Defining the concept of 'tick repellency' in veterinary medicine

Abstract

Although widely used, the term repellency needs to be employed with care when applied to ticks and other periodic or permanent ectoparasites. Repellency has classically been used to describe the effects of a substance that causes a flying arthropod to make oriented movements away from its source. However, for crawling arthropods such as ticks, the term commonly subsumes a range of effects that include arthropod irritation and consequent avoiding or leaving the host, failing to attach, to bite, or to feed. The objective of the present article is to highlight the need for clarity, to propose consensus descriptions and methods for the evaluation of various effects on ticks caused by chemical substances.

Fig. 1

Flow diagram of the proposed in vivo test for the evaluation of tick repellency and associated effects on new infestation of an acaricidal product in dogs. The diagram gives time-line, location in crate and/or on dogs and the effect being measured. *Tick count at 2 h is not mandatory as combing may disturb the process of infestation.