Promoting sustainable beekeeping and genetic diversity through drone comb trapping

Final Report for FNC13-904

Project Type: Farmer/Rancher
Funds awarded in 2013: $7,480.39
Projected End Date: 12/31/2015
Region: North Central
State: Indiana
Project Coordinator:
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Project Information

Summary:

Drones: The Forgotten Bees. Exploring the use of drone comb traps to fight varroa mites and improve genetic diversity in open-mated queens.

Honey bee drones (males) are being ignored by bee keepers as they focus on mite control and queen rearing. In this project, drone brood trap frames will be removed from honey production hives as a proven, non-chemical means to control mites during the spring and summer months. Instead of killing the drones like most methods suggest, capped drone frames will be moved into special drone rearing colonies so they can emerge as adults, saturate the local area, and potentially lead to better genetic diversity through open-mated queens.

Introduction:

Varroa destructor mites emerged as a serious problem for beekeepers in the 1980’s.  Now roughly three decades later, they continue to threaten the survival of bee populations (managed and feral) as well as the pollination dependent crops. Mites induce stress for honey bees and are a vector for many diseases attributed to colony losses.  Between 1948 and 2010, the number of producing colonies in the United States declined from 5.9 million bee hives to 2 million (USDA NASS).

Currently, all chemical miticide treatments negatively impact drone production.  Initially the chemical approach was an application of moderately toxic pesticides; Apistan (fluvalinate) and Checkmite (coumaphos). Although very effective, issues surrounding their use compounded; mites developed resistance, chemical traces were found in wax, queen rearing was impacted, drones were not surviving, and those drones that did survive had reduced sperm production.  Naturally occurring Thymol and Menthol also created post-treatment drawbacks with significant reductions in brood.  Mite Away Quick Strips containing formic acid were recently approved and unlike other treatments can be used during honey production.  Formic acid is the same naturally occurring chemical ants emit for defense.  Unfortunately, colonies treated with formic acid remove drone eggs and delay production of new drones.  Thus, although reported as safe, it results in half as many drones and occasionally a reduced worker brood population. 

Drone brood trap frames, on the other hand, are an effective non-chemical mite control method.  Yet again, the drones are also destroyed.  Research into the varroa mite’s reproductive cycle show female mites favor drone brood as a host for their eggs.  While drones are in the capped stage of development, immature mites feed off of the drone pupae’s blood.  Drones are favored because their cells remain capped an average of 2 days longer than a worker, and 6 days longer than queens.  This gives the female mite, who lays singular eggs in 30 hour increments, an opportunity to lay more eggs thus increasing the mite population an average of 1 to 2 more mites per cell.  With a potential of 8000 total cells on one frame of comb, 8000 to 16,000 more mites are possible in a frame of drone brood versus worker brood.  Because of this biological anomaly, beekeepers have turned to natural control efforts that trap mites in drone comb. Such efforts typically involve this comb being frozen, scraped out, or shocked with electricity.  Models supporting this method have predicted that reducing drone brood by 1% would reduce mite populations by as much as 25%. Once more, although very effective, drones are sacrificed.

Some mite control methods have been implemented which do not impact drones;  powered sugar dusting as a means to encourage bees to groom each other, screened bottom boards to keep fallen mites from returning to the colony, and local survivor queens genetically chosen for mite resistance are such examples.  Among these, queen rearing through high-end breeders and local micro-breeders is the best natural, long-term option.  This promotes bees that can deal with mites on their own accord.  There is just one problem; how do we pass on all improved genetics?

Mite resistant, survivor queen programs can be found in each of the Northern States where genetic lines are being developed with  both hygienic (cleaning out worker cells with mite infestations but not drone cells) and grooming behaviors (removing mites from the external surface of the bee).  Oddly, with all this attention to genetics, little effort has been given to drones whose sole task is to pass on genetic material.  This is easily evidenced by the amount of equipment found for sale in beekeeping catalogs for queens versus drones.  Most beekeepers concentrate on keeping hives alive for honey production and perceive drones as resource consumers – they eat, mate, and die. However, efforts to control mites by killing drones or making them infertile goes against the genetic progression being made in mite-resistant bees.  This oversight may very well result in more severe problems.  Unfortunately, solving this problem requires beekeepers to think differently and change some longstanding methods.

Genetic diversity is very important to honey bees.  It helps prevent infections, reduces the chance of non-viable drones being produced, and creates a hive of worker micro-colonies with diverse specialties based on the drone’s genetics.  Yet for this to happen, a queen must be able to mate with drones from different colonies; the number of different drones mated with averages 13; the total sometimes reaching 26.

Drones are created when, under many varying conditions, the queen lays an unfertilized egg in a larger sized cell. Being haploid, they only bring one allele with them from their mother.   If the drone’s mother (the queen) is a respected line, the male needs to be given the opportunity to mature, mate, and share his genetics (which is also the same as the queens) with other colonies as well.  By killing drones or making them infertile, the potential for bees to naturally evolve to adapt to mites is also being lost. 

