Hidden guests of CO₂ traps: Tracking Clogmia albipunctata, Drosophila suzukii, and other Diptera across Slovakia / Tajemniczy goście w pułapkach na CO₂: tropienie Clogmia albipunctata, Drosophila suzukii, i innych muchówek w Słowacji

97 Polskie Towarzystwo Entomologiczne DIPTERON Polish Entomological Society ISSN 1895 - 4464 Tom 41(08): 97–107 Akceptacja: 20 11 2025 Wrocław 06 12 2025 HIDDEN GUESTS OF CO₂ TRAPS: TRACKING CLOGMIA ALBIPUNCTATA, DROSOPHILA SUZUKII, AND OTHER DIPTERA ACROSS SLOVAKIA TAJEMNICZY GOŚCIE W PUŁAPKACH NA CO₂: TROPIENIE CLOGMIA ALBIPUNCTATA, DROSOPHILA SUZUKII, I INNYCH MUCHÓWEK W SŁOWACJI DOI: 10.5281/zenodo.17808535 Jozef Oboňa 1, Katarína Loziaková Peňazziová 2, Tomáš Csank3, Zuzana Pačanská 4, Soňa Pivka 5 1 Department of Ecology, Faculty of Humanities and Natural Sciences, University of Prešov, 17. novembra 1, SK – 08116 Prešov, Slovakia; e-mail: joz[email protected] 2 Department of Microbiology and Immunology, University of Veterinary Medicine and Pharmacy. Komenského 73, SK – 04181 Košice, Slovakia; e-mail: [email protected] 3 Department of Microbiology and Immunology, University of Veterinary Medicine and Pharmacy. Komenského 73, SK – 04181 Košice, Slovakia; e-mail: [email protected] 4 Department of Microbiology and Immunology, University of Veterinary Medicine and Pharmacy. Komenského 73, SK – 04181 Košice, Slovakia; e-mail: [email protected] 5 Department of Microbiology and Immunology, University of Veterinary Medicine and Pharmacy. Komenského 73, SK – 04181 Košice, Slovakia; e-mail: [email protected] Corresponding author: Jozef Oboňa ([email protected]) ABSTRACT: CO₂-baited BG-Sentinel 2 traps are widely used for mosquito surveillance; however, their non-target catches can also yield valuable insights into broader insect biodiversity. Building on previous research, we analyzed incidental captures collected from multiple sites across Slovakia, focusing on two invasive synanthropic species - the moth midge Clogmia albipunctata (Williston, 1893) (Psychodidae) and the spotted-wing drosophila Drosophila suzukii (Matsumura, 1931) (Drosophilidae). Using these traps, we successfully mapped their distribution across urban and semi-urban habitats, recording occurrences in several previously unreported localities. Our findings highlight the potential of CO₂ traps as practical tools for faunistic monitoring beyond mosquito targets, revealing patterns of distribution and spread of invasive Diptera. This study underscores the broader value of repurposing standard mosquito surveillance infrastructure for multi-taxa biodiversity assessments and early detection of invasive species in human-influenced environments. KEY WORDS: bycatch, Clogmia, CO₂ trap, Drosophila, faunistics, invasive species, Slovakia, urban ecology 98 INTRODUCTION Carbon dioxide (CO₂)-baited traps, such as the BG-Sentinel 2 (Biogents, Germany), have long been employed for targeted monitoring of hematophagous Diptera, particularly mosquitoes (e.g., Farajollahi et al., 2009; Cilek et al., 2024). Although these traps are optimized for host-seeking species, their non-target catches are often overlooked or discarded. However, recent studies have highlighted the considerable faunistic and ecological value of such incidental captures (Grootaert et al., 2025; Grundmann et al., 2025a,b; Kurina et al., 2025; Oboňa et al., 2025). By examining these non-target taxa, researchers have discovered previously undocumented species within families such as Phoridae, Bibionomorpha, and other Diptera groups, thereby broadening our understanding of insect biodiversity across Slovakia and illustrating the potential of CO₂ traps as complementary monitoring tools. Building on these findings, the present study further explores non-target Diptera, focusing specifically on two synanthropic and invasive species: the moth midge Clogmia albipunctata (Williston, 1893) (Psychodidae) and the spotted-wing drosophila Drosophila suzukii (Matsumura, 1931) (Drosophilidae). Both species are of growing concern in Slovakia due to their expanding ranges, strong synanthropic tendencies, and, in the case of D. suzukii, significant economic impact on soft fruit crops (e.g., Oboňa et al., 2016; Oboňa et al., 2017). In this study, we assess the effectiveness of CO₂-baited traps not only for detecting established mosquito populations but also for mapping the occurrence, distribution, and relative abundance of C. albipunctata and D. suzukii across semi-urban and urban landscapes. Through detailed analysis of incidental captures, we provide updated faunistic records and insights into the spatial dynamics of these species in Slovakia. Ultimately, our findings demonstrate the broader utility of CO₂-based surveillance systems for multi-taxa biodiversity monitoring in anthropogenically influenced environments. MATERIAL AND METHODS SAMPLING The bycatch analyzed in this study was collected during mosquito surveillance using BG-Sentinel 2 traps (Biogents, Germany) baited with pressurized CO₂ cylinders. Traps were deployed across 16 localities in Slovakia throughout 2024 (Map 1). Collection nets were replaced weekly, and samples were first stored at −20 °C and later at −80 °C until laboratory processing. After removing mosquitoes, the remaining material was preserved in 75% ethanol. The collected flies were then sorted to family level and subsequently identified to species level using the following keys: Limoniidae and Pediciidae – Podenas et al. (2006), Oosterbroek (2024); Psychodidae – Withers (1989), Ježek (1977, 1990), and Ježek and van Harten (2009); and Drosophilidae – Asplen et al. (2015). LOCALITIES Sampling was conducted at 16 sites representing a range of habitat types across Slovakia (for details, see Grundmann et al., 2025b; Grootaert et al., 2025, and Map 1). 