Biological controls of invasive weed established in New Zealand

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Biological controls of one of New Zealand’s worst invasive weeds – old man’s beard – have been established at several locations in the country.

Old man’s beard, introduced from Europe early last century, is a plant that disrupts native biodiversity. In biological control, living organisms are used to control the pest. Two types of biological control, sawflies and eriophyid mites, were recently released.

The sawflies, an insect from Europe, were released at a South Island site in 2019. A follow-up visit in 2020 showed that new generations of the insect were present. Eriophyid mites feed on the leaves and buds of the plant and can spread through the wind. They were released across both islands in 2020 and have become established in Manawatū-Whanganui, Canterbury and probably elsewhere. A new population was found near Hanmer Springs,​ over 65km from the initial release site.

Speaking at a recent conference, Arnaud Cartier,​ the invertebrate containment facility manager​ at Landcare’s Lincoln facility said that the biological controls will restore the “balance between the weed and its natural enemies.” The project is being conducted by Manaaki Whenua-Landcare Research.

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