Is Ornithoctona laticornis (Diptera: Hippoboscidae) expanding its range from Africa into Europe? First confirmed record in Romania

Abstract

The bird louse fly Ornithoctona laticornis (Diptera: Hippoboscidae), previously known only from Africa, has recently been recorded in Europe (Hungary) for the first time, raising questions about its potential range expansion. In this study, we document the first record of O. laticornis from the Syrian Woodpecker (Dendrocopos syriacus) in 2022 and another from the Great Spotted Woodpecker (Dendrocopos major) in 2023, both in Romania. Morphological description and molecular analysis of the mitochondrial cytochrome c oxidase subunit 1 gene confirmed the species identity. The main morphological criteria for the identification of O. laticornis were used in the updated key for the European genera of Hippoboscidae. The recurring presence of O. laticornis in resident European birds suggests either overwintering survival or multiple introductions via migratory hosts. Given the ability of hippoboscid flies to act as vectors of pathogens, this discovery underscores the importance of continued surveillance of avian ectoparasites in Europe. Further studies are needed to assess the distribution of the species, its genetic diversity, host range, and its potential role as a vector.

Graphical abstract

Highlights

• •First record of O. laticornis in resident woodpeckers in Romania.
• •Overwintering or multiple introductions of O. laticornis via migratory birds.
• •Updated key for the European genera of Hippoboscidae.

1. Introduction

Vector-borne diseases are a growing global concern as their vectors expand into new geographic regions, driven by climate change, habitat alterations, and increased movement of wildlife and humans (Hewitt, 2000; Colwell et al., 2008; Sunday et al., 2012). Blood-feeding insects, capable of transmitting pathogens to their hosts, are increasingly recognized for their role in spreading infectious agents across ecological and geographic boundaries (Bezerra-Santos and Otranto, 2020; Peña-Espinoza et al., 2023). Understanding the mechanisms behind these possible range expansions is critical for assessing potential health risks to wildlife and, in some cases, humans.

Among the expanding insect vectors, the louse flies or keds (Diptera: Hippoboscidae) represent a group of blood-feeding ectoparasites capable of long dispersal via their hosts. They parasitize both birds and mammals, with 213 recognized species worldwide (Dick, 2018; González et al., 2024; Yatsuk et al., 2024). These flies exhibit unique adaptations for ectoparasitism, including strong claws for attachment and a tendency to remain on the same host for extended periods (Yatsuk et al., 2023, 2024). Avian hosts are predominantly parasitized by members of the subfamily Ornithomyinae (Nartshuk et al., 2022), with some species of Lipopteninae also reported on birds (Krišovský et al., 2024; Mlynárová et al., 2024). In general, avian hippoboscids have a low specificity, as one species can parasitize several to many species of birds belonging to various families and orders (Maa, 1969a; Graciolli and Laps, 2024).

The ornithophilic genus Ornithoctona Speiser, 1902 (Ornithomyinae) currently comprises 13 species of obligate ectoparasites that parasitize as much as 54 families of avian hosts (Maa, 1969a, 1969b; Dick, 2018; Nartshuk et al., 2018; Yatsuk et al., 2023). The louse flies of this genus occur mainly in the tropical zones of both hemispheres, mainly in Africa, Asia, North, Central and South America. In particular, Ornithoctona rugicornis Maa, 1963 and Ornithoctona idonea Falcoz, 1929 occur exclusively in Africa, while Ornithoctona australasiae (Fabricius, 1805), Ornithoctona zootherae Yatsuk, Nartshuk and Matyukhin, 2023 and Ornithoctona soror Ferris, 1926 have only been found in Asia (Maa, 1969a, 1969b; Nartshuk et al., 2018; Yatsuk et al., 2023). Six species, specifically Ornithoctona erythrocephala (Leach, 1817), Ornithoctona fusciventris (Wiedemann, 1830), Ornithoctona hulahula Maa, 1969, Ornithoctona orizabae Bequaert, 1954, Ornithoctona nitens Bigot, 1885 and Ornithoctona oxycera Falcoz, 1929 have been reported from the Americas (e.g. Maa, 1969a, 1969b; Nartshuk et al., 2018; Vélez et al., 2020; Graciolli and Laps, 2024; Frixione et al., 2025). The species with the widest geographical distribution is Ornithoctona plicata von Olfers, 1816, which has been recorded in Africa, Asia, Australia and the Pacific Islands (Maa, 1969a, 1969b; Nartshuk et al., 2018; Sinclair, 1997; Suh et al., 2012) (see Supplementary file S1 for details).

