The aggregation-attachment pheromone of the tropical bont tick Amblyomma variegatum Fabricius (Acari,Ixodidae): Isolation,identification and action of its components

Combining a new in vitro bioassay with the analytical method capillary gas chromatography-mass spectrometry, the aggregation-attachment pheromone produced by fed males of the tropical bont tick Amblyomma variegatum was shown to consist of o-nitrophenol, methyl salicylate and pelargonic acid in the approximate amounts of 2/1/8 × 10^?6 g/tick. A synthetic pheromone blend composed of those three volatile compounds evoked an aggregation response in unfed males and females in a bioassay comparable to the response to a natural pheromone source. Of the individual components. only o-nitrophenol induced a significant, although not complete aggregation response. Methyl salicylate and pelargonic acid contribute to complete pheromone activity, but induce no aggregation response at all, when offered separately.