Low Varroa Growth Part 2 Descriptive Transcript

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PAUL KELLY:
Hi there. We’re here in the bee yard at the Honey Bee Research Center. My name is Paul Kelly. I’m the manager here. But I’d like to introduce to you Dr Berna Epson. Berna has been working with us since 2005. She’s a professor at Ataturk University in Turkey, but she comes back and forth and has done a lot of work with us. Back in 2005, Berna started a project looking at grooming behavior, the ability of bees to groom mites off their own bodies, and then correlating that with Varroa population growth in the colonies. We had some really exciting results from that project. And for the last three years, we’ve been expanding that project into a much bigger program. And Berna can explain that program to us. Berna, could you please explain the research project that we’re here to talk about?

BERNA EPSON:
Sure Paul, thank you. So the project’s objectives is, one of the objective is to develop honeybee populations with increased resistance against varroa mite and reduce the rate of deforming virus. The second goal is to train Ontario Queen producers in breeding methodologies for selecting varroa resistance colonies in the honeybee colonies. The third one is to find the gene who is responsible with the resistance to Varroa mite and Deformed Wing Virus. Right. Could you explain how we did this with colonies? A number of colonies we started with and how we worked through that to narrow it down to our breeder colony? Sure. So in the first year of the project, we monitored more than 200 colonies for mites fall, using sticky papers. Then 15 weeks later, we counted again. So between the two measurements, we selected 20 colonies with the highest varroa mite growth and 20 colonies with the lowest Varroa mite growth. Right. So you’re going from 200 down to two groups of 20. one with low varroa growth rate.

Yes. And one with high varroa growth rate based on the counts on the sticky papers that we were using in the colonies. That’s right. Right. I know you did more, so maybe you could explain a bit more what you did with the 20 colonies that were selected. Yes. So all the total colonies that we selected in total 40, they were tested for brood infestation, adult bee infestation, hygienic behaviour, defensive behaviour, nosema infection. And mite production, mite damage. We looked for all the tests. Wow, that’s a lot. So nosema, that’s pretty straightforward. We take a sample of forager bees, we vacuum up as they’re coming back from the entrance and then we dissect them and look at the levels of nosema spores under a microscope. So that would straightforward. What may need a bit more explanation is the hygienic behaviour and defensive behaviour. So let’s start with hygienic behaviour. Could you please describe that process? Yeah. For the hygienic behaviour to we used like liquid nitrogen. So we had like copper cylinders and we placed them into the (UNKOWN) area to freeze, to kill(UNKNOWN) After two days, we opened the hives and look for the prints that if the bees opened the cells and removed the pupa and we contact them.

So you’re taking capped pupa freeze, killing them and then looking at how bees clean them out as a measurement of hygienic behaviour. Right. OK, defensive behaviour. How was that measured? Yeah, for the defensive behaviour, we also used chemicals like (UNKNOWN) , which is the alarm pheromones. First we took a picture of the hive entrance without applying the alarm pheromones after applying the alarm pheromones for 30 seconds. We counted the bees in the hive entrance. So the difference between the first picture and the second picture is the defensive behaviour. Right. And you’re just able to count the number bees, the guard bees that respond to that alarm pheromones. Exactly. Right. Just a little aside, we earlier on when we started doing defensive testing in the colonies, we used the standard method where you wave a black flag in front of the colony and count the number of stings on the black flag. We are found bees here are gentle enough to that measurement doesn’t work at all. The bees just look at the flag going up and down and and we get no measurement at all.

So this sisal (UNKNOWN) acetate works really well. It’s a very quick test of defensive behaviour. So Berana could you explain where we went from there, like we’ve narrowed it down to these twenty colonies and then what did we do once we got the best and the worst poorly selected. In the second tier we selected three colonies from the high infested group, three colonies from the low infested group to raise queens. So we used those six colonies for grafting. At the end, 100 queens were introduced to random colonies from low group and hundreds of queens from high infested varroa mite group were introduced to 200 colonies. Then we again did the mite count in early spring. Then after 15 weeks we again might count. Right? ok, so you’re picking the best breeding from them getting into multiple colonies so that you could be testing large numbers and then narrowing it down again so that cycle can repeat itself. Yeah. And then we’re gonna do it again mite count in early spring and then 15 weeks later we will be again selecting 20 colonies with the highest varroa mite population to any colonies with the lowest varroa mite growth.

And then we will test them again for the brute infestation. Adult bee might damage Nosema defensive behaviour and hygienic behaviour. Sorry the results that you’ve seen from just looking at the varroa mite growth rate? What results are you seeing with that? So far the results showed us to the colonies from lower varroa mite growth had lower mite infestation rate, lower adult bee infestation rate high mite damage a lower deforming virus levels, higher immune system, they’re higher like blood samples compared to like high varroa growth colonies. So basically, you’re having lower numbers of mites, lower damage to the wings from the virus that’s vectored by the mites. That makes sense. We’ve also found that Nosema levels are low in the low varroa growth rate. So that’s an interesting association. Wouldn’t that naturally may not have expected. So they’re all they’re all quite positive. One thing that Berna didn’t mention there, though, we saw that the defensive behaviour. The (UNKNOWN) were more defensive, also had a lower varroa growth rate.

And that’s a concern for us because we don’t want to be greedy for more defensive behaviour, not something we really like to see. But that’s gonna take further exploration. It may just be an anomaly of the project that we’re working on. So what’s what are the next steps with this project? Yeah, for the 30 years we will do that again, same cycle. We’re gonna go over the colonies to see how many colonies were survived. And then we will be again selecting three colonies from the high group, three colonies from the low group for again, grafting. We’re gonna again raise the Queens. We’re gonna introduce the queen’s random colonies and then we will again see the mite counts two times and then select again 20 colonies with the lowest varroa mite growth and twenty colonies with the highest varroa mite growth. And then we are gonna do all the tests again. This year also, we will find out the genes associated to varroa mite and deforming (UNKNOWN). Right, So and the purpose of the genes looking for those genes would be to have an alternate method of selecting for this low varroa growth rate.