This blog post was written by postgraduate student Juan F. Dueñas Serrano as part of the course, Research Methods in Ecology (Ecol 608).

Set aside your work for a moment. Look for your favourite spot at home and allow yourself a moment of pleasant rest. Take a bottle of your preferred New Zealand wine and enjoy a sip while you read the label on the bottle. Does the description match your expectations? Hopefully, it will be a brief summary of the characteristics that help to define this delightful drink. Sometimes, labels will describe a picturesque bucolic scenery or use the notion of profound human values to remark on the quality of the product. Virtues such as honesty, character and, why not, spirit, are all often associated with wine. So let’s think about where all these images and language come from.

Leafroller moth’s caterpillar (Epiphyas
postvittana) on a grape leaf.
Photo by Jean Tompkins, Lincoln
University (used with permission).

Winemaking starts at the vineyard. It requires many years of study, experience and sometimes intuition to yield a grapevine that will satisfy the demands of discriminating consumers. But more than that, it requires a gifted land. Remember that the wine industry is a multi-million dollar business, so grapes are to be carefully selected and cultivated yet they also have to come in great volume. Accordingly, vineyards generally tend to become extensive mono-cultures, and like any other intensive resource use, this practice radically changes the landscape and carries with it a series of associated problems, such as increased vulnerability to pests. In the case of New Zealand vineyards, the introduced Australian leafroller moth Epiphyas postvittana is the unwanted guest and it must be controlled.

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Up until now, the conventional approach has been to apply pesticides over the precious vineyards to get rid of the inopportune ‘bug’. But this presumably affects the environment, increases the cost of the final product, and potentially, will have a negative impact on the very glass of wine you are enjoying. The solution might come from nature. Regulation of insect populations by predation occurs naturally in an ecosystem, thus, if handled carefully, this capacity might potentially provide the agricultural landscape with a service, an ‘ecosystem service’. This concept provides the basis for an alternative approach that tries to encompass the demands of a complex industry and the need of a truly sustainable landscape. After all, land is where the spirit of wine begins its journey.

This alternative to pesticides involves the manipulation of the habitat to enhance biological control, and it offers a great potential. A recent study published in the Journal of Applied Ecology by Mahumuda Begum and colleagues, including Lincoln University‘s Steve Wratten of the Bio-Protection Research Centre, features a series of greenhouse and field experiments that test the ability of selected flower’s nectar and pollen to enhance the function of the omnivorous parasitoid wasp Thichogramma carverae. This was is a natural enemy of the light brown apple moth. Flowers potentially supplement the wasp diet by providing important resources such as sugar from the nectar and protein from pollen.

The main idea behind this approach is to incorporate selected flowering plants into the agroecological scheme of vineyards, hence naturally increasing the density and longevity of the wasp. This approach benefits the vineyards in different ways. First, by avoiding the costs associated with breeding up and releasing large numbers of the parasitoid. Second, by reducing occurrence of weeds and cover crops that can potentially host different stages of the pest by planting instead the selected plants; and third, by reducing both the cost and the amount of pesticides that need to be applied to vineyards.

Allysum (Lobularia maritima) strips in an organic lettuce crop.
Photo from Lincoln University (used with permission).

But the process is not straightforward. Experiments were needed to determine the best plants to provide the required ‘ecosystem service’, in this case biological control. The selected plants should not interfere with the wasp’s ability to parasitise the moth. Additionally, the plants have to be a below-vine, shallow-rooted crop to avoid resource competition with grapevines. After conducting greenhouse experiments with combinations of several plant candidates in the presence of the parasite wasp and the moth, a trial in the field was performed to test greenhouse findings in a realistic situation. From the five plants originally selected, Begum and colleagues concluded that sweet alyssum (Lobularia maritima), a common garden plant, is the most effective candidate for the purpose described above.

This study demonstrates how the careful and informed manipulation of natural resources can improve the provision of ecosystem services. By integrating research on the functions that ecosystems naturally provide with reasonable economic revenue, we are taking a step forward towards the sustainability of our land. These alternatives to conventional practices are promising and will enable us to work with nature instead of against it. We will be assuming our role in providing environmental stewardship, or kaitiakitanga as Maori people beautifully put it, while giving wine a rightful ‘green spirit’.