Giant willow aphid found in Hawke’s Bay

Hawke’s Bay Regional Council is monitoring the spread of the Giant willow aphid after the insects were recently discovered on willows by most of our rivers.

“We are starting to find the Giant Willow Aphid, and getting reports of it being in a few locations so this bug is definitely in Hawke’s Bay. So far, it seems that not a lot is known about the insect, or just how badly it could affect the willows long term,” says Mike Adye, HBRC’s Group Manager Asset Management.

This aphid was first detected in New Zealand in December last year. Since its discovery the insect has been reported from Northland, Auckland, Bay of Plenty, Taranaki, Gisborne, Hawke’s Bay, Wairarapa and Tasman District.

Plant & Food Research and the Ministry of Primary Industries provided information to HBRC on the aphid, and HBRC Works Group staff went looking for signs of the insect along the rivers. HBRC is also getting more reports from members of the public.

Mr Adye says that the damage is currently only on a few individual trees but the insect has been found at most Hawke’s Bay rivers.

“This could potentially be another threat to our willow edge protection zones, so we will be taking a very keen interest in any new information released and particularly any control methods that may be available.”

From 2005 HBRC battled Willow sawfly, an insect which defoliated many of the willows used for flood protection alongside stretches of Hawke’s Bay rivers. HBRC spent $9M on remedial action to keep the flood protection up to a high level. New tree species were planted to withstand further sawfly infestations and to help protect the stopbanks. Trees planted to replace willows devastated by willow sawfly are now well established and the river protection is back to where it was before the pest devastated the willows.

Background information attached but in summary:

Tuberolachnus salignus (Giant willow aphid) is a very large aphid with a body length of 5.0-5.8 mm. Wingless individuals (Apterae) are mid-brown to dark brown with several rows of black sclerotic patches. The early season colonies appear in summer and are situated at the base of the willow trees, moving up the stems with increasing numbers. In summer, colonies formed by individuals dispersing from other infestations start higher on the stem, some up to 3.5 m from the ground. By late summer colonies can contain tens of thousands of individuals. Colonies persist through the autumn and although they decline in late autumn, they continue to feed on the stems after leaf fall and into winter.

Hawke’s Bay Regional Council is monitoring the spread of the Giant willow aphid after the insects were recently discovered on willows by most of our rivers.

“We are starting to find the Giant Willow Aphid, and getting reports of it being in a few locations so this bug is definitely in Hawke’s Bay. So far, it seems that not a lot is known about the insect, or just how badly it could affect the willows long term,” says Mike Adye, HBRC’s Group Manager Asset Management.

This aphid was first detected in New Zealand in December last year. Since its discovery the insect has been reported from Northland, Auckland, Bay of Plenty, Taranaki, Gisborne, Hawke’s Bay, Wairarapa and Tasman District.

Plant & Food Research and the Ministry of Primary Industries provided information to HBRC on the aphid, and HBRC Works Group staff went looking for signs of the insect along the rivers. HBRC is also getting more reports from members of the public.

Mr Adye says that the damage is currently only on a few individual trees but the insect has been found at most Hawke’s Bay rivers.

“This could potentially be another threat to our willow edge protection zones, so we will be taking a very keen interest in any new information released and particularly any control methods that may be available.”

From 2005 HBRC battled Willow sawfly, an insect which defoliated many of the willows used for flood protection alongside stretches of Hawke’s Bay rivers. HBRC spent $9M on remedial action to keep the flood protection up to a high level. New tree species were planted to withstand further sawfly infestations and to help protect the stopbanks. Trees planted to replace willows devastated by willow sawfly are now well established and the river protection is back to where it was before the pest devastated the willows.

Tuberolachnus salignus (Giant willow aphid) is a very large aphid with a body length of 5.0-5.8 mm. Wingless individuals (Apterae) are mid-brown to dark brown with several rows of black sclerotic patches. The early season colonies appear in summer and are situated at the base of the willow trees, moving up the stems with increasing numbers. In summer, colonies formed by individuals dispersing from other infestations start higher on the stem, some up to 3.5 m from the ground. By late summer colonies can contain tens of thousands of individuals. Colonies persist through the autumn and although they decline in late autumn, they continue to feed on the stems after leaf fall and into winter.
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