Parasitic fauna of Eurasian beavers (Castor fiber) in Sweden (1997–1998)

Abstract

Background The parasitic fauna of beavers (Castor fiber and C. canadensis) has been well studied in many parts of their respective areas of distribution. In Scandinavia there have, however, been limited investigations conducted on the parasites of beavers in recent times. The present study is the first quantitative survey of parasites on beavers living in Sweden and elsewhere in Scandinavia. We investigated the parasitic fauna of the Eurasian beaver (C. fiber) in a North–South gradient in Sweden. The aim of the study was to investigate parasite distribution and prevalence in particular, related to average yearly air temperature and different age groups of beavers. A total of 30 beavers were sampled at eight localities, spanning a 720 km North–South gradient during the springs of 1997 and 1998. Results Five parasite taxa were identified. Four of these were present in all of the examined beavers, Stichorchis subtriquetrus (trematode), Travassosius rufus (nematode), Platypsyllus castoris (coleopteran), and Schizocarpus spp. (arachnid). A higher number of new infections of S. subtriquetrus, and more adults of T. rufus, were seen in beavers in southern Sweden where temperatures are higher. One-year old beavers had a higher infestation of S. subtriquetrus, but not of T. rufus, than older individuals. Conclusions The parasite fauna of Swedish beavers mirrored the impoverished parasite fauna of the original Norwegian population, and the high prevalence of parasites could be due to low major histocompatibility complex (MHC) polymorphism. Young beavers had a higher load of trematodes, probably depending on behavioural and ecological factors. Warmer temperatures in southern localities likely contributed to increased endoparasite loads.

First report of molecular taxonomic analyses of European beaver metazoan parasites from Hungary

“…The Hungarian population was almost exclusively originated from Bavaria (Bajomi 2011 ). This bottleneck effect might have resulted the loss of more than one of the beaver parasites as it was proposed by Åhlen et al ( 2021 ) in Sweden. As parasites represent significant component of the biodiversity and ecosystem, the conservation efforts should focus not only on host species but also on their parasites.…”

“…Among endoparasite helminth species, the flatworms Psilotrema castoris , Stichorchis subtriquetrus (Demiaszkiewicz et al 2014 ), Echinococcus multilocularis , Taenia martis (Campbell-Palmer et al 2015 ), Fasciola hepatica (Shimalov and Shimalov VT 2000); the nematode Travassosius rufus (Bystrianska et al 2021 ), Trichostrongylus capricola (Demiaszkiewicz et al 2014 ), Calodium hepaticum (Mészáros and Kemenes 1973 ; Fuehrer 2014 ), Trichinella spiralis (Różycki et al 2020 ) and Trichinella britovi (Seglina et al 2015 ) were found in C. fiber . Among ectoparasites, there are fur mites from the genus Schizocarpus , Demodex follicule mites (Izdebska et al 2016 ); two hard tick species Ixodes hexagonus (Haitlinger 1991 ) and Ixodes apronophorus (Kadulski 1998 ) and a unique epidermal tissue feeding beetle, Platypsyllus castoris (Åhlen et al 2021 ). Beavers can serve as a host for a wide range of rodent-related pathogens as well.…”