Objective To analyze the major components and cluster features of alkaloids, which are secreted by vemon gland of red imported fire ants, Solenopsis invicta, from China and USA.

Method Twenty four colonies of S.invicta were collected from Guangzhou, Huizhou, Shenzhen, Zhuhai, Dongguan of China and Alabama of USA.Alkaloids of vemon gland were extracted.Two data matrix were established with variable of relative contents of 15 kinds of cis-alkaloids and 7 kinds of trans-alkaloid respectively.The alkaloid fraction was analyzed by principal component analysis and cluster analysis.

Result and conclusion The results showed that the 15 types of alkaloids from the cis-alkaloids fraction were consolidated into two principal components, including cis-2-methyl-6-(4′-tridecenyl) piperidine, 2-methyl-6-(6′-pentadecenyl) -Δ^{1, 6}-piperidine, 2-methyl-6-pentadecyl-Δ^{1, 6}-piperidine and cis-2-methyl-6-undecylpiperidine seven types of alkaloids from the trans-alkaloid fraction were consolidated into one principal component, including trans-2-methyl-6-(4′-tridecenyl) piperidine and trans-2-methyl-6-(6′-pentadecenyl) piperidine.The results of cluster analyses demonstrate that alkaloids from the cis-alkaloids fraction can distinguish the USA populations from the Chinese populations, but alkaloids from the trans-alkaloid fraction can not.