Avian haemosporidian parasites from wild-caught mosquitoes with new evidence on vectors of Plasmodium matutinum

Avian haemosporidian parasites are spread worldwide and pose a threat to their hosts occasionally. A complete life cycle of these parasites requires two hosts: vertebrate and invertebrate (a blood-sucking insect that acts as a vector). In this study, we tested wild-caught mosquitoes for haemosporidian infections. Mosquitoes were collected (2021-2023) in several localities in Lithuania using a sweeping net and a CDC trap baited with CO2, morphologically identified, and preparations of salivary glands were prepared (from females collected in 2022-2023). 2093 DNA samples from either individual after dissection (1675) or pools (418 pools/1145 individuals) of female mosquito's abdomens were screened using PCR for the detection of haemosporidian parasite DNA. Salivary gland preparations were analyzed microscopically from each PCR-positive mosquito caught in 2022 and 2023. The average prevalence of haemosporidian parasites for all analyzed samples was 2.0% and varied between 0.6% (2021) and 3.5% (2022). DNA of Plasmodium ashfordi (cytochrome b genetic lineage pGRW02), P. circumflexum (pTURDUS1), P. homonucleophilum (pSW2), P. matutinum (pLINN1), P. vaughani (pSYAT05), Haemoproteus brachiatus (hLK03), H. majoris (hWW2), and H. minutus (hTUPHI01) were detected in mosquitoes. Coquilletidia richiardii (3.5%) and Culex pipiens (2.9%) were mosquito species with the highest prevalence of haemosporidian parasite DNA detected. Mixed infections were detected in 16 mosquitoes. In one of the samples, sporozoites of P. matutinum (pLINN1) were found in the salivary gland preparation of Culex pipiens, confirming this mosquito species as a competent vector of Plasmodium matutinum and adding it to the list of the natural vectors of this avian parasite.

Natural Vector of Avian Haemoproteus asymmetricus Parasite and Factors Altering the Spread of Infection

Avian haemosporidians (Apicomplexa, Haemosporida) are widespread blood protists, often causing severe haemosporidiosis, pathology, or even mortality in their hosts. Migrant birds regularly bring various haemosporidian parasites from wintering grounds to European breeding areas. Some haemosporidian parasites are prevalent in breeding sites and complete their life cycles in temperate climate zones and can be transmitted, but others do not. The factors altering the spread of these haemosporidians are not fully understood. Culicoides biting midges (Diptera: Ceratopogonidae) play an important role in the transmission of worldwide distributed avian haemosporidian parasites belonging to the genus Haemoproteus, but this information is particularly scarce and insufficient. The key factors limiting the spread of these pathogens in temperate climate zones, which we suspect and aim to study, are the absence of susceptible vectors and the ecological isolation of birds from vectors during the breeding period when transmission occurs. The primary objective of this study was to evaluate how the habitats of biting midges and bird breeding sites influence parasite transmission while also seeking to expand our understanding of the natural vectors for these parasites. Biting midges were collected using UV traps on the Curonian Spit, Lithuania, in different habitats, such as woodland and reeds, from May to September. Parous Culicoides females were identified, dissected, and investigated for the presence of Haemoproteus parasites using both microscopy and PCR-based tools. Among the dissected 1135 parous Culicoides females, the sporozoites of Haemoproteus asymmetricus (genetic lineage hTUPHI01) have been detected for the first time in the salivary glands of Culicoides festivipennis. The sporozoites of four Haemoproteus lineages were detected in Culicoides segnis, C. festivipennis, and Culicoides kibunensis biting midges. PCR-based screening showed that the females of seven Culicoides species were naturally infected with Haemoproteus parasites. The DNA of the parasite of owls, Haemoproteus syrnii (hSTAL2), was detected for the first time in Culicoides punctatus. The highest abundance of collected Culicoides females was in June, but the highest prevalence of Haemoproteus parasites in biting midges was in July. The abundance of Culicoides was higher in the woodland compared with reeds during the season. The acquired findings indicate the varied abundance and diversity of biting midges throughout the season and across distinct habitats. This variability could potentially impact the transmission of Haemoproteus parasites among birds with diverse breeding site ecologies. These outcomes hold the potential to enhance our understanding of the epizootiology of Haemoproteus infections within temperate climatic zones.

Contribution to the knowledge on black flies (Diptera: Simuliidae) as vectors of Leucocytozoon (Haemosporida) parasites in Lithuania

Black flies (Diptera: Simuliidae) are among the most bothersome blood-sucking dipterans causing severe irritation and distress to poultry, wild birds, animals, and humans globally. These insects are vectors of viruses, bacteria, parasitic protozoans, and nematodes of humans and animals. Parasitic protozoa belonging to Haemosporida (Apicomplexa) are distributed worldwide and black flies are the principal vectors of avian haemosporidian parasites of the genus Leucocytozoon, a common parasite of birds. Based on the detection of parasite DNA in insects, 13 black fly species were reported to be potential vectors of Leucocytozoon in Europe. Information about which species of Simulium can play a role in the transmission of Leucocytozoon parasites is insufficient and needs to be developed. The aim of our study was to determine which black fly species are involved in the transmission of Leucocytozoon parasites in the Eastern Europe. The black fly females were collected in Lithuania using entomological net. They were morphologically identified, dissected to prepare salivary glands preparations, and then screened for the presence of Leucocytozoon parasites using microscopy and PCR-based methods. In all, we collected 437 black fly females belonging to eight species. The DNA of Leucocytozoon (genetic lineage lCOCO18) was detected in one of analysed females identified as Simulium maculatum. All salivary gland preparations were negative for the presence of Leucocytozoon sporozoites. Our results included S. maculatum as a potential vector of Leucocytozoon parasites. Increasing the knowledge on vector ecology, behaviour and improving collection methods may be the key to understand the evolution and diversity of these parasites.

The contribution of insects to African swine fever virus dispersal: data from domestic pig farms in Lithuania

Outbreaks of African Swine Fever (ASF) in domestic pig farms in Lithuania typically begin in June and are detected through October, suggesting that insects might be involved in the transmission of the virus. Entomological collecting was performed to obtain two data sets: from farms with ASF outbreaks, and from farms without ASF outbreaks but in an ASF-infected area. Target insects from the families Muscidae, Calliphoridae and Tabanidae were analysed for the presence of ASF Virus (ASFV) DNA. Musca domestica L., Calliphoridae flies and Stomoxys calcitrans (L.) collected by entomological net during ASF outbreaks were confirmed to be ASFV positive. Viral DNA detected in insects collected by Nzi traps from farms with no ASFV outbreaks indicate that Culex, Lucilia, M. domestica and S. calcitrans are likely to play a role in spreading the ASFV mechanically. This finding could suggest contamination from outside of the farms: from infected wild boar or their carcasses. The role of Stomoxys flies as mechanical vectors could be accidental, because we did not find a significant correlation between the activity of S. calcitrans and the number of ASF outbreaks in pig farms, whereas temperatures positively correlated to the number of ASF outbreaks during 2018-2019.

