The influence of an analog of juvenile hormone on the silk gland of Africanized Apis mellifera larvae reared in vitro

Abstract

As the larval silk glands of Africanized honey bees are well characterized in hive conditions, we compared the silk glands of larvae of Africanized honey bees from the hive (in vivo - literature information) with larvae reared under laboratory conditions according to a specific bioassay (in vitro rearing of Africanized honey bees). We also continuously exposed the larva to a juvenile hormone analog (JHA), the pyriproxyfen, in three different concentrations: 12.5 mg/L, 25 mg/L, and 50 mg/L. Concerning morphological and histochemical analyses, there were no characteristics in glands that indicated the acceleration of the cocoon spinning time and no features of cell death. The glands seemed to be in secretory activity. Pyriproxyfen-treated larvae had a slightly shorter silk synthesis period than control, although only in the 50 mg/L experimental group, the tactoids from silk were clearly visible in optical microscopy, probably due to a higher secretion activity as the response to JHA. We observed that the presence of lipids under artificial feeding was independent of the nurse bee presence. Thus, we found that pyriproxyfen alters the functioning of the silk gland, under laboratory conditions in morphological, histological, and/or morphometric aspects.