Research Project No. 3 — Mite-Tolerant Drone Colony Breeding

The institute is hosting a potential study on rearing mite-tolerant drone colonies. Funding requests are currently under review.

Title: Varroa destructor–Tolerant Honey Bee Drone Breeding Project

Project Leader: Dr. Scott A. J. Johnson, Director, Low Technology Institute
Project Partners: University of Wisconsin Extension–Milwaukee and local beekeepers
Anticipated Dates of Project: Funding requested for April–December 2018; project will continue in future season under separate funding.

Abstract

Honeybees in Wisconsin and globally face the same issues: varroa mites, diseases, viruses, fluctuating agricultural resources, and pesticides. Together these problems contribute to what is known as colony collapse disorder. Varroa mites, however, are the leading cause of colony mortality as they destroy the brood (reducing a colony’s reproductive success) and transmit viruses (causing early winter colony collapse) (Rosenkranz et al. 2009). Currently, beekeepers must treat their hives with mild to fairly toxic miticides, severely modify the brood pattern, or both in order to keep varroa levels low. These are only short-term solutions, however. Most beekeepers agree that the long-term solution is to breed mite-tolerant bees. Just like with any attributes we want in our domestic animals, we must select for the trait by only breeding those that have those genes. For beekeepers focused on honey production or pollination, however, culling a majority of their hives every year is not an acceptable rate of loss. This project, therefore, proposes to keep hives specifically for developing mite-tolerant bees. As these bees will not pay for themselves with honey production, pollination service fees, or the sale of daughter colonies, they need external funding for start-up costs.

Project Description

Breeding mite-tolerant honeybees requires us to put our finger on the scale of genetic selection. Most efforts attempt to create queens with desired genetics, however, queens mate with multiple drones from neighboring hives, thus diluting her “good” genes. By developing a method to cull drones with poor genes, we will be working towards a mite-tolerant stain of bees accessible to regular beekeepers.

The heart of this method is strong selection for mite-tolerant, drone-heavy colonies. Mite loads build up from the spring through the fall in temperate-zone colonies. Parasitic mites weaken larvae and transmit diseases, thus hives that cannot tolerate Varroa will die in early winter. Colonies that develop “hygenic” behavior (discarding or isolated infested brood) or other mechanisms to live with mites are more likely to survive the winter. These colonies will be heavily split each spring to repopulate the dead-out colonies. This culling method has been used successfully on the island of Gotland to breed mite-tolerant bees (Weller 2008). The idea of selecting drone hives is also being carried out in Germany (Büchler et al. 2008; Kraus et al. 2007).

The management strategy for these hives will differ from that of beekeepers interested in honey production and pollination services. We will encourage drone brood cells, which increases the selection pressure, as mites prefer drone brood. We will not treat hives with miticides, as this would allow poor genetics to survive. We will test mite levels in each hive monthly and identify patterns that indicate successful mite-tolerance. Judging from other tolerance-breeding programs, we anticipate that in three to five years marked improvement will be seen. The largest risks of this method are a locally high mite rate in neighboring colonies (but our location is isolated by distance) and high colony losses (which we will combat by aggressive splitting).

Timeline

February: Recruit hosts, further refine specifics of management strategy with partners.
March: Set up hive areas.
April: Gather materials; install nucleus colonies; count mites.
May–July: Monitor hives; split and install into new hives; count mites.
August–September: Prepare for winter; combine weak colonies if necessary; count mites.

Benefits to the Environment, Economy, and/or Social Sustainability of Agriculture in Wisconsin

This project will benefit Wisconsin agriculture by working towards more stable pollinator populations using organic, chemical-free methods and reducing beekeepers and farmers expenses and labor. Bees—Wisconsin’s state insect—are responsible for pollinating many crops in the state, including alfalfa (and other fodder), apples, strawberries, cranberries, beans, and nursery plants. Some farmers depend on local, permanent bee populations, while others pay to bring in migratory colonies. Approximately 75 percent of Wisconsin’s agriculture depends on bees, but 40–50 percent of colonies die every winter, many due to mite infestation, which reduces the number of pollinators available in the next year; replacement colonies are usually purchased from outside Wisconsin. Beekeepers depend on fees from pollination services and the sale of honey and young colonies. By reducing beekeepers’ need to treat for mites, it would decrease the expense and labor of keeping bees and increase the strength and number of colonies.

Contributions to Development of Agricultural Educators

Agricultural educators from the UWEX Milwaukee extension service, instructors and researchers at local area colleges, and others offering beekeeping classes will be invited to learn about this project. Although beekeepers involved with commercial beekeeping may not be interested in replicating this project on their own, it will generate discussions, questions, critiques, and suggestions within the community, and may impact their management in the future. Many beekeepers apply mite treatment without understanding that this retards the development of mite-tolerant bees, even though everyone agrees that this is the long-term solution. Instructors can use the breeding focus of this project as an example to teach new beekeepers about selecting beneficial traits in their colonies. This project could provide a new weapon in the arsenal against colony collapse disorder, it will broaden the discussion about mite treatment and life cycle, and its outcome will certainly provide a useful case study.

