Programmed cell death during ovarian differentiation in queens of Apis mellifera Linné, 1758 (Hymenoptera, Apini)

RESUMO

In this study, we examined various aspects of ovarian development in adult honey bees queens (Apis mellifera). Caged honey bee queens showed an initial programmed germ cell differentiation that was independent of any external or environmental stimulus. In young queens, division of the stem germ cells resulted in cysts of clone cells (cystocytes) that were connected through intercellular bridges and appeared as rosettes. The cystocytes started differentiate shortly before the queens reached sexual maturity (about 5 days old). The oocyte subsequently appeared as a large, stained cell connected to parallel, double rows of smaller cells, or nurse cells. If the queens did not mate, germ cell differentiation was “switched off”, and development of the ovary was interrupted in an intermediate developmental stage, without follicular cell organization. Therefore, in such queens, there were no pevitellogenic follicles. This finding could explain why wvirgin queens rarely lay eggs and why after fecundation they require several days to start laying. The absence of previtellogenic follicles may also indicate that some stimulus is required for continuation of the vitellogenesis and ovary development.