Low Varroa Growth Part 1 Descriptive Transcript

PAUL KELLY: Hi there, my name is Paul Kelly. I’m the research and apiary manager at the University of Guelph Honeybee Research Centre. We’re here today to talk about a breeding project that we have ongoing, breeding bees for resistance to varroa mites. We’re at the Bovey Building at the University of Guelph Campus. My supervisor, Dr. Ernesto Guzman has his office here, and we have our molecular biology lab here as well. So, in this video we’ll interview Dr. Guzman about this breeding project. We have two more videos coming up where we’ll look at the results of this breeding work and how we’re planning to implement the breeding program in the beekeeping community. Ernesto comes to us from Mexico. He’s been here for a long time now, about 15 years. Is that right, Ernesto?


PAUL KELLY: OK, 16. They’re adding up, aren’t they? So, Ernesto is a bee pathologist and a bee geneticist, and he got to work for many years with killer bees in Mexico. So, we have nicer bees up here, right (UNKNOWN)?


PAUL KELLY: OK. So, he’s gonna outline this project of low varroa growth rate, breeding for low varroa growth rate. We’re calling it LVG for short. So, Ernesto let’s start off with talking a bit about varroa mites. How do varroa mites damage honeybees?

ERNESTO GUZMAN: Well, varroa mites feed upon the haemolin and fat tissue of the bee. The haemolin is equivalent to blood. And by feeding upon the haemolin and fat tissue, they debilitate the bee. They consume proteins from these organs. And the bee, when it emerges from a cell weights less, has less protein in their bloodstream, let’s call it in mammal terms – really, there’s no blood stream, we call it haemolin. And what happens is that that debilitation of the bee in shortening the lifespan of the insect by 50% or more.

PAUL KELLY: Right. That’s a big difference, 50% lifespan. Yeah. What other effects does it have? Other than just physically draining the bees, what other effects does it have on bees?

ERNESTO GUZMAN: Well, varroa mites, it’s important to say that they come from Asia. The Western honeybee is not the original host of the mite, but apis cerana, a cousin of the honeybee. And therefore, because this mite has been in contact with the Western honeybee for a relatively short period of time, has caused so much damage.

PAUL KELLY: So, there’s no resistance.

ERNESTO GUZMAN: There’s not much resistance. There are some traits that confer resistance to the bee, but to a lesser degree than the original host.

PAUL KELLY: How does the original host defend itself from…

ERNESTO GUZMAN: The original host defends itself by a series of behaviors which include grooming. That is, the removal of the mite from their bodies using their legs and mandibles. They also have a shorter developmental period in which the mites are not able to reproduce as much on the larvae of this species. And some of these traits are also present in our Western honeybee, but still the mite is quite damaging. Besides draining haemolin, besides consuming fat tissue of the bee, it also transmits viruses and there are about 18 different viruses.

PAUL KELLY: 18? Wow.

ERNESTO GUZMAN: 18 different viruses affecting the bees. But the most damaging of them is the so-called deformed wing virus, a virus that deforms the wings of the bees, that’s why it’s called deformed wing virus. It shortens also the lifespan of the bee, and together they contribute to cause so much damage to a house bee.

PAUL KELLY: So, how do bees respond? How does their immune system deal with both the viral load transmitted by the bees and the loss of body fluids and so on from the varroa mite?

ERNESTO GUZMAN: Well, bees, as other insects, rely on innate immunity, a type of generalized immune response that depends on cellular immunity and humoral immunity. Cellular immunity is given by haemocytes. Haemocytes are blood cells equivalent to white cells in mammals. These cells engulf and kill microorganisms in the haemolin of the bee. They also seal wounds caused by the mite when it bites the bee.

PAUL KELLY: Like with clotting?

ERNESTO GUZMAN: Yeah, it would help clotting, but when the mite bites the bee, somehow it inhibits this response and the wound remains open.

PAUL KELLY: So, the fluids can still flow, they can still draw.

ERNESTO GUZMAN: Still flows so that the mite keeps on feeding.

PAUL KELLY: Kind of like vampires.

ERNESTO GUZMAN: Kind of like vampires. (CHUCKLE) And then there’s also the humoral immunity, which it’s based on chemicals that also kill microorganisms like the virus, for example.

PAUL KELLY: Right. Yeah. OK, right. So, bees have all kinds of social behavior, what social behaviors could lead to suppression of this mite problems.

ERNESTO GUZMAN: Yeah, you made a very good point, Paul. Besides innate immunity, bees have social immunity and that is given by behavioral mechanisms that help them defend themselves from the mites. Two of the most important mechanisms of resistance against the mites that have behavioural basis are grooming behavior and hygenic behavior. Grooming behavior, as we said before for the Asian bee, it’s the ability of the bee to remove the mite with their legs and with their mandibles. And it could be done by one individual bee on herself, or it could be done by other bees helping each other. So, that’s why we call it social allo-grooming. And then we have hygenic behavior, that’s the ability of the bee to detect parasite cells with mites and they would uncap the cell, remove the larva or the pupa from the cell. And by doing that, they break the life cycle of the mite which is reproducing inside the cell.

