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

• Trichodectes pinguis pinguis is the chewing lice of brown bears (Ursus arctos).
• This is the first report of T. pinguis pinguis in brown bears in Scandinavia.
• T. pinguis pinguis could cause alopecia, hyperpigmentation and lichenification of the bears' skin.
• Infestations by T. pinguis pinguis could have an impact on the health of brown bears.

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.

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