Hydrocarbons in adult Chrysomela vigintipunctata (Scopoli) (Coleoptera : Chrysomelidae)

The hydrocarbon composition of the willow leaf beetle Chrysomela vigintipun ctala (Scopoli) (Coleoptera: Chrysomelidae) is presented in this paper. Sur face and internal hydrocarbons, total hydrocarbons of fed and starved insec ts, of the excrement and of the diet have been examined and compared. Norma l chain-, terminally branched monomethyl-, internally branched monomethyl-, dimethyl-, trimethyl alkanes and only four alkenes have been identified in the insect. The chain-lengths varied in the interval C-19 to C-43. Odd cha in alkanes dominate. Surface hydrocarbons are characterised by the presence of longer-chain (C-38,C-39 and C-41) dimethyl- and trimethyl-alkanes. Dime thyl- and trimethyl alkanes with an unusually great number of methylene gro ups between the branch points have been detected. The excrement and the wil low leaves have much simpler KC pattern: n-alkanes, terminally branched alk anes and alkenes. Based on the similarity between the HC pattern of the exc rement and willow leaves it is assumed that the dietary HC are eliminated w ith the excrement. (C) 1999 Elsevier Science Inc. All rights reserved.