The chemical defence of Doryphorina beetles (Coleoptera: Chrysomelidae)

The defensive secretions of adults of eight species of Doryphorina beetles have been analyzed. Four Leptinotarsa one Labidomera species ( L. trimaculata) produce amino acid derivatives, whereas two Calligrapha species produce cardiac glycosides. On the other hand, Zygogramma suturalis is so far unique in simultaneously producing cardiac glycosides and amino acid derivatives. The secretions of all species studied contain ethanolamine. Besides seven known compounds, (3Z)-2- aminohexa-3,5-dienoic acid and four new cardiac glycosides have been isolated and their structures determined by spectroscopic methods. The implications of these results for the taxonomy of the Chrysomelini are discussed, as well as the evolution of chemical defences in this group of beetles.