CHEMICAL SECRETIONS OF 2 SYMPATRIC HARVESTER ANTS, POGONOMYRMEX-SALINUS AND MESSOR-LOBOGNATHUS

Messor lobognathus, an apparent mimic of Pogonomyrmex salinus, shows l ittle chemical resemblance to its exemplar. The mandibular glands of M . lobognathus gave no volatile compounds. Those of P. salinus contain chiefly 4-methyl-3-heptanone. Both species contain a mixture of straig ht-chain alkanes, alkenes, and methyl-branched alkanes in their Dufour glands. Tridecane (64 %) is the major substance in M. lobognathus and dodecane (25 %) and pentadecane (24 %) are the major compounds of P. salinus. No secretion induced trail-following in either species. A mix ture of 9-, 11-, and 13-methylheptacosane formed the largest peak in t he chromatograms obtained from the postpharyngeal glands of both speci es, but otherwise the hydrocarbon mixtures in this gland too were dist inct.