British research offers hope in varroa battle

British scientists have developed a method that allows researchers to "switch off" genes in the bee-destroying varroa mite, which could eventually be used to drive the mites to "self-destruct".

The treatment is at an early, experimental stage but could be developed into an anti-varroa medicine, the BBC reported.

Varroa was now believed to be widespread throughout New Zealand since first discovered here in 2000, and has cost beekeepers thousands of dollars in chemical control costs. It has the potential to destroy bees' contribution to pollination of crops.

Giles Budge from the National Bee Unit in Yorkshire, northern England, said the mites operated a particularly "severe form of parasitism".

Bee researchers and parasite specialists are using a method called RNA interference (RNAi), which involves putting a tiny chunk of genetic code into an organism which would essentially switch off a specific gene.

The researchers added this piece of genetic material to a solution that they soaked the varroa mites in. The treatment found its way into the mites and switched off the targeted gene.

The University of Aberdeen's Alan Bowman said the RNA "fooled the immune system of the mite" into attacking itself.

"In the experiment, we've targeted a non-lethal gene. Because we were able to monitor it we have successfully silenced it.

"Now, we'll be looking to target genes which, when we silence them, the mite won't be able to function."

The varroa mite, which looks like a tiny brown crab, is believed to be the biggest global killer of honeybees. It injects viruses, suppresses the bees' immune system and feeds on their body fluids.

If untreated, it can take just 1000 mites to kill a colony of 50,000 bees and over the past decade, the mite has developed some resistance to chemical controls.

Researchers hoped to develop the method into a medicine, which could be added to the bees' food.

It could mean a treatment that does not damage the bees.

Currently, beekeepers use chemicals, or mitocides, in carefully controlled doses to control the parasite. They even use trapping methods -- physically removing mites from hives.

Francis Ratnieks, a bee researcher from England's University of Sussex, cautioned that it would be a long time before this technique could be applied in the control of varroa.

It might be possible to use gene knockout techniques to learn more about the physiology of pests and to use this to develop ways of controlling them. But it would be a huge undertaking involving many years of testing and certification, he said.

- NZPA