Dr. Vanessa Corby Harris Presents: Towards a More Comprehensive Assessments of Pollen Substitutes

Images: Sampling colonies at the North Dakota field site in the late summer of 2021

Beekeepers know that good nutrition ensures the overall health of their bees and that it can also help buffer other health challenges. But we often hear the question “what is considered ‘good’ nutrition, and how can beekeepers ensure that their bees have access to it?”
 
New research, informed by beekeepers and funded through PAm as part of the Healthy Hives initiative, was undertaken by Dr. Vanessa Corby-Harris of the USDA-ARS Carl Hayden Bee Research center in Tucson, Arizona. This research was designed to help beekeepers decide if, and how, to invest in protein supplements for their bees. 
 
Preliminary results of this research were recently presented by Dr. Vanessa Corby-Harris, and collaborating commercial beekeeper Blake Shook, in a webinar series for beekeepers.

Part 1 of the webinar series covers the experimental design and preliminary results. 

In part 2 of the webinar series Dr. Vanessa Corby-Harris covers additional results and collaborating beekeeper Blake Shook joins for a researcher/beekeeper Q & A. 

In an ideal scenario, the honey bee’s diet should come from an abundance and variety of natural pollens and nectars that are free of pesticides.
 
Whether it’s the late-winter timing of the almond pollination, summer drought conditions, or limited space with natural forage, for modern beekeeping, good nutrition is not always as simple as trusting that the bees can get what they need from the land.  This can have many consequences, including increased stress and lower honey production. 

Image:  BeeHealthCollective.org/Honey.  Honey production per colony has been steadily decreasing since 1997.  The most recent NASS Honey report indicated a 14% decrease in honey production in 2021, down from 2020.

Beekeepers do have the option of providing supplements to their bees to help fill in nutrition gaps. These supplements come in the form of sugar syrup to replace a nectar flow, and different mixes of finely ground protein powders to replace pollen. These supplements are not cheap to buy and make up a significant portion of beekeeping costs in an operation.

Image: BeeHealthCollective.org/Beekeeping. This chart from the Bee Health Collective represents data from the 2022 USDA NASS Honey Report on different beekeeping cost in 2021.   

​Working with about 400 colonies provided by commercial beekeeper Blake Shook of Desert Creek Honey, Dr. Corby Harris and her team compared six diets designed to supplement natural pollen: BeePro, UltraBee, MegaBee. AP 23, Global Patties with 4% pollen, and Global Patties with 75% pollen which were the positive control. Because providing no supplements would have likely resulted in dead colonies, no negative control was included.

​Dr. Corby-Harris and her team followed the colonies as they were fed in the fall prior to winter storage, and then out of storage into the almonds. Along the way, they monitored Varroa levels, Nosema levels, colony size in seams of bees and brood area, and they also sampled the fat bodies of the bees (indicators of overall nutritional health) for lipid and protein content.

Most hives survived cold storage (97% survival), and an early analysis of results indicated that the colonies fed Global Patties with 4% pollen were the largest going into the almonds. This is promising because that diet happened to be the most affordable option of the six options.

​Dr. Corby-Harris also found, through monitoring for Varroa, that mite levels in August had a significant impact on colony size coming out of indoor storage. Colonies that had more than 2% infestation levels in August were smaller than colonies that were below that level, even though all colonies had no detectable mites in September. This indicates the importance of surveillance and mite control for overall health.

Image: Dr. Corby-Harris presented preliminary data indicating that mite levels above 2% infestation in the August prior to indoor storage, negatively impacted colony size later in the year, despite falling to undetectable levels that September.

While the results aren’t a sweeping endorsement or condemnation of any one supplement, they do show that expense is not necessarily the indicator which diets will work best. Dr. Corby-Harris has been working through the data, with more results to come. Stay tuned for Project Apis m. to announce a follow-up webinar later this year.  
 
Leading up to the webinar, beekeepers submitted questions to Dr. Corby Harris. There was not enough time to touch on every topic during the webinar. The most commonly asked questions and Dr. Corby-Harris’s answers are copied here for beekeepers to see the researcher’s perspective on a challenging topic!
 
Beekeeper Q&A with Dr. Vanessa Corby-Harris
 
What is the rationale for using pollen supplements / substitutes?
Pollen subs are generally fed to colonies going into winter. There is some debate as to whether this is a good thing or not, and I’m happy to talk about that in more detail. Alison McAfee has a good article about that in ABJ December 2020 and Randy Oliver has some good insight into fall feedings on his website. But our experiment assumed that everyone would be fed (hence the no negative control) because that’s how our cooperator runs his operation.
 
When, how much & how often would you apply [the pollen substitutes]?
Ours was done in the four weeks leading up to cold storage, 1 lb/colony/week. They ate it all. This suggests to me that feeding was overall a good thing and that they needed the diet, since bees prefer to consume natural pollen and will not eat a substitute if enough pollen is coming in.
 
Should beekeepers strive to collect pollen and make their own pollen substitute? What is the best way for me to harvest and save pollen from our hive to feed back to the bees?
Natural pollen is always best for supplemental feeding. Even a very small amount of pollen in a sub can make the difference between healthy bees and unhealthy bees. You can use a pollen trap on a full sized hive during a pollen flow to collect what you need. But don’t leave it engaged for more than a day or so each week and give them breaks where the pollen trap screen is not in place (engaged). In my experience, if you leave the pollen trap for too long, the colony suffers. Also, outside pollen that you did not collect can be questionable and carry disease or pesticides, so you have to be careful.
 
