On this page, we will regularly highlight and summarize an important study on honey bees from the primary literature to grow the knowledge about honey bees particularly for our beekeepers!
Spring is in the air again, and as seeds of food and flowers are sown once more, beekeepers should consider sowing something else: microbes. Over the cold Northern winters, honey bees must stay sheltered in their insulated hives where they feed on stored food and await warm weathers. But just because the snow is gone doesn’t mean there aren’t challenges left to face, as the months of confinement coupled with lower-quality food, antibiotic, and pesticide exposures often leave overwintering bees in frail health. This is especially true for their microbiomes, as the medicines used to stave off disease wreak havoc on their gut flora. To help overcome these challenges, the authoring team supplemented the spring bee feed of their experimental hives with known probiotics, such as lactic acid bacteria and saccharomycete yeasts. They then allowed the control and experimental bees to forage alongside one another for the following season and measured the development of the hive population alongside the production of honey. In colonies where probiotics were seeded, queen egg production was up to 25% higher than the control colonies. Furthermore, these colonies produced over 16% more honey, or an average surplus of 7.5kg (16.5lb) per colony! Going forward, these results suggest it may be good practice to apply microbial supplements to colonies as they emerge from their winter slumber, for quicker recoveries and greater honey harvests.
Managed honey bee colonies can face a lot of stressors simultaneously, and growing evidence suggests that these stressors synergize—causing more harm as a whole than the sum of each.
We often consider mites, pathogens, poor forage, pesticides, and more; but did you ever think
that even the presence of ants could exacerbate these problems?! Dobelmann, Felden, & Lester (2023) show that interaction with the invasive Argentine ant (Linepithema humile) can increase
deformed wing virus (DWV) levels in honey bee colonies. DWV is not honey bee-specific and so
it likely jumps hosts from bee to ant to bee again, making it much harder to control and
increasing the rate of transmission between hives in an apiary. Luckily, Argentine ants have not
spread to Alberta (though they have been recorded in British Columbia), presumably because
they cannot tolerate the cold. Yet, as climate change increases global temperatures, the range
of hospitable habitat for these ants could creep North. Moreover, beekeepers all over the globe experience the nuisance of ants (not just Argentine ants) filing into their hives and marching back out with their stomachs full of honey or their mandibles clutching larvae. It stands to reason that these ants could also be spreading viruses as they parade through the hive.
With many thousand insects sharing a close and confined space in the colony, the honey bees need to ensure that there is enough fresh air to breathe while at the same time maintaining a suitable temperature inside the hive. This is particularly relevant for bees in the winter cluster, although this study was conducted in Arizona. The authors compared screened bottom boards (more ventilation) with solid bottom boards (less ventilation) and surprisingly found that screened bottom boards did not lessen the maintenance of temperature in their hives but lead to an increase in carbon-dioxide, which honey bees breathe out to get rid off (just like other animals). The concentration of carbon-dioxide is slightly higher underneath the colony than above it because it is heavier than air. Also, it unsurprisingly followed a daily rhythm but overall this study does not show that bees have a problem with avoiding poisoning from carbon-dioxide and keeping warm under the study’s conditions. It remains to be studied whether that conclusion holds true for wintering (especially indoors) here in Canada.
Even though this publication is a few months old, it shows some interesting effects of our grafting methods on queen quality. Honey bee queens are typically produced by queen-breeders by grafting eggs or young larvae from worker cells into queen cells. However, a previous study found that eggs laid directly into queen cells tend to be larger than eggs laid into worker cells. This study followed these results demonstrating that queens that develop from eggs that are laid into queen cells are larger and develop better than queens that are grafted as eggs or second instar larvae from worker cells into queen cells. Even more astonishingly, the queen daughters of these queens also differed in quality: The queen daughters of queens that developed (naturally) from eggs that were directly laid into queen cells were of superior quality than daughters of queens that were grafted as eggs or larvae. The study also showed that grafting eggs results in better queens than grafting larvae. So, while commercial queen production relies on grafting, it might not be optimal and perhaps alternative ways of mass queen production could be developed in the future.
Honey bees and humans are different. That’s not exactly a profound statement. Bees and
humans diverged some 600 million years ago and have been evolving on separate trajectories
ever since. A bee’s brain is only 0.0002% the size of yours. An adult bees’ diet is predominantly
nectar; yours is probably a lot more diverse. Yet, a recent study in Science shows that the
psychological phenomenon of “wanting” food is facilitated by very similar neurobiological
pathways in both bees and humans. In mammals, wanting is mediated by dopamine in the
brain. Dopamine surges when we think about food – when we remember a food we like, or
when we anticipate eating. The same appears to be the case for honey bees! Huang et al.
(2022) found that brain dopamine levels spike when bees go out to forage, but then drop again
once they begin feeding. When the researchers pharmacologically blocked dopamine signalling,
would-be foragers stayed in the hive instead of foraging. Moreover, dopamine levels rise when
foragers perform waggle dances and then return to normal levels once again when the dance
ends. So, it appears that the dopaminergic system is activated, not only when foragers are en
route to a food source, but when they recall the food source as well! The same neurochemical
system regulates “wanting” in humans and bees, illustrating that honey bees continue to be a
great model for studying the general neural mechanisms that regulate behavior. The more we
understand about bees, the better we can understand ourselves.
This study chemically analyzes what we all know: American Foulbrood has a characteristic smell! However, by identifying the specific chemicals in the air, it might be possible in the future to develop automated detection methods or tests that will allow us to catch AFB earlier to prevent full-fledged outbreaks.