Semiochemicals of the Scarabaeinae: VI. Identification of EAD-active constituents of abdominal secretion of male dung beetle, Kheper nigroaeneus.

Using gas chromatography with flame ionization detection (FID) and electroantennographic detection (EAD) in parallel, and employing chiral and achiral capillary columns, three constituents of the abdominal sex-attracting secretion of male Kheper nigroaeneus dung beetles were found to elicit reproducible EAD responses in male and female K. nigroaeneus antennae. One of these constituents is present in the secretion in such a small quantity that it could not be detected by FID, and it was not identified. The other constituents were identified as 3-methylindole (skatole) and (R)-(+)-3-methylheptanoic acid.