The study supports a new method to stimulate bee health

Beekeepers in the United States lost more than 55% of the colonies managed last year – the highest rate of loss since Inspectors from above America began to determine them in 2011.

A new study by the University of Vermont Scientists and international collaborators supports a new method to test hygienic behavior in honey bees that could promote the breeding of colonies more resistant to diseases in the future. They published their results in Frontiers in Bee Science.

“Beekeepers lose bees at a rate which, according to them, is not durable,” explains Samantha Algiers, director of Vermont Bee Lab at UVM and the main author of the study.

“In the 80s, beekeepers lost colonies 10 to 12% of the time … But now it’s like 30 to 50%. Imagine that it happens to someone who is a cattle breeder or a pork producer each year.”

The honey bee populations remain relatively stable despite heavy losses because beekeepers are good for raising new bees, she explains.

But this is done at the expense of time and resources for beekeepers, as well as the risk of native pollinators. Pathogens in managed bees can spread in populations of wild bees.

The Algiers laboratory works with beekeepers to raise colonies of robust honey bees and resistant to diseases that they can sell to amateurs and professional beekeepers. Helping beekeepers to identify hygienic behavior – the ability to identify unhealthy broods – is part of this process.

“It is certainly more desirable for a beekeeper to have bees that are better suited to take care of their illnesses themselves, rather than using chemical treatments and interventions to try to reduce these pathogens, which, of course, can have negative impacts on bees,” she said.

“Now, the trick is, how does a beekeeper identify a really hygienic colony? And there are various tests that you can do for that and this ubeeo is somehow a new way of testing for that.”

The Algiers team recently studied a screening tool developed by scientists from the University of North Carolina in Greensboro who tests colonies for hygienic behavior by imitating pheromones emitted by sick or dying bees. Researchers have found that the UBEEO test can identify the colonies resistant to several pests and pathogenic agents who can decimate bee populations, such as Vairimorpha (known to many beekeepers under the name of Noséma) and fungal infections, including Chalkbrood.

“Ubeeo is known to identify the colonies which are able to better resist Varroa mites, but it had not been used to look at other pests or pathogens,” explains Algiers. “We found that this new test could be used to identify the colonies resistant to these other stressors.”

How does it work

Imagine a colony of honey bees. Inside the box in the box are frames with hexagonal holes where a bee queen lays an egg inside each cell. As eggs hatch, nursing bees fuel development larvae and end up stuck on cells with wax to protect them as they ripen in adults.

When nursing bees detect a developing bee is sick or dead, they will lead the cell and remove the PUPA to protect the rest of the hive. This is called hygienic behavior and pheromones play an important role in this process.

“Other people have identified pheromones from death, these compounds associated with death,” said Kaira Waggoner, researcher at UNC Greensboro and co-author of the study.

“The famous biologist EO Wilson was one of the first to do so. He found that oleic acid was emitted by dead ants. The same was found with bees, and it is probably a stronger signal – it grows because the dead brood is essentially more subtle than these pheromones that come out of unhealthy pants are different and probably more subtle.”

The previous hygiene tests for beekeepers were based on the idea of ​​testing the ability of bees to detect dead broods. One of the most common methods, the dosage of the gel brood, is to pour liquid nitrogen on a section of capped cells and wait 24 hours to see if the bees start to remove the dead. The UBEEO test is different.

“Rather than using liquid nitrogen to kill pubs or development larvae, you use a mixture of synthetic pheromones which imitates the same chemicals that are emitted by death or sick brood,” explains Algiers.

“So, rather than testing the ability of bees to identify the dead brood, you test the ability of bees to identify the sick brood, which means that this test is a little more selective and realistic for what bees live.”

Waggoner co-developed Ubeeo during his doctoral studies after identifying chemical compounds associated with unhealthy brood odors. She co -founded will opt, (named Hymenoptera, the order of the bee), to bring Ubeeo to beekeepers on the ground. It became accessible to the public in 2024.

“It’s a very young technology,” says Waggoner. “We have now tested it in more than 10 different countries, and there are reproductive programs in at least five now, so there are much more data to come.”

Investigation

The study focuses on UBEEO tests carried out in three geographic regions – Vermont, North Carolina and Australia – to examine its effectiveness in the recognition of colonies resistant to pathogens and diseases. The UBEEO test is to spray a section of capped cells with synthetic pheromones, then wait two hours to see if nursing bees have started to inspect developing bees for problems.

The percentage of disturbed cells is the UBEEO score. Researchers found that higher UBEEO scores were associated with lower disease levels. The results have also shown various thresholds to disease resistance for pathogens of honey bees.

“What we have found, at least with this Australian data set is that they are only necessary to obtain a response of 13% on the UBEEO test to be really resistant in Chalkbrood. On the other hand, the colonies must obtain a response of 55 or 60% on the UBEEO test to be resistant to mites, explains Wagoner.

“The reactivity of honey bees depends largely on the virulent or the harmful of the specific disease. Chalkbrood kills the brood, so the bees do not have to be so sensitive to detect it.”

The acts of Varroa acts is more delicate. These tiny parasitic mites were introduced approximately four decades in the United States and are vectors of the population of bee disease. They constitute a significant threat to the colonies and reproduce by laying eggs inside capped cells and feed on developing PUPA.

If nursing bees do not detect a problem, Varroa mites will be released in the hive when the young honey bee emerges. This is where hygienic behavior becomes essential, because starting cells disrupt the life cycle of mites.

The study also revealed that the UBEEO test could identify the colonies with resistance to Vairimorpha (previously Noséma), a disease that affects adult bees and not developing in development. This observation has aroused new research on the functioning of hygienic behavior to maintain these levels of Vairimorpha.

“In the case of Vairimorpha, what they do is a bit of mystery,” said Algiers. “… there could be other behaviors that the hygienic colonies accomplish what we know.”