Presence of oily droplets from the dorsal setae of Pieris rapae larvae (Lepidoptera : Pieridae)

We found that Pieris rapae larvae secreted oily droplets from the dorsal se tae. By using GC-MS analysis, we identified palmitic acid and stearic acid as the major components in the secretion. We already reported that Cotesia glomerata, a parasitoid of P. rapae larvae, showed characteristic antennati on to palmitic acid and stearic acid in the host-infested edge of the leaf. Based on our previous reports together with the result of this study, we i nferred that the two fatty acids in the droplets were used by C. glomerata in her host searching.