One of the species, which has previously been reported exclusively from various localities in Africa, is Ornithoctona laticornis (Macquart, 1835). This louse fly has been recorded in Southern (Cape Province, Zimbabwe), Central (Cameroon, Congo) and East Africa (Uganda, Tanzania, Kenya, and Ethiopia) (Maa, 1969a, 1969b; Keve et al., 2024) and in Madagascar (Rahola et al., 2011) on a wide range of bird hosts (see Supplementary file S2 for details), several of which are long-distance migrants. O. laticornis exhibits low hosts specificity, and to date it has been detected in birds belonging to 33 genera of the order Passeriformers, two genera each from the orders Coraciiformes and Anseriformes, and one genus each from Columbiformes, Piciformes, Phoenicopteriformes, and Trogoniformes. All hosts originated from Afrotropical and Madagascan zoogeographical region and are mainly resident or sedentary birds, while some are partial migrants (intra-African movements) or long-distance migrants (see Supplementary file S2 for details).

The spread of O. laticornis from Africa to Europe was already predicted 40 years ago by Hutson (1984). However, the first confirmed record of O. laticornis outside Africa, particularly in Europe, was only recently reported from Hungary (Keve et al., 2024). A single specimen collected from a sedentary passerine bird, the Eurasian Blue Tit Cyanistes caeruleus (Linnaeus, 1758), was identified based on morphological features according to the taxonomic keys by Hutson (1984) and Rahola et al. (2011). This finding represents the first documented report of O. laticornis on a Palaearctic bird, which is mostly resident with only minor winter movements, and also the first recorded occurrence of the Ornithoctona louse fly in Europe. Keve et al. (2024) moreover provided the first partial sequence (639 bp) of the mitochondrial cytochrome c oxidase subunit 1 (cox1 mtDNA) for O. laticornis (GenBank Accession Number PP111350). Additional molecular data have not been available so far. The confirmation of the presence of O. laticornis in Europe raises questions about its ability to survive in new environments. Nevertheless, apart from this single record of O. laticornis, data on its European distribution, host range and dispersal potential are essentially lacking.

In this study, we report the first record of O. laticornis in Romania, based on two specimens collected from resident woodpeckers. The morphological and molecular identification were performed to confirm the species identity, and the identification key for its recognition was provided. Our findings contribute to the growing evidence that O. laticornis may be expanding its range within Europe, highlighting the need for further surveillance of avian ectoparasites and their potential role as vectors of pathogens.

2. Material and methods

2.1. Sample collection and morphological identification

Two louse flies were collected directly from the female of the Syrian Woodpecker Dendrocopos syriacus (Hemprich and Ehrenberg, 1833) and the Great Spotted Woodpecker Dendrocopos major (Hemprich and Ehrenberg, 1833) (one of each bird) in the Dunele Marine de la Agigea Nature Reserve (44.087099°N/28.642445°E) in Romania. The first specimen was collected in August 2022 and the second individual in March 2023. The louse flies were collected from birds caught in the mistnets at the Agigea Bird Observatory ringing station within the framework of a broader survey of avian ectoparasites. In total, a number of 13,751 birds of different species were examined in 2022 and 15,836 in 2023. Birds were visually inspected during standard ringing procedures, and all types of ectoparasites were collected.

The specimens were fixed in 96 % ethanol and taxonomic identification was performed by morphological determination under the stereomicroscope using the keys published by Oboňa et al. (2022), supplemented by Maa (1969a) and Keve et al. (2024). The material was deposited in the collection of the Laboratory of Population Genetics, Institute of Parasitology of the Slovak Academy of Sciences, Košice, Slovakia.

2.2. Molecular identification

Taxonomic identification of hippoboscid species based only on morphology may be faulty or unreliable due to the morphological plasticity of some species and overlapping key morphological identification markers between congeners. Thus, genotyping (PCR amplification and sequencing) was performed to confirm the taxonomic identification of the studied louse fly species.

