Location: Carl Hayden Bee Research Center
Project Number: 2022-30500-001-000-D
Project Type: In-House Appropriated
Start Date: Mar 11, 2025
End Date: Mar 10, 2030
Objective:
This project will develop cost-effective options for colony management by identifying and testing: 1) plant genotypes that improve bee nutrition; 2) characteristics of different bee stocks and mite control strategies to improve colony health; 3) factors and diet supplements important to the seasonal transition of worker phenotypes; 4) optimum timing for placing hives in cold storage; and 5) nutritional needs of overwintering queens and colonies.
Objective 1: Assess the relationship between abiotic stress and floral rewards from plant genotypes that provide high nutritional quality for bees in specific geographic regions.
Sub-obj. 1.A: Determine if water stress affects bloom phenology and foraging activity on sunflowers.
Sub-obj. 1.B: Determine the effect of water availability on pollen lipid and protein levels of different sunflower cultivars.
Sub-obj. 1.C: Determine if the effects of water stress on pollen nutrients translates to honey bees.
Objective 2: Quantify the effects of bee colony health, genetics and mite management on colony-level behavior, including foraging, brood production, and temperature and CO2 control in cold storage.
Sub-obj. 2.A: Compare colony growth, brood production, thermoregulation and hive CO2 concentration among different bee stocks, including Varroa-resistant stocks.
Sub-obj. 2.B: Compare colony-level behavior, including colony growth, foraging activity and thermoregulation, for different bee stocks subjected to a late summer cold storage treatment as part of an experimental Varroa control strategy.
Objective 3: Identify environmental and nutritional factors that sustain honey bee health and initiate the conversion of worker bees from summer to winter phenotypes.
Sub-obj. 3.A: Determine if the storage of nutrients in the fat body and cessation of brood rearing are related to ambient temperatures that cause clustering behavior.
Objective 4: Conduct research to assess if existing or experimentally-altered commercial dietary supplements meet the nutritional requirements to sustain honey bee health during key seasonal transitions and determine optimum timing of transferring hives to cold storage before winter.
Sub-obj. 4.A: Determine whether lipid-enriched diets fed to fall colonies increase fall bees’ lipid stores, maintain spring bees’ protein stores, and increase colony expansion in the spring and summer.
Sub-obj. 4.B: Determine optimum timing of transferring hives to cold storage for overwintering based on the formation of winter bees.
Objective 5: Evaluate the impacts of supplemental nutrition and forage on the duration of the queen winter reproductive hiatus, and subsequent recovery to full reproductive capabilities.
Sub-obj. 5.A: Determine the effects of overwintering cold storage on queen reproductive quality, reproductive hiatus, and recovery to full brood production in late winter and spring.
Sub-obj. 5.B: Determine whether colonies fed high-lipid supplementary diets in the late summer/early fall (August-October) maintain higher reproductive quality queens and produce more brood and workers in late winter/early spring than colonies fed unaltered diets.
Approach:
Objective 1: Hypothesis 1.A: Average flower size, bloom period, and bee attractiveness will not differ between water-stressed and unstressed plants within the same genetic line or between drought tolerant and susceptible lines. Water stress on floral attractiveness and pollen nutrients will be measured using sunflowers as a model system.
Hyp: 1.B: Water-stressed plants produce pollen with less protein and lipid than unstressed plants, but this nutrient depletion differs among genotypes. Pollen lipid and protein content will be measured, when water stressed, for the 10 sunflower genotypes that attract pollinators.
Hypothesis 1.C: Bees fed pollen from water-stressed plants will store fewer nutrients and have smaller hypopharyngeal glands than bees fed pollen from unstressed plant but those fed pollen from drought tolerant plant genotypes will store more nutrients and have larger glands than bees fed pollen from drought susceptible genotypes, when those plants are water-stressed.
Objective 2: Hypothesis 2.A: Bee stocks differ with respect to colony size, behavior, thermoregulation, and CO2 concentration. Bee colonies will be monitored to quantitatively describe bee stocks in terms of colony-level behavior and improve interpretation of field studies.
Hyp: 2.B: Late summer cold storage will reduce Varroa mite levels in different bee stocks. Colony behavior and mite densities will be monitored as they are moved from outdoor conditions to cold storage, and then again outside. Different genetic lines, including those selected for Varroa mite resistance, will be included.
Objective 3: Hypothesis 3.A: The transition from brood-rearing summer bees to nutrient-storing winter bees is initiated by decreasing ambient temperature and increasing hours spent in winter cluster. As time in bee cluster inside the hive increases in the fall, bees store more lipid in their fat bodies, making less available for brood rearing.
Objective 4: Hypothesis 4.A: Bees fed high-lipid diets in the fall have the same amount of fat body lipid and protein as bees fed unaltered diets before and after winter, and colonies fed a high-lipid diet in the fall will have the same amount of brood and adults the following spring and summer as colonies fed unaltered diets.
Hyp: 4.B: Changes in worker bee fat body metrics, cessation of brood rearing and transition to winter bees can be predicted using hours that a colony has spent in cluster.
Objective 5: Hypothesis 5.A: Queens from colonies that overwinter in cold storage will have higher reproductive quality and produce more workers and brood in the spring than colonies that overwinter outside of cold storage. Queen status and the health of worker bees and colonies in cold storage, without access to mid-winter forage, will be compared to colonies with access to mid-winter forage
Hyp. 5.B: Colonies fed high-lipid diets in the fall will maintain higher quality queens and produce more workers and brood in the late winter and spring than colonies fed unaltered diets.
Colonies in the early fall will be fed flaxseed oil, known to increase worker lipid stores, and overwintering queen reproductive physiology will be monitored.