99 Map 1. Sampling sites across Slovakia. Map created using Google Maps (https://www.google.com/maps). For data interpretation, species were categorized according to their frequency of occurrence in traps (1 case = 1 qualitative presence; total = 396 samples): sporadic – < 1% of cases; not common – 1–5%; common – 5–10%; very common – > 10%. The number in parentheses () indicates the exact number of positive samples. RESULTS A total of 20 species were collected using BG-Sentinel 2 traps across Slovakia in 2024. These represent only selected taxa and do not constitute a complete overview of all Diptera species recorded. The families Limoniidae, Pediciidae, and Psychodidae are presented in full, while only one representative species is included from Drosophilidae. ANNOTATED LIST OF RECORDED SPECIES Drosophilidae Rondani, 1856 Drosophila suzukii (Matsumura, 1931) Note: common (22), present in 6% of all samples (see Map 2, Fig. 1) Comments: The spotted wing drosophila has rapidly spread across Europe, establishing populations in several countries since its first detection (Calabria et al., 2012; Cini et al., 2012, 2014; Łabanowska et al., 2015; Kiss et al., 2016; Kenis et al., 2016; etc.). This invasive species poses a serious threat to agriculture, particularly to soft fruit production such as berries and cherries, where it causes substantial economic losses (De Ros et al., 2015; Kenis et al., 2016; Tait et al., 2021; Zhou et al., 2024; etc.). 100 Limoniidae Rondani, 1856 Achyrolimonia coeiana (Nielsen, 1959) Note: sporadic (1) Achyrolimonia decemmaculata (Loew, 1873) Note: sporadic (2) Achyrolimonia neonebulosa (Alexander, 1924) Note: sporadic (1) Atypophthalmus (Atypophthalmus) inustus (Meigen, 1818) Note: very common (42) Dicranomyia (Dicranomyia) modesta (Meigen, 1818) Note: sporadic (2) Erioptera (Erioptera) lutea Meigen, 1804 Note: sporadic (2) Gonempeda flava (Schummel, 1829) Note sporadic (1) Helius (Helius) longirostris longirostris (Meigen, 1818) Note: sporadic (1) Limonia nubeculosa Meigen, 1804 Note: very common (48) Limonia phragmitidis (Schrank, 1781) Note: not common (3) Metalimnobia (Metalimnobia) bifasciata (Schrank, 1781) Note: sporadic (2) Molophilus (Molophilus) griseus (Meigen, 1804) Note: sporadic (1) Molophilus (Molophilus) ochraceus (Meigen, 1818) Note: sporadic (1) Neolimonia dumetorum (Meigen, 1804) Note: sporadic (1) Pseudolimnophila (Pseudolimnophila) lucorum (Meigen, 1818) Note: not common (6) Pediciidae Osten Sacken, 1860 Ula (Ula) bolitophila Loew, 1869 Note: sporadic (1) Psychodidae Bigot, 1854 Clogmia albipunctata (Williston, 1893) Note: very common (64); present in 16% of all samples (see Map 3, Fig. 1) Comments: The cosmopolitan drain fly C. albipunctata is currently experiencing a notable expansion of its distribution range, with increasing records from diverse geographic regions (Oboňa et al., 2021, 2023; Kvifte, 2023; Marafi et al., 2025; etc.). While often considered a nuisance species, its presence in hospitals and domestic environments has raised significant public health concerns. Clogmia albipunctata has been implicated as a potential agent of facultative myiasis and as a passive carrier of bacteria and other pathogenic microorganisms, potentially facilitating their introduction into sterile or clinical settings (Akhoundi et al., 2022; Chen et al., 2022; Faulde et al., 2023; Mathison et al., 2024; Park et al., 2025; etc.). Psychodocha cinerea (Banks, 1894) Note: common (19) 101 Tinearia alternata (Say, 1824) Note: very common (91) Map 2. Sampling sites in Slovakia with positive localities (purple house symbols) for Drosophila suzukii (Matsumura, 1931). Map created using Google Maps (https://www.google.com/maps). Map 3. Sampling sites in Slovakia with positive localities (purple house symbols) for Clogmia albipunctata (Williston, 1893). Map created using Google Maps (https://www.google.com/maps). 