Genomic DNA was extracted from one air-dried louse fly (collected from D. major) by alkaline hydrolysis method (Rijpkema et al., 1996) and stored at −20 °C. The partial cox1 mtDNA gene (∼710 bp) was amplified using the universal primers HCO2198 (5′-TAA ACT TCA GGG TGA CCA AAA AAT CA-3′) and LCO1490 (5′-GGT CAA CAA ATC ATA AAG ATA TTG G-3′) (Folmer et al., 1994).

PCR amplification was performed in a total volume of 20 μL containing 10–20 ng of genomic DNA, 20 pmol of each of the primers and 1 × PCR Master Mix (Thermo Fisher Scientific Inc., Waltham, USA). The PCR amplification conditions were 5 min at 95 °C as an initial denaturation step, then 40 cycles of 40 s at 94 °C, 1 min at 48 °C, 1 min at 72 °C and a final polymerization step for 10 min at 72 °C.

The PCR product was visualised on a 1.5 % agarose gel, purified using the ExoProStar™ 1-STEP Kit (Illustra™, GE Healthcare, Little Chalfont, UK), and sequenced bidirectionally using the Automatic Genetic Analyser 3130xl (Applied Biosystems, Foster City, California, USA) and the BigDye Terminator v.3.1 Cycle sequencing kit (Applied Biosystems). The sequences were assembled using Geneious software (version 10.0.5, Biomatters, Auckland, New Zealand) and inspected for errors. Analysis of the assembled sequence were performed with BLAST via GenBank.

3. Results

The morphological examination of the louse flies revealed that the studied specimens were O. laticornis (see Fig. 1, Fig. 2, Fig. 3, Fig. 4). The dorsal and ventral views of the louse fly are presented in Fig. 1A and B, respectively. The morphological characteristics were as follows: wing similar to the genus Ornithomya (for more details see Theodor and Oldroyd, 1964, p. 38) and microtrichia (Fig. 2A) correspond to Ornithomya candida (Maa, 1967; p. 737). Head with antennae (Fig. 2B) are larger than in Ornithomya, 1.5-times as long as wide. The large antennae represent a key identification marker for O. laticornis (Fig. 1A). The palpy (Fig. 2C) are also similar to those of O. candida (Maa, 1967; p. 738). The length of the legs with long bristles (Fig. 2D) exceeds the width of the femora. The thorax is similar to that of the genus Ornithomya. The main difference on the ventral side is the size of the mesosternal processes (horns), representing the second most important identification marker for O. laticornis (Fig. 1B and 4A). The scutellum with four long setae (Fig. 3A) is similar to that of Ornithomya fringillina Curtis, 1836 (Oboňa et al., 2022; p. 93). The abdomen is densely covered with bristles on both sides (Fig. 3B–D). Urogenital area fenced with many long bristles (Fig. 3D) is similar to that of O. candida (see Maa, 1967; p. 741).

Fig. 1.

Ornithoctona laticornis (Macquart, 1835) female, collected from Dendrocopos major in the Dunele Marine de la Agigea Nature Reserve in spring 2023 with the key morphological identification markers. Dorsal view with large antennae (A), ventral view with the mesosternal processes (B). (scale: 2 mm).

Fig. 2.

Ornithoctona laticornis (Macquart, 1835) female. Wing apex with visible microtrichia (A), detail of head with antennae (B), palpy (C), leg with bristles (D). (scales: A – 1 mm, B – 2 mm, C – 0.5 mm, D – 1 mm).

Fig. 3.

Ornithoctona laticornis (Macquart, 1835) female. Scutellum (A), abdomen dorsal view (B), apex of abdomen (C), urogenital area (D).

Fig. 4.

The mesosternal processes (horns). Ornithoctona (A), Ornithomya (B).

The key species-specific morphological markers for the identification of O. laticornis are the shape of the mesosternal processes (horns; Fig. 4) and the head with large antennae (Fig. 2B). Other features are: the body densely covered with bristles (Fig. 1), the wings with microtrichia that extend only in the front 3r (between r2 and M₁₊₂) and 1m (between M₁₊₂ and M₃₊₄), the veins that are bare (Fig. 2A and B) (e.g. Maa, 1969a; Doszhanov, 1980, 2003; Hutson, 1984). However, many characteristics of O. laticornis (see Fig. 2A–C; 3C, D) completely overlap with those of O. candida, and therefore its holotype needs to be studied in the future.

