Archives of Insect Biochemistry and Physiology vol:76 issue:1 pages:30-42
In eusocial insects, the division of labor within a colony, based on either age or size, is correlated with a differential foraging (for) gene expression and PKG activity. This paper presents in a first part a study on the for gene, encoding a cGMP-dependent protein kinase (PKG) in the bumblebee Bombus terrestris. Cloning of the ORF allowed phylogenetic tracing which showed conservation of PKGs among social insects. Our results confirm the proposed role for PKGs in division of labor. Btfor gene expression is significantly higher in the larger foragers compared to the smaller sized nurses. More importantly, we discovered an age-related decrease in Btfor expression in both nursing and foraging bumblebees. We therefore speculate that the presence of BtFOR is required for correct adaptation to new external stimuli and rapid learning for foraging. In a second series of experiments, worker bumblebee of B. terrestris were treated with two insecticides imidacloprid and kinoprene that have shown to cause impaired foraging behavior. Compared to controls, only the latter treatment resulted in a decreased Btfor expression which concurs with a stimulation of ovarian growth and a shift in labor towards nest related tasks. The data are discussed in relation to Btfor expression in the complex physiological event of foraging and side-effects by pesticides.