A biosecurity response team remove a yellow-legged hornet nest from a property in Glenfield, Auckland. Photo / Niki Sherriff
A biosecurity response team remove a yellow-legged hornet nest from a property in Glenfield, Auckland. Photo / Niki Sherriff
Ministry of Primary Industries officials are confident the yellow-legged hornet is still contained on Auckland’s North Shore despite doubts from other biosecurity experts.
The number of worker bees caught by the agency in the past two weeks rose from 600 to 1092 – an 80% increase. Queen hornets have beenfound in Takapuna and Forrest Hill, suburbs bordering the original containment areas of Birkdale and Glenfield.
Biosecurity New Zealand commissioner north Mike Inglis confirmed the Takapuna nest was a primary one (queen only) found on January 25, while two nests in Forrest Hill – a secondary (queen and workers) and a primary – were located on January 22 and 23 through visible monitoring and manual tracking.
As of Monday the tally stood at 1092 workers destroyed, 49 queens located and 51nests. Of the 49 queens, 36 were discovered with nests.
Two queens were found through radio-tracking, in use since December, which has helped locate 10 nests, Inglis said.
The technique – attaching tiny radio transmitters to worker hornets and tracking them back to their nests – had quickly become a core part of MPI’s response. The agency had more than 100 in use and was sometimes able to recover them for reuse.
“Once we have a transmitter attached to a hornet, we are typically locating the nest within a few hours,” Inglis said.
He said the transmitters were deployed as soon as worker hornets reached more than 300mg in weight. Earlier in the season, they were too small to carry the devices.
“The trackers would become increasingly useful as summer progresses and hornets begin building larger secondary nests high up in trees where they’re less visible to ground searchers.”
Former Northland beekeeper and current biosecurity worker Brad Windust has challenged Ministry of Primary Industries’s (MPI) eradication strategy since the first queen hornets were found in Glenfield last October. He remained concerned the radio transmitter technology was introduced too late.
Windust was also critical that MPI hadn’t distributed traps to all beekeepers and orchardists across the North Island, which he believed would have provided early detection if any hornets had hitchhiked to other regions during the busy summer travel period.
He noted it was seven months since the first detection and there had been no vehicle movement control.
Yellow-legged hornet (far left) compared to species established in New Zealand: (from left to right) German wasp (Vespula germanica), Asian paper wasp (Polistes chinensis) and Australian paper wasp (Polistes humilis). Photo / Biosecurity New Zealand
MPI’s Technical Advisory Group, which includes international experts, advised that queen hornets do not travel far when food is abundant.
Inglis said detection patterns supported this with “no indication” that queens from last year had shifted beyond the monitored area.
He pointed to the increasing scale of the operation and the public response – more than 11,060 notifications nationwide – as further evidence that spread beyond the North Shore was unlikely.
Windust argued international flight-behaviour averages were irrelevant if a queen had travelled passively.
“The worst mistake in any eradication programme is assuming containment. If even one queen slipped out, she could produce and release hundreds more queens, putting us straight back to square one next season, just in a different area,” he claimed.
Former Northland beekeeper and current biosecurity worker Brad Windust.
Inglis said nest dissections to date showed no queens had been produced this season and that MPI was confident nests would be located and destroyed before any future queens emerged.
He said traps remained central, with more than 1084 deployed in graded zones extending 11km from detections.
Thermal drones had been trialled but were effective only for estimating the size of a known nests, not for broader surveillance, Inglis said.
Sarah Curtis is a news reporter for the Northern Advocate, focusing on a wide range of issues. She has nearly 20 years’ experience in journalism, most of which she spent court reporting in Gisborne and on the East Coast.
