Remember when those red, spotted beetles were seemingly everywhere earlier this year?
Due to warming temperatures, those pesky bugs are growing in numbers — and Brock University researchers have provided research-based strategies for managing their impact on grape and wine production in a special climate change edition of Biomolecules.
“This international collaboration between a leading viticulturalist, oenologist and industry extension specialist brought together three complementary skill sets to compile this comprehensive review and contextualize the research for winegrowers,” said leading author Gary Pickering, Professor of Biological Sciences and Psychology and Researcher at Brock’s Cool Climate Oenology and Viticulture Institute (CCOVI). “It is aimed at better understanding the impact climate change will have on the grape and wine industry, including considerations such as the increased presence of this invasive pest.”
The publication, “Prevalence and Management of Alkyl-Methoxypyrazines in a Changing Climate: Viticultural and Oenological Considerations,” was co-authored by Jim Willwerth, CCOVI Researcher and Assistant Professor of Biological Sciences; Andreea Botezatu (PhD ’14), of Texas A&M University; and Margaret Thibodeau, who successfully defended her PhD thesis in Biological Sciences at Brock earlier this year.
The authors explored the impact that climate change will have on the presence of methoxypyrazines, a class of molecules that contribute ‘green’ characteristics to wine.
CCOVI has been a world leader on research in this area.
These chemicals are naturally occurring in some grape cultivars, and can, in low levels, contribute favourably to the overall flavour profile of certain wines (like Sauvignon Blanc, for example).
In higher quantities, however, they produce an undesirable flavour that is likened to green pepper or peanut butter.
The compounds can also be introduced when Harmonia axyridis, or multi-coloured Asian ladybeetles, are inadvertently crushed and incorporated in with the grapes at harvest.
While these invasive pests have been present in wine-growing regions around the world for the last decade or so, warmer temperatures in Canada are allowing them to live longer and reproduce in higher numbers.
“They usually die off because our winters are so cold, but they are now surviving longer and since they are able to proliferate early in the season — and can actually get two or three generations in one season — there’s now more around on a regular basis,” Pickering explained.
The article outlines that there are insecticides and repellents that have shown promise for managing the presence of these ladybeetles in the vineyard, as well as remediation practices that can take place in the winery. The authors also note that viticultural practices, such as implementing a vine training system to increase temperature and light exposure, also have potential to manage concentrations of the chemical in its naturally occurring form in the grape.
“How the grapes respond to climate change is going to be dependent on the part of the world, and even the appellation that we’re talking about,” Pickering added. “For instance, we have a really interesting story here in Canada this vintage, with our two major grape growing regions —Ontario and B.C. — experiencing polar opposites in terms of weather and related vineyard stressors, yet both scenarios are predicted from the climate change models.”
That’s why the collaborative work that CCOVI and its partners do to support the grape and wine industry is more important than ever.
“Increased frequency of extreme weather events happening during the growing season are going to have different impacts, so it’s important for us to continue doing research on flavour compounds such as methoxypyrazines to better understand how to mitigate the impacts of climate change and maintain the high quality of our wines here in Canada,” Pickering said.