Kinetics of male pheromone production by Amblyomma variegatum (Acari: Ixodidae)

Abstract

Males of Amblyomma variegatum (F.), when attached on their host, produce a pheromonal blend composed of methyl salicylate, ortho-nitrophenol, and nonanoic acid, which acts as an aggregation-attachment pheromone. Using olfactometry assays, assays on hosts, and quantification of the compounds by capillary gas chromatography, the kinetics of pheromone production has been studied. Males engorged for at least 10 d elicit attachment from most of the tested females. Attractiveness of males for females is significant only between days 14 and 23 of engorgement. Before 10 d of attachment, the amounts of pheromones detected in hexanic male body extracts are very low (< 10 ng); they then increase to a maximum of 2 micrograms for the major compound per male. Large amounts can be detected until 80 d of engorgement. The inter-individual variation is very large throughout the engorgement period. The interest and the limitations of the different techniques used are discussed.