Setosa membrane structure and occurrence of eicosenol in honeybees (Apis sp.)

Morphological analysis showed that the setosa membrane of workers is reduced in Apis cerana and A. koschevnikovi in comparison to that of A. mellifera. This may be due to different predator pressures among these species. This finding is supported by the marked reduction in the amount of the alarm pheromone eicosenol detected on the sting apparatus (setose area) in A. cerana workers in relation to that found in A. mellifera workers. The setosa membranes of the three open nesting species, A. andreniformis, A. florae and A. dorsata are well developed despite eicosenol being completely absent in A. dorsata and present in only trace amounts in A. florea and A. andreniformis workers. We also confirm that during dissection the internal glands of the sting apparatus do not become contaminated with compounds such as eicosenol, which can be present on the sting surface in high concentrations.