Bee Health and Pollen Sourcing: Does mixed source pollen improve bee health?

A study conducted by Ramesh Sagili at Oregon State University looked at pollen sourcing and the effects on bee health. In this study, equal amounts of single-source pollen and multi-sourced pollen were packed into the comb cells of six frame hives. Each week, 100 newly emerged paint bees were introduced to the hive, while 20 nurse bees were removed from the colony for a protein estimation of the hypopharyngeal gland. This gland produces special food that is necessary for the development , metamorphosis, and pupation of the larvae. They also measured the brood area occupied by the eggs, larvae, pupae, pollen, and honey.

Figure 1: Mean hypopharyngeal protein
content of 20 nurse bees.

What did they find?
Analysis of the hypopharyngeal gland protein content yielded interesting results. Not only did they find a statistically lower gland protein content within the single-source pollen packed hives(Figure 1), but they also detected statistically lower amounts of crucial enzymes within the proteins isolated from single-source pollen packed hives (Figure 2). Differences brood size was also apparent; colony growth measurements were significantly lower within the single-source pollen packed hives (Figure 3).

So what does this mean?

Figure 2: Concentrations of two
enzymes found within the hypopharyngeal
protein of 20 nurse bees 

Findings from this study suggest that pollen from a diversity of sources will benefit hive health. Beekeepers should keep this in mind when determining the feeding regime for the hives. It doesn’t stop there, however, as growers should attempt to incorporate alternative pollen sources within their orchard system to help increase hive health. Strategies may include placement of hives next to hedgerows or vegetative strips, or leaving an area of clover, or some other cover crop, un-mowed during and after the pollination period. It would be best to leave the un-mowed area outside of the orchard as to reduce the risk of frost damage.

Figure 3: Brood area measured
over 7 weeks

Determining strategies that incorporate multi-sourced pollen sourcing on the farm does not just help the beekeeper. Healthy hives are larger colonies which are better at pollinating than weaker, smaller colonies. A larger colony also means a larger supply of bees which could lead to a stabilization or reduction of the current pollination service price. As research continues to shed light on bee health, hopefully we will be able to determine strategies to reduce colony loss and improve hive strength. Stay tuned.

Information source: Sagili, Ramesh. 2010. “Effects of Pollen Quality on Honey Bee Nutritional Status and Colony Growth.” 2009-2010 Annual Reports of the Almond Board of California. Almond Board of California.

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