The flying activity of biting midges (Ceratopogonidae: Culicoides) in Verkiai Regional Park, southeastern Lithuania

Culicoides biting midges are small dipterous insects (Diptera: Ceratopogonidae) which are known to be vectors of arboviruses, bacteria, protozoan and helminth parasites that can cause disease and mortality in livestock and poultry globally. Detailed knowledge of the Culicoides species composition and biology is essential to assess the risk of the introduction and transmission of pathogens. The aim of this study was to obtain data on Culicoides species composition and flying activity in southeastern Lithuania and to determine the meteorological variables related to the abundance of Culicoides biting midges. Biting midges were collected in Verkiai Regional Park, southeastern Lithuania, using an Onderstepoort trap once a week from April to October 2016 and 2018, and from April to July 2019; 7332 Culicoides females belonging to 22 species were identified. Both morphology and DNA barcoding were used for identification. The number of specimens trapped was highest for the Obsoletus Group, followed by Culicoides kibunensis and Culicoides impunctatus. The highest relative abundance and diversity of biting midges were found in May and June. The number of trapped biting midges correlated positively with the mean air temperature. The first biting midges in spring were caught when the mean daily temperature rose higher than 10 °C. No Culicoides were detected when the air temperature dropped below 5 °C in autumn. Wind speed and air humidity had no statistically significant effect on Culicoides abundance.

Molecular and morphological characterization of three new species of avian Onchocercidae (Nematoda) with emphasis on circulating microfilariae

Background

Blood parasites have been the subject of much research, with numerous reports of the presence of microfilariae in the peripheral blood (circulating microfilariae) of birds belonging to many orders. Current limitations in molecular characterization methods and species identification using morphological characters of circulating microfilariae are major obstacles to improving our understanding the biology of Filarioidea species, particularly in wildlife. The aim of this study was to partially fill these gaps, with particular emphasis on morphological features of microfilariae, which are the most readily accessible stages of these pathogens.

Methods

Peripheral blood samples of 206 birds belonging to genera Acrocephalus (five species) and Sylvia (five species) were examined using the buffy coat method to process the blood samples for the presence of microfilariae. Positive birds were dissected to collect adult nematodes. Microfilariae and adult nematodes were described, and sequences of their mitochondrial cytochrome c oxidase subunit I and nuclear 28S rDNA gene fragments were obtained and used for molecular characterization and Bayesian phylogenetic inferences.

Results

Overall prevalence of microfilariae was 2.9%. Microfilariae were found in the blood samples from six birds (2 Acrocephalus scirpaceus and 1 each of A. arundinaceus, Sylvia atricapilla, S. borin and S. curruca), which were dissected. All parasite species observed were new. Eufilaria acrocephalusi sp. n. and Eufilaria sylviae sp. n. were present in subcutaneous, peritracheal and periesophageal connective tissues in A. scirpaceus and S. borin, respectively. Splendidofilaria bartletti sp. n. was found in finger joins of S. atricapilla. Illustrations of microfilariae and adult nematodes are shown, and morphological and phylogenetic analyses identified the DNA barcode haplotypes that are associated with these species. Phylogenetic analysis places the parasites of different genera in different closely related clades.

Conclusions

Adult nematode morphological characters, which have been traditionally used in the taxonomy of Filarioidea species, have a phylogenetic value. Importantly, in our study parasites of different genera were readily distinguishable based on the morphology of their microfilariae. The link between molecular and morphology data requires more study in Filarioidea species research, particularly because this approach provides new knowledge on species identity using only readily accessible blood stages (microfilariae), thereby avoiding host dissection and thus minimizing harm to wildlife during research.

Culicoides biting midges involved in transmission of haemoproteids

BACKGROUND

Culicoides biting midges (Diptera, Ceratopogonidae) are known vectors of avian Haemoproteus parasites. These parasites cause diseases, pathology and even mortality in birds. The diversity of biting midges in Europe is great, but only four Culicoides species are known to be vectors of avian Haemoproteus parasites. In general, our knowledge about the role of the particular Culicoides species in the transmission of Haemoproteus parasites remains insufficient. Information gaps hinder a better understanding of parasite biology and the epizootiology of parasite-caused diseases. The aim of this study was to determine new Culicoides species involved in the transmission of Haemoproteus parasites.

METHODS

Biting midges were collected using a UV trap as well as sticky traps installed in bird nest boxes. Individual parous females were diagnosed for the presence of haemoproteids using both PCR-based and microscopic methods.

RESULTS

We collected and dissected 232 parous Culicoides females from 9 species using a UV trap and 293 females from 11 species from bird nest boxes. Culicoides obsoletus was the dominant species collected using a UV trap, and Culicoides kibunensis dominated among midges collected in nest boxes. PCR-based screening showed that 5.2% of parous biting midges collected using a UV trap and 4.4% of midges collected from nest boxes were infected with avian haemosporidian parasites. Haemoproteid DNA was detected in C. kibunensis, Culicoides pictipennis, Culicoides punctatus, Culicoides segnis and Culicoides impunctatus females. The sporozoites of Haemoproteus minutus (genetic lineages hTURDUS2 and hTUPHI01) were detected in the salivary glands of two C. kibunensis females using microscopy, and this finding was confirmed by PCR.

CONCLUSIONS

Culicoides kibunensis was detected as a new natural vector of Haemoproteus minutus (hTURDUS2 and hTUPHI01). Haemoproteid DNA was detected in females from five Culicoides species. This study contributes to the epizootiology of avian Haemoproteus infections by specifying Culicoides species as vectors and species that are likely to be responsible for the transmission of haemoproteids in Europe.

Development of Trypanosoma everetti in Culicoides biting midges

Trypanosoma species (Trypanosomatida, Kinetoplastea) are almost exclusively heteroxenous flagellated parasites, which have been extensively studied as the causative agents of severe trypanosomiasis in humans and domestic animals. However, the biology of avian trypanosomes remains insufficiently known, particularly in wildlife, despite information that some species might be pathogenic and affect the fitness of intensively infected individuals. Avian trypanosomes are cosmopolitans. Due to regular bird seasonal migrations, this host-parasite system might provide new insight for better understanding mechanisms of transcontinental dispersal of pathogens, their ecological plasticity, specificity and speciation. Trypanosoma everetti parasitizes numerous bird species globally, but data on its biology are scarce and its vectors remain unknown. This study aimed to test experimentally whether widespread Culicoides (Diptera: Ceratopogonidae) biting midges are susceptible to infection with this parasite. Two common house martins Delichon urbicum and two sedge warblers Acrocephalus schoenobaenus naturally infected with T. everetti were caught in the wild after arrival from African wintering grounds. Laboratory reared Culicoides nubeculosus and wild-caught Culicoides impunctatus biting midges were exposed by allowing them to take infected blood meals. The experimentally infected and control insects were maintained in the laboratory and dissected at intervals to follow the development of the parasite. Infections were determined using microscopic examination and PCR-based testing. Four closely related haplotypes of T. everetti were found, and each was present in different individual parasite-donor birds. These parasites readily developed and produced metacyclic trypomastigotes in C. nubeculosus and C. impunctatus biting midges. Molecular characterisation of T. everetti was developed. According to Bayesian phylogenetic analysis using a DNA fragment encoding 18S rRNA, the five species of small avian trypanosomes were closely related. Wild caught Culicoides biting midges were also collected and screened for the presence of natural infections. In all, 6.8% of wild-caught biting midges belonging to five Culicoides species were PCR-positive for kinetoplastids, including Trypanosoma species. Culicoides biting midges are readily susceptible and likely naturally transmit avian trypanosomes and thus, should be targeted in epidemiology research of avian trypanosomiasis.

