Wine News It's a Bug's Life in the Vineyard

It's a Bug's Life in the Vineyard

Vineyards are teeming with insect life as beneficial bugs do battle with the bad guys.
© Wine Australia | Vineyards are teeming with insect life as beneficial bugs do battle with the bad guys.
Vineyards might look peaceful and idyllic but they are also a battleground in a never-ending insect war.
By Natalie Sellers | Posted Saturday, 24-Oct-2020

Well, 2020 has been such a diabolical year and it would be understandable to wonder what's next –  a massive plague of insects?

However, with the planet staring down the barrel of a sixth mass extinction, that's exactly what's required. Along with regular targets like tigers, elephants and whales sitting in the firing line, a less obvious – but just as profound – part of that extinction has been the steady decline of insects.

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Although most people are aware that the bug world's poster child for conservation, the honeybee, is facing a myriad of threats, but it is far from alone. A 2019 report by the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services suggested that 10 percent of all insect species are under direct threat with another 40 percent in decline.

Not only do these sobering statistics have dire consequences for food production, other animals and entire ecosystems, they also, unsurprisingly, have consequences for wine.

The villains

Italian winemaker Angelo Minelli has spent much of his life in the vineyard having previously worked for Ca' del Bosco in Italy's Franciacorta region, while also running his own family venture, Azienda Agricola Quaresmini, and his observations make for grim reading.

"The bees are not the only one, but the various world of insects near us has disappeared. Over the past 30 years I have witnessed a substantial, almost unidirectional decline of the insects present in our vineyards. Certainly, some variability is normal in all this, generally there are climatic variations and the way in which our soils – such as the change of tree species and urbanization increases – have generated the decrease. These factors should lead to fluctuations but not such profound changes."

The culprits? The usual suspects, as Minelli points out: "The massive and reckless use of insecticides as well as the profound climate changes have led to a drastic reduction in the insects present in our vineyards."

Although, it must be acknowledged that some variability in populations is normal, the heavy-handed and widespread use of pesticides – along with climate change – has left much of the insect world with little refuge.

The heroes

Most people are unlikely to weep over a lack of creepy-crawlies but, for winemakers, their role is essential. As Minelli says: "We often do not give the necessary importance to insects. They constitute 70 percent of animal species and represent a vital element for the planet. The ecosystem represents an important network of connections that can have significant repercussions on human activities."

In the vineyard, hero insects include butterflies, ladybirds and, of course, bees, with pollination and pest control among their chief duties. As Minelli explains: "Many insects have the ability to be active pollinators but in turn can be natural 'pesticides', as one species can feed on another according to the patterns of nature."

In that vein, it's not just the presence of pretty butterflies and ladybirds that can aid vineyard health. Although rather less fetching, predatory mites generally belonging to the Phytoseiidae family are doing fine work in various vineyards in Europe by munching the tiny but lurid yellow and red spider mites. Spider mites, which like to feast on vine sap, prevent the leaves and shoots from properly developing making photosynthesis a challenge.

In the US, it’s the damaging Pacific and Willamette spider mites that chomp on grapes leaves which the Phytoseiidae control and, in northeastern Italy, the Phytoseiidae subspecies Kampimodromus aberrans has become an increasingly valuable pest predator. Many vineyards throughout the world are using predatory mites as a natural alternative to ecologically destructive pesticides, which, depending on the pesticide, certain mites can build up a tolerance to.

The terrifying-looking Phytoseiulus is actually one of the good guys, predating on spider mites.
© Zootaxa | The terrifying-looking Phytoseiulus is actually one of the good guys, predating on spider mites.

The promotion of natural insect predators also helps the wider environment, as Minelli says. "The presence and abundance of predators can be significant when preserving or having wooded areas adjacent to the vineyards. Also the reduction in the use of copper and sulfur used for the fight against diseases preserves the variability of insects."

Wasps are another method of pest control and have been encouraged by certain producers around the world. Certain wasps inject their eggs into the eggs of vine pests, like the light brown apple moth, weevils and mealybugs, annihilating the next generation of nuisance, making for a decidedly sinister but effective form of natural pesticide.

Another important role wasps play is that they help in the spread of the vital Saccharomyces cerevisiae yeast in the vineyard by biting the grapes in order to bring food to their queen. In doing so, they leave a little bit of the yeast they carry in their gut from previous grapes behind, which helps kick-start natural fermentation in the grapes while ensuring yeast strains remain diverse.

However, the role of invertebrates isn't simply restricted to reducing vineyard pests, or prompting fermentation; earthworms play a key role in vineyards by breaking down plant matter and ensuring healthy soils, while naturally tilling the earth. After all, soil is an ecosystem all to itself – rich in microbes and nutrients essential to vine health.

The Chilean company, Biofiltro has capitalized on the amazing composting power of the earthworm by designing a system harnessing the creatures to treat wastewater, making it reusable again for agriculture. It's been so successful, various vineyards in the US like Fetzer Vineyards O’Neill Vintners & Distillers and Northstar Winery are now stalwart fans.

Saving the day?

It's not just in Europe and the US that the benefits of insects are being touted. Holm Oak Vineyards in Tasmania are keen champions of insect biodiversity preferring to use an "integrated pest-management approach" rather than large-scale pesticides.

Although, some pesticides are still used, as Holm Oak winemaker Bec Duffy explains. "Broad spectrum pesticides that kill all insects can be destructive. However, using the correct pesticide at the right time will have minimal impact and will keep the population of unwanted insects below undesirable impact levels. We predominantly use Dipel, which is a biological insecticide, which does not harm important beneficial insects such as bees and insect predators."

Like Minelli, Duffy's focus is to "encourage beneficial insect populations. Provide an environment which is not conducive to the growth in population of harmful insects.”

Building an ideal habitat isn't always at odds with pesticides, as Duffy explains. "Dipel can be used in organic viticulture. The use of insect attracting plants and increased biodiversity in the vineyard can still be achieved if a vineyard is not organic or biodynamic.

"Copper and sulfur products used widely in organic and biodynamic – as well as conventional – to control downy and powdery mildew in vineyards can be harmful to some beneficial insects, whereas some synthetic chemicals used to control these diseases are less harmful."

Eschewing monocultures and restoring biodiversity is key, as Minelli says. "It is important to underline the concept of biodiversity reduction that determines problems on the food chain and consequently on agricultural production – 80 percent of wild plants are pollinated by insects, while 60 percent of birds feed mainly on insects. In the vineyard ecosystem we know how important the activity and the balance between parasites and their antagonists is."

According to Minelli, key methods to help preserve biodiversity include, "the practice of maintaining hedges and grassing improves the presence of insects", along with encouraging, their natural allies, flowers.

These natural pretty assets are key to restoring balance to the vineyard.

"Butterflies love white flowers – such as lily of the valley and echinacea – while bees prefer blue and yellow – rich in pollen – blooms such as daisies. Calendula, nettle and cornflower are much loved by ladybugs," Minelli points out.  Hover flies and lacewings, which both pollinate and prey on destructive aphids, are also drawn to certain highly adapted plants, like phacelia, that can make their home in the vineyard.

So for insects to return to the vineyard, their allies and antagonists need to return too. And let's face it – how bad does the idea of flower-strewn vineyards rich with the buzzing of insects really sound?

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