The main morphological criteria for the identification of O. laticornis were used in the updated key for European genera of Hippoboscidae (see also Oboňa et al., 2019, 2022, 2023). As a new genus Ornithoctona has been repeatedly confirmed in Europe, we present a new updated key.

3.1. Key for European Hippoboscidae (updated Oboňa et al., 2022)

• 1.
  Wings fully developed and functional … 2

  • –
    Wings reduced, with strong veins or absent (either by reduction or loss) … 10
• 2.
  Tarsal claws simple, but with a pale basal lobe; humeral callus weak, postpronotum rounded, not produced anteriorly as conical lobes … 3

  • –
    Tarsal claw bifid and with a pale basal lobe; humeral callus strong, postpronotum rounded, pair of conical lobes on either side of head, on birds … 5
• 3.
  Wing with one or two cross-veins; R₄₊₅ well separated from C until apex; on mammals … 4

  • –
    Wings with three cross-veins enclosing cells posterior to radial veins; apical half of vein R₄₊₅ running very close to C; on birds … Ornithoica
• 4.
  Wing clear and hyaline, with only one cross-vein; head broader than long; thorax markedly flattened; on mammals … Lipoptena

  • –
    Wing distinctly crenulated and tinted, with two cross-veins; head not broader than long; thorax not so markedly flattened; on mammals … Hippobosca
• 5.
  Wing with three cross-veins posterior to radial veins; scutellum with four or more strong marginal setae … 6

  • –
    Wing with one or two cross-veins posterior to radius; scutellum at most with two strong marginal setae … 8
• 6.
  Vein R₂₊₃ with apical 3/5 fused with C; wing membrane entirely bare … Ornithophila

  • –
    Vein R₂₊₃ well separated from C except at apex; wing membrane usually with microtrichia … 7
• 7.
  Antennae twice as long as wide, its length shorter than half length of eye, mesosternal processes reduced (Fig. 4B), as long as wide … Ornithomya

  • –
    Antennae large, 1.5-times as long as wide (Fig. 2B), its length exceeds half-length of eye, mesosternal processes strongly reminiscent horns (Fig. 4A), twice as long as wide … Ornithoctona
• 8.
  Wing with only one cross-vein … Pseudolynchia

  • –
    Wing with two cross-veins … 9
• 9.
  Scutellum with two strong setae … Icosta

  • –
    Scutellum with setulae … Olfersia
• 10.
  Wings reduced, with strong veins … 11

  • –
    Wing absent (either by reduction or loss) … 12
• 11.
  Wing long and narrow, at least six-times as long as wide and twice as long as head and thorax; female abdomen with strong spiniform setae in posterolateral area; male abdomen without spiniform setae … Stenepteryx

  • –
    Wing short and broad, at most three-times as long as wide and about 1.5-times as long as head and thorax; tip of wing usually attenuated, C reaching to about 0.75 length of anterior wing margin; female abdomen only with short fine setae in posterolateral area … Crataerina
• 12.
  Wings either reduced to a veinless knob or broken off; haltere absent … Melophagus

  • –
    Wings broken off, leaving a broad flat veined stump; haltere present … Lipoptena

The taxonomy based on morphological markers was supplemented by molecular genotyping to enable more reliable species identification. Analysis of the 639 bp cox1 region of the louse fly revealed 100 % identity with O. laticornis from Hungary (PP111350). The sequence obtained in this study was deposited in GenBank, EMBL, and DDBJ databases under the accession number PV034357.

4. Discussion

In the current study, we confirmed the first occurrence of O. laticornis in Romania by morphological and molecular identification, making also the second record of this species in Europe.

Keve et al. (2024) recently documented O. laticornis in Hungary on a sedentary bird, the Eurasian Blue Tit. They hypothesized that unidentified migratory birds may have carried an imago from Africa during spring migration and that the adult fly survived until October. Given the time gap between the spring migration and the detection of O. laticornis in autumn, the authors further suggested that a fertilized O. laticornis female was introduced from Africa, and successfully laid larvae ready to pupate that later emerged on European local bird hosts.