Molecular characterization of swallow haemoproteids, with description of one new Haemoproteus species

Haemoproteus species (Haemosporida, Haemoproteidae) are cosmopolitan bird blood parasites, which often cause relatively benign infections in adapted avian hosts, but severe and even lethal haemoproteosis might develop due to internal organ damage if these pathogens inhabit non-adapted (wrong) hosts. Haemoproteids of swallows (Hirundinidae) remain fragmentarily investigated, with only two haemoproteid species reported in this bird family, which members are cosmopolitan, diverse and inhabit various terrestrial ecosystems, particularly in tropical countries. This study describes and provides molecular characterization of Haemoproteus parahirundinis n. sp. (cytochrome b lineage hHIRUS05), parasite of the most broadly distributed swallow, the Barn swallow Hirundo rustica. Gametocytes, gametes and ookinetes of the new species were examined and compared with other haemoproteids described in swallows. The phylogenetic analysis indicated the existence of a largely undescribed Haemoproteus species diversity in birds of the Hirundinidae and also suggests that all lineages of haemoproteids reported in swallows are transmitted by Culicoides biting midges, but not louse flies of the Hippoboscidae, which often inhabit their nests. The biting midges should be the first targets in vectors research of swallow haemoproteids. This study indicates existence of Haemoproteus species, which are readily distinct based on morphological characters of their blood and sporogonic stages, but differ only negligently in partial cytochrome b sequences, the main markers broadly used in molecular characterization of haemoproteids. That calls for further taxonomic research on haemoproteid in swallows, many species of which are endangered or even threatened with extinction because of habitat degradation.

A new methodology for sporogony research of avian haemoproteids in laboratory-reared Culicoides spp., with a description of the complete sporogonic development of Haemoproteus pastoris

BACKGROUND

Haemosporidian parasites of the genus Haemoproteus (Haemoproteidae) are widespread and cause haemoproteosis in birds and therefore, their diversity, ecology and evolutionary biology have become subjects of intensive research. However, the vectors and transmission patterns of haemoproteids as well as the epidemiology of haemoproteosis remain insufficiently investigated. Several species of Culicoides (Ceratopogonidae) support complete sporogony of haemoproteids belonging to the subgenus Parahaemoproteus. However, experimental research with these fragile insects is difficult to design in the field, particularly because their abundance markedly depends on seasonality. This is an obstacle for continuous sampling of sufficient numbers of naturally infected or experimentally exposed midges from wildlife. We developed simple methodology for accessing sporogonic development of haemoproteids in laboratory-reared Culicoides nubeculosus. This study aimed to describe the mosaic of methods constituting this methodology, which was applied for investigation of the sporogonic development of Haemoproteus (Parahaemoproteus) pastoris, a widespread parasite of the common starling Sturnus vulgaris.

METHODS

The methodology consists of the following main stages: (i) laboratory rearing of C. nubeculosus from the egg stage to adult insects; (ii) selection of naturally infected birds, the donors of mature gametocytes to expose biting midges; (iii) experimental exposure of insects and their laboratory maintenance; and (iv) dissection of exposed insects. Biting midges were exposed to H. pastoris (cytochrome b lineage hLAMPUR01) detected in one naturally infected common starling. Engorged insects were dissected at intervals in order to follow sporogony. Microscopic examination and PCR-based methods were used to identify the sporogonic stages and to confirm the presence of the parasite lineage in infected insects, respectively.

RESULTS

Culicoides nubeculosus females were successfully reared and exposed to H. pastoris, which completed sporogonic development 7-9 days post-infection when sporozoites were observed in the salivary glands.

CONCLUSIONS

The new methodology is easy to use and non-harmful for birds, providing opportunities to access the sporogonic stages of Parahaemoproteus parasites, which might be used in a broad range of parasitology and genetic studies. Culicoides nubeculosus is an excellent experimental vector of subgenus Parahaemoproteus and is recommended for various experimental studies aiming investigation of sporogony of these pathogens.

The life-cycle of the avian haemosporidian parasite Haemoproteus majoris, with emphasis on the exoerythrocytic and sporogonic development

BACKGROUND

Haemoproteus parasites (Haemosporida, Haemoproteidae) are cosmopolitan in birds and recent molecular studies indicate enormous genetic diversity of these pathogens, which cause diseases in non-adapted avian hosts. However, life-cycles remain unknown for the majority of Haemoproteus species. Information on their exoerythrocytic development is particularly fragmental and controversial. This study aimed to gain new knowledge on life-cycle of the widespread blood parasite Haemoproteus majoris.

METHODS

Turdus pilaris and Parus major naturally infected with lineages hPHYBOR04 and hPARUS1 of H. majoris, respectively, were wild-caught and the parasites were identified using microscopic examination of gametocytes and PCR-based testing. Bayesian phylogeny was used to determine relationships between H. majoris lineages. Exoerythrocytic stages (megalomeronts) were reported using histological examination and laser microdissection was applied to isolate single megalomeronts for genetic analysis. Culicoides impunctatus biting midges were experimentally exposed in order to follow sporogonic development of the lineage hPHYBOR04.

RESULTS

Gametocytes of the lineage hPHYBOR04 are indistinguishable from those of the widespread lineage hPARUS1 of H. majoris, indicating that both of these lineages belong to the H. majoris group. Phylogenetic analysis supported this conclusion. Sporogony of the lineage hPHYBOR04 was completed in C. impunctatus biting midges. Morphologically similar megalomeronts were reported in internal organs of both avian hosts. These were big roundish bodies (up to 360 μm in diameter) surrounded by a thick capsule-like wall and containing irregularly shaped cytomeres, in which numerous merozoites developed. DNA sequences obtained from single isolated megalomeronts confirmed the identification of H. majoris.

CONCLUSIONS

Phylogenetic analysis identified a group of closely related H. majoris lineages, two of which are characterized not only by morphologically identical blood stages, but also complete sporogonic development in C. impunctatus and development of morphologically similar megalomeronts. It is probable that other lineages belonging to the same group would bear the same characters and phylogenies based on partial cytb gene could be used to predict life-cycle features in avian haemoproteids including vector identity and patterns of exoerythrocytic merogony. This study reports morphologically unique megalomeronts in naturally infected birds and calls for research on exoerythrocytic development of haemoproteids to better understand pathologies caused in avian hosts.

Sporogony of four Haemoproteus species (Haemosporida: Haemoproteidae), with report of in vitro ookinetes of Haemoproteus hirundinis: phylogenetic inference indicates patterns of haemosporidian parasite ookinete development

BACKGROUND

Haemoproteus (Parahaemoproteus) species (Haemoproteidae) are widespread blood parasites that can cause disease in birds, but information about their vector species, sporogonic development and transmission remain fragmentary. This study aimed to investigate the complete sporogonic development of four Haemoproteus species in Culicoides nubeculosus and to test if phylogenies based on the cytochrome b gene (cytb) reflect patterns of ookinete development in haemosporidian parasites. Additionally, one cytb lineage of Haemoproteus was identified to the species level and the in vitro gametogenesis and ookinete development of Haemoproteus hirundinis was characterised.

METHODS

Laboratory-reared C. nubeculosus were exposed by allowing them to take blood meals on naturally infected birds harbouring single infections of Haemoproteus belopolskyi (cytb lineage hHIICT1), Haemoproteus hirundinis (hDELURB2), Haemoproteus nucleocondensus (hGRW01) and Haemoproteus lanii (hRB1). Infected insects were dissected at intervals in order to detect sporogonic stages. In vitro exflagellation, gametogenesis and ookinete development of H. hirundinis were also investigated. Microscopic examination and PCR-based methods were used to confirm species identity. Bayesian phylogenetic inference was applied to study the relationships among Haemoproteus lineages.

RESULTS

All studied parasites completed sporogony in C. nubeculosus. Ookinetes and sporozoites were found and described. Development of H. hirundinis ookinetes was similar both in vivo and in vitro. Developing ookinetes of this parasite possess long outgrowths, which extend longitudinally and produce the apical end of the ookinetes. A large group of closely related Haemoproteus species with a similar mode of ookinete development was determined. Bayesian analysis indicates that this character has phylogenetic value. The species identity of cytb lineage hDELURB2 was determined: it belongs to H. hirundinis.

