They found that healthy hedgehogs were significantly less likely to carry ticks than sick hedgehogs.
Ticks are a problem for hedgehogs, a species in decline in Britain, and now on the protected species list, as they cause anaemia and can weaken a hedgehog severely.
An ecological survey conducted over ten years, involving 226 wild hedgehogs, found that ticks choose their 'host' based on odour linked to a hedgehog's health status.
The tick is associated predominantly with hedgehogs, but is occasionally found on dogs, cats and even humans. Ticks are attracted to hosts from a distance by different stimuli including vibrations, body heat and odour. Since hedgehogs have no specialised skin glands, odour sources that attract hedgehog antagonists from a distance are limited to footprints and faeces.
The compound indole is likely to be involved in the attraction of ticks to sick hedgehogs as it was the only major compound found to exist in significantly higher amounts in faecal odour from sick hedgehogs compared with healthy ones. Ticks were attracted to synthetic indole and also showed a preference for faeces from sick, as opposed to healthy, hedgehogs.
Dr Toni Bunnell says: "This study sheds light on the mechanisms of parasite host interaction between ticks and hedgehogs. Future studies will aim to identify the chemical compounds possibly released by healthy hedgehogs."
The study, entitled The fecal odour of sick hedgehogs (Erinaceus europaeus) mediates olfactory attraction of the tick Ixodes hexagonus, is published in the current edition of Chemical Ecology."
Source: University of Hull