Journal of Chemical Ecology

, Volume 17, Issue 8, pp 1593–1610

Palatability of aposematic queen butterflies (Danaus gilippus) feeding onSarcostemma clausum (Asclepiadaceae) in Florida

Authors

  • David B. Ritland
    • Department of ZoologyUniversity of Florida
Article

DOI: 10.1007/BF00984691

Cite this article as:
Ritland, D.B. J Chem Ecol (1991) 17: 1593. doi:10.1007/BF00984691

Abstract

Queen butterflies (Danaus gilippus) are generally considered unpalatable to predators because they sequester and store toxic cardenolides from their larval food plants. However, a major queen food plant in Florida, the asclepiadaceous vineSarcostemma clausum, is shown here to be a very poor cardenolide source, and queens reared on this plant contain no detectable cardenolide. A direct evaluation of queen palatability using red-winged blackbirds indicates thatS. clausum-reared butterflies are essentially palatable to these predators (85% of abdomens entirely eaten), indicating little protection from either cardenolides, other sequestered phytochemicals, or de novo defensive compounds. Wild-caught queens that presumably fed as larvae uponS. clausum and also had access to adult-obtained chemicals, such as pyrrolizidine alkaloids (PAs), were relatively palatable as well (77% of abdomens eaten); they did not differ significantly in palatability from the labreared butterflies. Together, these findings suggest that; (1)S. clausumfed queens are poorly defended against some avian predators, and (2) for the particular queen sample examined, PAs do not contribute substantially to unpalatability. The discovery thatS. clausum-feeding queens are essentially palatable is of additional significance because it compels a reassessment of the classic mimicry relationship between queen and viceroy butterflies. Viceroys have been shown recently to be moderately unpalatable; therefore, the established roles of model and mimic may be reversed in some cases.

Key Words

Chemical defensemimicrycardenolidespyrrolizidine alkaloidsAsclepiadaceaeLepidopteraDanainaeDanaus gilippusLimenitis archippusSarcostemma

Copyright information

© Plenum Publishing Corporation 1991