CONCLUSIONS

Culicoides nubeculosus is susceptible to and is a likely natural vector of numerous species of Haemoproteus parasites, thus worth attention in haemoproteosis epidemiology research. Data about in vitro development of haemoproteids provide valuable information about the rate of ookinete maturation and are recommended to use as helpful step during vector studies of haemosporidian parasites, particularly because they guide proper dissection interval of infected insects for ookinete detection during in vivo experiments. Additionally, in vitro studies readily identified patterns of morphological ookinete transformations, the characters of which are of phylogenetic value in haemosporidian parasites.

A new species of Antocha Osten Sacken, 1860 (Diptera: Limoniidae) from Sichuan, China

The short-palped crane fly, Antocha (Antocha) bella Markevičiūtė Podenas sp. nov., is described from specimens collected in Sichuan, China. Redescriptions of Antocha (Antocha) fortidens Alexander, 1933 and Antocha (Antocha) nebulipennis immaculata Alexander, 1938, illustrations of distinguishing morphological features, general distribution, checklist and key to species of Antocha Osten Sacken from Sichuan, China are provided.

Identification of a new vector species of avian haemoproteids, with a description of methodology for the determination of natural vectors of haemosporidian parasites

BACKGROUND

Haemosporidian parasites are transmitted by dipteran blood-sucking insects but certain vectors remain unidentified for the great majority of described species. Sensitive PCR-based methods are often used for the detection of haemosporidian infection in wild-caught insects. However, this approach alone cannot distinguish between different sporogonic stages and thus is insufficient to demonstrate that the parasites produce the infective stage (sporozoite), which is essential for transmission. To prove that PCR-positive insects could act as vectors, the record of sporozoites is needed. We developed a methodology for the determination of natural vectors of avian Haemoproteus species and other haemosporidians. The essence of this approach is to apply PCR-based and microscopic diagnostic tools in parallel for sporozoite detection in insects.

METHODS

Culicoides biting midges transmit avian Haemoproteus parasites, but certain insect species, which are involved in transmission, remain insufficiently investigated. Biting midges were collected in the wild and identified; parous females were dissected and preparations of thorax content containing salivary glands were prepared. Remnants of the dissected midges were screened using PCR-based methods. Only thorax preparations of PCR-positive biting midges were examined microscopically.

RESULTS

In total, 460 parous females belonging to 15 species were collected and dissected. DNA of haemosporidians was detected in 32 (7%) of dissected insects belonging to 7 species. Of the thorax samples PCR-positive for Haemoproteus parasites, two preparations were microscopically positive for sporozoites. Both biting midges were Culicoides kibunensis. Haemoproteus pallidus (hPFC1) was identified, indicating that transmission of this infection occurs at the study site. It was proved that seven species of biting midges take bird blood meals naturally in the wild.

CONCLUSIONS

Culicoides kibunensis is a new vector species of avian haemoproteids and is a natural vector of H. pallidus. Numerous studies have identified vectors of Haemoproteus parasites experimentally; however, this is the first direct identification of a natural vector of Haemoproteus infection in the Old World. We suggest using the described methodology for vector research of Haemoproteus and other haemosporidians in the wild.

A new one-step multiplex PCR assay for simultaneous detection and identification of avian haemosporidian parasites

Accurate detection and identification are essential components for epidemiological, ecological, and evolutionary surveys of avian haemosporidian parasites. Microscopy has been used for more than 100 years to detect and identify these parasites; however, this technique requires considerable training and high-level expertise. Several PCR methods with highly sensitive and specific detection capabilities have now been developed in addition to microscopic examination. However, recent studies have shown that these molecular protocols are insufficient at detecting mixed infections of different haemosporidian parasite species and genetic lineages. In this study, we developed a simple, sensitive, and specific multiplex PCR assay for simultaneous detection and discrimination of parasites of the genera Plasmodium, Haemoproteus, and Leucocytozoon in single and mixed infections. Relative quantification of parasite DNA using qPCR showed that the multiplex PCR can amplify parasite DNA ranging in concentration over several orders of magnitude. The detection specificity and sensitivity of this new multiplex PCR assay were also tested in two different laboratories using previously screened natural single and mixed infections. These findings show that the multiplex PCR designed here is highly effective at identifying both single and mixed infections from all three genera of avian haemosporidian parasites. We predict that this one-step multiplex PCR assay, being convenient and inexpensive, will become a widely used method for molecular screening of avian haemosporidian parasites.

Different paths - the same virulence: experimental study on avian single and co-infections with Plasmodium relictum and Plasmodium elongatum

Co-infections are prevalent worldwide, however, we are still struggling to understand interactions between different parasites and their impacts on host fitness. In the present experimental study we analysed the infection dynamics of two avian malarial parasites Plasmodium elongatum (genetic lineage pERIRUB01) and Plasmodium relictum (genetic lineage pSGS1) and their impacts on host health during single and co-infections. We reveal that P. elongatum intensity of parasitemia is enhanced by the presence of P. relictum during co-infection, while the parasitemia of P. relictum stays the same. This illustrates how development of a parasite (P. elongatum) which infects both mature and young (polychromatic) red blood cells (RBCs) is facilitated during co-infection with a parasite which specialises in adult RBCs only (P. relictum). The virulence of co-infections was similar to that of the more virulent parasite (P. elongatum). However, the profile of infection and the mechanisms that caused mortality were different. Birds infected with P. elongatum only start to die due to non-regenerative anaemia, when intensity of parasitemia is light and the number of polychromatic RBCs decrease dramatically. Meanwhile, co-infected birds start to die when the mean intensity of parasitemia reaches 10% and the number of polychromatic RBCs increases abnormally, reflecting regenerative anaemia. Our findings reveal that typically measured parameters of virulence (e.g., mortality rate, level of hematocrit) can be the same during single and co-infections, but the mechanisms responsible for the observed virulence can be different. This information serves a better understanding of the processes underpinning the interactions of co-infected parasite species.

Primers targeting mitochondrial genes of avian haemosporidians: PCR detection and differential DNA amplification of parasites belonging to different genera

Haemosporida is a diverse group of vector-borne parasitic protozoa, ubiquitous in terrestrial vertebrates worldwide. The renewed interest in their diversity has been driven by the extensive use of molecular methods targeting mitochondrial genes. Unfortunately, most studies target a 478 bp fragment of the cytochrome b (cytb) gene, which often cannot be used to separate lineages from different genera found in mixed infections that are common in wildlife. In this investigation, an alignment constructed with 114 mitochondrial genome sequences belonging to four genera (Leucocytozoon, Haemoproteus, Plasmodium and Hepatocystis) was used to design two different sets of primers targeting the cytb gene as well as the other two mitochondrial DNA genes: cytochrome c oxidase subunit 1 and cytochrome c oxidase subunit 3. The design of each pair of primers required consideration of different criteria, including a set for detection and another for differential amplification of DNA from parasites belonging to different avian haemosporidians. All pairs of primers were tested in three laboratories to assess their sensitivity and specificity under diverse practices and across isolates from different genera including single and natural mixed infections as well as experimental mixed infections. Overall, these primers exhibited high sensitivity regardless of the differences in laboratory practices, parasite species, and parasitemias. Furthermore, those primers designed to separate parasite genera showed high specificity, as confirmed by sequencing. In the case of cytb, a nested multiplex (single tube PCR) test was designed and successfully tested to differentially detect lineages of Plasmodium and Haemoproteus parasites by yielding amplicons with different sizes detectable in a standard agarose gel. To our knowledge, the designed assay is the first test for detection and differentiation of species belonging to these two genera in a single PCR. The experiments across laboratories provided recommendations that can be of use to those researchers seeking to standardise these or other primers to the specific needs of their field investigations.

