THE SCIENCE
Wētā Work Burrowing into the behaviour of ground weta SOPHIE PREECE Luring wētā away from the “buffet” of budburst is a potential outcome of research into the native insect munching Awatere Valley vines. The project, funded by the New Zealand Wine Futures Fund (NZWFF), seeks to develop an environmentally and economically sustainable solution to the growing problem of ground wētā, Hemiandrus bilobatus, grazing tender foliage in spring.
“We are trying to understand what the insect is after feed-wise at that time of the year.” Dr Jessica Vereijssen “That’s a real challenge,” says Dr Jessica Vereijssen, a crop protection entomologist at Plant & Food Research, who is used to working with introduced pest species like the meadow spittle bug, a potential vector for Xyella fastidiosa. “With a lot of the horticultural pests we work with, the last option - if you can’t find a solution - is always to spray them with a pesticide. With the wētā, we have to make sure it stays alive and that we don’t affect it.” The three-year project will build on work already done by Lincoln University and Massey University, and on the existing management tool of wrapping plastic sleeves around vine trunks to deter wētā from accessing the shoots. The plastic sleeves are costly to install and maintain, and they result in a significant waste management issue, so the new project will look at practical and environmentally sustainable alternatives, such as planting a crop between the vines, providing a sweet food source at budburst to disrupt the vine grazing. “We are trying to understand what the insect is after feed-wise at that
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Dr Jessica Vereijssen
time of the year, in the vines,” says Jessica. “And whether we can change its behaviour, by luring it away, for example, from the vines and providing it with a more suitable habitat and more suitable feed.” Professors Mary Morgan-Richards and Steve Trewick of Massey University’s Wildlife and Ecology Group, co-authors of Ecology and systematics of the wine wētā and allied species, with description of four new Hemiandrus species, have already gained good insights into the natural behaviour of the wētā in some Awatere vineyards and will be an important part of the project team, says Jessica. The new project, starting 1 July, will build on their learnings, in discussion with impacted growers and also Mana Whenua, perhaps learning how Māori interacted with wētā in traditional gardens. Like much of her work, it will require the enquiry and deductions of a detective, says Jessica. “I love that. Where do they go? Where do they sleep?” Researchers will watch the wētā behaviour over budburst, then again in February, to see whether they clamber up vines at other times of the year. “It’s a really simple question, but we don’t know that. If
they are always in the vines, is it possible they are providing a biological control of, say, mealybugs? If we lure it away, would it increase the mealybug problem in vineyards?... These are things we would like to find out, through talking to people and observations as well.” Jessica says it’s important that any solution is practical and economically viable for growers to implement, while also protecting the interests of the insect. The NZWFF is funded through New Zealand Winegrowers levies and project managed by Bragato Research Institute (BRI). The wētā project has co-funding from Indevin, Pernod-Ricard, Yealands and Hortus to support a Massey University PhD student. BRI Project Manager Stephanie Flores says the proposal was a great fit for the Futures Fund, where the requirement was novelty. “Plant & Food Research is a key research partner, and we’re excited to be working with Jessica for the first time,” Stephanie says. “She brings experience working in various crops throughout New Zealand, as well as a fresh approach to wine research that brings together social science, ecology and financial sustainability.”
The ground weta vineyard project is one of two initiatives starting this year thanks to funding through the New Zealand Wine Futures Fund. The second is a University of Auckland project looking to upcycle grape marc using advanced microbiological methods.
I NEW ZEALAND WINEGROWER I JUNE/JULY 2022