Hormone-dependent protein patterns in integument and cuticular pigmentation in Apis mellifera during pharate adult development

The epidermal proteins from staged Apis mellifera pupae and pharate adults and the progress of cuticular pigmentation until adult eclosion were used a s parameters to study integument differentiation under hormonal treatment. Groups of bees were treated at the beginning of the pupal stage with the ju venile hormone analog pyriproxyfen (PPN) or as pharate adults with 20-hydro xyecdysone (20E). Another group was treated with both hormones applied succ essively at these same developmental periods. Controls were maintained with out treatment. The epidermal proteins, separated by SDS-PAGE and identified by silver staining, were studied at seven intervals during the pupal and p harate adult stages. The initiation and progress of cuticular pigmentation was also monitored and compared to controls. The results showed that PPN re duced the interval of expression of some epidermal proteins, whereas 20E ha d an antagonistic effect, promoting a prolongation in the time of expressio n of the same proteins. In PPN-treated bees, cuticular pigmentation started precociously, whereas in 20E-treated individuals this developmental event was postponed. The double hormonal treatment restored the normal progress o f cuticular pigmentation and, to a large extent, the temporal epidermal pro tein pattern. These results are discussed in relation to the 20E titer modu lation and morphogenetic hormone interaction. (C) 2001 Elsevier Science Ltd . All rights reserved.