Colony-level variation in foraging behavior of the red imported fire ant (Solenopsis invicta)

Among social insects, maintaining genetic variation in a behavior can allow a colony to exhibit more flexible, rapid responses to environmental changes and promote homeostasis. In addition, genetic variation in traits enables adaptive evolution. In the United States, the red imported fire ant, Solenopsis invicta, is predominantly polygynous with many unrelated queens reproducing in a single colony. Previous evidence indicates that in multilineage colonies genetic variation in traits such as foraging behavior increases colony fitness. Variation in foraging behaviors and division of labor in some social insects has been associated with variation in expression of the foraging gene (for). In this study, we collected fire ant colonies from Texas and Mississippi and split each field colony into standardized lab colonies which were given different foraging environments. In behavioral assays region, natal colony, and treatment all had significant and persistent effects on foraging behavior. We next examined the effects of cGMP-dependent protein kinase G (PKG), the enzyme product of for, on foraging behavior. Lab colonies with treated with 8-Br-cGMP to artificially activate PKG. Behavioral assays revealed that this treatment had a significant effect on fire ant recruitment and predation compared to control colonies. Currently, we are assaying fire ant colonies in the field and lab for colony level variation in PKG activity and expression of for. This study suggests that significant variation in foraging behavior exists among fire ant colonies and may underlie variation in the ecological effects of fire ants and variation in methods necessary for their control.