The widespread biting midge Culicoides impunctatus (Ceratopogonidae) is susceptible to infection with numerous Haemoproteus (Haemoproteidae) species

Background

Haemoproteus parasites are widespread, and some species cause disease in wild and domestic birds. However, the insect vectors remain unknown for the majority of species and genetic lineages of avian Haemoproteus. This information is crucial for better understanding the biology of haemoproteids, the epidemiology of haemoproteosis, and the development of morphological characters of sporogonic stages in wildlife haemosporidian parasites. It remains unclear whether the specificity of Haemoproteus parasites for vectors is broad or the transmission of a given parasite can be restricted to a single or few species of vectors. The aim of this study was to examine the sporogonic development of four species of common European avian haemoproteids in the common biting midge Culicoides impunctatus.

Methods

Wild-caught females of C. impunctatus were infected experimentally by allowing them to take blood meals on naturally infected Muscicapa striata, Cyanistes caeruleus, Ficedula hypoleuca and Motacilla flava harbouring mature gametocytes of Haemoproteus balmorali (genetic lineage hSFC9), H. majoris (hPARUS1), H. motacillae (hYWT1) and H. pallidus (hPFC1), respectively. Infected insects were collected, maintained under laboratory conditions and dissected daily in order to detect the development of ookinetes, oocysts and sporozoites. Microscopic examination and polymerase chain reaction based methods were used to detect the parasites. Bayesian analysis was applied to identify phylogenetic relationships among Haemoproteus lineages.

Results

All investigated parasites completed sporogony in C. impunctatus, indicating broad susceptibility of this biting midge for numerous Haemoproteus parasites. Ookinetes, oocysts and sporozoites were reported, described and compared morphologically. The investigated parasite species can be distinguished at the sporogony stage, particularly with regards to the morphology and rate of development of mature ookinetes. Analysis of data from the literature, and this study, shows that 12 genetically distantly related Haemoproteus parasites complete sporogony in C. impunctatus.

Conclusions

Susceptibility of C. impunctatus is broad for Haemoproteus parasites, indicating that this biting midge is an important natural vector of numerous species of avian haemoproteids in Europe. Some Haemoproteus species can be readily distinguished using morphological characters of ookinetes and sporozoites, as well as the rate of ookinete development. These characters can be used for the identification of Haemoproteus species during sporogony in vectors, and are worth more attention in these parasite taxonomy studies at the species levels.

Electronic supplementary material

The online version of this article (doi:10.1186/s13071-017-2317-z) contains supplementary material, which is available to authorized users.

Experimental evidence for hybridization of closely related lineages in Plasmodium relictum

Over 50 avian Plasmodium species have been described. However, PCR-based information shows much broader diversity of genetic lineages in these parasites. This discrepancy indicates insufficient knowledge about taxonomic diversity and boundaries of a single species in avian Plasmodium species. In recent taxonomy, most of genetically closely related lineages that share the same morphology and development patterns are attributed to the same biological species, but there is no information if these lineages are able to cross. This information is crucial to understand if these lineages form single or multiple evolutionary units. Due to presence of sexual process and sporogonic development of Plasmodium parasites in mosquitoes, self and cross-fertilization can occur and be identified during the oocyst stage. We initiated in vivo hybridization experiments of two widespread Plasmodium relictum lineages (pSGS1 and pGRW11) in experimentally infected Culex pipiens pipiens form molestus mosquitoes. To study putative hybrid oocysts, we used a laser microdissection technique together with PCR-based analyses of mitochondrial and nuclear genes. We demonstrate that both pSGS1 and pGRW11 lineages develop in infected mosquitoes in parallel, but also form hybrid oocysts of these two lineages. Our results are in accord to a recent global phylogeographic study of P. relictum that suggested that cross-fertilization between pSGS1 and pGRW11 might occur. This information helps to understand population structure, gene flow and the evolutionary process of haemosporidian parasites.

Description, molecular characterisation, diagnostics and life cycle of Plasmodium elongatum (lineage pERIRUB01), the virulent avian malaria parasite

Plasmodium elongatum causes severe avian malaria and is distributed worldwide. This parasite is of particular importance due to its ability to develop and cause lethal malaria not only in natural hosts, but also in non-adapted endemic birds such as the brown kiwi and different species of penguins. Information on vectors of this infection is available but is contradictory. PCR-based analysis indicated the possible existence of a cluster of closely related P. elongatum lineages which might differ in their ability to develop in certain mosquitoes and birds. This experimental study provides information about molecular and morphological characterisation of a virulent P. elongatum strain (lineage pERIRUB01) isolated from a naturally infected European robin, Erithacus rubecula. Phylogenetic analysis based on partial cytochrome b gene sequences showed that this parasite lineage is closely related to P. elongatum (lineage pGRW6). Blood stages of both parasite lineages are indistinguishable, indicating that they belong to the same species. Both pathogens develop in experimentally infected canaries, Serinus canaria, causing death of the hosts. In both these lineages, trophozoites and erythrocytic meronts develop in polychromatic erythrocytes and erythroblasts, gametocytes parasitize mature erythrocytes, exoerythrocytic stages develop in cells of the erythrocytic series in bone marrow and are occasionally reported in spleen and liver. Massive infestation of bone marrow cells is the main reason for bird mortality. We report here on syncytium-like remnants of tissue meronts, which slip out of the bone marrow into the peripheral circulation, providing evidence that the syncytia can be a template for PCR amplification. This finding contributes to better understanding positive PCR amplifications in birds when parasitemia is invisible and improved diagnostics of abortive haemosporidian infections. Sporogony of P. elongatum (pERIRUB01) completes the cycle and sporozoites develop in widespread Culex quinquefasciatus and Culex pipiens pipiens form molestus mosquitoes. This experimental study provides information on virulence and within species lineage diversity in a single pathogenic species of haemosporidian parasite.

PCR detection of malaria parasites and related haemosporidians: the sensitive methodology in determining bird-biting insects

Background

Knowledge about feeding preference of blood-sucking insects is important for the better understanding epidemiology of vector-borne parasitic diseases. Extraction of DNA from blood present in abdomens of engorged insects provides opportunities to identify species of their vertebrate hosts. However, this approach often is insufficiently sensitive due to rapid degeneration of host DNA in midguts. Recent studies indicate that avian malaria parasites (Plasmodium spp.) and related haemosporidians (Haemosporida) belonging to Haemoproteus can persist both in vectors and resistant blood-sucking insects for several weeks after initial blood meals, and these parasites can be readily detected by polymerase chain reaction (PCR)—based methods. Because avian haemosporidians are cosmopolitan, prevalent and strictly specific to birds, the determination of haemosporidian DNA in blood-sucking dipterans can be used as molecular tags in determining bird-biting insects. This hypothesis was tested by investigation of prevalence of natural haemosporidian infections in wild-caught mosquitoes (Culicidae) and biting midges (Ceratopogonidae: Culicoides).

Results

Females of mosquitoes (1072 individuals of three species) and biting midges (300 individuals of three species) were collected in wildlife using simple netting. They were identified and tested individually for the presence of both the haemosporidian parasites and the bird blood using PCR-based methods. Seven different Haemoproteus and two Plasmodium lineages were detected, with overall infection prevalence of 1.12 and 1.67 % in mosquitoes and biting midges, respectively. In all, the detection rate of avian haemosporidian parasites was three fold higher compared with the detection of avian blood.

