Seasonal changes in chemical composition of epicuticular waxes from the leaves of Baccharis linearis

Extracts from the epicuticular waxes of leaves from Baccharis linearis coll ected at the same locality at different seasons of the year were compared i n terms of relative yields, chemical composition and biological activity (f eeding deterrancy against Spodoptera littoralis larvae and brine shrimp let hality bioassays). Variations detected in the concentration of some of the 13 secondary metabolites isolated in this study are discussed in connection with relevant seasonal changes of incidental environmental factors such as temperature, solar radiation, water stress and presence of predatory insec ts. (C) 1999 Elsevier Science Ltd. All rights reserved.