Submitted to: Behavioral Ecology and Sociobiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 8, 2000
Publication Date: N/A
Interpretive Summary: The red imported fire ant is an important medical and agricultural pest in the south and southeastern United States, causing at least a billion dollars in damage and control costs annually. A multiple queen form of this pest ant occurs in larger numbers than the more common single queen form. The multiple queen form differs from the single queen form in that workers from different nests are accepted as nestmates, whereas workers from the single queen form are very aggressive toward workers from other colonies. It has been suggested by other researchers that the multiple queen form originates from the adoption of newly mated fire ant queens into monogyne colonies and that existing multiple queen colonies are maintained through adoption of additional newly mated queens. Scientists at the Center for Medical, Agricultural and Veterinary Entomology, USDA/ARS, Gainesville, FL investigated the behavior of single and multiple queen workers toward newly ymated queens and discovered that the workers from both forms are very aggressive to these queens and kill them. This information indicates that newly mated queens are not treated the same as workers and that the theories proposed for multiple queen formation and maintenance will need to be modified.
Technical Abstract: Nestmate recognition is of prime importance in maintaining colony integration and organization. Monogyne fire ant colonies (Solenopsis invicta Buren) are highly territorial and aggressive toward non-nestmate conspecific workers. In contrast, workers from polygyne nests in the United States show no aggression toward workers from other conspecific colonies (polygyne or monogyne). Nests within a polygyne population form a 'supercolony', with free exchange of workers and food between nests. The difference in conspecific nestmate recognition is a major distinguishing feature of the two S. invicta forms in the United States. An exception to this behavioral dichotomy is the highly aggressive response of both forms to heterospecific intruders. We report here the discovery of a second exception to this dichotomy. High levels of worker aggression are released by the introduction of newly mated queens (NMQs) into both polygyne and monogyne colonies. This suggests that nestmate recognition involving femal sexuals does not follow the same template/cue mechanism used to explain the nestmate recognition behavior of workers. In addition, previous hypotheses for the initial formation of polygyne fire ant colonies based on the adoption of NMQs into queenright monogyne colonies are probably not valid.