Conclusions

Molecular markers of avian malaria parasites and other haemosporidians are recommended for getting additional knowledge about blood-sucking dipterans feeding on bird blood. Many genetic lineages of avian haemosporidians are specific to avian hosts, therefore, the detection of these parasite lineages in blood-sucking insects can indicate their feeding preferences on the level of species or groups of related bird species.

Avian haemosporidian parasites (Haemosporida): A comparative analysis of different polymerase chain reaction assays in detection of mixed infections

Mixed infections of different species and genetic lineages of haemosporidian parasites (Haemosporida) predominate in wildlife, and such infections are particularly virulent. However, currently used polymerase chain reaction (PCR)-based detection methods often do not read mixed infections. Sensitivity of different PCR assays in detection of mixed infections has been insufficiently tested, but this knowledge is essential in studies addressing parasite diversity in wildlife. Here, we applied five different PCR assays, which are broadly used in wildlife avian haemosporidian research, and compared their sensitivity in detection of experimentally designed mixed infections of Haemoproteus and Plasmodium parasites. Three of these PCR assays use primer sets that amplify fragments of cytochrome b gene (cyt b), one of cytochrome oxidase subunit I (COI) gene, and one target apicoplast genome. We collected blood from wild-caught birds and, using microscopic and PCR-based methods applied in parallel, identified single infections of ten haemosporidian species with similar parasitemia. Then, we prepared 15 experimental mixes of different haemosporidian parasites, which often are present simultaneously in wild birds. Similar concentration of total DNA was used in each parasite lineage during preparation of mixes. Positive amplifications were sequenced, and the presence of mixed infections was reported by visualising double-base calling in sequence electropherograms. This study shows that the use of each single PCR assay markedly underestimates biodiversity of haemosporidian parasites. The application of at least 3 PCR assays in parallel detected the majority, but still not all lineages present in mixed infections. We determined preferences of different primers in detection of parasites belonging to different genera of haemosporidians during mixed infections.

Haemoproteus tartakovskyi (Haemoproteidae): Complete sporogony in Culicoides nubeculosus (Ceratopogonidae), with implications for avian haemoproteid experimental research

Numerous recent studies have addressed the molecular characterization, distribution and genetic diversity of Haemoproteus spp. (Haemoproteidae). Some species of these blood parasites cause severe disease in birds, and heavy infections are often lethal in biting midges (Ceratopogonidae) and other blood-sucking insects. However, information about the vectors of haemoproteids is scarce. This presents an obstacle for better understanding the mechanisms of host-parasite interactions and the epidemiology of haemoproteosis. Here we investigated the sporogonic development of Haemoproteus tartakovskyi, a widespread bird parasite, in experimentally infected biting midges, Culicoides nubeculosus. These biting midges are widespread in the Europe. The insects were cultivated under laboratory conditions. Unfed females were allowed to take blood meals on wild caught siskins Carduelis spinus naturally infected with H. tartakovskyi (lineage hSISKIN1). Engorged females were maintained at 22-23 °C, dissected at intervals, and examined for sporogonic stages. Mature ookinetes of H. tartakovskyi were seen in the midgut content between 6 and 48 h post infection, oocysts were observed in the midgut wall 3-4 days post infection (dpi). Sporozoites were first reported in the salivary gland preparations 7 dpi. In accordance with microscopy data, polymerase chain reaction amplification and sequencing confirmed presence of the corresponding parasite lineage in experimentally infected biting midges. This study indicates that C. nubeculosus willingly takes blood meals on birds and is a vector of H. tartakovskyi. These biting midges are readily amenable to cultivation under laboratory conditions. Culicoides nubeculosus transmits Haemoproteus parasites infecting parrots, owls and siskins, birds belonging to different families and orders. Thus, this vector provides a convenient model for experimental research with avian haemoproteids.

Biting midges (Culicoides, Diptera) transmit Haemoproteus parasites of owls: evidence from sporogony and molecular phylogeny

BACKGROUND

Haemoproteus parasites are widespread, and several species cause diseases both in birds and blood-sucking insects. These pathogens are transmitted by dipterans belonging to the Ceratopogonidae and Hippoboscidae, however certain vector species remain unknown for the majority of Haemoproteus spp. Owls are often infected by Haemoproteus parasites, but experimental studies on vectors of these infections are lacking. The aim of this study was to investigate sporogonic development of two widespread Haemoproteus parasites of owls, H. noctuae and H. syrnii in experimentally infected biting midges Culicoides impunctatus and Culicoides nubeculosus. We also followed in vitro sporogonic development of these infections and determined their phylogenetic relationships with Haemoproteus spp., for which vectors have been identified.

METHODS

Wild-caught C. impunctatus and laboratory reared C. nubeculosus were infected experimentally by allowing them to take blood meals on one individual long-eared owl (Asio otus) and one tawny owl (Strix aluco) harbouring mature gametocytes of H. noctuae (lineage hCIRCUM01) and H. syrnii (hCULCIB01), respectively. The engorged insects were maintained in the laboratory at 16-18 °C, and dissected at intervals in order to follow the development of ookinetes, oocysts and sporozoites. We also observed in vitro development of sexual stages of both parasites by exposure of infected blood to air. The parasite lineages were determined by polymerase chain reaction-based methods. Bayesian phylogeny was constructed in order to determine the relationships of owl parasites with other avian Haemoproteus spp., for which vectors have been identified.

RESULTS

Both H. noctuae and H. syrnii completed sporogony in C. nubeculosus, and H. noctuae completed sporogony in C. impunctatus. Ookinetes, oocysts and sporozoites of these parasites were reported and described. Gametes and ookinetes of both species readily developed in vitro. In accordance with sporogony data, the phylogenetic analysis placed both parasite lineages in a clade of Culicoides spp.-transmitted avian Haemoproteus (Parahaemoproteus) spp.

CONCLUSIONS

Culicoides nubeculosus and C. impunctatus are vectors of H. noctuae and H. syrnii. Phylogenies based on cytochrome b gene indicate parasite-vector relationships, and we recommend using them in predicting possible parasite-vector relationships and planning research on avian Haemoproteus spp. vectors in wildlife.

Complete sporogony of Plasmodium relictum (lineage pGRW4) in mosquitoes Culex pipiens pipiens, with implications on avian malaria epidemiology

Plasmodium relictum (lineage pGRW4) causes malaria in birds and is actively transmitted in countries with warm climates and also temperate regions of the New World. In Europe, the lineage pGRW4 has been frequently reported in many species of Afrotropical migrants after their arrival from wintering grounds, but is rare in European resident birds. Obstacles for transmission of this parasite in Europe have not been identified. Culex quinquefasciatus is an effective vector of pGRW4 malaria, but this mosquito is absent from temperate regions of Eurasia. It remains unclear if the lineage pGRW4 completes sporogony in European species of mosquitoes. Here we compare the sporogonic development of P. relictum (pGRW4) in experimentally infected mosquitoes Culex pipiens pipiens form molestus, C. quinquefasciatus, and Ochlerotatus cantans. The pGRW4 parasite was isolated from a garden warbler Sylvia borin, multiplied, and used to infect laboratory-reared Culex spp. and wild-caught Ochlerotatus mosquitoes by allowing them to take blood meals on infected birds. The exposed females were maintained at a mean laboratory temperature of 19 °C, which ranged between 14 °C at night and 24 °C during daytime. They were dissected on intervals to study the development of sporogonic stages. Only ookinetes developed in O. cantans; sporogonic development was abortive. The parasite completed sporogony in both Culex species, with similar patterns of development, and sporozoites were reported in the salivary glands 16 days after infection. The presence of sporogonic stages of the lineage pGRW4 in mosquitoes was confirmed by PCR-based testing of (1) the sporozoites present in salivary glands and (2) the single oocysts, which were obtained by laser microdissection from infected mosquito midguts. This study shows that P. relictum (pGRW4) completes sporogony in C. p. pipiens at relatively low temperatures. We conclude that there are no restrictions for spreading this bird infection in Europe from the point of view of vector availability and temperature necessary for sporogony. Other factors should be considered and were discussed for the explanation of rare reports of this malaria parasite in Europe.

