1. Managed honey bee (Apis mellifera) colonies are kept at much greater densities than naturally occurring feral or wild colonies, which may have detrimental effects on colony health and survival, disease spread, and drifting behavior (bee movement between natal and non-natal colonies).
2. We assessed the effects of a straightforward apiary management intervention (altering the density and visual appearance of colonies) on colony health. Specifically, we established three “high density / high drift” (“HD”) and three “low density / low drift” (“LD”) apiary configurations, each consisting of eight bee colonies. Hives in the HD apiary configuration were of the same color and placed 1m apart in a single linear array, while hives in the LD apiary configuration were placed 10m apart at different heights, facing outwards in a circle, and made visually distinctive with colors and symbols to reduce accidental drift between colonies. We investigated disease transmission and dynamics between the apiary configurations by clearing all colonies of the parasitic mite Varroa destructor, and subsequently inoculating two randomly-chosen colonies per apiary with controlled mite doses.
3. We monitored the colonies for two years and found that the LD apiary configuration had significantly greater honey production and reduced overwinter mortality. Inoculation and intervention status interacted to affect brood mite levels, with the highest levels in the inoculated colonies in the HD configuration. Finally, foragers were more than three times more likely to drift in the HD apiary configurations.
4. Synthesis and applications. Our results suggest that a relatively straightforward management change – placing colonies in low-density visually complex circles rather than high-density visually similar linear arrays – can provide meaningful benefits to the health and productivity of managed honey bee colonies.
UGA-Emory honey bee studies
The Pilot study started in 2014 using 6 apiaries each consisting of 7 colonies
- In 3 apiaries the colonies were placed in a circle with entrances facing out and 2 meters separating colonies
- In 3 apiaries the colonies were placed in a circle with entrances facing out and 10 meters separating colonies
The ED study started in 2015 using 6 apiaries each consisting of 8 colonies
- In 3 apiaries the colonies were placed in a line with all entrances facing the same direction and 2 meters separating colonies
- In 3 apiaries the colonies were placed in a circle with entrances facing out and 10 meters separating colonies
The TO study started in 2016 using 10 apiaries consisting of 14 colonies
- In 5 apiaries 2 colonies were inoculated with mites expected to be of high virulence
- In 5 apiaries 2 colonies were inoculated with mites expected to be of low virulence
The VA study started in 2015
- 8 apiaries each with 10 colonies
The CI study started in 2014
- HM, LM, and F bees inoculated with HM, LM, or F mites
In each study colonies were initially cleared of mites and then 2 colonies in each apiary were randomly chosen to inoculate with mites
- In the pilot study colonies were inoculated once
- In the ED study colonies were inoculated twice
Variables
- wave = sequential month since start of experiment
- sticky.screen.72hrs = standard Varroa measurement tool - sticky screen left under colony for 72 hours and mites that are trapped are counted - date indicates when screen first placed
- note: sometimes sticky screens could not be left for exactly 72 hours; in these cases the mite count is prorated to 72hours
- queen.status = whether the colony is queen right or not or whether there is a virgin queen
- mite inoculation = record of date of inoculation and how many mites were added to the colony
- colony.weight.kg = the colony weight is measured in kilograms
- alcohol.mite.count.300bees = appoximately 300 bees are rinsed in alcohol to remove mites
- note: measurement values are prorated to 300 bees
- adult.bees.A & B = each side of each frame is examined in a colony. A percentage score for these frames are recorded (ex. adult bees make up 50% of a frame)
the percentages for the colony are added together to get the final measurement. In order to reduce error associated with different workers measurements
two people measure each colony and the final measurements are averaged (*note: in the CI study only one measurement was taken but this was recorded
twice to make it consistent with the existing R code)
- brood.coverage.A & B = same measurement procedure as above but for brood instead of adult bees
UGA_Emory_Master_Spreadsheet.xlsx