102 Fig. 1. Overview of the number of positive samples per month for both species. DISCUSSION The comparison of Diptera assemblages obtained from mosquito trap collections in Košice Zoo (see Oboňa et al., 2025) revealed both similarities and differences in species composition and relative abundance. Within the family Psychodidae, all three previously recorded species (T. alternata, P. cinerea, and C. albipunctata) were consistently captured. Tinearia alternata remained very common in both surveys. While P. cinerea was classified as very common in earlier study, it appeared only as common in the present dataset, suggesting minor fluctuations in local population density or differences in trap efficiency. The high frequency of C. albipunctata represents a new observation, possibly reflecting seasonal dynamics or microhabitat preferences within the zoo environment. Among Limoniidae, several core species were repeatedly captured, confirming results from Oboňa et al. (2025). Atypophthalmus inustus and L. nubeculosa remained very common, confirming their widespread presence in the sampled habitats. Other species such as A. decemmaculata and E. lutea were only sporadically captured, indicating temporal variability or sensitivity to environmental factors such as humidity, vegetation structure, or larval substrate availability. Newly recorded taxa (e.g., A. coeiana, A. neonebulosa, D. modesta, P. lucorum, and U. bolitophila) highlight the broader diversity of Diptera incidentally captured during mosquito monitoring. The sporadic occurrence of these species suggests that they are occasional visitors to trap sites rather than stable local residents, consistent with other European faunistic studies using CO₂-based traps. The presence of D. suzukii, absent from previous datasets (Oboňa et al., 2025), underscores the potential of BG-Sentinel traps to collect a wider taxonomic spectrum beyond 0 5 10 15 20 25 30 35 jun july august september october Clogmia albipunctata Drosophila suzukii 103 hematophagous Diptera. Its frequent occurrence supports the idea that CO₂-baited traps can attract species with diverse ecological niches, including frugivorous and saprophagous taxa. Overall, the comparative analysis demonstrates that while core saprophagous and marshland-associated species such as A. inustus, L. nubeculosa, and T. alternata remain consistently abundant, the composition of non-target Diptera in mosquito traps varies temporally and ecologically. These findings reinforce the utility of BG-Sentinel traps not only for mosquito monitoring but also for documenting local dipteran biodiversity (see also Grootaert et al., 2025; Grundmann et al., 2025a,b; Kurina et al., 2025). Our additional data confirm that CO₂ traps are effective not only for the originally targeted mosquito species but also for invasive and synanthropic taxa such as C. albipunctata and D. suzukii. Clogmia albipunctata was detected at multiple localities, including urban and peripheral areas where it had not previously been recorded (Map 3). Its occurrence even at higher altitudes suggests that urban microclimates may facilitate its expansion. Although the maximum altitude remains around 300 m a.s.l. (Oboňa et al., 2016), CO₂ traps can detect smaller peripheral populations outside the predicted range. Similarly, D. suzukii was recorded mainly during late summer and autumn (Map 2, Fig. 1), consistent with its seasonal activity and polyphagous ecology (Asplen et al., 2015). These data enhance understanding of the species’ spread in Slovakia and can help anticipate its potential impact on fruit crops. In summary, CO₂-baited traps represent an efficient method for the simultaneous monitoring of multiple invasive and synanthropic Diptera species. They enable the creation of detailed distribution maps, assessment of seasonal dynamics, and detection of range limits. This approach is therefore well suited for long-term faunistic and ecological studies in Slovakia and the wider Central European region. CONCLUSION This study demonstrates that CO₂-baited BG-Sentinel 2 traps, although originally designed for mosquito monitoring, are highly effective for detecting and mapping non-target Diptera, including invasive synanthropic species such as C. albipunctata and D. suzukii. Analysis of bycatch allowed us to document these species across multiple urban and semi-urban sites in Slovakia, providing updated faunistic records and new insights into their current distribution and potential for further spread. Our findings corroborate previous research showing that incidental captures from CO₂ traps hold substantial faunistic and ecological value. Incorporating non-target data into routine mosquito surveillance can enhance early detection of invasive species, contribute to urban biodiversity assessments, and inform management strategies for synanthropic Diptera. Overall, CO₂-based monitoring represents a cost-effective, multi-taxa approach that strengthens our understanding of insect diversity and invasion dynamics in human-modified habitats. 104 ACKNOWLEDGEMENTS We would especially like to thank the anonymous reviewers for their constructive comments, which greatly improved the manuscript. This work was co-funded by the European Union under the project 101132974 - OH SURVector. Views and opinions expressed are, however, those of the author(s) only and do not necessarily reflect those of the European Union or European Health and Digital Executive Agency (granting authority). 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