| abstract | Members of the pisentii group of the genus Macrocheles, a phoretic assemblage associated with the dung beetle subtribe Scarabaeina, were found on only two of the five species of Scarabaeus that occur in southern France. M. pisentii, the phoront-specific species associated with S. semipunctatus in the Mediterranean basin, was attracted to other species of Scarabaeus in disc olfactometer and arena tests, suggesting that the kairomone that mediates the relationship between M. pisentii and its natural phoront is not unique to S. semipunctatus. It is suggested that phoretic specificity is based not only on chemical cues, but on ecological isolation of the mite through adaptation to the multidimensional niche, or hypervolume, of its host. |