Aphids wreak havoc on Wairarapa hives

Hives with many frames of this crystallised sugar may lead to bee starvation. PHOTO/SUPPLIED

An invasive species of giant aphids, whose honeydew killed 40 eels in Longbush last month, is also killing bees in Wairarapa, according to a researcher.

"Billions" of giant willow aphids infested a Longbush property over summer, secreting honeydew from willows which killed the eels on the property.

Dr John McLean from the National Beekeepers Association of New Zealand said that was not the only problem the giant willow aphids had caused.

He is doing research to introduce a biological control agent to combat the species after a few beehives in Wairarapa were recently lost to starvation as a result of the aphid's honeydew.

"We need to get this aphid under control, otherwise the bees are going to be starving by the winter time," he said.

When the bees collect the aphid's honeydew, they take it back to the hive where it crystallises, forming solid melezitose crystals "which are only 14 per cent soluble".

Dr McLean said the melezitose itself was not a good source of nutrients for the bees.

"A beekeeper can lift up the box which would be heavy and think there are good stores for the bees in winter, but really it's rubbishy melezitose, and the bees starve."

Dr McLean said it was also difficult for beekeepers to extract the melezitose from the hives, with beekeepers having to clean their extracting apparatus every five or six boxes, as opposed to every hundred boxes with purer honey.

"I've been searching world literature and have found that in England, the willow aphid is more or less in check by a fungus [Neozygites turbinatus] which penetrates and kills the aphid.

"Trying to bring a biological control agent from overseas is a tough thing to do though so it's going to be a bit of a challenge for the scientists at Scion to lock into this, but we're hoping to persevere with it."

The Apiculture New Zealand Research Focus Group made an application to the Sustainable Farming Fund for support for scientists "to get on to this, but they didn't fund us this year". However, scientists and researchers were doing preliminary work "to get a handle on the situation", Dr McLean said.