Can Harmonia axyridis affect the taste of European wines?

Abstract: The multicoloured Asian ladybeetle Harmonia axyridis Pallas is now established inCentral Europe and is likely to spread soon over the whole continent. In the United States, H.axyridis moves to vineyard shortly before harvest. When disturbed or crushed during vinification,the ladybeetles release alkylmethoxypyrazines, which can strongly affect the quality of white andred wines. In Europe, wine growers are beginning to worry about the impact of H. axyridis on thequality of their processed wines. In this study we artificially contaminated harvested grapes of thevariety 'Chasselas' and 'Pinot noir'', the two main varieties of Switzerland, with three differentdensities of H. axyridis and determined the impact of crushed ladybeetles on the taste ofprocessed wines. The addition of ladybeetles did neither affect fermentation nor the basicchemical properties of processed wines. However, at the organoleptic level the contamination ofgrapes had a significant effect. Contaminated 'Chasselas' wines were of lower fruitiness, fineness,structure, acidity, equilibrium and exhibited a "rancid oil" odour. Moreover, the quality ofcontaminated 'Pinot noir' was rated low, in particular, its fruitiness, spiciness, fineness, structure,softness, robustness as well as intensity and quality of tannins was poor. Even though H. axyridisis rarely present in vineyards of Western Switzerland, our results emphasise that there is a risk ofwine contamination. Thus, the evolution of the multicoloured Asian ladybeetle in Europeanvineyards should be carefully monitored in order to anticipate future problems.