Comparison of the composition of epicuticular wax from red raspberry (Rubus idaeus L.) and hawthorn (Crataegus monogyna Jacq.) flowers

Epicuticular waxes have been characterised from the flowers of raspberry an d hawthorn, on both of which adult raspberry beetles (Byturus tomentosus) c an feed. The flower wax from both species had similar alkane profiles and a lso contained long-chain alcohols, aldehydes and fatty acids. The range of the carbon numbers detected for these classes of compounds was broadly simi lar in both but the relative amounts of each differed between species. Rasp berry flower wax also contained fatty acid methyl eaters, a group of compou nds that has rarely been detected in plant epicuticular waxes, however, the se were not observed in hawthorn flower wax. Long-chain alcohol-fatty acid esters with carbon numbers ranging from C36 to C48 were also detected in bo th plant species. However, an examination of their constituent acids indica ted that in hawthorn the esters based on the C16 fatty acid predominated, w hilst in raspberry flower wax, esters based on the C20 fatty acid were most abundant. Both species also contained pentacyclic triterpenoids, which acc ounted for, on average, over 16 and 48% of the total wax extracted from ras pberry and hawthorn flowers respectively. In the former, ursolic and oleano lic acids accounted for over 90% of the pentacyclic triterpenes. whilst haw thorn Rower wax, in addition to containing these acids, also contained high relative concentrations of both free and esterified alpha- and beta -amyri ns. (C) 2000 Elsevier Science Ltd. All rights reserved.