Update on the defensive chemicals of the Little Black Ant, Monomorium minimum (Hymenoptera: Formicidae)

Authors: Chen, Jian; Cantrell, Charles; Oi, David; Grodowitz, Michael

Submitted to: Toxicon
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/14/2016
Publication Date: 9/25/2016
Publication URL: http://handle.nal.usda.gov/10113/5566978
Citation: Chen, J., Cantrell, C.L., Oi, D.H., Grodowitz, M.J. 2016. Update on the defensive chemicals of the Little Black Ant, Monomorium minimum (Hymenoptera: Formicidae). Toxicon. 122:127-132.

Interpretive Summary: Invasive ants can cause significant ecological and economic impact. Current practice for controlling invasive pest ants depends heavily on synthetic insecticides, which have hazardous impacts beyond their intended uses. New safer and more sustainable technologies are needed to improve pest ant management. Study on the chemistry of defensive secretions of native ants that compete with invasive ants may help us identify new naturally occurring toxins that are useful for managing invasive ants. This study identified seven new compounds in the defensive secretion of little black ants. This is the also first report on the natural occurrence of three compounds.

Technical Abstract: Alkaloids, including 2,5-dialkylpyrrolidines and 2,5-dialkylpyrrolines, have been reported to be components in the venom of little black ants, Monomorium minimum (Buckley). Two fatty amines were recently reported as minor compounds. By analyzing the discharge collected from the stinger apparatus (milking), this study revealed the presence of an additional seven compounds in the defensive secretion of this ant species. Compounds identified were 9-decenyl-1-amine, N-methylenedecan-1-amine, N-methylenedodecan-1-amine, 2-(1-non-8-enyl)-5-(1-hex-5-enyl)-1-pyrroline, N-methyl-2-(hex-5-enyl)-5-nonanyl-1-pyrrolidine, ß-springene ((E,E)-7,11,15-trimethyl-3-methylene-1,6,10,14-hexadecatetraene) and neocembrene ((E,E,E)-1-isopropenyl-4,8,12-trimethylcyclotetradeca-3,7,11-triene). ß-springene and neocembrene were found only in the defensive secretion of queens. Analyses of the contents of isolated poison and Dufour’s glands of the queen indicated that all amines and alkaloids were from the poison gland and that ß-springene and neocembrene were from the Dufour’s gland. This demonstrated that the defensive secretion in M. minimum queens consists of components from both glands. This is also the first report on the natural occurrence of 9-decenyl-1-amine, N-methylenedecan-1-amine, and N-methyllenedodecan-1-amine.