THE passion fruit vine produces 鈥済as bombs鈥� in its leaves that release deadly
cyanide when eaten. This keeps most creatures at bay, but Helene Engler of the
University of Texas at Austin and her colleagues have now found that the larvae
of the South American butterfly Heliconius sara can outwit the
plant鈥檚 defences. Far from being poisoned, the caterpillars use cyanogen, the
cyanide precursor found in the vine鈥檚 leaves, as a source of nitrogen
(Nature, vol 406, p 144). 鈥淭his is the first example of an insect capable of
cyanogen metabolism while avoiding the internal release of toxic cyanide,鈥�
Engler says.
Understanding how it does so could help make important crops that contain
cyanogen, such as lima beans and cassava, safer and more nutritious, she
says.