Effect of season on the development of hypopharyngeal glands and its morphological characteristics under brood rearing conditions in honey bee colonies (Apis mellifera)

The hypopharyngeal glands (HPGs) are a major member of protein synthesis in worker bees, which is involved in larval growth. In this experiment, the effect of season (summer, winter and spring) on the development of HPGs and its morphological characteristics under brood rearing conditions in honey bee colonies (Apis mellifera) was investigated. To carry out this experiment, 10 honey bee colonies with the same conditions in all seasons were used. The results showed that there was a significant difference between the different seasons in the acini area of the HPGs of worker bees (at the ages of 3, 6, 9 and 15 days). During the winter, spring and summer, the HPGs fully developed under brood conditions but had morphological differences. Also, the level of unsealed/uncapped brood rearing (including: eggs and larvae) was significantly different between different seasons. According to the results obtained from the development of HPGs in summer and winter, an upward and downward trend in glands growth was observed, which is known, but in the spring we saw a steady trend in the growth of glands, which could be a new theory of the development of HPGs in the spring according to the level of brood rearing.