Similarity in venom alkaloid chemistry of alate queens of imported fire ants: implication for hybridization between Solenopsis richteri and S. invicta in the Southern United States.

Both cis- and trans-2-methyl-6-undecylpiperidines, MC11P, have been previously reported as the major components of the venom of alate queens of the imported fire ants, Solenopsis richteri (black) and S. invicta (red). To identify the minor components of venom alkaloids from alate queens and compare the venom alkaloid chemistry of alate queen of their hybrid (S. richteri×S. invicta) with that of the two parental fire ant species (S. richteri and S. invicta), silica-gel short-column chromatography was utilized for separating cis-stereoisomers of venom alkaloids from trans-stereoisomers. GC/MS Analyses of venom-alkaloid chemistry of alate queens demonstrated that fewer alkaloid peaks were detected in the chromatograms of the alate queens compared to those of workers. Three new compounds, 7, 12, and 13, were detected as minor components in the venom of alate queens of all three fire ant species. Alate queens of hybrid fire ants showed cis- and trans-alkaloid patterns similar to those of the parental species. Similarity in venom-alkaloid chemistry of alate queens of S. richteri and S. invicta, and their hybrid may indicate their reproductive compatibility in the hybrid zone in southern United States, where all three species occur sympatrically.