The effects of different levels of protein and silymarin on the population growth and Hypopharyngeal gland surface of honey bee workers (Apis mellifera meda)

A pollen substitute is a valuable resource to maintain bee colonies strong and healthy, in the absence of pollen in sufficient quantities in nature. Hence, the current study was performed to investigate the effects of different levels of dietary proteins and silymarin (SM) as a natural antioxidant, on honey bee worker colonies. The study was carried out as a completely randomized design in an experiment conducted using 36 honey bee colonies in a completely randomized design with nine experimental treatments (four levels of crude protein 0, 20, 30 and 40%, two levels of silymarin 0 and 0.2 mM and pure pollen (control)), and four replications at Agricultural Sciences and Natural Resources University of Khuzestan in autumn 2015. In current study parameters such as workers in sealed broods, newborn workers bee weight, body protein and, the amount of development of Hypopharyngeal gland surface were studied. Soybean meal, maize and wheat gluten were included as pollen substitutes. Based on the results of the pre-experiment, SM supplement at a dose of two-tenths mM improved the survival of bees. Capped broods number using the divided box into squares with 2 × 2 cm, newborn workers bee weight using the balance, body protein based on the percentage of body weight and development of the Hypopharyngeal gland surface using microscopes and micrometers were measured. The results showed that there was a significant difference between treatments in terms of laying eggs (P <0.05). The highest and lowest rate of workers in sealed broods were related to treatment containing 30% protein and SM (12467 cells) and sucrose treatment (2042 cells), respectively. Also, the highest and lowest newborn workers bee weight were related to pollen treatment and the sucrose treatment, respectively (P <0.05). Body protein of worker bees in studied treatments had significant differences (P <0.05), so that the widest and narrowest percent body protein were observed in a diet containing 30% protein and SM and sucrose treatment, respectively. The Hypopharyngeal gland surface in the colonies fed with different diets was significantly different (P<0.05) and the widest and narrowest of its surface were observed in the diet containing 30% protein and SM and sucrose treatment, respectively. According to the current results, to maximize the reproduction of bees, a diet containing 30% crude protein is proposed.