Influence of dose and ratio of mixtures of pheromone components on the attraction of the tropical bont tick, Amblyomma variegatum

The responses of Amblyomma variegatum adults to constituents of their aggregation-attraction pheromone presented in an air stream were studied using a locomotion compensator. Behaviours to vapours from two mixtures were compared, the first a 1:1 mixture of o-nitrophenol and methyl salicylate, the second a four component mixture (R) containing o-nitrophenol, methyl salicylate, 2,6 dichlorophenol and phenyl acetaldehyde in the ratio 10:10:2:1, respectively No difference was found between the kineses responses ofA. variegatum adults for either mixture: both elicited an increase in angular velocity and a reduction in speed, Moreover; attraction to vapours of either mixture was reduced significantly as the source dose was increased: both mixtures were good attractants at a source dose of 10 mug of the main components, but were not attractive at source doses 100 times higher. As with many other arthropods, A. variegatum adults are responsive to the ratio, as well as to the dose, of constituents in an attractant mix. We suggest that the quantity and ratios of compounds in attractive mixtures released from commercial dispensers should be measured before use in any control programme.