SEQUESTRATION OF LICHEN COMPOUNDS BY LICHEN-FEEDING MEMBERS OF THE ARCTIIDAE (LEPIDOPTERA)

A survey for the presence of sequestered lichen compounds in 103 wild- caught imagines representing eight different genera and 16 different s pecies of the Arctiidae was conducted. Known lichen compounds were det ected for the first time in 24 of the analyzed specimens (representing five different genera and 11 different species) based on their HPLC r etention times and on their UV-absorption spectra. The anthraquinone p arietin, the depside atranorin, as well as a hydrolytic cleavage produ ct of the latter were among the lichen compounds most frequently detec ted in wild-caught imagines. The observed variation of sequestered lic hen compounds in wild-caught imagines with unknown feeding history may be due to several reasons. Lack of lichen compounds in imagines may h ave been caused, for example, by larvae feeding on lichens with no or only minute amounts of phenolic products. The age of the specimens ana lyzed may also influence the results obtained. Avoidance of lichen com pounds by selective feeding on those parts of lichen thalli that have no or little lichen products may be another reason for the lack of lic hen compounds in imagines. Preliminary feeding experiments conducted w ith larvae of Eilema complana, for example, indicated that the larvae fed exclusively on the algal layer and cortex of the lichen Cladonia p yxidata, whereas the medulla, which is rich in fumarprotocetraric acid , was avoided. As expected, imagines hatching from the larvae were fre e of this lichen compound. Any ecological role of the sequestered lich en compounds for the herbivores is unknown. It is possible, however, t hat sequestered lichen compounds may be utilized for the chemical defe nse of arctiid moths or against microbial pathogens.