Chemical secretions of two sympatric harvester ants,Pogonomyrmex salinus andMessor lobognathus

Messor lobognathus, an apparent mimic ofPogonomyrmex salinus, shows little chemical resemblance to its exemplar. The mandibular glands ofM. lobognathus gave no volatile compounds. Those ofP. salinus contain chiefly 4-methyl-3-heptanone. Both species contain a mixture of straight-chain alkanes, alkenes, and methyl-branched alkanes in their Dufour glands. Tridecane (64%) is the major substance inM. lobognathus and dodecane (25%) and pentadecane (24%) are the major compounds ofP. salinus. No secretion induced trail-following in either species. A mixture of 9-, 11-, and 13-methylheptacosane formed the largest peak in the chromatograms obtained from the postpharyngeal glands of both species, but otherwise the hydrocarbon mixtures in this gland too were distinct.