Key component in plant recognition of damage from insect herbivory. Isolated from the oral secretions of the beet armyworm caterpillar, it acts as a chemical signal to corn seedlings to produce volatile compounds to attract the caterpillar predator, parasitic wasps. Isolation and structure elucidation: H. T. Alborn et al., Science 276, 945 (1997). Biosynthesis: P. W. Paré et al., Proc. Natl. Acad. Sci. USA 95, 13971 (1998). Stereoselective synthesis: G. Phonert et al., Chem. Commun. 1999, 1087.