Bees fed killed pathogen spores display pathogen resistance

Robyn Williams: And thanks for the prompt; time for another catch-up with Professor James Nieh at University of California, San Diego, he of waggle dance fame. We mentioned the possibility of a vaccine to protect the honeybees from mites, which had been killing so many.

James Nieh: What we're looking here with our mites is we're actually looking at bees, which are sometimes called Africanised bees. These are hybrids with Apis mellifera scutellata, and they are thought to be more resistant to mites. What we're doing right now with that is we're trying to document the differences in their behaviour and that of our managed honeybees, the European honeybees, to see if we can figure out how they survive, because these feral bees are not treated for mites, they either live or die. And what we have found so far is they have about the same level of mite infestations, and they are about as hygienic, meaning anti-mite behaviour, as our managed colonies. So we think the answer is actually that they flee, they abscond more readily when they have a heavy mite load, and therefore that they are released from the pressure of these parasites, they can go and found a new nest and therefore have a lower mite density.

Robyn Williams: But you haven't mentioned the way in which they might be protected by something you're working on.

James Nieh: Right. So the other thing we're looking at is Nosema. So Nosema, I should actually say Vairimorpha, that's the new genus name that scientists have, although most people will know it by Nosema. It's a very common disease, it's found all over the world, it infects the majority of all colonies at some time during their colony lifecycle, and it causes a kind of dysentery. It reproduces in the gut, and it generally reduces honeybee health. It typically is not the cause of bee death but it contributes to other stressors that they have.

We in this case are taking a book from the early history of vaccinations, where we took this pathogen, these spores, we heat-killed them in an autoclave, and we fed them to young bees, either as larvae or as newly emerged adults. And we found that when they were subsequently challenged by being fed live spores, which is the usual infection route, that they were significantly more resistant.

So if you remember the old cow pox days where you were vaccinated with cow pox, and then later on you were more resistant or even actually the development of many vaccines begins with administering a heat-killed vaccine, either injected or orally, and then you see that your immune system is able to recognise that and act accordingly when you're exposed to the real thing later on.

Robyn Williams: I hope that works and it saves the bees.

James Nieh: We do hope that it will be helpful for the bees.

Robyn Williams: Professor James Nieh in San Diego.

Entomologists are searching for a solution to honeybees being impacted by Varroa mites. The mites mainly feed and reproduce on larvae and pupae causing malformation and weakening of honeybees, while transmitting a range of viruses. Infestation ultimately causes a reduction in honeybee population, supersedure of queen bees and eventual colony breakdown and death.

James Nieh's lab at the University of California San Diego is investigating inoculation. They have taken the spores of another pathogen, and after heat treatment, fed the dead spores to larvae. The larvae then show more resistance to live spores. James plans to try a similar approach with the varroa mites in the hope the approach may lead to a treatment for colonies infected with varroa mites.

Nieh Lab at UC San Diego

GuestJames NiehProfessor of Biological SciencesAssociate Dean of Biological SciencesUniversity of CaliforniaSan Diego CA USA

PresenterRobyn Williams

ProducerDavid Fisher

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