Insect metabolism: Preventing cyanide release from leaves
Organisms that produce hydrogen cyanide gas to protect themselves against predators can do so by the enzymatic breakdown of a class of compounds known as cyanogens (such as cyanogenic glycosides). Here we show how a neotropical butterfly, Heliconius sara, can avoid the harmful effects of the cyanogenic leaves of Passiflora auriculata (passion vine), on which its larvae feed exclusively. To our knowledge this is the first example of an insect that is able to metabolize cyanogens and thereby prevent the release of cyanide. The mechanistic details of this pathway might suggest new ways to make cyanogenic crops more useful as a food source.