The major component of the trail pheromone ofT. impurum is methyl 2-hydroxy-6-methylbenzoate (methyl 6-methyl salicylate). The poison reservoir of each worker contains about 1.0 ng of this substance in the venom. To ascertain the degree of specificity of the substance as pheromone and to determine any correlation between structure and biological activity, 38 synthetic analogs were tested in a bioassay. Sixteen compounds showed activity at 100 ng per artificial trail. The importance of the methyl group and methyl ester were demonstrated, while the hydroxyl group has a relatively small effect.

The volatile components of the Dufour gland secretion of workers cf the ant Harpagoxenus sublaevis have been analysed by gas chrom atography and mass spectrometry. Over 20 com ponents have been identified, consisting of linear and terpenoid hydrocarbons. Each gland contains approximately 6 ng of hydrocarbons with n-heptadecene (40% ) and /n-heptadecadiene (30% ) as the major components. Two terpenoid hydrocarbons, (E)-β-farnesene and a homofarnesene isomer were also identified.

The Dufour glands of worker ants of Tetramorium caespitum, and the morphologically similar T. impurum are filled with similar, but species-specific mixtures of linear hydrocarbons and three homologous sesquiterpene corhpounds. Glands of workers ofT. caespitum contain, on average, 70 ng of oil containing C13 to C17 linear hydrocarbons with n-pentadecane (64%) and a mixture of pentadecenes (14%) as major components.T. impurum glands are smaller and contain an average of 40 ng of the same mixture but with n-pentadecane (49%) and a sesquiterpenoid compound (19%) the major components. Two isomeric pentadecenes, (Z)-6-pentadecene and (Z)-7-pentadecene are present in both species.T. semilaeve workers contain on average only 30 ng of a simple mixture of hydrocarbons with pentadecane contributing more than 90% of the total.

No abstract

The poison gland of Munica rubidu contains nanogram quantities of four alkylpyrazines, methylpyrazine, 2,5dimethylpyrazine, trimethylpyrazine and 3-ethyl-2,5-dimethylpyrazine, of which only the last induces pronounced trail-following behaviour. Myrmicu rubru and M . rubidu workers follow each other's trails equally well when allowance is made for the much greater size of M.rubidu workers. The cross activity in trail-following between M . rubidu, M . rubru and Tetrumorium cuespitum is understandable in terms of the amounts and proportions of the different pyrazines present in their glands and their responses to the synthetic substances and appropriate mixtures of them.