Project description:During the nest-founding phase of the bumble bee colony cycle, queens undergo striking changes in maternal care behavior. Early in the founding phase, prior to the emergence of workers in the nest, queens are reproductive and also provision and feed their offspring. However, later in the founding phase, queens cease feeding offspring and become specialized on reproduction. This transition is synchronized with the emergence of workers in the colony, who assume the task of feeding their siblings. Using a social manipulation experiment, we tested the hypothesis that workers socially regulate the transition from feeding brood to specialization on reproduction in nest-founding bumble bee queens. Consistent with this hypothesis, we found that early-stage queens with workers prematurely added to their nests reduce their brood-feeding behavior and increase egg-laying, and likewise, late-stage queens increase their brood-feeding behavior and decrease egg-laying when workers are removed from their nests. Further, brood-feeding and egg-laying behavior were negatively correlated in these queens. We used an Agilent brain EST-based microarray to explore a second hypothesis, that workers alter brain gene expression in nest-founding queens. We found evidence that brain gene expression in nest-founding queens is altered by the presence of workers, with the effect much stronger in late-stage founding queens. Additionally, expression levels of some genes were correlated with quantitative differences in brood-feeding and egg-laying behavior. This study provides new insights into how the transition from feeding brood to specialization on reproduction in bumble bee queens is regulated during the nest initiation phase of the colony cycle.
Project description:In social insects, workers perform distinct tasks according to the caste they belong to, and workers from different castes differ in their age (nest workers are usually younger than foragers are). The caste shift thus seems inseparable from age, preventing from deciphering the role of labour division and age in regulating individual physiology and ageing rates. We set up an experimental protocol separating age and caste effects by defining four groups of black garden ant (Lasius niger) workers: young foragers (Y.F), old foragers (O.F), young nest workers (Y.NW) and old nest workers (O.NW). Proteomics highlighted differences between individuals according to their age, whereas metabolomics revealed caste-related differences. Our study highlighted that age and caste influence specifically different aspects of the physiology of ant workers.