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

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.