Diet-based defensive secretions in harvestmen

Harvestmen are known to secrete a wide range of defensive chemicals in order to protect themselves from predators. An earlier study examined the phylogenetic pattern of defensive secretions produced by 22 species of harvestmen. This research, however, assumed that there is a genetic link between the defensive secretions. I wished to determine whether harvestmen defensive secretions may be diet-based by introducing several irritants into their food and then testing their secretions in the same manner. I performed a GC-MS analysis on 13 samples from the Vonones sp. But I found no initial GC-MS readings that showed this species of harvestmen to contain any irritants in their secretions. The absence of irritants does not allow any evaluation of whether harvestmen secretions are genetically or dietarily based.