Chewing lice Trichodectes pinguis pinguis in Scandinavian brown bears (Ursus arctos)

Abstract

In April 2014 and 2015, we noted localized alopecia (neck, forelimbs, and chest) and hyperpigmentation on two adult brown bears (Ursus arctos) captured in central-south Sweden for ecological studies under the Scandinavian Brown Bear Research Project. In spring 2015, a brown bear was shot because of human-wildlife conflict in the same region. This bear also had extensive alopecia and hyperpigmentation. Ectoparasites were collected from the affected skin areas in all three individuals and preserved in ethanol for identification. Based on morphological characteristics, the lice were identified as Trichodectes spp. and Trichodectes pinguis pinguis. To our knowledge, these are the first reported cases of chewing lice in free-ranging brown bears in Scandinavia.

Keywords: Alopecia; Biting lice; Brown bear; Sweden; Trichodectes pinguis; Ursus arctos.

Graphical abstract

Fig. 1

A 5-year-old female brown bear (Ursus arctos), ID No. W1017, captured in Sweden. a) and b) April 2014: Hair loss in the ventral region of the neck and upper chest probably caused by Trichodectes spp. c) April 2015: Hair loss and scar tissue in the neck; no lice were found.

Fig. 2

A 15-year-old male brown bear (Ursus arctos), ID No. W1211, parasitized by Trichodectes pinguis pinguis. Notice the areas with partial or complete hair loss, hyperpigmentation and lichenification of the skin. a) April 2015 at the time of capture. b) June 2015 when feeding on a carcass.

Fig. 3

Brown bear (Ursus arctos) killed because of human-wildlife conflict in south-central Sweden in May 2015. The bear showed extensive alopecia in the area covering a) the chin, ventral part of the neck; b) axillar region, and abdomen.

Fig. 4

Specimen of Trichodectes pinguis pinguis recovered from a brown bear (Ursus arctos) killed because of human-wildlife conflict in south-central Sweden in May 2015. The distance between the measuring bars is 1 mm.