Dennis vanEngelsdorp Honey Bee Epidemiology Lab
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Sentinel Apiary Pollen Diversity

5/16/2016

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By: Haley Gamertsfelder  And Meg Wickless


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In the Spring semester of 2016, two University of Maryland undergraduates, Meg Wickless and Haley Gamertsfelder, continued work on the Sentinel Apiary Project’s pollen analysis. In 2015, participating beekeepers sent in biweekly samples of pollen collected with a pollen trap throughout the months of May, June, July, August, September, and October. Once these samples reached the lab, they were stored to be sorted, which is where we, the undergrads, come in.

Combined, the two of us spent about 120 hours in the lab working on this project.

Our job was primarily to sort the pollen samples out by color.  After weighing out 3 grams from the beekeeper’s sample, piles were made of every color we could identify.  Each pile of different colors were weighed and, again, stored in small tubes. When we weighed and stored each color, we coded each color to its correct mass by an assigned number.  We learned the hard way that this was not the most efficient course of action.  When it was time to analyze the data, we had to dig through all our sorted samples (well over 100 little plastic baggies in one huge freezer drawer) and assign a color in place of the number to every tube in every sample.  So, a note to future students working on the project: assign colors immediately!  When data was analyzed, recorded, and put into pie-chart form, we were able to see the nutritional diversity of multiple colonies and how each colony’s diversity changed over time. Because the only data we were working with was pollen color and mass, we had to assume that a diversity of pollen colors was equal to a diversity in the bees’ diet and which/how many amino acids they were consuming.  We felt that we could assume this because different species’ of plants vary greatly in terms of what’s in their pollen.  Protein content alone can vary from 2.5% to 61% between different plant species, and on top of that, different species contain different amino acids.
 

Bees need a healthy amount of protein, and enough of all the amino acids they need to survive, which is exactly why the information we obtained could be useful.  If bees aren’t getting everything they need, nutritionally, beekeepers often supplement their colonies. From what we’ve determined, we can tell with some degree of confidence whether or not a colony needs a supplement, but we can’t tell what a beekeeper should supplement with.  In order to know that, we would need to trace each color of pollen back to a specific plant, so we could know how many of each amino acid a colony is getting.  That is most likely the next step in this research - tracking down which pellet of pollen came from which species of plant.
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In our end-of-semester wrap up, we chose to highlight 3 particular apiaries as a representation of our project in whole. The samples we were provided had a designation indicating the apiary or bee keeper they came from. The three whose results we are going to share were from SAAK in Allegany County Maryland, SAAJ in Blount County Alabama, and SAAF, in Montgomery County, Maryland. We chose these particular samples out of many others due to their abundance of samples.
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Apiary SAAJ saw the highest nutritional diversity in the month of July, and the lowest in the month of October.  From this, we might assume that many favorable flowers were blooming in July, but perhaps only one favorable flower was still blooming come October.  Colors of pollen were compared as accurately as possible between these 4 months, and each color of pollen was assigned a specific color on the pie chart, which remains consistent for all 4 charts.  One interesting observation that can be made with this in mind is that the pollen represented by the color orange, we can refer to it as Pollen O, on the chart is one of a few dominant sources in July. However, when the other July sources mostly go away in September and October, the presence of Pollen O increases until it is almost 70% of the colony’s diet.
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​Apiary SAAK saw the highest nutritional diversity in the month of August, and the lowest in the month of June.  This was puzzling since June is the end of spring/beginning of summer, we generally assume many plants are in bloom. Whether these results are because a bees preferred foraging sources were in bloom, so they relied heavily on those, or the reason being this area actually experiences low biodiversity in June, we can only guess. With this data the beekeepers over in Allegany County may choose to give their bees a dietary supplement in the month of June if this pattern persists.
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Apiary SAAF saw the most nutritional “evenness” in August, with high diversity in October. The bees in June relied almost solely on 2 foraging sources. Which as with Apiary SAAK seems to go against the laws of biodiversity. The colors on the pie charts indicate a different pollen color (while not matching the pollens color, as we had no bright blue pollen.) We assigned these colors to be able to watch the preference changes of the bees. As we can see with SAAF, the “green” pollen which seems preferred in August, becomes a minor source come September and October. This could be because other preferable sources became available or perhaps the plants producing “green” pollen stopped blooming.

