American Foulbrood (AFB) is a highly contagious bacterial brood disease in honey bees. The disease is caused by the bacterium Paenibacillus larvae which produce spores that are viable in the environment for decades. Protecting honey bees from AFB is extremely important and recently a new product has been developed that demonstrates providing some degree of immunity to the disease. The Canadian Food Inspection Agency (CFIA) has conditionally licensed the product, under veterinary supervision, and it is expected to be distributed on a limited basis to commercial beekeepers in Canada starting this Spring. To learn more about AFB, and the potential benefits this new product could provide, read this week’s blog.
Product for American Foulbrood Protection Approved for Canada's Honey Bees
American foulbrood (AFB) is caused by the Paenibacillus
larvae bacterium which produce spores that are viable in the environment
for decades. Worker bees can transport the spores and spread the disease, but
it is the larval stage that shows clinical symptoms of infection. Infected
brood usually die at the pre-pupal or pupal stage, severely weakening the
colony and eventually killing it. Because of its virulent nature and
detrimental effects on honey bee colonies, AFB is classified as a notifiable
disease worldwide.
Antibiotics, such as Oxytetracycline, are largely
ineffective at eradicating the disease as they are only effective against the
vegetative state of the bacteria, which is when bacteria can grow and
reproduce. Once a hive shows the clinical symptoms of the disease, the only
effective way to eradicate it and prevent the spread of the disease is by
burning the equipment, and the colony.
Therefore, it is extremely important to protect honey bees
from AFB, and there is now a new product that could help. This product is being
called a vaccine in the media and throughout published research. In an original
study done by Dickel et al. (2022) the group of researchers demonstrated
that the oral administration of an inactivated AFB bacterin to the queen bee is
safe and induces some level of protection in the next generation of larvae
against AFB infection in a hybrid lab and field study. The suggested delivery
of this new product is that the inactive bacteria is mixed into powered sugar
and glucose syrup for the worker bees to eat, and their secretions are fed to
the queen. Then the next generation of developing bees, produced from the
queen, have increased immunity to AFB.
The research trails, funded by Dalan Animal Health, showed
between 30% to 50% decrease in AFB infection among colonies that received the
product compared to colonies that received the placebo product in the hybrid
lab and field study. The researchers fed the queens the product for 8 days
in queen cages in the lab, and those queens were released into nucleus hives. Then,
18 days post-queen placement, frames of brood were collected and fed food with
a known concentration of AFB spores and assessed for mortality over time in the
lab.
It is known that this is an antibody-free immunological
response since insects lack antibodies. It is proposed that information about
the disease agent is transferred to the next generation with the help of the
egg yolk protein Vitellogenin carrying immune elicitors, such as pieces of
bacteria. Another proposed mechanism of action is a transfer of mRNA and
proteins as well as epigenetic factors. Further research is needed to determine
this product’s mechanism of action.
This product could be beneficial in protecting honey bees
from AFB and decrease the economic impact of the disease. That being said, the
efficacy of the product is still largely unproven both from a multitude of
research trials, and through beekeeping practices. In Fall 2023, the Canadian
Food Inspection Agency (CFIA) conditionally licensed the product, under
veterinary supervision, and it is expected to be distributed on a limited basis
to commercial beekeepers in Canada starting this Spring. The United States
Department of Agriculture (USDA) conditionally licensed the product by Dalan
Animal Health back in January 2023. Some key differences exist between having a
product licensed by CFIA versus USDA, including the level of efficacy a product
must demonstrate. Since there is differences in the standard a product must
meet, it is typical that CFIA will license a product after USDA. Both CFIA and
USDA only license products that have been proven to be safe for livestock and
humans, when following manufacturer instructions.
Although this product could provide multiple benefits to the
Canadian honey bee industry, it is important to recognize that beekeepers must
still remain vigilant in detecting potential AFB infections. Beekeepers should
examine brood for discolored larvae; dead larvae; brood that appears greasy,
sunken, or punctured; and poor brood pattern. Additionally, beekeepers should
perform the rope test regularly, and especially on any abnormal looking larvae.
Finally, if a beekeepers does have reason to suspect an AFB infection this must
be reported to the provincial apiculturist immediately.
References
Dickel, F., Bos, N.M.P., Hughes,
H., Martín-Hernández, R., Higes, M., Kleiser, A. and Freitak, D., 2022. The
oral vaccination with Paenibacillus larvae bacterin can decrease
susceptibility to American Foulbrood infection in honey bees—A safety and
efficacy study. Frontiers in Veterinary Science, 9.
Connecting with ATTTA Specialists
If you’d like to connect with ATTTA specialists or learn more about our program, you can:
visit our website at https://www.perennia.ca/portfolio-items/honey-bees/
Email abyers@perennia.ca