Mite-biting behavior in feral swarms: The Pennsylvania Queen Improvement Project

Final report for FNE17-863

Project Type: Farmer
Funds awarded in 2017: $15,000.00
Projected End Date: 12/31/2018
Grant Recipient: Always Summer Herbs, LLC
Region: Northeast
State: Pennsylvania
Project Leader:
Jeffrey Berta
Always Summer Herbs
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Project Information


Our objective was to measure the total mite count, Mite-biting Behavior (MBB), and Winter Survivorship in captured feral honeybee colonies, and compare to the current line of MBB-selected stock, versus a control group.  We want to understand if and why feral colonies are more winter hardy than our currently available bees, and if MBB plays a role in that hardiness, or perhaps some other trait. We successfully captured 54 swarms, and measured all data during the summer 2017, and then evaluated winter survival in the spring of 2018.

The results showed that Group 1-MBB colonies, bees that chew mites, were significantly heavier than the Group-3-control group. Also,  Group 2-feral bees, were similar to the control group. Statistics proved a positive correlation  between MBB and hive weight; the more chewed mites, the higher the weight. The average weights were: Group 1 - 132 pounds, Group 2 - 85 pounds, and Group 3 - 97 pounds.

Winter survival was measured in March of 2018, by number of colonies.  The results are: MBB had 21 out of 30 survive (70%), feral colonies had 10 out of 16 survive (62.5%), and the control had 6 out of 18 survive (33.3% ).

Project Objectives:

Our objective was to trap feral honeybee swarms, measure mite counts, biting-behavior, and survivorship, and then compare them to current line of MBB stock and a control group. Feral colonies have survived winter for years without human intervention and mite treatment; these could be genetic treasure for the future of breeding mite resistant bees.


Varroa mites are the single greatest threat to sustainable beekeeping in the Northeastern US and across the world. Varroa mite counts are a documented link to decreased colony weight, strength, health, and are the top factor associated with Winter mortality. Varroa transmits viruses and immunosuppresses bees such that virus titers can rise greatly, and weakened colonies are susceptible to secondary, opportunistic diseases such as foulbrood and Nosema. Currently, the majority of commercial beekeeper use treatments of insecticide/miticides for Varroa parasites. These treatment methods have come under scrutiny as to their long-term efficacy because of mites developing resistance, and the side effects on bees, including their ability to rear brood. This project assayed feral swarm colonies for a recently identified novel grooming behavior MBB, and characterized its relationship to overall mite counts, colony weight and ultimately Winter survival. We proved that MBB in positively correlated to higher hive weights and better winter survival. Therefore, selecting for this trait in honey bee populations will increase the sustainability of beekeeping by reducing pesticide/labor inputs, and the cost of replacing dead colonies, and increasing bee health, honey production and profitability.


Click linked name(s) to expand/collapse or show everyone's info
  • Dr. Margarita Lopez-Uribe - Technical Advisor
  • Mark Gingrich
  • Bernie Svidergol
  • Dwight Wells
  • Hon. Dan O'Hanlon
  • Daryl Martin
  • Tom Gaul


Materials and methods:

We set out swarm traps following Dr. Seeley’s designs in remote areas that are favorable for bees, and far from modern beekeepers, and commercial bees.  For isolation, we have conferred with the Pennsylvania Apiary Department to select locations far from registered managed hives.  Swarm boxes were baited and installed on trees, and checked regularly, and when a feral swarm moved in, we will removed the trap and replaced it with a new one.  The swarm trap, which is a standard 8/10 frame deep, is moved to a isolated project beeyard.  The captured bees are managed in similar equipment as the other test groups. We started in late March and removed the traps in September.  We anticipated that each participant can capture at least 4 swarms, which was not the case.  We set out over 28 swarm traps, and visited them 516 times, and collected 56 swarms, of which 17 were established in colonies for the study.  Note: Most locations captured between 0 and 4, Ohio skews the numbers by reporting 42.  Many swarms were destroyed by bears while still in the trap before they could be transferred, and many small ones failed to establish.  We had 16 feral bee colonies going  into winter which comprise Group 1.


From a past grant (FNE16-836) we had valuable genetic stock lines that have overwintered, and have been measured in for the same parameters that we used for this 2017 project. This project progressively builds on, and furthers past findings and recommendations guided by our adviser.  We had 30 colonies of MBB genetics for Group 2. 

The control group were Italian bees from Jackie Park-Burris. After some time several queens failed, or crashed from excessive mites loads. We had 18 colonies for Group 3.

