Which factor is a primary cause of winter losses in bee colonies?

Lack of proper food resources is indeed a primary cause of winter losses in bee colonies. During the winter months, honey bees rely on stored honey and pollen for sustenance as foraging becomes impossible due to cold weather and reduced flowering plants. If a colony has not stored enough food or has been unable to access their stored reserves, the bees may starve. Additionally, colonies that run low on food can become stressed, making them more vulnerable to diseases and pests. Ensuring that a colony has sufficient food resources going into winter is a critical factor for their survival during the colder months.

The other factors, while they can affect bee health, are not as direct of a cause for winter losses. High humidity levels can induce mold and negatively affect the bees, but they do not directly lead to starvation. Excessive rain during winter can affect other aspects of bee life but is less impactful than food scarcity. Low levels of queen activity may indicate other underlying problems within the colony, but it is typically the availability of food that determines a colony’s ability to survive winter.