Submitted to: Insect Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 27, 2012
Publication Date: N/A
Interpretive Summary: Fire ants are one of the worst invasive ants in the world, causing billions of dollars in annual cost for their management. They also have a great negative impact on biodiversity. Most activities of an ant colony are mediated by chemical signals, such as foraging, mating, defense, offense, immigration, nestmate recognition and care of brood and eggs. There is evidence that chemical stimuli are also involved in regulating digging behavior of ants; however, the source and chemical nature of those stimuli have never been revealed for red imported fire ants. Scientists at National Biological Control Laboratory, USDA, ARS, Stoneville, MS, found red imported fire ants showed significant digging and residing preference toward substrates treated with mandibular and Dufour gland secretions. They also found that 2-ethyl-3,6-dimethylpyrazine, an newly identified alarm pheromone component of the fire ants, might not contribute to the digging preference observed in bioassays with mandibular gland extracts. This study is the first to look into the effect of exocrine sections on the digging behavior of fire ants. Identification of sources for chemicals which affect ant digging behavior might help in chemical characterization of those chemicals. Chemicals that affect digging behavior have a potential of being used in the development of new methods for controlling fire ants, such as new mound treatment formulations.
Technical Abstract: There was evidence that ant-derived chemical stimuli were involved in regulating the digging behavior in Solenopsis invicta Buren. Unfortunately however, the source gland(s) and chemistry of such stimuli have never been revealed. In this study, extracts of mandibular, Dufour, postpharyngeal and poison glands were evaluated for their effect on ant digging and residing preferences of S. invicta workers from three colonies. In the intracolonial bioassays, workers showed significant digging preference to mandibular gland extract in 2 of 3 colonies and significant residing preference in 1 of 3 colonies; significant digging preference to Dufour gland extract in 1 of 3 colonies and significant residing preference in 2 of 3 colonies; but no digging and residing preferences were found for postpharyngeal and poison gland extracts. In intercolonial bioassays, significant digging and residing preferences were found for mandibular gland extracts in 3 of 6 colony combinations. Significant digging preference to Dufour gland extracts was found in 4 of 6 colony combinations and significant residing preference in all 6 colony combinations. For postpharyngeal gland extracts, significant digging preference was found only in 1 of 6 colonial combinations and no significant residing preference was found. For poison gland extracts, no significant digging preference was found; significant residing preference was found in 1 of 6 colony combinations; however, a significant residing deterrence (negative residing preference index) was found for 2 of 6 colony combinations. Statistic analyses using data pooled from all colonies showed that mandibular and dufour gland extracts caused significant digging and residing preferences in both intracolonial and intercolonial bioassays but not postpharyngeal and poison gland extracts. By analyzing the data pooled from the same three colonies used for gland extract bioassays, it was found that, in no cases, 2-ethyl-3,6-dimethylpyrazine, a alarm pheromone component from mandibular gland, significantly increased the digging and residing preferences.