Lace bug helping with woolly nightshade war

18 August 2014

Bay of Plenty Regional Council has been testing out a new weapon to fight the pest plant woolly nightshade. The results are looking promising especially for forest owners.

Regional Council Land Management Officer Andrew Blayney said heavy damage to woolly nightshade has been seen at a Welcome Bay property this year following the release of 300 lace bugs there in 2010.

“It’s a landowner’s responsibility to control woolly nightshade on their own property. We help them do that as effectively as possible, such as by testing new control methods. We’re one of the first regions to use the lace bug through the National Biocontrol Collective. We knew it would take some time to see the results, but this year we’re really starting to see the bugs make an impact across the whole 70 hectare site,” he said.

“This is part of our work to keep woolly nightshade in check throughout the Bay of Plenty. We’re increasing our surveillance, compliance and biological control development efforts now, instead of directly subsidising landowner control efforts,” Mr Blayney said.

Woolly nightshade is a problem weed because of its ability to grow in dense stands that crowd out more desirable pasture and forest plants. It is covered in fine hairs which can cause skin, eye, nose and throat irritations for people and stock who come into contact with it.

The lace bugs feed on the leaves of woolly nightshade, drying them out and stunting the growth of the plant. This prevents plant reproduction, reducing spread, and can eventually cause the plant to die.

“We’re getting better results from the lace bugs here than in other parts of the country. They’re doing especially well in shaded areas such as under pine trees. That’s a good sign because controlling woolly nightshade in pine blocks has been difficult to date,” said Mr Blayney.

“Traditional control will still be needed. We can’t supply lace bugs for use on all properties in the Bay of Plenty, but once established in our worst affected areas, they should help reduce large weed infestations and will disperse naturally on to surrounding properties over time.”

“The next release sites will be large pine blocks that are infested with woolly nightshade. We’d love to hear from anyone that has a suitable site,” Mr Blayney said.

Land occupiers in the Bay of Plenty are legally responsible for controlling woolly nightshade on their own properties. Information on controlling woolly nightshade and other weeds is available at www.boprc.govt.nz/pestplants or by calling a Land Management Officer, phone 0800 884 880.

The 2010 Bay of Plenty lace bug release was completed through the National Biocontrol Collective which is made up of regional councils, unitary authorities and the Department of Conservation, working together with New Zealand Landcare Research who led the lab testing and breeding.

“Lace bug is originally from South America. We followed a really rigorous process before releasing it here – that included ten years of research by New Zealand Landcare Research, consultation with iwi and approval by the Environmental Risk Management Authority,” Mr Blayney said.

Facts about lace bug
• The lace bug is 5mm long
• Like woolly nightshade, lace bugs are native to South America.
• Female lace bugs can lay up to 900 eggs 0.5mm in length.
• The lace bug has been used successfully as a biocontrol agent in South Africa for a decade
• See Landcare Research factsheet for further information:http://www.landcareresearch.co.nz/__data/assets/pdf_file/0018/20547/Woolly_Nightshade_Lace_Bug.pdf

Facts about woolly nightshade
• Scientific name: Solanum mauritianum
• Also known as tobacco plant
• A shrub or small tree, growing up to 10m tall
• Leaves are large and greyish-green, covered in felt-like hairs and has a kerosene-like pungent smell when crushed
• Flowers are purple clusters at ends of branches almost year-round
• Large berries – initially green but ripen to yellow
• Toxic to humans and possibly stock – irritates the skin, eyes, nose and throat
• Seeds mostly spread by birds
• Native to South America and introduced to New Zealand as a garden plant

Visit the Bay of Plenty Regional Council website for high resolution images

ENDS

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