Cuticular hydrocarbon profiles differentiate tropical fire ant populations (Solenopsis geminata, Hymenoptera: Formicidae)

Authors: HU, LIN - Chinese Academy Of Sciences; Vander Meer, Robert - Bob; Porter, Sanford; CHEN, LI - Chinese Academy Of Sciences

Submitted to: Chemistry and Biodiversity
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/7/2017
Publication Date: 6/11/2017
Citation: Hu, L., Vander Meer, R.K., Porter, S.D., Chen, L. 2017. Cuticular hydrocarbon profiles differentiate tropical fire ant populations (Solenopsis geminata, Hymenoptera: Formicidae). Chemistry and Biodiversity. 14(11):e1700192. https://doi.org/10.1002/cbdv.201700192.
DOI: https://doi.org/10.1002/cbdv.201700192

Interpretive Summary: Fire ants of the genus Solenopsis are characterized by a potent sting, aggressive behavior, and large populations. The most notable of these species are S. invicta and S. geminata, both of which have been transported from their homeland in Central and South America to many places around the world, where they affect many economic sectors with an impact of more than $6 billion/year. Taxonomically this genus is often difficult to identify, therefore, alternative methods of identification are important. Scientists from the ARS, USDA Center for Medical, Agricultural, and Veterinary Entomology, Gainesville, Florida Agricultural Research Service (USDA-ARS), Gainesville, Florida and The Institute of Zoology, the Chinese Academy of Sciences, Beijing, PR China have addressed this problem by demonstrating in this research report that two populations of S. geminata can be distinguished through analysis of their cuticular hydrocarbons. These compounds are used to prevent desiccation, but have evolved in some ant species to act also as nestmate recognition cues. Several components and ratios of components can be diagnostic of the two-color forms. The possibility of these color types being sibling or cryptic species will be examined in future reports.

Technical Abstract: The cuticular hydrocarbons (CHCs) from hexane rinses of workers from two Florida populations (dark and red forms) of the tropical fire ant, Solenopsis geminata, were separated by silica gel chromatography and identified by GC-MS analysis. Both the dark form and the red form produce similar CHCs with carbon chain lengths ranging from 17 to 35. However, the relative percentages of these CHCs were consistently different between the two-color forms. The largest CHC component in the dark form is tricosane, and tricosene for the red form. There were several significant differences in percent composition, for example, the dark form was characterized by a low tricosene:tricosane ratio ' 0.25, whereas this ratio was ' 2.5 for the red form. The ratio of tricosene:tricosane can be used as a diagnostic biomarker to delimit the dark and red forms. Cluster analysis showed that the CHCs patterns of dark form colonies are completely separated from the CHC pattern of red form colonies. Differences in social behaviors, e.g., nestmate recognition between workers from the dark form and the red form await further investigation.