Characterization of dog repellent factor from cuticular secretion of female yellow dog tick, Haemaphysalis leachi.

During its natural life cycle, the yellow dog tick, Haemaphysalis leachi, has three hosts, and it has to spend enough time on each of them to complete a blood meal. When irritated, the females of this tick species produce a cuticular secretion that contains a dog-repelling allomone. This improves the tick's chances of survival by deterring the dog from biting the tick off its body. Employing response-guided isolation techniques in conjunction with gas chromatography-mass spectrometry, the defensive allomone of H. leachi was found to consist of the six homologous aliphatic aldehydes from hexanal to undecanal. A mixture of synthetic versions of these six aldehydes in quantities corresponding to those secreted by one tick elicited strong aversion reactions in the majority of dogs of various breeds.