Chemistry of defensive secretions in nymphs and adults of fire bug,Pyrrhocoris apterus L. (Heteroptera,Pyrrhocoridae)

The defensive secretions from the nymphs and the adults of both sexes inP. apterus were chemically investigated. Forty components were identified from the nymphal posterior dorsoabdominal glands and 35 from the adult metathoracic glands of both sexes. Within the 43 identified chemicals, we found 23 aldehydes, five saturated hydrocarbons, five alcohols, three ketones, three lactones, two terpenes, one phenol and one ester. Thirteen of these compounds had never been reported within the Heteroptera. Whereas eight components are specific to the nymphs, methyl pentenal, (E)-2-hexenol, and heptadecanal are the only adult-specific components. The biological role of all the identified chemicals is almost unknown inP. apterus and is discussed comparatively with regard to other Heteroptera.