New publication: Tick infestation on medium–large-sized mammalian hosts: are all equally suitable to Ixodes ricinus adults?
By Atle Mysterud, Christian Hügli, and Hildegunn Viljugrein in Parasites & Vectors.
In Europe, the generalist tick, Ixodes ricinus, is the main vector of several tick-borne pathogens causing diseases in humans and livestock. Understanding how diferent species of hosts limit the tick population is crucial for management. In general, larger ectoparasites are expected to select hosts with larger body size. Consistent with this, larval and nymphal I. ricinus can feed on a wide range of diferent-sized vertebrates, while the adult female stage is expected to rely on a medium–large-sized host for reproduction. However, we still have a limited understanding of whether medium-sized hosts other than roe deer can serve as hosts to adult ticks, and other factors than size may also afect host selection.
To increase our understanding of the suitability of the diferent species of medium-sized hosts for adult ticks, we sampled mainly roadkill mammals from within the questing season of ticks. We counted life stages of ticks on roe deer (Capreolus capreolus) (n=29), red fox (Vulpes vulpes) (n=6), badger (Meles meles) (n=14) and red squirrel (Sciurus vulgaris) (n=17) from spatially overlapping populations in Norway, and analysed variation between species across diferent body parts with a mixed-efects negative binomial model (with and without zero-infation).
Red squirrel hosted a high density of larval and nymphal I. ricinus, but only one individual had adult female ticks. Roe deer hosted by far the largest number of adult ticks. Badgers had very few ticks, possibly due to their thick skin. Red foxes had intermediate numbers, but a high proportion of subcutaneous, dead ticks (69.3%), suggesting they are not very suitable hosts. Body mass predicted the presence of adult I. ricinus ticks. However, species was a better predictor than body mass for number of ticks, suggesting there was species variation in host suitability beyond body mass per se.
Our study provides evidence that roe deer are indeed the main suitable reproduction host to adult I. ricinus ticks, and are likely a key to host limitation of the tick population in this northern ecosystem.
Parasites & Vectors
Vol. 14, 254 (2021)
Published 13 May 2021
1. Centre for Ecological and Evolutionary Synthesis (CEES), Department
of Biosciences, University of Oslo, Blindern, P.O. Box 1066, 0316 Oslo,
2. Norwegian Veterinary Institute, Sentrum, P.O. Box 750, 0106, Oslo, Norway