MBB is defined by a honeybee biting one or more legs off of a Varroa mite, and an assay has been developed by Dr. Greg Hunt at Purdue University (Hunt & Andino ABJ 2011) for accurately measuring the proportion of chewed mites in a colony. This will yield measurable results, and a potential tool for breeding selections. The method has two major components, collection of mites, and evaluation of chewed legs. The collection of mites in the field by beekeepers is simple: (1) an oiled board is inserted over the bottom board (floor) of the colony, (2) the board is allowed to remain for 24-48 hours, (3) the mite boards are removed from the colonies, and brought to safe processing area/lab.  And then the second component is evaluation: (4) sift through the contents and pluck out the dark mature mites, (5) glue/set the mites "legs up" on a glass microscope slide/petri dish, and count the total number, (6) view each mite on the slide under a low power microscope/15X-handlense and count how many mites have chewed/missing legs, (7) calculate the MBB, as a percentage, example: 12 chewed mites/ 36 total = 33% . The collection portion is simple for beekeepers to collect in field with minimal training and tools. The evaluation component, steps 4-7, is more skilled, labor intensive and time consuming. Fortunately it can be done later as time allows by the beekeeper, or outsourced to a technician.


There are three groups that were compared: (1) Feral swarms that were captured during 2017 (2) HHBBC-overwintered best MBB queens generated from our 2016 SARE grant, and 2017 AI queens generated at Purdue, and (3) Control Group-queens obtained from commercial queen producers, which have not been selected for any traits.  This study  allowed us to determine if the MBB traits in feral bees is associated with reduced mite loads, increased colony weight, and increased overwintering success, and if breeding for the MBB trait is warranted and feasible.  The beeyards locations planned to be in the HHBBC members respective states: Jeff Berta W-PA, Tom Gaul W-PA, D Martin C-PA, Bernie Svidergol C-PA, Mark Gingrich E-PA, Dwight Wells W-OH, and Dan O’Hanlon-WV. Each yard started with about 4 colonies from each group.  Practically, all colonies were measured at least 3 times.

Research results and discussion:

We have collected the field data for the Summer 2017 and Spring 2018, we have attached 2 spreadsheets, the first with the raw data, the second is sorted into groups and has the alive/dead results from Spring 2018.  Dr. Margarita Lopez-Uribe Penn State University provides figures showing winter mortality Figure 1 and 2; Group 1 had the the best winter survival of 70%, group 2  62.5%, and the Group 3 control was 33.3%.

Note: There may be some minor variations in the statistics vs the tabular data, this because September data was selected so there would not be a pseudo replication of data in the stat programs.

Margarita-Fig1 Margarita-Fig2-survived-winter

Dr. Brock Harpur Purdue University provides a figure for the relationship of biting vs hive weight;  statistically proving the more chewing behavior the more hive weight.


Spreadsheets field data

SARE-Mite-Data-composite-2017-analysis-SORT SARE-Mite-Data-2017-SORTED-BY-GROUP-Sheet-1

Research conclusions:

Mite-biting behavior is a valuable trait to to continue to select for sustainable beekeeping because of increased hive weight, the more honey the more money! Also, better winter survival means less money spent to replace 'dead-out' colonies in the spring.  Both of these factors will help keep beekeepers in business.

The feral colonies show promise, they chew mites, and have better than average winter survival, and are locally adapted. Research suggests that they are more immune to viruses as well. More work is justified studying feral bees and scientifically including them in our breeding efforts moving forward.

Participation Summary
7 Farmers participating in research

Education & Outreach Activities and Participation Summary

372 Consultations
5 On-farm demonstrations
5 Workshop field days
4 Other educational activities: Dr. Harpur is taking the lead by starting and article on this on the Purdue University Extension page, which will also be linked to the Penn State Extension too. The info summary and report link will be listed on the HHBBC facebook page before March of 2019.

Also, a table at the Pennsylvania State Beekeepers Association was set up with a video slide show, we met with people who have participated at the field days and were interested in acquiring MBB stock. About 50 people.

