Abstract: 【Aim】 This study aims to determine the geographical differences in the components and relative contents of venomous alkaloids in the red imported fire ant, Solenopsis invicta, from two invaded areas. 【Methods】 Workers of S. invicta were collected from USA and South China, and then extracted with HPLC grade hexane followed by GC-MS analysis. The chemical identity of GC peaks was identified and their relative percentage content was obtained. 【Results】 The cis alkaloids and trans alkaloids from body extract of fire ant workers could be readily separated by silica gel column chromatography. By using GC-MS technique, 7 cis alkaloids, 8 piperideines, and 7 trans alkaloids were identified from alkaloid fractions of fire ant colonies collected in the invaded areas of USA and China. The relative percentage contents of these components were different in different degrees between the USA populations and the South China populations. 【Conclusion】 The chemistry of venom alkaloids of the red imported fire ant between USA and China is quite similar. Only S. invicta is found in China, suggesting that S. richteri and hybrid fire ants may have not invaded China yet.

Key words: Fire ants, Solenopsis invicta, poison gland, alkaloids, piperidine, GC-MS analysis