SELECTIVE OVIPOSITION BY DANAUS PLEXIPPUS (L.) (LEPIDOPTERA: NYMPHALIDAE) IN A MIXED STAND OF ASCLEPIAS FRUTICOSA AND A. CURASSAVICA IN SOUTHEAST QUEENSLAND

Abstract

Abstract The numbers of eggs and larvae of wanderer butterfly were recorded on Asclepias fruticosa and A. curassavica growing in the same habitat in southeast Queensland. Many more immatures were found on A. curassavica , although this is a rare and inconspicuous host plant. The apparent preference for A. curassavica could be associated with the lower cardiac glycoside concentration of this species (370μg/0.1g dry leaf weight, SD = 156) compared with A. fruticosa (450 ± 193). We measured cardenolides using a modification of techniques found in the literature, which enbles us to measure glycosides in single leaves. A closer investigation of cardiac glycosides in plants with and without immatures across both species revealed no clear or consistent pattern. The difficulties of making conclusions about cardiac glycosides and wanderer butterfly oviposition based on comparisons of distribution of immatures on plant species are discussed and an alternative approach suggested.