Pheromones of the Scarabaeinae, II*. Composition of the Pheromone Disseminating Carrier Material Secreted by Male Dung Beetles of the Genus Kheper

Gel electrophoresis o f the white flocculent pheromone disseminating secretions produced by males o f the three dung beetle species, Kheper lamarcki, K. nigroaeneus and K. subaeneus, re­ vealed that three different proteins with molecular masses o f ca. 15 kDa are the major constitu­ ents o f these secretions. The molecular mass o f these components in the secretions o f K. lamarcki and K. nigroaeneus was determined more accurately by 252C f plasma desorption mass spectro­ metry to be 15451 ± 10 and 15477± 10 Da respectively. The N-terminal amino acids in the major proteinaceous component o f the secretions revealed similarities as well as differences in the primary structures o f the proteins secreted by the three species. The amino acid composi­ tion o f the secretions o f the three species is closely related. Due to the presence o f large amounts o f aspartic and glutamic acid, and small amounts o f the basic amino acids, the pro­ teinaceous component o f the carrier material is expected to have a low isoelectric point which, together with the presence o f large amounts o f the hydrophobic amino acids, may impart properties that are to be expected for a carrier material which is used for the dissemination o f inter alia long-chain fatty acids and their esters. Exposure o f bovine pancreas trypsin, bovine albumin and the carrier protein o f K. lamarcki to the vapour o f 2,6-dimethyl-5-heptenoic acid, the major volatile constituent with electroantennogram activity in the secretion o f this species, followed by quantitative determination o f the acid adsorbed on these proteins, showed that albumin and the carrier protein have an approximately equal affinity for the acid, whereas trypsin retained only about one third o f the amount o f the acid adsorbed on the other two proteins. It was concluded that albumin should be a suitable substitute for the carrier protein in field tests with synthetic constituents o f the abdominal secretion o f these insects.