In general, hippoboscids of the genus Ornithoctona exhibit low host specificity, parasitizing multiple bird species across various families, and even different orders (e.g. Maa, 1969a, 1969b; Nartshuk et al., 2018). The greatest number of host birds belonging to different families has been recorded for O. plicata (26 families), followed by O. erythrocephala (23), O. australasiae (20) and O. fusciventris (20) (Nartshuk et al., 2018). According to the classification of Skoracki et al. (2016), O. laticornis can also be considered polyxenous, as it parasitizes hosts from more than one avian order, in particular Passeriformes, Coraciiformes, Anseriformes, Columbiformes, Piciformes, Phoenicopteriformes, and Trogoniformes (see Supplementary file S2 for details). The broad host range of O. laticornis indicates that this louse fly could successfully exploit new hosts upon arrival in Europe. Interestingly, all confirmed European records to date have been from non-migratory birds, but the underlying reasons remain unclear. On the other hand, O. laticornis has been recorded on several long-distance migratory birds in its native African range (see Supplementary file S2), making its dispersal to Europe via trans-Saharan migrants a plausible scenario. However, further monitoring across a broader range of avian hosts, particularly migratory species, is needed to better understand potential patterns of host selection in this species.

Ornithophilous louse flies are known to disperse over long distances via migratory birds, potentially infesting indigenous species (Nartshuk et al., 2019). Their specialized legs, equipped with hook-like structures on the pulvilli, enhance attachment and reduce the risk of dislodgement (Yatsuk et al., 2023, 2024). Unlike other hippoboscids, avian louse flies retain their wings, enabling them to switch hosts via flight. Although they are generally considered to be short-distance fliers, able to glide only for short distances by air (Jaakola et al., 2015; Liu et al., 2019), they can potentially travel much longer distances when attached to their highly mobile avian hosts.

The Syrian Woodpecker and the Great Spotted Woodpecker, hosts of O. laticornis in Romania, and the Eurasian Blue Tit, host of this louse fly in Hungary, are primarily resident, non-migratory birds of the Palaearctic zoogeographical region. While the Syrian Woodpecker is native to southeastern Europe and the Middle East, with its range extending eastward to Iran, the Great Spotted Woodpecker has a wide distribution across Eurasia, from the British Isles to Japan, and in North Africa from Morocco to Tunisia (Winkler et al., 2020). Although the Great Spotted Woodpecker occurs also in North Africa, the presence of O. laticornis has not been recorded in this bird species on the continent, as until recently it was only recorded in sub-Saharan Africa. In contrast, in the Afrotropical and Madagascan zoogeographical region, this louse fly has been detected on long-distance migratory birds of the genera Lanius, Oriolus, Cecropis, Hirundo, Phylloscopus, Muscicapa, Saxicola, Turdus, Phoeniconaias and Anas (see Supplementary file S2), which breed in the Palaearctic, including Europe, and winter in Africa. Nevertheless, O. laticornis has not yet been documented on birds of these genera in Europe. Therefore, its occurrence in two consecutive years at the same location in Romania suggests that it was probably recently introduced to Europe from Africa by one of the above-mentioned long-distance migrants and was able to overwinter and reproduce in a new territory.

Hutson (1984) suggested that O. laticornis might have been previously overlooked in Europe due to misidentification, given its morphological similarity to Ornithomya species. In fact, a great morphological similarity was found between the studied louse fly and O. candida. In Europe, O. laticornis can also be confused with Ornithomya avicularia (Linnaeus, 1758), Ornithomya fringilina Curtis, 1836 or Ornithomya rupes Hutson, 1981 (see notes in Keve et al., 2024). Although it is possible that O. laticornis represents a newly introduced species in Europe, it is far more likely that it has been present for some time but remained undetected or misidentified due to its morphological resemblance to the aforementioned species, resulting in an underestimation of its actual distribution in Europe. As an alternative explanation, the ongoing shifts in the distribution of vectors, already observed in other blood-feeding insects (Wawman, 2025), may indicate the potential range expansion of O. laticornis rather than being a previously undetected resident. Both scenarios (misidentification and recent introductions) are not mutually exclusive and could explain the presence of O. laticornis in Europe.

