Journal of Chemical Ecology, Vol. 13, No. 8, 1987 NOVEL PYRAZINES FROM THE HEAD OF AUSTRALIAN PONERINE ANT Rhytidoponera metallica BERHANE TECLE, * CHANG-MING SUN, JOSEPH J. BROPHY, and ROBERT F. TOIA Department of Organic Chemistry University of New South Wales P.O. Box 1, Kensington New South Wales 2033, Australia (Received August 11, 1986; accepted October 27, 1986) Abstract--The novel pyrazines, (E)- and (Z)-5-methyl-3-(2-methylbutyl)-2- (3-methylbut-l-enyl)pyrazine, (E)- and (Z)-5-methyl-3-isopentyl-2-(3-meth- ylbut-l-enyl)pyrazine, (E)- and (Z)-5-methyl-3-(2-methylbutyl)-2-(3-meth- ylpent-l-enyl)pyrazine, (E)- and (Z)-5-methyl-3-isopentyl-2-(3-methylpent- 1-enyl)pyrazine, together with the known pyrazines, 2,5-dimethyl-3-(2- methylbutyl)pyrazineand 2,5-dimethyl-3-isopentylpyrazine,have been iden- tified from the head of the Australian ponerine ant Rhytidoponera metalliea. Alkanes and alkenes, in small amounts, were also detected. Key Words--Ant, Rhytidoponera metalliea, pyrazine, GC-MS, Hymenop- tera, Formicidae, ponerine. INTRODUCTION Chemical investigations on ants of the subfamily Ponerinae (Formicidae) have been notable for the fact that pyrazines have been detected in the heads of the majority of species from various genera to date examined, e.g., Anochetus, Odontomachus, Ponera, Hypoponera, Rhytidoponera, Brachyponera, Meso- ponera, and Dinoponera (Attygale and Morgan, 1984; Fales et al., 1984; Her- man et al., 1984). In most of the species that did not contain pyrazines, sulfides have been detected (Casnati et al., 1967; Crew and Fletcher, 1974; Longhurst et al., 1979, 1980). Although pyrazines have been detected in other subfamilies of the Formicidae (Dolichoderinae, Myrmicinae, Myrmeciinae, and Formi- ~Present address: Pesticide Chemistry and Toxicology Laboratory, 210 Wellman Hall, University of California, Berkeley, California 94720. 1811 0098-0331/87/0800-1811 $05.00/0 9 Plenum Publishing Corporation