Winter Survival of Honey Bee Colonies

A study involving Inra, Acta and the ITSAP-Institut de l’abeille examines the physiological mechanisms involved in the winter survival of honey bees. The researchers showed that a protein with antioxidant properties, vitellogenin, is associated with a 30% increase in the probability of colony survival during winter.

The production of this vitality protein is promoted by the quality of the environment in which bees prepare for winter, notably the presence of flowering cover crops established by farmers in autumn and resources associated with natural habitats.

A direct consequence of agricultural intensification is the decline of flora providing food resources for pollinators. In particular, in large-scale arable farming areas, the lack of resources at the end of the season can compromise, in the honey bee, the accumulation of reserves (honey and pollen) that are important for colony survival during winter. To address this situation, the placement of apiaries near the few plants that still flower in late summer and autumn is a common practice among beekeepers in cereal-growing plains. Colonies composed of individuals with high vitellogenin levels achieved winter survival rates of around 90%.

Restoring floral resources in large-scale arable farming areas therefore represents an important challenge for bee colonies. This study, conducted by researchers from Inra in collaboration with Acta and the Itsap-Institut de l’abeille, helped to shed light on the physiological mechanisms at work in bees benefiting from these floral resources. In colonies located near flowering cover crops, bees had more fat bodies, energy reserves necessary for winter survival. They also showed increased vitellogenin levels, a strong antioxidant that is favorable to individual longevity. This improvement in bee vitality further increased the chances of winter survival of the colonies. Thus, colonies composed of individuals with low vitellogenin levels showed a winter survival rate of 60%, whereas colonies composed of individuals with high vitellogenin levels reached survival rates of around 90%.

It was therefore shown that the establishment by farmers of cover crops based on plants producing nectar and pollen from as early as September (white and brown mustard, Alexandrian clover, purple and common vetch, phacelia, sunflower) increases the diversity of resources collected by bees and consequently contributes to improving their vitality. However, the most significant effect was achieved through natural environments such as hedgerows and forest edges.

This cause-and-effect relationship between floral resources and bee vitality constitutes direct evidence of the value of measures aimed at preserving natural habitats in agricultural areas. But when these habitats become too scarce, appropriate management of cover crops makes it possible to combine agronomic objectives (nitrate trapping, control of soil erosion) with objectives related to bee protection.

See also:

► Vitellogenin
► Overwintering of bee colonies

Source: https://www.techno-science.net/actualite/survie-hivernale-colonies-abeilles-melliferes-N16009.html