The evidence for rapid gametocyte viability changes in the course of parasitemia in Haemoproteus parasites

Avian haemosporidian parasites of the genus Haemoproteus (Haemoproteidae, Haemosporida) are widespread, and some species cause diseases both in vertebrate hosts and blood-sucking insects. Parasitemia of Haemoproteus species usually is long-lasting, with gametocytes present in the circulation for several months. However, the viability of gametocytes and their ability to produce sexual cells have been insufficiently understood in the course of parasitemia. We initiated the sexual development in vitro conditions and calculated proportions of normal and anomalous ookinetes, which developed in two species of Haemoproteus. Mature gametocytes of the parasites were obtained from naturally infected avian hosts at different days of parasitemia. Haemoproteus (Parahaemoproteus) lanii (cytochrome b lineage hRB1) was isolated from one red-backed shrike Lanius collurio. Two isolates of Haemoproteus (Parahaemoproteus) tartakovskyi (cytochrome b lineage hSISKIN1) were used: one was obtained from a siskin Carduelis spinus and one from a common crossbill Loxia curvirostra. The wild-caught birds were kept indoors under controlled conditions, and blood was taken from them every 1 or 2 days during 10-14 days. After each blood sampling, the sexual process and ookinete development were initiated in vitro by exposure of infected blood containing mature gametocytes to air. Smears were prepared at intervals of 15 min, 3 h, and 12 h after the exposure; they were examined microscopically. In all, 25 experiments were performed; each experiment was repeated two times. The ratios of macro- and microgametocytes did not change in all experimental infections during this study. Sexual process occurred, and both normal and anomalous ookinetes developed in all parasites. The proportion of normal ookinetes did not change significantly in both isolates of H. tartakovskyi. Between 8 and 10 days of observation, the proportion of normal ookinetes of H. lanii decreased 6 times compared to the beginning of the experiment. That was accompanied with the rapid decrease of parasitemia and the inability of the majority of mature gametocytes to escape from erythrocytes and produce gametes, indicating disorder of the gametogenesis. There was clear difference in the gametogenesis between H. tartakovskyi and H. lanii from this point of view. This study shows that the viability of Haemoproteus gametocytes might change dramatically in the course of parasitemia within 1-2 days, and the presence of mature gametocytes in the circulation does not necessarily indicate their ability to exflagellate and produce ookinetes. We predict that this finding is important epidemiologically due to relationship with sporogony success.

Complete sporogony of Plasmodium relictum (lineages pSGS1 and pGRW11) in mosquito Culex pipiens pipiens form molestus, with implications to avian malaria epidemiology

Plasmodium parasites (Plasmodiidae) cause malaria in many species of terrestrial vertebrates and are transmitted mainly by mosquitoes (Culicidae). Avian malaria is often caused by Plasmodium relictum , a cosmopolitan hemosporidian infection. Numerous genetic lineages of P. relictum have been described. However, it remains unclear if these lineages can be transmitted by Culex pipiens pipiens form molestus, which is widespread but has been insufficiently investigated as a possible vector of avian malaria. The aim of this study was to test experimentally if 2 common P. relictum lineages complete sporogony in the experimentally infected insects. The mosquitoes were cultivated under laboratory conditions. Unfed females were allowed to take blood meals on domestic canaries experimentally infected with the lineages pSGS1 and pGRW11 of P. relictum . These lineages are widespread and cause malaria in many species of birds. Infected female flies were examined for sporogonic development of each parasite lineage. Both exposed groups were maintained under the same laboratory conditions. Mosquitoes were dissected at intervals, and the midguts and salivary glands were prepared in order to detect sporogonic stages. Numerous ookinetes, oocysts, and sporozoites of both parasite lineages were observed. Polymerase chain reaction confirmed the presence of corresponding parasite lineages in the experimentally infected insects. Sporogonic stages of both lineages were morphologically similar and developed synchronously in this mosquito; however, the lineage pGRW11 developed a significantly greater number of oocysts than did the lineage pSGS1. This study shows that Culex p. pipiens f. molestus is susceptible to 2 widespread lineages of P. relictum and worth more attention in avian malaria epidemiology. We recommend C. p. pipiens f. molestus for experimental research of avian malaria parasites, principally because it willingly takes blood meals on birds and because it is easy to establish and maintain new colonies of this insect under laboratory conditions using wild-sampled eggs, larvae, or imago.

The identity and genetic characterization of Simulium reptans (Diptera: Simuliidae) from central and northern Europe

Although Simulium reptans Linnaeus is one of the first two blackfly species ever described its identity and taxonomy are still not precisely defined. S. reptans and closely related species from central and northern Europe were characterized based on genetic variability, haplotype number and haplotype distribution. S. galeratum can be considered a synonym of S. reptans, but despite this, two distinct species are present in Great Britain and central Europe. The available name S. reptantoides Carlsson can be used for the second species; earlier reported as S. reptans from Great Britain and central Europe. A total of 80 mitochondrial cytochrome c oxidase I gene sequences were analyzed: 44 S. reptans, 36 S. reptantoides; 38 from Great Britain, 19 from Slovakia, 8 from Lithuania, 3 from Latvia and 12 from Sweden. In 73 individuals a 606 bp section (long sequences), and in all 80 individuals a fully overlapping 453 bp section (short sequences) were analyzed. Results confirmed that S. reptans and S. reptantoides are two genetically isolated species. The variation between these species is 80.01% of total variation; approximately six times higher than the variation among the populations within species. The genetic divergence between species is 7.02% in long sequences and 7.46% in short ones. The genetic divergence within species is 1.18% in S. reptans and 0.83% in S. reptantoides in long sequences, and 1.38% and 1.05% in short sequences. Maximum likelihood trees, maximum parsimony trees and the haplotype network constructed using TCS showed that each species consists of two units, labelled as A and B forms. The distribution of the S. reptans forms is not identical-in Slovakia and the Baltic area only S. reptans B was found, meanwhile both A and B forms were present in Great Britain and Sweden; with the A form clearly dominant. In contrast, both forms of S. reptantoides were present in Great Britain and Slovakia, and absent in Scandinavia and the Baltic area. Additional studies comprising more individuals from larger areas of Europe are required to verify the taxonomic position of these species' forms.

