Winter bees

Factors that influence winter bee production

Proposed model for regulation of production of winter bees. The production of winter bees is likely regulated by Interactions among temperature and photoperiod cues, environmental nutritional resources, brood/brood pheromone levels, and forager pheromone (ethyl oleate). From Doke et al., Current Opinion in Insect Science needs of early spring-blooming crops such as almonds, apples and cherries. Indeed, the February/March Cali- fornia bloom requires 1.7 of the 2.5 million US honey bee colonies to pollinate 860 thousand acres of almonds, and this demand is projected to continue to rise. This demand could be met, at least in part, by improved overwintering: a 10% reduction in overwintering loss could provide an additional 250 000 colonies for early spring pollination.
The overwintering state of a honey bee colony is charac- terized by changes in the behavior and physiology of individual bees, including reduced individual activity, changes in endocrine profiles, increased nutrient stores and increased longevity, as well as changes at the colony level, including cessation of brood rearing and most remarkably, formation of a thermoregulating cluster. In non-temperate parts of the world, there are seasonal factors other than winter (i.e. dry, rainy, or hot periods with little forage available) seem to trigger a broodless state followed by absconding of the nest site in search of a new one [78]. While certain aspects of the two life cycle events are similar (i.e. lack of forage, decreased/halted foraging, and cessation of brood rearing), overwintering provides a unique challenge for the honey bees to over- come; extreme cold.
Previous studies have demonstrated that levels of Varroa mites, viruses, geographic location, and genotype are correlated with winter colony losses [4–9]. However, the effects of these factors on overwintering bees at the molecular, physiological and behavioral level have not been comprehensively studied, making it challenging to develop better management approaches to improve overwintering success. Here, we describe our existing knowledge of the environmental and physiological factors regulating entrance, maintenance, and exit from the over- wintering state in honey bees in temperate regions. We then discuss factors associated with overwintering losses. Finally, we synthesize this information to provide recom- mendations for beekeepers to maximize overwintering survival and highlight areas of future investigation.
Overview of the annual colony cycle in temperate regions
Honey bee colonies exhibit distinct seasonal states (see Figure 1) [2]. In temperate climates, brood rearing starts in winter (when the average maximum ambient temper- ature is as low as 4 8C), peaks in spring, decreases through summer, and ceases in early fall [6,10,11􏰁􏰁,76]. Brood build-up in the spring typically leads to swarming, where the majority of the workers leave the colony with the old queen in search of a new nest site, leaving behind a new
Current Opinion in Insect Science needs of early spring-blooming crops such as almonds, apples and cherries. Indeed, the February/March Cali- fornia bloom requires 1.7 of the 2.5 million US honey bee colonies to pollinate 860 thousand acres of almonds, and this demand is projected to continue to rise. This demand could be met, at least in part, by improved overwintering: a 10% reduction in overwintering loss could provide an additional 250 000 colonies for early spring pollination.
The overwintering state of a honey bee colony is charac- terized by changes in the behavior and physiology of individual bees, including reduced individual activity, changes in endocrine profiles, increased nutrient stores and increased longevity, as well as changes at the colony level, including cessation of brood rearing and most remarkably, formation of a thermoregulating cluster. In non-temperate parts of the world, there are seasonal factors other than winter (i.e. dry, rainy, or hot periods with little forage available) seem to trigger a broodless state followed by absconding of the nest site in search of a new one [78]. While certain aspects of the two life cycle events are similar (i.e. lack of forage, decreased/halted foraging, and cessation of brood rearing), overwintering provides a unique challenge for the honey bees to over- come; extreme cold.
Previous studies have demonstrated that levels of Varroa mites, viruses, geographic location, and genotype are correlated with winter colony losses [4–9]. However, the effects of these factors on overwintering bees at the molecular, physiological and behavioral level have not been comprehensively studied, making it challenging to develop better management approaches to improve overwintering success. Here, we describe our existing knowledge of the environmental and physiological factors regulating entrance, maintenance, and exit from the over- wintering state in honey bees in temperate regions. We then discuss factors associated with overwintering losses. Finally, we synthesize this information to provide recom- mendations for beekeepers to maximize overwintering survival and highlight areas of future investigation.
Overview of the annual colony cycle in temperate regions
Honey bee colonies exhibit distinct seasonal states (see Figure 1) [2]. In temperate climates, brood rearing starts in winter (when the average maximum ambient temper- ature is as low as 4 8C), peaks in spring, decreases through summer, and ceases in early fall [6,10,11􏰁􏰁,76]. Brood build-up in the spring typically leads to swarming, where the majority of the workers leave the colony with the old queen in search of a new nest site, leaving behind a new
Current Opinion in Insect Science 2015 10:185-193

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