Figure 6. Hormone-dependent initiation of vitellogenin expression in honeybee (A) workers and (B) queens. Curves represent ecdysteroid (ECD) and juvenile hormone (JH) caste-specific titers during pupal and early adult stages. Red arrows indicate the stages when hormone treatments were performed. The black arrows mark the normal onset of vitellogenin expression, which is advanced in juvenile hormone-treated (blue arrows) or delayed in 20E-treated bees (green-arrows). Pp, Pb: pink or brown-eyed pupae with unpigmented cuticle; Pbl, Pbm, Pbd: brown-eyed pupae showing light, intermediary or dark pigmented cuticle; Pbm I, Pbm II: progressive ages within Pbm phase; Pha: pharate adult. Hormonal titers data: Feldlaufer et al. (1985), Rembold (1987), Hartfelder and Engels (1998) and Pinto et al. (unpublished data).