Melyrid beetles ( Choresine ): A putative source for the batrachotoxin alkaloids found in poison-dart frogs and toxic passerine birds

doi:10.1073/pnas.0407197101

Melyrid beetles (Choresine): A putative source for the batrachotoxin alkaloids found in poison-dart frogs and toxic passerine birds

^*Smithsonian Conservation Research Center, Front Royal, VA 22630; ^†Department of Birds and Mammals, California Academy of Sciences, San Francisco, CA 94103; ^§Herowana Village, Eastern Highlands Province, Papua New Guinea; ^¶Entomology, Bernice P. Bishop Museum, Honolulu, HI 96813; and ^∥Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Department of Health and Human Services, Bethesda, MD 20892

Contributed by John W. Daly, September 28, 2004

Abstract

Batrachotoxins are neurotoxic steroidal alkaloids first isolated from a Colombian poison-dart frog and later found in certain passerine birds of New Guinea. Neither vertebrate group is thought to produce the toxins de novo, but instead they likely sequester them from dietary sources. Here we describe the presence of high levels of batrachotoxins in a little-studied group of beetles, genus Choresine (family Melyridae). These small beetles and their high toxin concentrations suggest that they might provide a toxin source for the New Guinea birds. Stomach content analyses of Pitohui birds revealed Choresine beetles in the diet, as well as numerous other small beetles and arthropods. The family Melyridae is cosmopolitan, and relatives in Colombian rain forests of South America could be the source of the batrachotoxins found in the highly toxic Phyllobates frogs of that region.

Footnotes

↵ ‡ To whom correspondence should be addressed. E-mail: jdumbacher{at}calacademy.org.
Author contributions: J.P.D., S.R.D., and J.W.D. designed research; T.F.S. and J.W.D. analyzed chemical data; J.P.D. and J.W.D. wrote the paper; A.W. provided local expertise critical to the discovery; A.W. and J.P.D. conducted field collections; and A.S. identified beetles to species and provided entomological expertise.
Abbreviations: BTX, batrachotoxin; h-BTX, homo-batrachotoxin; BTX-A, batrachotoxinin A.