Chemical polymorphism of the cuticular lipids of the cabbage white Pieris rapae

The epicuticular composition of different body parts of the Cabbage White, Pieris rapae L., was investigated using GC and GC/MS. The major group of components, hydrocarbons, occurs in two distinct classes, which show different distributions on the cuticle of the insects. Unbranched shorter chain compounds (C-21 to C-31, linear group) dominate on body, head and wings, while longer chain, polymethyl-branched compounds (C-35 to C-39, branched group) are predominantly found on the antennae. Several other components like 1,3-pentacosadiene and oxygenated aliphatic compounds occur in minor amounts on the cuticle. The reason for this polymorphism is discussed.