Dissemination of Results

The results of this project will be available in person and on-line. In the late summer or early fall of the funding period, we will hold a field day, inviting any extension, college and university, and private beekeeping educators to attend. The breeding hives will be inspected and the overall project goals, methods, and data will be presented. Attendees will be sought through email lists, social media posts, and other advertising channels available to UWEX Milwaukee and the Low Technology Institute. In addition, Johnson will be available for visitors at other times, as he lives on site. A demonstration hive may also be placed at the UWEX’s Kohl Farm apiary. Detailed information about the project will be available on the UWEX Milwaukee County Facebook group (200+ certified beekeepers,) as well as the institute’s website including full data tables, descriptions, and other information useful to educators in Wisconsin and beyond.

Measurable Impacts on Educators, Farmers, and Others

First-year results will be measured by the number of field-day attendees and others taking part in on-line discussions. Mite-tolerant colonies are our ultimate goal, but this may take years of selective breeding. The funding requested here will provide enough resources to get the project going, and future years will only require a fraction of the cost to continue. Long-term success would be sustained greater winter survival rates, lower mite loads throughout the year, and mite-reducing behavior in the colonies when compared to national average data (and tested for statistical significance). If any of this can be achieved, the method can be reproduced in other locations in hopes of similar results. Daughter colonies can be donated to start new breeding programs, and farmers, beekeepers, and many others would benefit. Throughout the run of this project, data, observations, and other information can be used by educators as a case study.

Budget

Supplies – $1056.00
Two nucleus colonies from local breeder × $200 each
These local bees have already overwintered in Wisconsin (unlike other bees, which typically come from the southeast US). This is more likely to start our gene pool with cold-adapted bees. Additional (free) colonies will be sought from local swarms.

Six hives, consisting of two deep boxes with ten frames each × $100 each
These are the standard hive types used in the US and allow for easier swapping between colonies. The project leader has been building hives from scratch for years, and $100 is the most economical market value cost for materials for a two-deep, 10-frame Langstroth hive with bottom and top. Additional funds will be sought this year and the next for four additional hives.

Cinder blocks × $3 each
Two for each colony to keep hives off the ground.

Refreshments for field day × $20

Travel – $196.20
60 miles for project leader to purchase supplies and nucleus colonies × $0.545/mile
No mileage is needed for setup, monitoring, or the field day as this all happens within a mile of the institute’s location.

300 miles for Johnson to travel to and from Milwaukee, twice × $0.545/mile
As part of the collaboration with UWEX, Johnson will travel to Milwaukee to talk with beekeepers and provide the UWEX apiaries with colony splits.

Printing/Publicity – $100
Creating and printing pamphlet describing project for field day and other visitors × $50
A short two- or three-page pamphlet will be produced outlining the goals and method of this project. It will be distributed on the field day and to any interested visitors.

Creating, maintaining, and advertising an on-line page with description and data × $50
The Low Technology Institute’s page (lowtechinstitute.org) will host a dedicated page for this project. It will have complete descriptions of goals and methods as well as data and video updates. The institute’s social media channels will also be used to raise awareness among beekeepers and educators through membership in a variety of on-line groups. UWEX’s Facebook profile and other locations will also be used to provide information about this project.

Other: Labor – $700
70 hours of labor setting up, managing hives, collecting data, etc. × $10/hour
This discounted labor rate is for a part of the hours likely to be required in the first year. If additional funds are secured, they will make up the difference. Approximately twenty of these hours are expected to be used in direct contact with educators.

References

Büchler, R., Garrido, C., Bienefeld, K., Erhardt, K., 2008. “Selection for Varroa tolerance: concept and results of a long-term selection project.” Apidologie 39: 598.

Kraus, F.B., Büchler, R., Siede, R., Berg, S., Moritz, R.F.A., 2007. “Trade-off between survival and male reproduction in Varroa destructor infested honeybee colonies (Apis mellifera).” Ethology, Ecology & Evolution 19 (4): 263–73.

Rosenkranz, Peter, Pia Aumeier, and Bettina Ziegelmann. 2009. “Biology and control of Varroa destructor.” Journal of Invertebrate Pathology 103: S96–S119.

Weller, S. 2008. “Populationsdynamik der parasitischen Bienenmilbe Varroa destructor in vorselektierten Bienenvölkern (A. mellifera L.) unter besonderer Berücksichtigung der Reproduktion.” MA thesis at the Faculty of Biology atthe University of Hohenheim, 97 pp.