Participation Summary:

322 Farmers participated
1 Number of agricultural educator or service providers reached through education and outreach activities
Education/outreach description:

Our outreach was primarily by field days were we distributed MBB/Leg-chewer genetics. We gave the participants either queens, virgin queens, cells, or grafted larvae as part of the programmed event.  Along with education on how to introduce and produce queens, and testing for for Varroa mites, and chewing.  The following events took place:

Charlie Vorisek NW PA Beekeepers, Linesville PA-82 beekeepers

Mark Gingrich York county Beekeepers, Bethlehem PA-70 beekeepers

Steve Repasky Burgh Bees, Sewickley PA-90 beekeepers

Bernie Svidergol 2Cs and a B Beekeepers-10 beekeepers

Dwight Wells NWC OH Beekeepres-70 beekeepers

Pennsylvania State Beekeepers Assoc in Nov, we had a table set up with our results and ongoing PA Queen Improvement Project. About 50 people 

For total of 322 participants at field days, plus likely about 50.  Total impact about 372 people.


Learning Outcomes

322 Farmers reported changes in knowledge, attitudes, skills and/or awareness as a result of their participation
Key areas in which farmers reported changes in knowledge, attitude, skills and/or awareness:

Since beekeepers have become frustrated by their bees dying overwinter, and more recently even before Christmas, they are eager to find a way to decrease this.  We have found that the primary reason for Colony mortality is high infestations of Varroa mites. Thus, we taught the participants how to measure the Varroa percentages, what those percentages mean, and different management options, including MBB/Leg-chewer genetics.  Ultimately, the big message is that genetically resistant stock is a pillar of IPM. People were excited that there are more options to keep their colonies alive, rather than using harsh chemical treatments and have let us know that they plan to adopt at least one of these practices.

Project Outcomes

42 Farmers changed or adopted a practice
1 Grant applied for that built upon this project
1 Grant received that built upon this project
$15,000.00 Dollar amount of grant received that built upon this project
110 New working collaborations
Project outcomes:

Received another 2018 Northeast SARE grant, FNE18-886 PA Queen Project and the HHBBC Field Test Mite-Biting Behavior using Backyard Scientists for $15,000.

We had chewed mites on glass slides under a low power microscope, so people could see what varroa mites look like.  Along with explaining how to perform mite counts using: bottom board, powdered sugar or alcohol wash methods. Many excited beekeepers said things that were very positive, such as "I never knew what mites looked like until I came here", and "I did not know I was supposed to be looking for mites, and that is what killed my bees", and " I hate those creepy little mites, I glad those bee are chewing them up into little pieces!"

We have returning field 'alumni' participants who have had our Leg-chewer bees from the the last 3 years.  A few quotes from them "I have not really had to treat since using the ankle biter bees, or if I have, only a few times", and "My winter losses are a lot less now than they have been", and "They can be a little more excitable, but make more honey, but just so long as they are even meaner to the those "*#%" mites, I'm OK with them being a little feistier".  Besides the 7 beekeepers involved in this study, about 35 'alumni' participants are adopting the measurement practices and moving towards MBB genetics as an IPM tool.

Personally, after being the project manager on many USDA SARE grants since 2011, I am starting to see real improvement in our Pennsylvania colonies with both honey production and winter survival.  The Pennsylvania Queen Improvement Project has gained traction, about 5 clubs plan on doing a field day every year weather we have funding or not. It warms my heart to see such a grass roots beekeeper support, and joy; and most of all happy, hardy honeybees!

Assessment of Project Approach and Areas of Further Study:

The study did get a good sampling of feral bees to look at and evaluate, so we successfully performed our experiment.  Many of the swarms were really awful bees, mean, aggressive, disease ridden, non-productive; but, a few were exceptional bees and show promise.  We know that we have any real 'winners' from our feral swarms that we captured, and continued maintain and monitor them.  

Moving forward, I feel we should continue to capture swarms and evaluate them.  However, they should be kept separate and isolated from other bees so to keep them pure.  Also, this will prevent the mites from transferring between colonies, which can kill promising hives.  We had to treat for mites in several locations to keep our bees alive, because the mite percentages exceeded critical levels.  The transferring/migration of mites between the commercial bees, or poor quality swarms could be the cause for this occurring.  Hence the the bees should be kept apart for mite migration reasons, but that would make the geographic variations so great it would be difficult to perform any meaningful statistics on the data. 

Based on this grant we obtained another USDA SARE grant for backyard scientists. They are helping us with the stock evaluation, and we are helping them change their behavior, so they will use IPM methods of varroa control, instead of wishful thinking. Another grant is planned with Purdue and Penn State for 2020 which will follow on with more extension and stock improvement. These USDA SARE are invaluable tools to help try our new ideas, and get better bees in the hands of our local beekeepers.

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.