Abstract: 【Aim】 To assess the dynamic changes in the main components of venomous alkaloid in workers of the red imported fire ant, Solenopsis invicta maintained indoors over a long time. 【Methods】 Every 10 days, 0.5 g fire ant workers were taken from a laboratory-maintained colony and extracted 48 h with hexane solvent. The main components of venomous alkaloid in the extract were prepared by silica gel column chromatography and identified using GC-MS. The quantity of each major alkaloid component was measured with the external standard method. 【Results】 The fire ant worker extract was mainly composed of 9 cis alkaloids and 5 trans alkaloids, and these 14 compounds were quantified every 10 days for 90 d. Among these compounds, the content of trans-2-methyl-6-(4′-tridecenyl) piperidine was the highest, which was 3 391.57μg/g on the 1st day, and then decreased to 556.70 μg/g on the 90th day. The content of cis 2-methyl-6-pentadecylpiperidine was the lowest, which was 10.27 μg/g on the 1st day, and 2.93 μg/g on the 90th day. 【Conclusion】 When the fire ant workers are maintained in the laboratory, the contents of venomous alkaloid components first decrease continuously to a very low level, and then sustain at this level. Combined the death of the fire ant workers in the laboratory, it can be inferred that when the alkaloid content in the fire ant nest is quite low, the number of the large size workers in the nest will be very few.

Key words: Solenopsis invicta , alkaloids, piperidine, dynamic analysis, GC-MS analysis