SEMIOCHEMICALS OF DUNG BEETLES OF THE GENUS KHEPER.

Ben V. Burger, Warren G.B. Petersen, and Zenda M. Munro
Department of Chemistry, University of Stellenbosch, Stellenbosch 7600,South Africa

In the absence of dung beetles, dung dropped by grazing animals is oflittle nutritional value to plants. By burying fresh dung withina day or two dung beetles also destroy the habitat of dung breeding flies,some of which are carriers of cattle diseases. Although dung beetlesplay an exceedingly important role in nature, almost nothing is known abouttheir semiochemical communication. Male Kheper beetles occasionalyproduce a white proteinaceous abdominal secretion if they are unsuccessfulin finding a female after their arrival at a fresh dung source. Thissecretion contains minute quantities of a complex mixture of organic compounds. Although a few of these compounds are present in the secretions of allfour the Kheper species investigated, each species produce a qualitativelyand quantitatively unique mixture of compounds. According to a GCanalysis with FID/EAD recording in parallel, each secretion contains afew smaller molecules giving strong EAD responses. Skatole was foundto be an EAD-active component of each of the secretions. The abdominalsecretion of Kheper subaeneus, for example, contains skatole and(E)-2,6-dimethyl-6-octen-2-ol as EAD-active constituents. Althoughthis terpene alcohol was barely be detected by FID, even when enormousquantities of an extract of the secretion was used for GC analysis, itgave a very strong EAD signal. Only one of the enantiomers of eachof the chiral EAD-active constituents of the secretion of K nigroaeneusis EAD active. The identification and synthesis of the EAD-activeconstituents of the abdominal secretions of three Kheper specieswill be discussed.