Molecular characterization of five widespread avian haemosporidian parasites (Haemosporida), with perspectives on the PCR-based detection of haemosporidians in wildlife

Haemosporidians (Haemosporida) are cosmopolitan in birds. Over 250 species of these blood parasites have been described and named; however, molecular markers remain unidentified for the great majority of them. This is unfortunate because linkage between DNA sequences and identifications based on morphological species can provide important information about patterns of transmission, virulence, and evolutionary biology of these organisms. There is an urgent need to remedy this because few experts possess the knowledge to identify haemosporidian species and few laboratories are involved in training these taxonomic skills. Here, we describe new mitochondrial cytochrome b markers for the polymerase chain reaction (PCR)-based detection of four widespread species of avian Haemoproteus (Haemoproteus hirundinis, Haemoproteus parabelopolskyi, Haemoproteus pastoris, Haemoproteus syrnii) and 1 species of Plasmodium (Plasmodium circumflexum). Illustrations of blood stages of the reported species are given, and morphological and phylogenetic analyses identify the DNA lineages that are associated with these parasites. This study indicates that morphological characters, which have been traditionally used in taxonomy of avian haemosporidian parasites, have a phylogenetic value. Perspectives on haemosporidian diagnostics using microscopic and PCR-based methods are discussed, particularly the difficulties in detection of light parasitemia, coinfections, and abortive parasite development. We emphasize that sensitive PCR amplifies more infections than can be transmitted; it should be used carefully in epidemiology studies, particularly in wildlife parasitology research. Because molecular studies are describing remarkably more parasite diversity than previously expected, the need for traditional taxonomy and traditional biological knowledge is becoming all the more crucial. The linkage of molecular and morphological approaches is worth more of the attention of researchers because this approach provides new knowledge for better understanding insufficiently investigated lethal diseases caused by haemosporidian infections, particularly on the exoerythrocytic (tissue) and vector stages. That requires close collaboration between researchers from different fields with a common interest.

Mitochondrial COI and morphological evidence for host specificity of the black cherry aphids Myzus cerasi (Fabricius, 1775) collected from different cherry tree species in Europe (Hemiptera, Aphididae)

Partial sequences of the mitochondrial COI gene of forty eight European and two Turkish population samples of Myzus cerasi from different winter hosts (Prunus spp.) were subjected to phylogenetic analyses. The analysed M. cerasi samples emerged as paraphyletic relative to a Myzus borealis sample used as an out-group, and formed two major clades in neighbor joining, maximum parsimony, maximum likelihood and Bayesian inference trees, corresponding to subspecies living specifically on Prunus avium and P. cerasus. Multivariate discriminant analysis (method of canonical variates) was applied to find out if morphological variation of samples correlated with mitochondrial COI and host plant information. Mean scores on the first two canonical variables clustered samples fully in accordance with their COI haplotypes and host plants confirming the existence of two morphologically similar winter host - specific subspecies of M. cerasi in Europe. No single morphological character enabled satisfactory discrimination between apterous viviparous females of the two subspecies. A three-character linear discriminant function enabled 92.37% correct identification of apterous viviparous females of M. cerasi cerasi (n = 118) and 93.64% of M. cerasi pruniavium (n = 110). A key for the morphological identification of the two subspecies is presented and their taxonomic status is discussed.

Haemoproteus infections (Haemosporida, Haemoproteidae) kill bird-biting mosquitoes

Haemoproteus parasites (Haemosporida, Haemoproteidae) are widespread; some species cause severe diseases in avian hosts. Heavy Haemoproteus infections are often lethal for biting midges (Ceratopogonidae), which transmit avian haemoproteids, but there is no information regarding detrimental effect on other blood-sucking insects. We examined effects of Haemoproteus tartakovskyi (lineage hSISKIN1), Haemoproteus lanii (lineages hRB1and hRBS2) and Haemoproteus balmorali (lineage hCOLL3) on the survival of Ochlerotatus cantans, a widespread Eurasian mosquito. Wild-caught females were infected by allowing them to feed on naturally infected birds with light (0.01%) and high (3.0-9.6%) parasitaemia. Mosquitoes fed on uninfected birds were used as controls. Both experimental and control groups were maintained under the same laboratory conditions until 20 days post-exposure (dpe). Dead insects were counted daily and used for parasitological examination and PCR-based testing. No difference was discernible in the survival rate of control mosquitoes and those fed on meal with light parasitaemia. There was a highly significant difference in the survival rate between the control group and all groups fed on meals with high parasitaemia, with the greatest mortality reported 1-3 dpe. For 4 dpe, the percentage of survived control mosquitoes (88%) was 2.2-, 3.6- and 4-fold greater than that of groups fed on meals with high parasitaemia of H. balmorali, H. tartakovskyi and H. lanii, respectively. Numerous ookinetes were observed in the gut area and adjacent tissues located in the head, thorax and abdomen of infected insects 0.5-1 dpe. The migrating parasites damage organs throughout the entire body of mosquitoes; that is the main reason of mortality. To the end of this study, 46% of mosquitoes survived in control group, but the survival rates of experimental mosquitoes fed on meals with high parasitaemia were between 2.6- and 5.8-fold lower. This study indicates that widespread Haemoproteus infections are markedly virulent for bird-biting mosquitoes, which rapidly die after feeding on heavily infected blood meals.

Further observations on in vitro hybridization of hemosporidian parasites: patterns of ookinete development in Haemoproteus spp

Increasingly frequent outbreaks of zoonotic infections call for studies of wildlife parasites to reach a better understanding of the mechanisms of host switch, leading to the evolution of new diseases. However, speciation processes have been insufficiently addressed in experimental parasitology studies, primarily due to difficulties in determining and measuring mate-recognition signals in parasites. We investigated patterns of sexual process and ookinete development in avian Haemoproteus (Parahaemoproteus) spp. (Haemosporida, Haemoproteidae) using in vitro experiments on between-lineage hybridization. Eleven mitochondrial cytochrome b (cyt b) lineages belonging to 9 species of hemoproteid were isolated from naturally infected passerine birds. The parasites were identified to species on the basis of morphology of their gametocytes and polymerase chain reaction amplification of segments of the cyt b gene. Sexual process and ookinete development were initiated in vitro by mixing blood containing mature gametocytes with a 3.7% solution of sodium citrate and exposing the mixture to air. Ookinetes of all lineages except Haemoproteus payevskyi (lineage hRW1) and Haemoproteus nucleocondensus (hGRW1) developed; the 2 latter species did not exflagellate. Between-lineage hybridization was initiated by mixing blood containing mature gametocytes of 2 different parasites; the following experiments were performed: (1) Haemoproteus pallidus (lineage hPFC1) × Haemoproteus minutus (lineage hTURDUS2); (2) H. pallidus (hPFC1) × Haemoproteus tartakovskyi (hSISKIN1); (3) Haemoproteus belopolskyi (hHIICT3) × Haemoproteus lanii (hRB1); (4) Haemoproteus balmorali (hSFC1) × H. pallidus (hPFC1); (5) H. belopolskyi (hHIICT1) × Haemoproteus parabelopolskyi (hSYBOR1); (6) H. tartakovskyi (hHAWF1) × H. tartakovskyi (hSISKIN1); (7) H. pallidus (hPFC1) × H. lanii (hRB1); (8) H. tartakovskyi (hHAWF1) × H. parabelopolskyi (hSYBOR1). We report 4 patterns of between-lineage interactions that seem to be common and might prevent mixing lineages during simultaneous sexual process in wildlife: (1) the blockage of ookinete development of both parasites; (2) the development of ookinetes of 1 parasite and blockage of ookinete development of the other; (3) selective within-lineage mating resulting in ookinete development of both parent species and absence of hybrid organisms; (4) absence of selective within-lineage mating resulting in presence of ookinetes of both parents and also development of hybrid organisms with unclear potential for further sporogony. The present study indicates directions for collection of source material in the investigation of mechanisms of reproductive isolation leading to speciation in these parasites. The next steps in these studies should be the development of nuclear markers for distinguishing hemosporidian hybrid organisms and the experimental observation of further development of hybrid ookinetes in vectors.