While we were able to compile results to have a sneak peak into the foraging preferences of honey bees, more can be done. After we did our research we saved the sorted pollen in a freezer. Eventually this pollen can be viewed under microscope to determine exactly which species it came from. From this we can learn which amino acids or proteins are derived from the source, and what the bees are intaking.
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Now that the semester is drawing to a close, we’d like to thank University of Maryland’s Bee Informed Partnership lab for giving us the opportunity to work on this exciting project!
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The National Honey Bee Disease Survey: Varroa & Nosema in the US

5/5/2016

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By: Kirsten Shoshanna Traynor​


​The National Honey Bee Disease Survey investigates honey bee apiaries throughout the US to see if three exotic honey bee pests are still absent from our shores. Samples collected from 41 states and two territories reveal that we are still free of the Tropilaelapse mite, Slow bee paralysis virus, and the Asian honey bee Apis cerana.  If you think varroa is tough to manage, its diminutive cousin Tropilaelapse can reproduce much faster, resulting in many more mites feeding on developing honey bee larvae.  We don’t want any of these three exotics as they would add additional stress and pressure to honey bee health.
 
While sampling for these exotics, we used the opportunity to collect additional data on the health of honey bees nationwide. We sampled for varroa, nosema and a suite of honey bee viruses. Here we report on the varroa and nosema results.
 
Varroa
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Varroa levels typically peak in late summer and early fall, when the average infestation rate nationwide rises above the treatment threshold. This means too many colonies are entering the winter with a high parasite load, making it more difficult for them to survive the winter. 
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​Migratory beekeepers receive a lot of flak for the poor health of their colonies. But the data tells a more complex story. Migratory beekeepers are much more successful than stationary beekeepers at managing their varroa populations. Throughout the survey, migratory beekeepers have significantly fewer varroa mites. They’re either doing a better job of treating for varroa, or the physical movement of their colonies may be reducing the mite’s ability to reproduce. 
 
(In the figure, each dot represents the varroa load of a sampled apiary. Migratory beekeepers are in red, while stationary beekeepers are in blue. The solid line depicts the average trend for each type of operation. Every year, the varroa levels rise in the late summer and early fall, but they rise more steeply for stationary beekeepers.) 
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​Nosema
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In all samples, nosema—a gut parasite that can give bees dysentery—peaks in late winter and early spring, when colonies often start intensive brood rearing. While migratory beekeepers are better at maintaining their varroa, their colonies typically have higher levels of nosema than stationary beekeepers. But despite elevated levels, the average almost never exceeds the recommended treatment threshold of 1 million spores per bee. 
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Viruses
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We sampled for a suite of honey bee viruses to track how they change over time. The results suggest an escalation in prevalence of several viruses over the last 5 years. Black queen cell virus, Chronic bee paralysis virus (CPBV), Kashmir bee virus (KBV), and Lake Sinai virus-II (LSV-2) were found in increasingly more samples in later years. Undetected in 2009, the prevalence of CBPV has doubled annually, a worrisome trend in light of all the other stressors impacting honey bee health. 
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Varroa & Viruses
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Varroa acts like a dirty hypodermic needle and helps to transmit viruses. The more mites in a colony, the more infected the bees tend to be. Viruses just want to reproduce. They infect a host and then start reproducing using the host’s genetic machinery. So to determine which bees were most infected, we looked at how many copies of the virus the bees carried. The number of viral copies of Deformed wing virus (DWV) and Acute bee paralysis virus (ABPV) were closely linked to the mite infestation level. The more varroa, the more viral copies we found. Only LSV-2 showed the opposite relationship, decreasing as varroa levels increased. 
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Nosema & Viruses
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While LSV-2 levels had a negative relationship with varroa mite infestation, this virus closely tracked rates of nosema infection. The more nosema spores in a colony sample, the more viral copies we founds of LSV-2.
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A Baseline for the Future
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It’s hard to know if colony health is improving or worsening, if we don’t have a starting point with which we can compare future samples. The five year survey confirmed the absence of three exotic pests and established a baseline of disease. Such longitudinal surveys offer a rare look at seasonal and yearly patterns of parasites and viruses that threaten honey bee health. Results from such surveys can help identify the causes of poor honey bee health and provide warning signs of emergent threats. An increasing trend in multiple viruses and parasites may suggest a compromised honey bee immune system, unable to protect itself well against a wide multitude of stressors such as a fragmented agricultural landscape, increased pressure from pesticides, and poor nutrition, leading to increased colony mortality.
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