SEMIOCHEMICALS OF THE SCARABAEINAE .4. IDENTIFICATION OF AN ATTRACTANT FOR THE DUNG BEETLE PACHYLOMERUS-FEMORALIS IN THE ABDOMINAL SECRETION OF THE DUNG BEETLE KHEPER-LAMARCKI

Both sexes of the dung beetle Pachylomerus femoralis were observed to be attracted to the male dung beetle Kheper lamarcki when it exhibited typical calling behaviour including the release of a white flocculent sex-attracting secretion. Using GC-MS analysis and gas chromatography with electroantennographic (EAD) and flame ionization detection (FID) in parallel, methyl and ethyl propanoate, methyl and ethyl butanoate, methyl and ethyl pentanoate, and methyl and ethyl 4-pentenoate were i dentified as the constituents of the secretion that elicited electroan tennographic responses in the antennae of male and female P. femoralis . In field tests, mixtures of these compounds were found to be about a s attractive as horse dung. These esters appear to constitute an attra ctant for Ii femoralis, enabling this species which does not form ball s, to detect and utilize dung balls formed by K. lamarcki. P. femorali s has been observed to exploit food types as diverse as dung from rhin oceros and primates. It is therefore, possible that, on the other hand , this species utilizes different kairomones to detect various types o f dung and that the coincidental presence of some or all of the compon ents of one of these kairomones in the abdominal secretion of K. lamar cki is responsible for its attraction to calling K. lamarcki males.