Pheromone production and its relationship to water conservation: studies on a trichlorophenol in the American dog tick,Dermacentor variabilis(Acari: Ixodidae)

2,4,6-trichlorophenol (2,4,6-TCP), a component of a synthetic chlorophenol mixture highly attractive to the American dog tick, Dermacentor variabilis (Say), was tested to determine its efficacy as a tick-attractant. Attraction was more pronounced for fed ticks than nonfed ticks, making 2,4,6-TCP ideal as a supplement for acaricide-containing baits in tail tags and ear tags. With the exceptions of eggs and larvae, all life cycle stages contain 2,4,6-TCP, and its presence correlates with having ingested a bloodmeal. The occurrence and attractive properties of 2,4,6-TCP suggest that it has possible pheromonal function. Production of 2,4,6-TCP likely favors water conservation by desalinating tick body fluids after a salt (chloride)-rich bloodmeal. Applying this physiological interpretation provides an explanation for the observed presence of sex pheromone, 2;6-dichlorophenol, in males of this species