Project Objectives:
  1. Raise mature adult drones from drone trapping frames in drone rearing colonies;
  2. Compare drone rearing colonies headed by mated queens versus caged, unmated (virgin) queens;
  3. Expand micro-breeder queen operation with open mated queens and drone saturation from drone rearing colonies;
  4. Utilize drone trapping frames to manage mite populations in honey production hives;
  5. Educate beekeepers on the importance and benefits of drones;
  6. Compare 5 different lines of bees to determine the tendency to exhibit grooming behavior (chewing mites); and
  7. Compare overwintering success of the 5 lines of bees and drone rearing colonies.

Research

Materials and methods:

Five lines of bees were selected, purchased, and installed in 20 hives – 4 hives of each line.  Emphasis during the selection was on hygienic behavior, honey production, over-wintering capabilities, and gentle temperament.  The 5 lines chosen were:

  1. Purdue Ankle Biters for queen grafting
  2. New World Carniolan for drone and honey production
  3. Buckfast for drone and honey production
  4. Russian for drone and honey production
  5. Local Survivor stock for drone and honey production

Four mated queens were purchased from each of the drone and honey production lines noted above. An established Purdue Ankle Biter breeder queen was used to produce open mated queens from this line.  These new queens were installed into queenless, 5 frame nucs during the first 2 weeks of May, 2013.  The nucs were created from hives in our apiary and consisted of 2 frames of brood at various stages of development and 2 frames of honey and/or pollen along with the associated bees on the frames.  The fifth frame was drawn out foundation only.  

During queen introduction, 1 Apivar strip per colony was used to ensure mite loads were reduced to a consistent level for the 20 new colonies.  Apivar is a contact miticide and the active ingredient, Amitraz, is distributed throughout the hive by bees contacting the strips and then contacting other bees. 100% of the queens were accepted and started laying eggs within 5 days. 

These colonies were fed 1:1 sugar water until all the foundation was drawn out in 2 ten frame hive bodies.  Additionally, new green plastic drone foundation was placed periodically into the hives so wax comb could be drawn out.

No honey was collected from these hives during the first year.  Where needed, fall feeding consisted of 2:1 sugar water.  Each colony had approximately 60 pounds of stored honey prior to the winter.  Dry sugar and/or winter patties were supplied as a winter emergency food source.

The winter of 2013/2014 was one of the worst on record for bees in Indiana.  It was terrible because not only was it much, much colder than normal but the cold lasted a very long time and later into the year than is typical.  This atypical weather resulted in a large loss of the newly established colonies created for this project.  Therefore, in the spring of 2014, the same queen lines were repurchased and new colonies were created using the methods already mentioned.  Any overwinter losses during the winter of 2014/2015 were made up with queens grafted from existing colonies and open mated in the existing onsite apiary.

During 2014 and 2015, each of these 20 colonies was tested monthly (May – August) to determine the percentage of mites that have been chewed during 24 hour mite drops.  Sticky boards were placed under screened bottom boards for 24 hours.  Each mite on the sticky board was carefully removed with a small paint brush and placed into an alcohol wash in a white dish where they could be easily counted.  They were transferred onto a glass slide upside down and evaluated under a microscope for evidence of bee “grooming” indicated by missing parts – usually chewed off feet.

During the summer of 2014 and 2015, two drone rearing methods were compared: 

1) two colonies were reared by mated queens; and

2) two colonies were reared using virgin caged queens. 

Additionally, during this timeframe, Purdue ankle biter queens were open-mated with drone saturation from these drone rearing colonies.

Getting an accurate ratio of drones to nurse bees can be an area of concern for drone rearing colonies.  A feral colony will typically build 17% drone comb and have a 10% drone population.  Each honey producing hive contained 2 frames of drawn out drone foundation installed initially into the hives at 2 weeks intervals resulting in 10% drone comb after the first 4 weeks.   Each of the 4 drone rearing colonies had 1 drone frame from each line of bees (4 drone frames  = 20% drone comb). 

To maintain the drone rearing colonies, a biweekly schedule was maintained to do the following:

  • Drone brood trap frames (green frames) from honey producing hives were moved to drone rearing colonies. This allowed the drone brood to emerge in the drone rearing colonies. 
  • In the colonies reared by a virgin caged queen, a frame of emerging worker brood was also added for every 2 drone brood trap frames moved into the colony.
  • 1/4 of a pollen patty and sugar water was provided to each of the drone rearing colonies.
  • Powdered sugar dustings were done to help control the varroa mite population in the drone rearing colonies.

Additionally, the virgin caged queen was replaced every other cycle (monthly).

Research results and discussion:

Drone rearing colony results (4 hives):

2013/2014

No drone rearing colonies were established as this time was used to draw out comb on green drone frames.

2014/2015

Hive 1 reared by mated queen failed in early August

Hive 2 reared by mated queen failed in mid August

Hive 3 reared by caged virgin queen failed in the first part of September

Hive 4 reared by caged virgin queen survived until end of September when drone frame exchanges ended

2015/2016

Hive 1 reared by mated queen failed in early August

Hive 2 reared by mated queen failed in late July

Hive 3 reared by caged virgin queen survived until end of September when drone frame exchanges ended

Hive 4 reared by caged virgin queen survived until end of September when drone frame exchanges ended

 

Drone and queen production hive results ( 20 hives):

2013/2014 (As noted above, the first winter was extremely harsh and atypical.)

