LAUSR

Maternal effects have been recognized in animals and plants for a long time (Bernardo 1996; Roach & Wulff, 1987). Maternal effects are that the phenotype of offspring is influenced by maternal phenotype rather than its own genotype (Van Dooren et al., 2016; Schwabl & Groothuis, 2019). Vertebrate females can adjust their investment in eggs to get higher quality offspring (Cunningham & Russell, 2000). Insects can also adaptively vary investment in their eggs (Passera, 1980). Honeybees are typical eusocial insect species, and the queen is the only female individual amongsterile workers (Winston, 1991). Previous studies showed that female larvae fed with richer nutritional diet develop into queens, whereas lower nutritional diet results in the development of workers (Haydak, 1970). The space in Abstract Queen-worker caste dimorphism is a typical trait for honeybees (Apis mellifera). We previously showed a maternal effect on caste differentiation and queen development, where queens emerged from queen-cell eggs (QE) had higher quality than queens developed from worker cell eggs (WE). In this study, newly-emerged queens were reared from QE, WE, and 2-day worker larvae (2L). The thorax size and DNA methylation levels of queens were measured. We found that queens emerging from QE had significantly larger thorax length and width than WE and 2L. Epigenetic analysis showed that QE/2L comparison had the most different methylated genes (DMGs, 612) followed by WE/2L (473), and QE/WE (371). Interestingly, a great number of DMGs (42) were in genes belonging to mTOR, MAPK, Wnt, Notch, Hedgehog, FoxO, and Hippo signaling pathways that are involved in regulating caste differentiation, reproduction and longevity. This study proved that honeybee maternal effect causes epigenetic alteration regulating caste differentiation and queen development. Sociobiology An international journal on social insects