PHYSIOLOGICAL ECOLOGY Excretion of Phosphoric Acid by Red Imported Fire Ants, Solenopsis invicta Buren (Hymenoptera: Formicidae)

Food sources,mineral redistribution, and excreta are someof theways ants enrich their mound environment. Phosphorus excretion has not been reported in red imported Þre ants, Solenopsis invicta Buren. QuantiÞcation of phosphoric acid in worker fecal droplets and larval anal liquid of S. invicta was performed. Phosphoric acid was trimethylsilylated using N,O-bis(trimethylsilyl)trißuoroacetamide, and the tris(trimethylsilyl) phosphate was analyzed using gas chromatography-mass spectrometry. Phosphoric acid made up 2.13 1.08% (SD) of the dry weight of worker fecal droplets and 2.09 0.72% of the larval anal liquid. The rate of phosphoric acid production in workers was 0.08 0.024 g/ant/d. Because the hindgut of red importedÞre ant larva is separated from themidgut, the excretory products in larval anal liquid are primarily of metabolic origin. The presence of phosphoric acid in larval anal liquid shows that red imported Þre ants excrete phosphoric acid.