Submitted to: Molecular Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/9/2013
Publication Date: 1/22/2014
Citation: Manfredini, F., Lucas, C., Nicolas, M., Keller, L., Shoemaker, D.D., Grozinger, C.M. 2014. Molecular and social regulation of worker division of labor in fire ants. Molecular Ecology. 23:660-672. Interpretive Summary: Fire ants are considered significant ecological, agricultural, and public health pest throughout their invasive range in the U.S.A. A research entomologist at the Center for Medical, Agricultural, and Veterinary Entomology, USDA-ARS, Gainesville, Florida, in collaboration with scientists from the University of Lausanne and Pennsylvania State University describe here the results of a study using whole-genome microarrays to characterize the genomic state of fire ant workers. The results demonstrate that numerous genes are differentially expressed between foraging and non-foraging fire ant workers in queenright colonies but not in queenless colonies. This study provides an ideal platform to move deeper into the understanding of how social life is regulated in fire ants.
Technical Abstract: Division of labor is a major achievement of social regulation in insect societies. Despite the great interest for this theme, the molecular basis for the regulation of division of labor has been investigated in detail only in honey bees, while nothing is known about the regulatory mechanisms operating in other social insects that might be very different from the honey bee model. In the fire ant Solenopsis invicta, social organization regulated by workers’ division of labor is associated with age, size and localization in the colony. However, nothing is known about the molecular mechanisms underpinning these processes. We used a microarray platform to characterize the genomic state of fire ant workers. We identified numerous genes significantly differentially expressed between foraging and non-foraging workers in queenright colonies. Interestingly, this difference disappeared after the queen was removed and no major differences were detectable between queenright and queenless workers when we did not consider the task performed. However, queenless workers had a genomic profile more similar to foraging than non-foraging workers for genes that were upregulated. These results indicate that S. invicta is an ideal model to characterize new mechanisms of molecular and social organization of division of labor. There is evidence that fire ants rely on reproductive and worker division of labor, but the extent to which these mechanisms are used appears to be different from the honey bee model. Therefore, this approach is fundamental to shed light about how the pathways that regulate social behavior evolved in different social systems.