Battle against varroa mite boosted by fungal development
Help may be in sight at last for New Zealand beekeepers battling varroa mite infestations.
Ruakura Plant and Food Research scientist Dr Mark Goodwin and his team have officially announced a new natural weapon in the battle against the mite, and media reports say the new product is expected to be on the market next year.
The recent development is based on metarhizium, a common fungus which grows naturally in soils throughout the world and causes disease in various insects by behaving as a parasite. It is harmless to bees and humans. The Waikato scientist found that the longer it was used, the more mites it killed, and he has reported mite mortality rates of about 90 per cent.
The voracious parasite, which feeds on the pupae of bees, has been devastating bee populations overseas and in New Zealand as there are no wholly effective chemical treatments. For organic apiaries, treatment options are even more limited. An alternative to the available miticides has been eagerly awaited, and reports suggest the product will replace three synthetic treatments. With roughly one third of New Zealand’s food sources reliant on pollination by bees, it was difficult to estimate how much the new product would be worth to the economy, said Dr Goodwin, who is regarded as a world leader in his field.
The varroa mite arrived in New Zealand nine years ago and reached Golden Bay last year after infected hives were brought in from the Motueka region. Since then, local beekeepers have been trying to fight the parasite with alternative treatments, as many fear losing their organic status.
Beekeeper Keith Tomlinson, who runs Heaphy Honey with his partner Nancy-Jean Bell, has been struggling with organic control methods that have proved to be time-consuming, expensive and not very effective. He said the fungal product showed a lot of promise though it remained unclear how it was going to be kept in the beehive. Previous organic agents have been rejected by the bees themselves.
“Bees clean out anything that does not belong in the hive, and will biff the spores out. It has been a problem so far finding a vehicle to keep the fungus inside the hive so it can do its job. It is cumulative, and the fungus will have to stay in the hive for several weeks to be effective,” said Keith.
“The commercial products available now have a high kill rate until of course the mites develop a resistance, as they have done overseas. This is why people have been trying to develop a natural way to control varroa. It is not going to be 100 per cent effective and will not kill varroa completely, and may still need to be combined with another control method. Maybe the new product will be cheaper and effective. We just don’t know yet.”
The effect of the mites on bee populations was already obvious said the beekeeper. He has already been approached by people with home orchards who face problems with pollination this season and predicts that, based on the overseas experience, all the uncontrolled beehives and all the wild bee populations will disappear in the near future.
Ina Holst
