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United States Department of Agriculture

Agricultural Research Service

Title: Semiochemicals Released by Electrically Stimulated Red Imported Fire Ants, Solenopsis Invicta

Authors
item Vander Meer, Robert
item Slowik, T. - TEXAS TECH UNIVERSITY
item Thorvilson, H. - TEXAS TECH UNIVERSITY

Submitted to: Journal of Chemical Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 20, 2002
Publication Date: November 15, 2002
Citation: VANDER MEER, R.K., SLOWIK, T.J., THORVILSON, H.G. SEMIOCHEMICALS RELEASED BY ELECTRICALLY STIMULATED RED IMPORTED FIRE ANTS, SOLENOPSIS INVICTA. JOURNAL OF CHEMICAL ECOLOGY. 2002. v. 28(12). p. 2585-2600.

Interpretive Summary: The high population densities of the red imported fire ant, Solenopsis invicta Buren, in the southern and southeastern United States cause medical, agricultural, and other problems, such as shorting out electrical contacts. The electrical problem occurs in a wide variety of equipment, from air conditioning units to stoplight switches. Invading ants are electrocuted and often accumulate in large numbers before repairs are necessary. Scientists at the Center for Medical, Agricultural and Veterinary Entomology, USDA, ARS, Gainesville, Florida and the Texas Tech University, Department of Plant and Soil Science, Lubbock, Texas combined their expertise to investigate the cause of this phenomenon. Chemical communication systems regulate many activities of fire ant colonies, e.g. recruitment pheromones attract and stimulate workers to follow a trail to food. Alarm pheromones activate and attract workers to intruders or other disturbances. Electrocuted ants may release pheromones that attract additional worker ants into the electrical contacts. We used behavioral bioassays and chemical analyses to show that electrically-stimulated fire ants release venom alkaloids, as well as alarm and recruitment pheromones. The behaviors associated with these products support the hypothesis that the accumulation of fire ants in electrical equipment is the result of a single worker accidentally closing an electrical contact, then releasing exocrine gland products that attract other workers to the site, who in turn are electrically stimulated.

Technical Abstract: The red imported fire ant, Solenopsis invicta Buren, has evolved sophisticated chemical communication systems that regulate the activities of the colony. Among these are recruitment pheromones that effectively attract and stimulate workers to follow a trail to food or alternative nesting sites. Alarm pheromones alert, activate and attract workers to intruders or other disturbances. The attraction and accumulation of electrocuted fire ant workers in electrical equipment may be explained by their release of pheromones that draw additional worker ants into the electrical contacts. Workers subjected to a 120-Volt, alternating-current power source released venom alkaloids as revealed by gas chromatography. We also demonstrated the release of alarm and recruitment pheromones that elicited attraction and orientation. It appears that fire ants respond to electrical stimulus by generally releasing exocrine gland products. The behaviors associated with these products support the hypothesis that the accumulation of fire ants in electrical equipment is the result of a foraging worker finding and closing electrical contacts, then releasing exocrine gland products that attract other workers to the site, who in turn are electrically stimulated.

Last Modified: 7/30/2014
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