US varroa discovery offers hope for NZ bees

Ground-breaking discoveries by United States researchers could eventually help protect New Zealand honeybees from the deadly varroa mite that has killed off many of the nation's feral bees and damaged the economics of running apiaries.

Michigan State University researchers have been able to produce in the laboratory for the first time proteins that help channel sodium ions through cell membranes of varroa mites - which could lead to development of a specific varroa control which would not affect bees, according to the research, which was published in the Journal of Biological Chemistry.

In New Zealand most varroa control is done with chemical miticides such as fluvalinate, which paralyses the mite and eventually kills it.

However, there are growing concerns that varroa may develop resistance to fluvalinate (sold as Apistan) - something which is already happening overseas, including in the United States.

"The insecticide used to control varroa mites, fluvalinate, targets the mite sodium channel," said Professor Ke Dong, an entomologist.

"Successfully producing the mite sodium channel in the lab now allows scientists to develop new chemicals that target the mite sodium channel but don't affect the honeybees."

The researchers also found an amino acid in the mite sodium channel that made the pest resistant to tetrodotoxin, or TTX, a deadly poison found in puffer fish not currently used as an insecticide.

TTX is thought to be the toxin in grey side-gilled sea slugs which has been killing dogs on Auckland and Coromandel beaches - it is apparently present in beach sediments.

Varroa mites can kill an entire hive within a year, feeding on bee blood and transmitting viruses.