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Cholesteryl oleate: Mounting sex pheromone of the hard tick Dermacentor variabilis (Say) (Acari: Ixodidae)

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<mark>Journal publication date</mark>1989
<mark>Journal</mark>Journal of Insect Physiology
Issue number11
Volume35
Number of pages7
Pages (from-to)873-879
Publication StatusPublished
<mark>Original language</mark>English
Externally publishedYes

Abstract

The moulting sex pheromone of Dermacentor variabilis, the American dog tick, is cholesteryl oleate. This steryl ester, when present in amounts from about 1 to 0.1 female equivalents elicited male mounting responses that were indistinguishable from the natural controls. Other steryl esters present on the tick's body surface also elicited responses, but a significantly lower intensity than cholesteryl oleate. Long regarded as a waste product of vertebrate blood feeding, this material is secreted by sexually mature females during feeding and accumulates on the surface of the body cuticle. Mate-seeking males, attracted to the females by the presence of 2,6-dichlorophenol, recognize and mount the feeding females. The accumulation of cholesteryl oleate on the female's body surface during blood feeding is an indication of successful parasitism and acts as a signal of female mating readiness. Compounds of unknown composition that co-chromatographed with steryl esters were also found in fed females of 4 other ixodid tick species. Bioassays performed with crude extracts of these different species suggest that mounting sex pheromones are widespread in the Ixodidae and may also use the same or similar steryl esters, either alone or in mixtures, as in D. variabilis.