Epigenetic and endocrine determinants of lifespan differences between the castes of social insects

Social insects are promising model organisms in the study of longevity mechanisms. They have a caste system, in which the same genomes may produce phenotypes significantly distinguished by longevity. The ontogenetic trajectories of bees depend on the duration of supply by a specific nutrient mixture (royal jelly) at the larval stage. Longer feeding by the royal jelly leads to the formation of the queen epigenome, which is different from the epigenome of a working bee. Such epigenetic differences, in turn, induce endocrine changes manifested in increased synthesis of juvenile hormone and activation of TOR (target of rapamycin) signaling pathway, as well as in the modulation of insulin/IGF-1 pathway in queen-destined larvae. In adults, these processes influence the synthesis of vitellogenin (egg yolk precursor determining many aspects of insect ontogenesis). Epigenetic and andocrine mechanisms that underlie differences in longevity among the castes of social insects are discussed.