PAUL KELLY: OK, right. They’re very good defensive mechanism, but they don’t work well enough with our bees. And can you explain what we do as beekeepers to complement the bee’s own response? Like how do beekeepers keep their bees alive with such a devastating organism lives on it. It’s called varroa destructor for a very good reason, it’s a pretty bad critter.

ERNESTO GUZMAN: Absolutely. Well, beekeepers try to control the mite by using miticides, which are chemicals from synthetic or organic origin that are applied to the colonies in the hives that kill mites. And most beekeepers do that, but there are some problems with using these chemicals.

PAUL KELLY: And what would those problems be with using the chemicals? So, if they’re effective at killing the mites, what could be a problem with that?

ERNESTO GUZMAN: Well, there are a number of problems, but the two most relevant problems are that they might promote the development of resistance in the mites against the chemical ingredients in these medicines. So, that happens with all sorts of pesticides. Pests develop resistance against the pesticide, bacteria, viruses, fungi, develop resistance against antibiotics or antiviral medicines. And so, that’s nature. The parasite is trying to defend itself from the damage that this chemical is causing them. So, for practical purposes, one, miticides may kill perhaps 95-97% of the mites one year and then the next year, but after five or 10 years, it may be killing less than 50% of them because the mites have developed resistance. And the other problem is residues in high products. When we medicate our bees, we’re basically putting pesticides inside the hive and honey and wax can be contaminated with those compounds, if not used properly.

PAUL KELLY: Right. It is a real challenge. Dr. Jim (UNKNOWN) from Ohio State, I thought put it pretty well. He said, “We’re trying to kill one bug that lives on another bug inside a box of food that people are gonna eat.” So, we have to be very careful with what we’re doing. Could you talk a bit about some of the other methods of controlling mites, natural chemicals and what other options there may be?

ERNESTO GUZMAN: Yeah, one option that we have tried also in our lab, it’s testing natural compounds. For example, oregano oil or thyme oil, the essential oil find that we use in kitchens in our cooking. Clove oil.

PAUL KELLY: So, very safe, naturally occurring.

ERNESTO GUZMAN: Very safe, natural occurring compounds. However, there are issues with them, too. For example, we haven’t found the right method of application, a good delivery system to make them work effectively in the hives. And the same thing happens with the other option of bio control, using microorganisms like fungi to parasitize the mite and kill it. And we haven’t found a good method of delivery of fungi to kill mites, and they are also slightly toxic to the bees. And therefore, a third option to control the mites would be to breed bees that show more resistance to the mite than the average bees.

PAUL KELLY: Right. So, just kind of summing that up then, the synthetic pesticides are very effective, but resistance develops, there can be contamination issues. Natural chemicals can be effective, but their effectiveness is a bit more variable and it still requires proper timing and that sort of thing. So, the ultimate goal basically is breeding bees for resistance.

ERNESTO GUZMAN: Well, the long term goal will be to have resistant bees against the mite.

PAUL KELLY: Right. So, let’s talk about this project then. And if you can give us an overview of our low overall growth rate or LVG project, that would be great.

ERNESTO GUZMAN: Yes. Well, we’ve been working on learning how this mechanisms of resistance work, like grooming behavior, like hygienic behavior over the course of many years. But the specific project has three goals, three objectives. One is to develop populations of honeybees that show resistance to varroa growth rate. That is that having several mechanisms functioning to prevent the population of mites to grow. Objective number two, it’s to test this techniques in the field and then transfer the methodology to queen breeders mainly, but to beekeepers in general. And the third objective of the project has to do with pinpointing genes at the cell level that contribute to these resistance given by LVG.

PAUL KELLY: Right. So, that would be looking for genetic markers that show that bees have those traits that we’re looking for. And just kind of, again, summarizing, we’re looking for the hygenic behavior, the grooming behavior, those kinds of social behaviors. At the end of the day that amounts to less mites. So, if we look for less mites, we’re indirectly breeding for those social behaviors.

ERNESTO GUZMAN: Not only that, we’re also breeding for less viruses in the bees, ’cause if you reduce the population of mites, you also reduce the population of viruses.

PAUL KELLY: Right. Thanks very much, Dr. Guzman. So, we’ve got two more videos coming up, the next one will be Dr. (UNKNWON) Emsen and she’ll be sharing some of the results of the project. We’re really excited about how well things are working, and (UNKNWON) will explain that. And our third video will be talking to Les Eccles. Les Eccles works for the Ontario Beekeepers Association Tech Transfer program. So, he’s been directly involved in this project right from the beginning. His role and that the role of the tech transfer program will be to implement this breeding project in the beekeeping community, to share the simple methods that beekeepers can use in breeding bees for resistance to verroa mites. So, thank you very much for watching. Take care of your bees, we’ll see you next time.