Sessions

Carnus hemapterus is a holarctic insect species belonging to the order of Diptera and the family of Carnidae, whose larvae feed saprophytically on nest material (feather remnants, dried blood and feces) of birds. In contrast, winged adults—which emerge in spring during the birds' breeding season under the influence of the hosts' body temperature—typically shed their wings after locating a host and act as obligate ectoparasites, feeding on the blood of nestlings developing in the nest. Although this studied fly species has previously been recorded from numerous avian hosts worldwide and various blood parasites have been detected in them, their eco-epidemiological and vector roles remain unclear to this day.

During our studies parasite collection was carried out between 2023 and 2026 during the birds' breeding season, mainly the months from May to August, across 12 counties of Hungary from a total of 81 collection sites. Over 5,300 individuals belonging to 79 species of 16 avian orders were examined, of which 469 birds proved to be infested, showing an overall prevalence of approximately 8.8%. A total of 2,646 C. hemapterus specimens were collected, comprising 1550 females, 1041 males and another 55 individuals of undetermined sex.

In the course of our investigations we described three new avian hosts for C. hemapterus that are not mentioned in previous literature: the Black Stork (Ciconia nigra), the Black Kite (Milvus migrans), and the Lesser Grey Shrike (Lanius minor). Based on our results, artificial nest boxes and cavities are favorable for C. hemapterus where the prevalence (22.76%) was significantly higher than in natural nests (4.74%). The highest prevalence values were found in Falconiformes (30.96%) and Strigiformes (23.65%), with Common Kestrels (Falco tinnunculus) proving to be heavily infested as Carnus flies were found on nearly 40% of the nestlings. As a result of our sample collection we can confirm earlier hypotheses stating that the highest parasite load is characteristic of the most intensive phase of nestling growth.

Beyond morphological identification molecular (PCR) analyses were also performed for the species-level identification of the flies. Through the genetic analysis of morphologically "non-classical", e.g. darker specimens we verified that these specimens also belong to the C. hemapterus species meaning that only this single blood-sucking Carnus species was successfully detected in Hungary. Furthermore, we investigated the presence of DNA of blood parasites and other vector-borne bacteria transmitted by blood-sucking arthropods in these flies. According to our results it is unlikely that C. hemapterus plays an important role in the transmission of the vector-borne pathogens studied.