Bee industry awaits sign of latest threat

NEW ZEALAND bees could be vulnerable to a mysterious condition which has wiped out thousands of northern hemisphere hives, says a leading researcher.

Dr Mark Goodwin of HortResearch says though our bees "are looking great" compared to those overseas at the moment, the experience of the past 25 years suggests that eventually everything gets here for example, the parasitic varroa mite, which attacks honey bees.

Colony Collapse Disorder (CCD) results from a loss of the foraging bees and also the house bees, leaving the hive so depleted it cannot maintain the standard temperature of 35C required to keep the brood (the larva and pupa stage) viable and the hive dies out.

Bees play an integral role in the world food supply by pollinating fruit and vegetable crops but Europe has been experiencing a catastrophic loss in bees, and England has reported a 50% loss in its most recent season. The events might not be linked.

Despite the best efforts of American scientists, the cause of CCD remains unknown.

A varroa-borne virus is uppermost on the list of Goodwin's suspects.

Another prominent suspect is the introduction of a new breed of insecticide over the past 10 years: neonicotinoids that work by disrupting insects' nervous system. There is a widespread suspicion that these chemicals are finding their way into the nectar to be picked up by foraging bees.

Tests on dead bees in one region in Germany showed that 99% of those examined had a build-up of the neonicotinoid Clothianidin sold by Bayer under the trade name Poncho. The company said that this was a result of an application error.

In New Zealand, the Environmental Risk Management Agency has licensed 23 neonicotinoid-based products on the market, including Poncho.

Penn State University entomologist Maryan Frazier has said that the sheer number of chemicals in bee hives meant pesticides had to be suspected.

"Bees die for all kinds of reasons and insecticides are a biggie," Goodwin says. But he thinks the evidence that insecticides cause CCD is not compelling. It would not explain why the house bees leave the hive, as well as the foraging bees, suggesting a pre-existing condition. Sick bees usually leave the hive to die, he says.

Controlling varroa and its deadly passengers remains the prime focus of New Zealand beekeeping research.

HortResearch has a programme on Mercury Island aimed at breeding a varroa-resistant bee but Goodwin says this should be seen as a tool to help against varroa rather than as a magic bullet.