The identical cox1 sequences of O. laticornis from Hungary (Keve et al., 2024) and Romania (current study) suggest presence of genetically identical (or very similar) populations of O. laticornis in Europe, which can be explained by two possible scenarios: i) multiple independent introductions to Europe from the same African source population or ii) a single introduction event from Africa to Europe followed by local dispersal within Europe.

Louse flies may have a negative impact on their hosts, with heavy infestations leading to skin irritation, feather damage, inflammation, chronic stress, immune suppression, and reduced fitness (Waite et al., 2014; Ombugadu et al., 2019). These blood-feeding parasites may serve as potential vectors for various infectious agents, including protozoa, bacteria, helminths, and possibly viruses (Rahola et al., 2011; Bezerra-Santos and Otranto, 2020). In the Palaearctic-African bird migration system, resident birds in Africa may act as reservoirs for tropical avian blood parasites (Valkiunas, 1993), increasing the risk for Palaearctic migrants to become infected immediately upon reaching their African winter quarters. However, despite research efforts, there are still large gaps in knowledge of pathogens and emerging vector-borne diseases in hippoboscid flies (Peña-Espinoza et al., 2023). Data on the presence of pathogens in Ornithoctona louse flies is currently lacking, but given that O. laticornis is an obligate ectoparasite of birds, it is likely that it could serve as a potential vector for various infectious agents. Therefore, monitoring of hippoboscid-associated pathogens in species of the genus Ornithoctona would be of great benefit in the future.

5. Conclusion

Our study provides the first confirmed record of Ornithoctona laticornis in Romania, marking the second detection of this sub-Saharan ectoparasite species in Europe. This finding raises important questions about its recent introduction or overlooked presence in the region and underscores the need for continued monitoring of avian ectoparasites. The ability of O. laticornis to survive in both south-eastern and central Europe suggests that its establishment may already be underway. Given the presence of suitable hosts and climatic conditions, the species may be more widespread than currently documented, requiring further surveys to determine its full distribution.

The integration of morphological and molecular tools is essential for the correct identification of ectoparasite vectors that are “on the move” such as O. laticornis, and for the differentiation of morphologically similar species. Future studies should also investigate their host preferences, possibilities of host-switches during migration, the seasonal dynamics in host breeding grounds, as well as potential role in the transmission of pathogens. More molecular data (e.g., cox1 mtDNA) will also be crucial for the assessment of genetic diversity and population connectivity in Europe. As global changes continue to influence the movements of parasitic species, understanding the range dynamics of emerging ectoparasites like O. laticornis will be crucial for predicting potential ecological and epidemiological consequences.

CRediT authorship contribution statement

Jozef Oboňa: Writing – review & editing, Writing – original draft, Methodology, Conceptualization. Eva Čisovská Bazsalovicsová: Writing – review & editing, Writing – original draft, Supervision, Methodology, Funding acquisition, Conceptualization. Ľudmila Juhásová: Writing – review & editing, Methodology. Peter Manko: Writing – review & editing, Visualization. Laura Mlynárová: Writing – review & editing, Visualization, Funding acquisition. Alexandru-Mihai Pintilioaie: Writing – review & editing, Resources. Laura-Elena Topală: Writing – review & editing, Resources. Ivica Králová-Hromadová: Writing – review & editing, Writing – original draft, Funding acquisition. Martin Hromada: Writing – review & editing, Writing – original draft, Funding acquisition.

Funding

This work was financially supported by the Scientific Grant Agency of the Ministry of Education, Science, Research and Sport of the Slovak Republic (project no. VEGA 2/0033/25), and by the Slovak Research and Development Agency under contract no. APVV-22-0440. The work of L. Mlynárová was funded by the EU NextGenerationEU through the Recovery and Resilience Plan for Slovakia under the project No. 09I03-03-V05-00006 and the Recovery and Resilience Plan of the Slovak Republic under the contract 09I3-03-V06-00052.

The research conducted by A.-M. Pintilioaie was supported by the Operational Program Competitiveness 2014–2020, Axis 1, under POC/448/1/1 Research infrastructure projects for public R&D institutions/Sections F 2018, through the Research Center with Integrated Techniques for Atmospheric Aerosol Investigation in Romania (RECENT AIR) project, under grant agreement MySMIS no. 127324.

Declaration of competing interest

The authors declare that they have no conflict of interest.

Appendix A. Supplementary data

The following is the Supplementary data to this article: