Argasid Ticks of Palearctic Bats: Distribution, Host Selection, and Zoonotic Importance

Abstract

The soft ticks (Ixodida: Argasidae) are ectoparasites of terrestrial vertebrates with a wide geographic distribution, occurring on all continents. These ticks are obligate blood-feeders, most of them show high degrees of host-specialization and several species in arid and tropical regions are important parasites of livestock and men. Species commonly occurring on domestic animals and man are generally well-known, with many studies focusing on their ecology, distribution or vectorial role. However, wildlife-specialist soft ticks are less studied. Nearly half of all soft tick species are bat specialists, with five species (Carios vespertilionis, Chiropterargas boueti, Chiropterargas confusus, Reticulinasus salahi, and Secretargas transgariepinus) occurring in the Western Palearctic. There is no comprehensive study on the distribution, hosts or pathogens in these soft ticks, although most species were shown to carry several viral, bacterial, or protozoan pathogens and also to occasionally infest humans. Based on a literature survey and 1,120 distinct georeferenced records, we present here the geographical range, host selection and vectorial potential for bat-specialist soft ticks occurring in the Western Palearctic (chiefly Europe, North Africa, and the Middle East). Carios vespertilionis shows the largest distribution range and was found on most host species, being ubiquitous wherever crevice-roosting bats occur. All the other species were located only in areas with Mediterranean climate, with Ch. boueti, Chiropteraragas confusus, and R. salahi are missing entirely from Europe. These three species have a host spectrum of bats roosting primarily in caves, while S. transgariepinus and Ca. vespertilionis is feeding primarily on crevice-roosting bat species. All but one of these soft tick species are known to feed on humans and may be vectors of important disease agents (Rickettsia spp., Borrelia spp., Bartonella spp., Ehrlichia spp., Babesia spp., several nairo-, and flaviviruses). As several crevice-roosting bat species show a continuous adaptation to human-altered areas, with certain species becoming common city-dwellers in the Western Palearctic, the study of bat specialist soft ticks is also important from an epidemiologic point of view.

Maps of ticks (Acari: Argasidae, Ixodidae) for Austria and South Tyrol, Italy

“…The distribution map recently presented by Sándor et al. ( 2021 ) shows the occurrence of C. vespertilionis up to 60 N latitude. The taxonomical status of this tick species like that of many other argasids is not certain.…”

“…1972 ), 2 (Sándor et al. 2021 ). A total of five known locations of the soft tick C. vespertilionis is mapped in Fig.…”

“…The short-legged bat tick C. vespertilionis (also known as Argas vespertilionis) is widely distributed in the Old World from the Palaearctic to South Africa (Hoogstraal 1956). The distribution map recently presented by Sándor et al (2021) shows the occurrence of C. vespertilionis up to 60 • N latitude. The taxonomical status of this tick species like that of many other argasids is not certain.…”

“…1. In South Tyrol, two C. vespertilionis locations were reported from the Bozen and Bruneck area (Sándor et al 2021), which are shown together with two locations of North Tyrol in Fig. 9.…”

“…Main hosts are cave-dwelling, insectivorous bats, such as the common noctule (Nyctalus noctula) and the common pipistrelle (Pipistrellus pipistrellus) in Austria (Mahnert 1971). The following locations have been documented: 1 (Pfoser 1948), 1 (Mahnert 1971), 1 , 2 (Sándor et al 2021). A total of five known locations of the soft tick C. vespertilionis is mapped in Fig.…”