Identification of methyl 6-methylsalicylate as the trail pheromone of the Japanese pavement ant Tetramorium tsushimae (Hymenoptera: Formicidae)

The Japanese pavement ant Tetramorium tsushimae Emery (Hymenoptera: Formicidae) has a mass recruitment system for foraging. We successfully separated the trail pheromone from the ant worker extract by preparative gas chromatography, and estimated it as methyl 6-methylsalicylate based on the Kováts retention indices and mass spectra, which coincided with those of the synthetic compound. We also confirmed that the synthetic methyl 6-methylsalicylate elicited a trail-following response in the workers even at approximately 0.3 pg/cm of the trail line. The strength for this response was similar to the estimated level of trail pheromone in the abdominal extracts of workers. It seems likely that the glandular source was the poison gland, because poison gland extract evoked trail-following responses in significantly more workers than other gland extracts. We therefore identified the trail pheromone of this ant species as methyl 6-methylsalicylate and tentatively identified its source as the poison gland.