LAUSR

BACKGROUND Worker division of labor is particularly predominant in social insects. The foraging (for) gene, which encodes cGMP-dependent protein kinase (PKG), has been implicated in the regualtion of behavioral transitions in honeybees, but information regarding its function in other social insects is scarce. RESULTS We investigated the role of the for (Sifor) gene in the red imported fire ants, Solenopsis invicta, and found that Sifor and PKG exhibited different expression patterns in different castes, body sizes, ages, and tissues of fire ants, especially both in foragers and nurses. Foragers displayed greater locomotor activity but showed no preference for larval or adult odors, whereas nurses showed lesser locomotor activity but had a strong preference for larval odors. We found that the expression of Sifor was significantly higher in the heads of foragers (compared to nurses). RNA interference-mediated Sifor knockdown in foraging workers induced behavioral transition of foragers toward the nurse phenotype characterized by reduced locomotor activity and a stronger preference for larval odors. In contrast, treating nurses with 8-Br-cGMP, an activator of PKG, resulted in behavioral transition toward the forager phenotype characterized by higher locomotor activity but reduced preference for larval odors. CONCLUSION Our results suggest that Sifor plays a critical role in the behavioral transition between foragers and nurses of workers, which may be a promising target for RNAi-based management of worker caste organization in S. invicta. This article is protected by copyright. All rights reserved.