Happy Wednesday Thursday, lovely readers. My heart wanted to get this in your inbox on Wednesday morning, but my job and kids said otherwise. Today we are talking about ladybugs (yes those cuties) and the effect they can have on wine.
In 2019, I found myself working in the cellar of a small winery in Tuscany thanks to a desperate call from my dear friend Anastasia. I arrived just as the harvest began, joining her and the assistant winemaker, Simone. The workload was beyond what the two of them could possibly handle after the winemaker acquired a new vineyard and decided to start producing a secondary line of wines. Lunchtime was our reprieve from the long and laborious days, and about once per week we would sneak out of the cellar for an indulgent hour at the local agriosteria. Agriosteria del Frantoio serves traditional Tuscan fare composed completely of the highest quality raw materials: Tuscan PGI Extra Virgin Olive Oil that they mill, organic vegetables that they grow, ancient grains, and an entirely Tuscan wine list highlighting producers who share their love & respect for the territory.
It was during these lunches that I was able to taste drink a slew of wines from subregions and grapes I had never seen in the USA, made in styles that I had never experienced from Tuscany, by producers who are too small to export to the USA. The wine list was tiny, so naturally it challenged us to try every wine offered. Had we just a few more weeks together, I have no doubt we would have accomplished just that. Anastasia and I had a few epigrams we would shoot back and forth throughout our time working together, one of which was, “not all Supertuscans and Roundup”, our way of acknowledging the wave of holistically produced regional wines, far beyond the stereotypical straw bottle Chianti and obsequious International blends.
During one of our last afternoon escapes, we ordered a bottle of bianco macerado (orange wine for you cool kids) made of Trebbiano, Malvasia, and Vermentino by a producer called Calafata from central Tuscany in the province of Lucca. The server who had come to know us over the past weeks eagerly suggested it and we were heightened with excitement as he opened what we hoped was another one of a kind bottle. As I took in my first sniff, the aroma I met was far from what I was expecting and quite unpleasant. Peanut butter, pickles, green peppers, more peanut butter. “Is this… how it is meant to smell?”, I thought to myself. I had little context for wines that would be considered “natural” at that point in my career, so I didn’t make a stink about it and we just rolled on with lunch as per usual.
When I made it home to Detroit and returned to my restaurant job, I couldn’t stop thinking about the peanut wine. I hounded everyone that I thought might have an inkling of wine knowledge in their brain,“Have you ever had wine that tastes like peanuts? Like pickles and asparagus and peanut butter??”. No one had a clue, passing it off as simply “natty funk”, until my OG mentor casually said “I’ve heard ladybugs can do that” as he walked by me. That was the extent of the conversation.
Well, now it’s 2023 and I’ve tasted thousands of wines since our days at the Agriosteria, but I can still taste the peanuts fresh on my breath anytime I think of that wine.
Before I get into the mildly scientific section of this Substack, let’s get a few things straight:
Vineyard dwelling Coccinellidae, specifically Harmonia axyridis, aka multicolored Asian lady beetle (MALB), let’s call them ladybugs.
Alkyl-methoxypyrazines are a group of odor active compounds that ladybugs emit for certain behavioral functions, aggregation, and mate attraction. Peanuts, green bell pepper, earthy, asparagus are all aromas and flavors associated with these compounds. We will refer to them as MPs.
2-isopropyl-3-methoxypyrazine is the most abundant type of MP given off by ladybugs, it displays aromas of “peanuts”, “potatoes”, “peas”, and “earthy”. These are IPMPs.
Basically, ladybugs aggregate on grape bunches in the vineyard as harvest draws near, ride the grapes into the winery, get crushed into the juice, and their dying bodies give off MPs that have an effect on the aroma and flavor of the wine (they can actually impart the same MPs postmortem too 💀). Seems premeditated if you ask me. To my understanding, Ladybug taint was not investigated until the early 2000s after a group of North American vintners linked the unpleasant aromas widely affecting their wine to the crushed ladybugs. This begins to explain its absence from major wine educational publications (i.e. CSW, WSET, CMS) where faults like TCA, mercaptan, and brettanomyces are well recorded. The implicated ladybugs, Harmonia axyridis, originate from Asia and were artificially introduced to North America and Europe as a form of aphid control, but they are invasive and climate change is only increasing their survivability and dispersal. According to a 2007 study by Pickering et al. published in the Journal of Food Science, thresholds for detection of LBT are expected to get lower the more widely it is discussed in wine communities [1]. I don’t want to imagine tasting more foul peanut butter wine soon, but I fear it may be inevitable when we couple climate changes in North America with the rise of minimal intervention winemaking.
It turns out that this fault is detectable at extremely low levels. Most aromatic and volatile components in wine are present and active in the µg/L to mg/L range [2,3], while MP concentrations are measured in parts per trillion or ng/L [4], and contribute to aroma at these trace concentrations [5,6,7,8]. IPMP is detected at lower levels in non aromatic white wine as compared to aromatic whites or reds. This makes me think my sensitivity may be higher for IPMP than my sensitivity to cork taint *cue embarrassing story about presenting a ~mildly~ corked wine to a buyer last week*.
I know what you’re thinking, “but Caroline, I love my green bell pepper aromas in Chinon and my earthy notes in Bordeaux… is this because of ladybugs??” Rest assured, MPs are endogenously produced by varieties such as Cabernet Franc, Cabernet Sauvignon, Sauvignon Blanc, and Carmenère. At low levels, these MP aromas add to the complexity of well made wines, but when they rise to higher concentrations an unbalanced greenness/earthiness can spoil the enjoyment (just like LBT).
One could argue that ladybug taint is not a fault at all, and it is simply a pure reflection of what was happening in the vineyard that growing season aka terroir. Others may argue that what was reflected was poor vineyard management. Everyone’s palate is calibrated differently both naturally and by training, so there is no universal right and wrong when it comes to aroma and flavor. All I know is I really don’t like peanut butter wine. At least now, I have someone to blame 🐞(thanks science).
Have you ever tasted LBT affected wine? Or am I just a total nut job? Pun fully intended.
Talk soon 🐛