Can Plan Bee help select for traits to help with Varroa resistance

The National Honey Bee Genetic Improvement Program (Plan Bee) is focused on improving the most important honey bee traits for beekeepers and pollination dependent industries.

This has involved assessing a broad range of traits including pest and disease resistance, brood pattern, population, honey production, aggression and hygienic behaviour.

When traits are combined with parentage or genotypic data, assessment can be made about the heritability of these traits and potentially queens can be selected to meet a certain need.

Naturally, beekeepers are now greatly concerned about the impact of Varroa mite, and genetic improvement has a role to play.

As part of the way that Plan Bee is supporting the industry, lead researcher Dr Nadine Chapman from University of Sydney is assisting in assessing the role a synthetic compound known as UBeeO could have in measuring response to unhealthy brood odour (UBO).

UBeeO triggers hygienic behaviour and could help select for Varroa resistance.

The data collected during the testing will be included in a larger data set that is informing the genetic analysis being carried out by Plan Bee.

This work has the potential to perhaps help breeders select queens that are more likely to cope with Varroa.

UBeeO testing in Australia
Testing of UBeeO in Australia is part of the Bee Genetics Varroa Resistance breeding project, being led by queen bee breeder and Australian Queen Bee Breeders Association committee member, Corinne Jordan.

Plan Bee's involvement in UBeeO has been via the same route as for other traits. Breeders get in touch to discuss the traits they want to assess and ask for assistance.

Dr Chapman went out to assist in testing approximately 100 colonies for their UBeeO response. The following week, the colonies were assessed for other traits and sampled for genetic testing by another Plan Bee team member, Emily Noordyke, from NSW DPI.

The aim of the project is to prove breeding for Varroa resistance is possible and sustainable. It will help beekeepers in areas still unaffected by Varroa prepare.

Unhealthy brood odour
UBeeO has been developed by a group from the United States and examines bees' response to unhealthy brood odour (UBO).
This odour can occur due to being infested with Varroa, viral infection, or other brood disease.

UBeeO, made up of chemicals found in unhealthy brood, is sprayed onto a known area of capped brood and two hours later the number of uncapped cells are counted.

Colonies with greater than 60% of the cells uncapped are considered hygienic. These colonies may then be able to maintain the mite population below three mites per 100 bees and survive without treatment.

Response to the test has been linked with low Varroa infestation level, high Varroa removal, overwintering in colonies not treated for Varroa, and traditional freeze killed brood (FKB) hygienic behaviour tests.

United States researcher, Dr Kaira Wagoner, from the University of North Carolina at Greensboro, has led the team which developed UBeeO spray.

UBeeO results
Corinne Jordan secured early access to the UBeeO spray - an expensive exercise which has been funded by collaborating with other queen breeders, honey producers and private donations.

In 2023, Ms Jordan and Dr Chapman undertook tests of the UBeeO spray at Goldfields Honey in Central West NSW.

"We spray tested 100 colonies there with the UBeeO spray looking for high responders," Ms Jordan said.

"In Australia so far, we have found that we don't really have high responders. We're lucky if we get into what's known as the medium range which is around 40% to 60%.

"Goldfields Honey had one in that range, and they also had some good responses in the low range.

"There are potential tools that are available to us now that Varroa has been declared endemic. However, UBeeO is an efficient selection tool and the only one that we could use when we don't have Varroa because it essentially mimics a Varroa infection in the brood cells.

"The issue with breeding for Varroa has always been, how can you do it when you don't have Varroa?

"Other methods were to use hygienic testing methods like the liquid nitrogen freeze killed brood (FKB) test but they're not as effective as the UBeeO test."

Public link

Please use the above public link if you want to share this noodl on another website.