Contents of the poison apparatus of some species of Pheidole ants

Abstract Four Old World species of Pheidole ants contain different mixtures of farnesene-type hydrocarbons in their poison apparatus, and the mixture is different between the minor and major workers within a species. A bishomofarnesene (C 17 H 28 ) provides approximately half of the secretion of the Dufour glands of minor workers of Pheidole pallidula . ( Z , E )-α-Farnesene constituted 96% of the Dufour secretion of major workers of P. pallidula , but only 20% of that of minors. The Dufour glands of minor workers of Pheidole sinaitica contain a mixture of farnesene homologues with ( Z , E )-α-farnesene and the bishomofarnesene also found in P. pallidula predominant. The mixture in major workers was similar but had, in addition, a small amount of ( E )-β-farnesene. The Dufour glands of Pheidole teneriffana minors contain chiefly the same bishomofarnesene found in P. pallidula and P. sinaitica while major workers contain ( Z , E )-α-farnesene. Pheidole megacephala minor workers contained small amounts of eight farnesenes, while major workers contained essentially no farnesenes. The poison glands of minor workers of P. pallidula contain 3-ethyl-2,5-dimethylpyrazine. No pyrazine compounds were found in the major workers of P. pallidula or the minor workers of P. sinaitica . The poison glands of the major workers of P. sinaitica contained larger amounts of tetra-substituted pyrazines. No pyrazines were found in the poison reservoirs of major or minor workers of P. teneriffana or P. megacephala .