How good is the pollen substitute compared to pollen?
That will depend on the metric you are testing, but generally all pollen supplements perform worse than pollen. But they are not meant to substitute for pollen over the long term, so maybe that’s OK. If the choice is supplement versus feeding nothing, I’d go with the one that helps the hives to survive. But it all depends on your location, the season, your operation, etc.
 
Did you use open powder feeding or internal hive patty feeding?
Internal patty feeding on the top bar of the top box. They ate it all.
 
Are pollen substitutes high in protein bad for my bees?
Not necessarily. Higher protein subs are probably good for when the colony population is expanding, because they need protein to make brood food. But in the late summer and fall, that may not be the case. I have a hunch that the Global 4% did well because, as others have shown, dwindling pollen resources in the fall are correlated with a winter phenotype. There is some good work by Heather Mattila and Gard Otis on that topic.3
 
When should I feed pollen substitutes and how frequently?
We fed 1 lb/hive/week in the fall between mid-August and late September. How much you need to feed will depend on where you live, the time of year, etc.
 
What are the best natural pollen sources?
“Weeds” are generally good.
 
Growing to a sideliner, is pollen substitute worth it / necessary?
I don’t know. It depends on where you live. If you winter your bees outdoors in a warm climate, you might want to wait to feed until later in the fall. If they winter outdoors in a cooler, temperate climate my answer is it depends on whether your bees are rearing brood and whether the foragers are flying at all. Brood rearing requires pollen and flying requires syrup.
                                                        
How did global patties 14% stack up against the rest?
I only tested the Global 4% and Global 75%. The latter was our positive control and was a specially requested recipe. The Global 4% did the best compared to the other diets we tested.
 
What about feeding bees for graphing queens?
I don’t rear queens but I expect that good diet is important because the workers will have to get enough protein to rear the grafted queens.
 
What amounts of proteins and lipids do the various patties have?
I haven’t done that work yet for the Global patties, but here is a table from one of our recent publications.4  We didn’t test the Global Patties here.

What does the future of feed for bees look like?
Well, natural forage is best. But natural is not always available, and that’s where diets come in. I don’t think that diets will ever go away or not be needed. One thing that I think a lot about is the lipid content of diets and the seasonality of nutrient needs. What is good for a spring bee is not good for a fall bee and vice versa. There is still a lot of work to still be done. I hope that we can one day tell beekeepers exactly what to feed at certain times of the year (when it’s needed but not when natural pollen is available) depending on where they live.
 
What are the best substitutes for each season (spring vs. fall, winter?), and each activity (queen production, nuc production, ect).
In this context – fall feeding before cold storage and after honey production – the Global 4% performs the best. But I don’t know that would be the case for other seasons and activities. For example, something that is higher in pollen or protein might be better for the spring/summer. Both seasons are important for making strong hives in the spring, because what happens in the fall affects the size of hives in the spring.
 
Where can I purchase the best products?
These were all from commercial vendors that can be found online.
 
I am interested in the views of pollen substitutes versus Randy Oliver’s recent study/ How do the findings in this (Texas?) study compare with those in Randy Oliver's California study?
We didn’t end up doing the trial in Texas, so that’s an important change to mention. They went to cold storage for the winter instead, which means that the colonies were not rearing much or any brood through the winter. That is different from what would be happening in TX. I agree with everything that Randy said in his series in ABJ (July-December 2021). Our experiments were very similar in terms of when we did the evaluations, how we evaluated, and the drought situation, but with just a few key differences. First, we did not have a negative control (for reasons stated above), only a positive control. We tested Global 4% instead of Global 15% and did not test the Healthy Bees or Bulk Soft products, and our version of the positive control was the Global patty + 75% pollen because Global could make them for us at a larger scale. We also looked at BeePro. Second, the colonies were wintered in cold storage. Third, the hives had a ton of honey on them in the fall, so we did not feed them syrup before they went into cold storage. Fourth, they did not receive any pollen sub or syrup in the late winter/early spring between when they came out of cold storage and when the almonds bloomed. Global product overall worked the best in both studies, even though we used Global 4% and Randy used Global 15%.
 
What are the economics of pollen substitutes?
Since 1) the Global 4% diet seemed to perform slightly better than the other diets by the time we measured them at the end of February and 2) Global 4% is the cheapest commercially available diet, go with the cheaper product.
 
 
References:
 
1)NASS Honey Report released March 18th, 2022.
https://downloads.usda.library.cornell.edu/usda-esmis/files/hd76s004z/7m01cp956/df65wc389/hony0322.pdf
 
2) Bee Health Collective, BeeHealthCollective.org
 
3) Mattila, Heather R., and Gard W. Otis. "Dwindling pollen resources trigger the transition to broodless populations of long‐lived honeybees each autumn." Ecological Entomology 32.5 (2007): 496-505.
https://doi.org/10.1111/j.1365-2311.2007.00904.x
 
4) Corby-Harris, V., Bennett, M.M., Deeter, M.E. et al. Fatty acid homeostasis in honey bees (Apis mellifera) fed commercial diet supplements. Apidologie 52, 1195–1209 (2021). https://doi.org/10.1007/s13592-021-00896-0