Surveillance for Ixodes ricinus ticks (Acari, Ixodidae) on the Faroe Islands.

ABSTRACT

Ixodes ricinus ticks are expanding their geographic range in Europe, both latitudinally in Scandinavia, and altitudinally in the European Alps. This paper details the findings of both passive and active surveillance on the Faroe Islands. Active field surveillance, using tick dragging, was conducted at 38 sites across the main seven inhabited islands of the Faroes during June-August 2015. Field sampling was conducted at all wooded sites on the islands of Vágar, Streymoy, Eysturoy, Borðoy, Kunoy and Suðuroy as well as in urban parks in the capital Tórshavn, among seabird colonies and at a bird observatory on Nólsoy, at moorland sites on Vágar and Borðoy, and a coastal headland on Suðuroy. In addition, as part of the promotion of a new passive surveillance scheme for the Faroes, new tick records were submitted during summer 2015 and early spring 2016. During tick dragging, only three questing I. ricinus ticks (two nymphs, one male) were found at two separate sampling locations in the village of Tvøroyri on the southernmost island of Suðuroy. No questing ticks were found at any other field site. The passive surveillance of ticks identified an additional 33 records of I. ricinus collected during the last 10 years on the Faroes, with almost half of these records from 2015. Although this represents the first finding of questing I. ricinus and overwintering I. ricinus on the Faroe Islands, there appears to be little evidence so far to suggest that Ixodes ricinus are established on the Faroe Islands. Additional reports of ticks through the passive surveillance scheme are reported from seven inhabited islands. Reports of ticks on both companion animals and humans suggest that ticks are being acquired locally, and the records of ticks on migratory birds highlight a possible route of importation. This paper details the likely ecological constraints on I. ricinus establishment and density on Faroe and makes recommendations for future surveillance and research.