Parent-of-origin expression and small RNAs in female honey bee embryos

Female honey bee larvae exhibit remarkable phenotypic plasticity, developing into either workers or queens, in part due to differences in diet during early development. It is currently unknown whether intragenomic conflicts contribute to caste differentiation. Previous work has investigated matrigene/patrigene conflict in honey bee subspecies with extreme variation in reproductive physiology and behavior. However, it is unknown to what extent this conflict occurs in embryonic development of less divergent crosses or whether this contributes to caste differentiation. Conflict between the host genome and transposons (TEs) is another potential driver of these developmental differences. However, research into whether differential regulation of TEs contributes to caste differentiation are lacking. In many species, PIWI-interacting RNAs (piRNAs) have evolved to regulate TE expression. In Drosophila, maternal piRNAs in gametes influence chromatin states in embryos. Recent evidence suggests piRNAs are present in A. mellifera and are potentially maternally inherited in embryos. In this study, we further investigate the contribution of matrigene/patrigene conflict to caste differentiation. Additionally, we explore the potential of piRNAs as a mechanism of epigenetic inheritance in honey bees and assess their contribution to caste differentiation via regulation of TEs.