South Carolina State University, Orangeburg, South Carolina, Sophomore, major: Biology

Mentor: Robert Vander Meer

Species Specificity of Fire Ant Alarm Pheromone

Abstract:  Fire ants have many behavioral responses which are meditated by chemicals they produce. These specific chemicals are called pheromones. One pheromone system is called the alarm pheromone, which is known to be responsible for elevating workers to a heighten state of awareness, rapid movement, and attraction to the source. Due to the heighten awareness and attraction of fire ants, the alarm pheromone has the potential to be used in baits, resulting in quicker location of bait particles. In additional, the alarm pheromone has been shown to disrupt normal colony functions and to attract parasitic decapitating phorid flies.

In this study we conducted bioassays to determine the species specificity of alarm pheromones between three related species of ants; Solenopsis invicta, Solenopsis geminata, and Solenopsis xyloni.  The behavioral response of fire ants to alarm pheromones was measured on a scale from 1 to 5, 1 being no reaction and 3 being the first sign of alarm. The results from the bioassay showed that Solenopsis invicta responded to all species. The Solenopsis geminata only responded to Solenopsis xyloni and its own alarm pheromone. The Solenopsis xyloni responded to only itself and Solenopsis geminata. Bioassays were followed with dissection of the heads and mandibular glands for GC, and Mass Spectrometry analysis to determine the chemical make up of the alarm pheromone in all three species of fire ants. The GC separated the complex compounds found in the head and mandibular glands. The results from the different compounds were identified by the Mass Spectrometry. The compound, pyrazine was identified in all species alarm pheromone. In both Solenopsis geminata and Solenopsis xyloni, Propanal, 3-(methyitho) and 2-furanmethanol were found; they may be use in the alarm pheromone.

Whitney is dissecting fire ant mandibular glands.

Whitney is preparing a dry ice acetone bath for freezing ants prior to dissection.