Overwintering colony health and survival are major concerns for the beekeeping industry, because the ambient temperature is a primary factor affecting larval development of honey bees. Prolonged exposure to the cold temperature leads to higher larval mortality, with a reduced life expectancy for those surviving to adulthood. By measuring the amount of winter losses, beekeepers can eva‎luate the success or failure of each colony in overwintering and therefore they get informed about relative level of inbreeding in their apiary, and take the necessary measures to improve the performance of the colonies that have low survival rates. The present study was conducted to eva‎luate the factors affecting the honey bee population and their relationship with the overwintering power of the colony. For this purpose, the information of 198 colonies during the years 2019 and 2020 was examined at the bee research and queen breeding station in Gilan province. There were 105 colonies for 2019 and 93 colonies for 2020. The data were collected twice a year, once before the cold season, i.e. summer, and again after the end of the cold season and at the beginning of honey bee activity in spring. The hygienic behavior, the brood survival, the population of broods and adult bees before overwintering and the amount of the pollen storage were measured. Data analysis was done by SAS 9.4(2022) software. Using the Genmod procedure, and considering the effects of several different traits on overwintering power, it was investigated simultaneously.The final results of the research showed that the hygienic behavior had no significant effect on the overwintering power (P>0.05) and it was clarified by estimating the odds ratio that no significant difference was observed between the two different groups (P>0.05). The effect of the brood survival on overwintering power was significant (P<0.05). The relationship between the number of the empty cells counted to eva‎luate this trait and the winter losses showed that the decrease in the brood survival will lead to an increase in the winter losses. The effect of the amount of the pollen stored before the cold season as a food item on the ability to survive in the winter was not significant (P<0.05). The effect of the population of the brood before the winter on the overwintering power was not significant (P>0.05). The population of the adult bees before winter had a great effect on the success of the colony in overwintering and this effect was completely significant (P<0.05). The relationship between the population of the adult bees before winter and winter losses showed the higher population of the adult bees, the lower the winter losses. Scince in some regions and some years, honey bees do not collect enough nectar to survive in the winter, in this research, the effect of the year on the overwintering was also investigated. Due to the limited number of years examind in this research (two years), the effect of the year on overwintering power was not significant (P>0.05). The odds ratio of overwintering success of the colonies of 2019 compared to the colonies of 2020 was also estimated and it showed the difference between these two years was not significant (P>0.05). By measuring the amount of winter losses, in addition to knowing the level of inbreeding in their apiary, beekeepers can separately estimate the success or failure of each colony in wintering and take the necessary measures to improve the performance of colonies whose survival of babies is low.

علي صادقي سفيدمزگي , عباس پاكدل

احمد نيككار

سعيد انصاري مهياري , نفيسه پورجواد