Abstract: 【Aim】 The red imported fire ant, Solenopsis invicta Buren, one of the worst invasive species in the world, has been found to occur in South China in 2004 and caused serious destruction to agricultural and forestry industry as well as to ecosystem in the infested region. The elaborate survey and analysis on food composition transported by fire ant foragers in the field would not only let us accurately assess the potential impact of fire ant forager predation on arthropod communities, but also provide us a scientific basis for improving baiting efficacy for fire ant control. 【Methods】 Foraging solid materials including arthropod pieces and plant seeds were collected by exposing foraging trails and capturing each foraging ant transporting a particle toward to the mound in two habitats, mulberry orchard and barren land, in Guangzhou, Guangdong province, South China. Meanwhile, the size of the foragers transporting those items was measured for the analysis of forager polymorphism. Each solid particle was identified and measured individually by the combination of length and width and weighed, and the components and content of liquid stored in crops of foragers collected on exposed foraging trails were analyzed using Thin Layer Chromatography (TLC) and amino acid analysis. 【Results】 The results showed that solid particles that fire ant foragers transported for consumption mainly consisted of animal particles and plant seeds, and the former originated from 21 groups (including 14 orders of insects) of 7 classes of 3 phyla of animals. Solid foraging materials from Class Insecta accounted for 45.53% and 46.10% of the solid foraging materials in both habitats of mulberry orchard and barren land. During foraging, 80% foragers, which were medium-sized workers, preferred taking solid particles as large as 1.400±0.043 mm -2.306±0.063 mm in length and 0.723±0.028 mm-1.261±0.051 mm in width, being 0.203-0.413 mg in weight. The liquid foods from the foragers’ crops were composed of fructose, glucose, and amino acids. There were 33 and 32 kinds of amino acids with the total contents of 1 544.31 mg/L and 861.48 mg/L in crop liquid from foragers in mulberry orchard and barren land, respectively, of which 31 kinds of amino acids were shared by foragers in both habitats. 【Conclusion】 In South China, fire ant foragers prey insect pieces as major food sources. Most foragers involving in transporting solid particles back to nests are medium-sized workers. We assumed that foragers in mulberry orchard and barren land prefer liquid food rich in amino acids and monohydrates.

Key words: Solenopsis invicta, foraging worker, dietary composition, solid particle, crop liquid, polymorphism