The behavioral response by the red imported fire ant Solenopsis invicta to recognition chemicals on inanimate objects

In some ant species, cuticular hydrocarbons have been identified as nestmate recognition signals. The red imported fire ant Solenopsis invicta has a sparse set of cuticular hydrocarbons, suggesting the possibility that cuticular lipids may also be used as recognition chemicals. Cuticular hydrocarbons and lipids were extracted from S. invicta workers by brief soaking in pentane. The pentane extracts were applied to a silica column, and cuticular hydrocarbons were separated from polar cuticular lipids. Analysis of the polar cuticular lipids by high-resolution mass spectrometry showed a wide variety of fatty acids and esters. In preliminary studies, cuticular hydrocarbons and polar cuticular lipids were applied to glass beads, and the beads were presented to S. invicta workers. In general, the workers were more attracted to the glass beads coated with cuticular extracts compared to the controls. We have now extended these studies to examine how the location of the glass beads in lab colonies influenced the responses by the workers. The glass beads were placed in certain areas of the lab colonies: near the food, near the entrance of the nest, and inside of the nest.