Qualitative analysis of red imported fire ant nests constructed in silica gel.

Red imported fire ants, Solenopsis invicta Buren, build nests by excavating soil. Incorporation of ant-derived chemicals in nesting material has long been known; however, only a few chemicals have been identified. This paucity of identified ant-derived chemicals may be due to the interference from soil-borne compounds in chemical analysis. In the laboratory, red imported fire ants were able to build their nest using moistened silica gel as the only building material. This provided an opportunity to establish a profile of ant-derived chemicals in nest material without the presence of any soil-borne artifacts. A new method for profiling ant-derived chemicals in nest material by using GC-MS was developed. All nests contained cuticular hydrocarbons and venom alkaloids. Phosphoric acid, glycerol, lactic acid, and malonic acid also were identified from samples collected from the silica gel nest.