained the integrity of the cuckoo species through random mating. To achieve this, cuckoo males could perform flexible migration among gentes or engage in early copulation with females before reaching the breeding sites, allowing female cuckoos to store sperm from various gentes. Future studies collecting additional samples from diverse cuckoo gentes with overlapping distribution and investigating the migratory and copulation patterns of each sex would enhance our understanding of sex-biased differentiation among cuckoo populations in China.