Micro-chemical investigations of volatile chemicals of some myrmicine ants

Abstract

The volatile chemicals originating from the poison glands, Dufour glands, mandibular glands and postpharyngeal glands of several species of myrmicine ants have been investigated. A number of novel micro-methods were developed and several advances made in existing methods for handling and identification of small quantities of natural products, i ncludi ng GC trappi ng, ozonolysi s, epoxi dat ion and cleavage of epoxides, borohydride reduction, and formation of chiral derivatives.
The trail pheromone of workers of the ant Tetramorium oaespitum L. is a 70:30 mixture of
2.5- dimethylpyrazine and 3-ethyl-2,5-dimethylpyrazine with an average total amount of 3.9 ng per worker or 0.03% of the volume of the poison gland (2.7 ± 0.4 ng of
2.5- dimethylpyrazine and 1.15 ± 0.25 ng of
3-ethyl-2,5-dimethylpyrazine). A 70:30 mixture of the respective synthetic pyrazines evoked the highest activity in artificial trail following tests.
The postpharyngeal gland of Solenopsis geminata contains about 10 yg of hydrocarbons per ant. Three components, heneicosane, (Z)-9-tricosene and tricosane represent 85% of the volatile components of the gland. The poison vesicle contains about 19 yg of alkaloids per ant and the major components are cis- and trarts-2-methyl-6-undecylpi peridines. The Dufour gland is filled with a variety of hydrocarbons of Cj5-C23 range. The Dufour gland also contains its trail pheromone which appears to be a sesquiterpenoid hydrocarbon derivative.
The Dufour glands of Myrmiea sulcinodis, M. rugulosa and M. sehencki contain species-specific mixtures of linear alkanes and alkenes of C13 to Cig range and terpenoid hydrocarbons, namely (Z-E)-a-farnesene, homofarnesene and bishomofarnesene. The structures of the two latter compounds were confirmed as 7-ethyl- 3,ll-dimethyldodeca-l,3,6,10-tetraene and 7-ethyl-3,ll-dimethyltrideca-l,3,6,10-tetraene by micro-degradation. The Dufour and mandibular gland contents of a further species, here called M. albuferensis, was found to be different from all the other eight, chemically examined species. By its glandular substances, it most closely resembles M. seabrinodis.
The 3-octanol from the mandibular glands of Myvmica ants consists essentially of the (R)-enantiomer and in at least one species where this substance is a pheromone, this enantiomer is ethologically active, while the antipode is inactive.