Alkyl-Dimethylpyrazines in Mandibular Gland Secretions of Four Odontomachus Ant Species (Formicidae: Ponerinae)

Abstract

Ponerine ants are known to contain mixtures of pyrazines in their mandibular glands. We analyzed the mandibular gland contents of four ponerine species (Odontomachus chelifer, O. erythrocephalus, O. ruginodis, and O. bauri) by gas chromatography coupled with mass spectrometry, and found that each species contains specific mixtures of trisubstituted alkylpyrazines among other volatiles. Attempts to identify alkylpyrazines solely by mass spectral interpretation is unrealistic because spectra of positional isomers are indistinguishable. To avoid misidentifications, we synthesized a large number of reference compounds and compared their mass spectral and gas chromatographic properties with those present in the Odontomachus species under investigation. Most of the compounds identified were 2-alkyl-3,5-dimethylpyrazines. Interestingly, when the third substituent was an isopentyl group, the two methyl groups were found to be located at the 2 and 5 ring positions. Using our data, we recognized several misidentifications in previous publications.

Electrophysiological and Alarm Responses of Solenopsis invicta Buren (Hymenoptera: Formicidae) to 2-Ethyl-3,5-dimethylpyrazine

“…Ants have evolved a wide variety of compounds in communicating threats [5]. Pyrazines are a major group of pheromonal compounds isolated from mandibular glands and venom reservoir in ants [6][7][8]. Pyrazines originating from mandibular glands typically trigger alarm responses, whereas those from poison glands often serve a trail following function [7].…”

“…Pyrazines seem to be widespread among the two subfamilies, Ponerinae and Myrmicinae, of the Formicidae. Few species in Dolichoderinae, Ecitoninae, Ectatomminae, and Formicinae produce pyrazines as alarm and trail pheromones [8,9]. Most ant pyrazines are tri-substituted derivatives.…”

“…Mono-, di-, and tetra-substituted pyrazines are much less common. Numerous dimethylalkylpyrazines, which show 2,5-dimethyl-3-alkyl or 2,6-dimethyl-3-alkyl substitution patterns, have been detected from mandibular gland secretions of a variety of ant species [7,8].…”

“…2-Ethyl-3,6-dimethylpyrazine ( Figure 1) is a component of poison gland secretions of ant species in Myrmicinae (Acromyrmex, Atta, Daceton, Manica, Messor, Metapone, Myrmica, Pheidole, Pogonomyrmex, and Tetramorium) [8,10,11] and Ectatomminae (Eciton burchelli) [12], and primarily functions as a trail-following pheromone. There are several reports of 2-ethyl-3,6-dimethylpyrazine in mandibular glands of dolichoderine (Iridomyrmex purpureus), ectatommine (Ectatomma sp.)…”

“…2-Ethyl-3,6-dimethylpyrazine elicited rapid and erratic movement of fire ant workers, apparently functioning as an alarm pheromone. 2-Ethyl-3,5-dimethylpyrazine ( Figure 1), an isomer of 2-ethyl-3,6-dimethylpyrazine, is a mandibular gland component of ponerine ants, Odontomachus brunneus [16], O. chelifer [8], O. troglodytes [17]. Unlike other pyrazine components from O. troglodytes workers, however, this pyrazine failed to release significant alarm behaviors [17].…”