This is the second of two posts about the VSBA 2015 Fall Meeting. See the intro post for a short summary of the meeting, and the prior post for a discussion of Dr. David Tarpy’s talks. This second post is about the sessions given by Dr. Ernesto Guzman on selective breeding and the use of natural oils and nutraceuticals in a hive.
Dr. Guzman is Professor and Head of the Honey Bee Research Centre at the University of Guelph in Guelph, Ontario, Canada. His lab is focused on three areas: genetics, behaviour and parasitic mites of honey bees. Like Dr. Tarpy, Dr. Guzman received his Ph.D. from the University of California at Davis. He is author and co-author of more than 250 publications including journal articles, books, book chapters and summaries in conference proceedings.
Basis of Selective Breeding for the Honey Bee
His first talk was about selective breeding, which he defines as the systematic mating of selected individuals (queens and drones) to produce more desirable progeny (workers). This should be based on a defined objective to achieve a set of desirable traits. Sample traits might include honey production, gentleness, hygienic behavior, varroa resistance, race or color. It is generally hard to focus on more than two or three traits as part of a single program.
Once the objective is defined, the first step is to define a selection process based on the desired traits to identify the most promising colonies. The second step is to perform mating control with the selected colonies.
It should be noted that each trait has an environmental factor and a genetic factor. Honey production, for example, is mostly due to the environment: what kind of forage is available, the weather patterns, and other aspects. Only about 20% of honey production is based on genetics. Hygienic behavior, on the other hand, is over 60% genetic. It is easier to select for a trait that is mostly genetic rather than one that is more environmental, and impact of the selection and mating will be seen more quickly for more genetic traits as well.
For each trait selected, a measurement of the trait is defined in order to rank available colonies. Some examples include:
- Honey Production could be based on the number of supers harvested, the number of frames harvested, or the increase in weight of the hive. Dr. Guzman prefers the number of frames approach.
- Aggression could be measured by the number of stings on a leather patch in 20 seconds, or a manual rating of aggression during a simulated inspection. For a manual rating, is important that the same person rates each hive.
- Hygienic Behavior might use nitrogen freezing of a frame, or cutting a square out of wax frame and freezing it before replacing it. The measurement is then how much of the frozen comb is cleaned out by the bees in 24 hours. Dr. Guzman mentioned here that pin-pricking an area of brood is another method, but this proves to be ineffective as most bees sense the fluids from the dead drones and clean it out rather quickly.
- Varroa Control might record the amount of mite drop on a sticky board or the mite count from an alcohol wash. There is an environmental factor here, based on exposure to other hives and initial number of mites, so the measure could look at the net increase or decrease in mites over a given period.
Guzman also recommends ranking the traits, to avoiding testing every hive for every trait. That way you can evaluate and select hives using the first trait, and then evaluate the next trait only in hives selected based on the first criteria. He gave an example of this which I’ll discuss in a moment.
Mating control is difficult, with three main methods: geographic isolation, instrumental insemination, and drone flooding. For geographic isolation, an island, desert, or large remote area is required. His lab maintains a strain of the Buckfast Bee developed by Brother Adam. Each year they transport selected colonies to the isolated Thorah Island in Ontario to mate the hives and maintain the line.
Guzman mentioned that effective instrumental insemination is not easy. Even if you manage to master the required instruments and techniques, getting the sperm to successfully enter the spermatheca is quite difficult. As a result, inseminated queens often have a lower sperm count than naturally mated queens, reducing their overall quality.
The most common mating approach is drone flooding, which if done properly can achieve up to 90% mating control. This entails having drone production colonies to create a large number of desired drones, thus increasing the chances that your queens will mate with the selected drones. I know that our local breeder Chris Hewitt uses this method by generating frames of drone brood from desired stock and placing them around his apiaries to help ensure they mate with his virgin queens.
For an example of this breeding approach, Dr. Guzman was asked by beekeepers in Mexico to develop bees with improved honey yields and reduced defensive behavior. They evaluated honey yields based on frame production for thousands of colonies to select the 20% with the best above-average yields, and then conducted mock inspections for each of these to pick the top breeders for the next generation.
Honey production was evaluated by looking at the yield in each hive as a percentage increase over the average yield for the entire apiary. This removed some of the environmental basis of honey production since this approach normalized the measurement across different apiaries with varying average yields.
For the defensive behavior, the protocol called for two puffs of smoke and pulling two combs from the hive. The inspector would then rate the hive on its overall aggressiveness.
At the end of the six-year project, they had achieved a nearly 20% increase in average honey production and a measurable decrease in the aggressiveness of the bees. Note that Mexico has Africanized bees known to be highly aggressive, so this result is particularly relevant.
Dr. Guzman has written a book on this topic, “Elemental Genetics and Breeding for the Honey Bee,” though I am unable to find it on the internet. He had a few copies with him for sale at the conference.
Microbes and natural compounds for the control of honey bee parasites
Guzman’s second talk was about research they’ve done on using natural compounds to treat for parasites. He pointed out that average colony losses have been above 30% across North America for the last seven winters. In Ontario there appear to be several factors working in synergy that result in such losses. Varroa is definitely the main culprit of winter losses, involved in over 85% of colony deaths. Colonies with a 6% varroa infestation going into winter had greater than a 50% chance of dying by spring.
There are three standard ways to treat for Varroa: chemicals, manual manipulations, and natural compounds such as organic acids or essential oils. The use of chemicals is effective but the mites have often adapted to these after a few years of use. Manipulations such as splits and drone trapping are effective but time consuming, and therefore not scalable for large operators. The organic acids tend to have variable effectiveness based on environmental conditions, based on factors such as temperature and humidity.
As a result, it would be beneficial to have an alternative to these methods that was more effective, scalable, and less susceptible to adaptation. This could include biological controls, natural compounds, or more resistant bees. Dr Guzman’s lab has investigated the first two, and he shared the results seen to date.
His student Alice Sinia tested local fungal isolates in Ontario for their effectiveness against mites. Fungus is environmentally safe and tends to be host specific, so the hope was to find something that would impact the mites with limited impact on adult bees. They tested a number of candidates and found a number of them that would attack mites, but unfortunately also had too high an impact on adult bees. Further research is needed to see if a fungus can be found that kills mites, and not bees.
For essential oils, Guzman observed that there is not a lot of research into these compounds. Many oils have shown good results in the lab, but need better delivery methods in the hive. They tested 24 different compounds and found good results with thymol, oregano, and clove oil. They are currently testing a new delivery method with thymol oil and are hoping to make it commercially available in the future. They plan to do further study of oregano oil as well.
In another study, they tested the use of fungus and probiotics against Nosema ceranae. They found some fungus that worked well against the spores, though the probiotics had the most promise. They are considering additional research with probiotics.
The line “watch that scene” occurs in the chorus, rather after the line “see that girl” that was used for the post on Dr. Tarpy’s talks. Given that Dr. Guzman’s first talk was right after Dr. Tarpy, and his research involves watching what is happening to bees in a hive, this seems rather appropriate.