Line/Type of Bee

% chewed mites

Winter Survivability

Purdue Grooming

Not tested first year

100%

Buckfast

Not tested first year

100%

Local Survivor Stock

Not tested first year

     0%

Russian

Not tested first year

     0%

New World Carniolan

Not tested first year

     0%

2014/2015 (This was also a cold and long winter but not as bad as previous year)

Line/Type of Bee

% chewed mites

Winter Survivability

Purdue Grooming

70%

100%

Buckfast

17%

100%

Local Survivor Stock

5%

   75%

Russian

15%

   75%

New World Carniolan

7%

   50%

2015/2016 (This was a warmer and shorter winter)

Line/Type of Bee

% chewed mites

Winter Survivability

Purdue Grooming

70%

100%

Buckfast

18%

  75%

Local Survivor Stock

17%

 100%

Russian

22%

 100%

New World Carniolan

15%

 100%

Impact of Results/Outcomes

This project raised awareness of the importance of drones in honey bee breeding programs.  Additionally, more hobby beekeepers were introduced to the importance of drones in a colony.

Participation Summary

Educational & Outreach Activities

Participation Summary

Education/outreach description:
  • Article in September 2014 Bee Culture magazine
  • Talks at local bee club meetings about drones
  • Blog about drones
  • YouTube channel set up with videos about drones
  • Organized and started a local bee club which averages 30 people per monthly meeting
  • Attended a local elementary school where I introduced over 650 kids to the importance of bees
  • Provided an observation hive and materials for a local farm to use at their road side stand.
  • Wrote several articles on drones for our local bee club blog.  These were also posted on the club’s facebook page.   Over 1000 hits per month to the website and blog.
  • Organized and hosted a bee event called ‘The Buzz’.  Over 400 people attended to learn about bees.
  • Assisted at the Purdue University Bee Lab Queen Rearing School with over 30 people in attendance.
  • Founding member of the Indiana Queen Breeder’s Association
  • Participant in the Heartland Honey Bee Breeder’s Coop which brought together queen breeders from several states in the Midwest to share the ‘best’ queens and drones.

Project Outcomes

Recommendations:

Potential Contributions

Drone rearing colonies reared by caged virgin queens might be used to keep drones alive and available for mating purposes while minimizing mites in honey production hives via the drone trapping frames.  However, it was a very time consuming process requiring accurate timing.  It might be a technique for larger queen producers to employ but is probably not feasible for hobby beekeepers.  Additionally, the process could lend itself as a means for queen breeders to exchange drones by swapping drone rearing colonies and therefore lead to increased genetic diversity in several apiaries.  Or, as a technique to bring drones from warmer climates into a colder climate prior to the typical drone maturity date – resulting in earlier mated queens in northern climates.

The caged virgin queens lived in banked colonies for an average of 45 days before needing to be replaced.  This is longer than originally anticipated.

The drone rearing colonies reared by caged virgin queens always had more drones during visual inspections.   It is probable these colonies lured drifting drones away from the drone rearing colonies reared by mated queens.

If mite populations could be controlled in the drone rearing colonies reared by mated queens, there is a better chance more beekeepers might employ this process.  Concerns, however, that miticide treatments needed to accomplish this might impact the viability of drone sperm.   Attempted to test the viability of drone sperm with and without an apivar miticide treatment using the molecular testing clinic available at North Carolina State University.  The initial process was to mark emerging drones, wait for them to mature, collect enough of the marked mature drones to mail to the clinic for testing.   Not enough marked mature drones were available for collection – it was late in the season and drones were already being ejected from the hives.   A new problem was presented though – sending drones through the mail.  Very little information is available related to caging drones and sending them through the mail.  Since drones typically do not feed themselves, this could be a problem.  During this project,  several techniques were practiced and finally an acceptable configuration was developed to cage drones so that they could be mailed.   

On a related note, different types of stains to test drone sperm viability were researched.  Something that would allow a beekeeper to do this testing in an apiary much like a farmer checks a bull’s semen on the farm would be helpful.  Further research is needed in this area.

Attended a  cryopreservation seminar.  A more viable technique for preserving drone semen has recently been developed.  This could lead to a germplasm repository for beekeepers.

 

Future Recommendations

In this project, drone rearing colonies were all located within 5 to 10 feet of each other.  Drones are known to drift from colony to colony and apparently prefer colonies with virgin queens to those with mated queens.  High drifting rates occurred.   Recommend trying this process again and moving the drone rearing colony types further away from each other to minimize drifting.

Test drone sperm viability and impacts of mite treatments.  Recommend testing apivar and recently EPA approved oxalic acid mite treatments to see if it impacts the viability of drone sperm.  If no issues, this project could be tried again using mite treatments to keep the mite populations low in the drone rearing colonies.

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.