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Allomonal defence secretions of the American dog tick Dermacentor variabilis (Acari: Ixodidae) promote clustering

1995; Springer Science+Business Media; Volume: 19; Issue: 12 Linguagem: Inglês

10.1007/bf00052080

1572-9702

Jay A. Yoder,

Vector-borne infectious diseases

The release of the defence secretion from the large wax glands (‘sensilla sagittiformia’) of Dermacentor variabilis ticks modifies the behaviour of other ticks by inducing clustering. A coating of natural tick secretion onto test objects (delipidized ticks, glass beads or filter paper discs) also elicits a clustering response, but a topically applied squalene, its major component, does not have this effect. The clustering response appears to be species specific: D. variabilis cluster on conspecific ticks that secreted but they fail to cluster on Amblyomma americanum or Ixodes scapularis ticks unless coated with secretions from D. variabilis. Volatile components in the defence secretion are involved in recruiting conspecific ticks to those that secreted. When attacked by predatory fire ants, Solenopsis invicta, D. variabilis clustered on individuals that had released the defence secretion. This suggests that the secretion protects ticks from predation by functioning as an alarm pheromone. If confirmed, this is the first report of an alarm pheromone and its glandular source in ticks. The terminology applicable to the integumental glands of ticks is discussed.