Dr Heather Hendrickson and post doctoral fellow Danielle Kok examine a phage sample that could be used to immunise honeybees against American Foulbrood, a disease that used to be a death sentence for hives.
A new cocktail created by a team of University of Canterbury researchers could soon be putting a stop to that with a cocktail of ‘phages’, viruses that infect bacteria, that attack and consume the bacteria causing the disease.
Since 2018, Dr Heather Hendrickson and her team at the Active Bacteriophages for AFB Eradication project (ABAtE) have been isolating bacteriophages to test their efficiency in destroying different strains of AFB, with funding from the NZ Honey Trust, the Agricultural and Marketing Research and Development Trust (AGMARDT), and Sustainable Food and Fibre Futures.
AFB is caused by Paenibacillus larvae. The bacteria attacks bee larvae, colonising their midguts and eventually killing the larvae. Worker bees cleaning out the remains of the dead larvae then end up contaminating food stores with the spores of the bacteria, which can stay alive in honey or on beekeeping equipment for more than 40 years, making them extremely difficult to eradicate.
It’s so contagious and deadly to apiculture that, in the EU, the law requires that infected hives and equipment be destroyed, while many states in the USA require infected hives to be burned completely.
Aotearoa’s bees, as well as being producers of honey and other bee products, are key pollinators that ensure the success of other agricultural industries. It's estimated that they contribute more than $5 billion to the economy each year simply through pollination services. Under New Zealand law, all equipment, bees, and products that have come into contact with AFB have to be destroyed within seven days.
That’s a heavy blow for our major pollinators, who have been experiencing population loss worldwide. In 2021, the Ministry of Primary Industries estimated that there was a loss rate of 13.6 per cent over winter in New Zealand.
Recently in January 2023, the United States Department of Agriculture approved a vaccine for AFB that embedded inactive P. larvae in the royal jelly that’s fed to larvae. “According to the literature, the AFB vaccine is able to prevent death in 30 to 50 per cent of honeybee larvae,” said Dr Hendrickson. “In New Zealand, this level of protection would still leave many infected honeybee larvae in a hive which would ultimately still need to be incinerated. However, phages have been shown to completely prevent AFB infection if the right phages are applied in advance to protect a hive.”
The phages were found to be naturally occurring in soil samples collected from apiary sites and sent to the lab by beekeepers from all over Aotearoa. The phages were filtered out and then poured onto a bacterial ‘lawn’ of P. larvae to see which areas were affected.
“All of the soil samples that contained phages have come from healthy hives,” said Dr Hendrickson, “which shows that healthy hives already have them and they protect honeybee larvae from an AFB infection.” So far, the team has discovered 26 new phages and combined these in four unique ‘cocktails’ that successfully kill 93 per cent of all known strains of P. larvae, save two that originate from around the Otago region. The team is progressing towards finding the right match for them.
When that happens, it will be an exciting day not just for beekeepers and honeybees, but also for other primary industries such as kiwifruit, aquaculture, and cherries, which could use the same method for treating the different diseases that plague them in the future.
For now, however, Dr Hendrickson and her team would love for beekeepers, especially in Otago, to continue sending them soil samples.
If you would like a free soil-sampling tube and return envelope, please email danielle.kok@canterbury.ac.nz.
