Efficacy of kaolin treatments against Drosophila suzukii and their impact on the composition and taste of processed wines

Drosophila suzukii is a very polyphagous species that can also tack and develop in a great variety of grape cultivars. In Switzerland, the control of D. suzukii mainly relies on prophylactic measures and kaolin, a white inert aluminosilicate mineral who's particles stick to the leaf surface and form a physical barrier that help to reduce ovipositions by the pest. Here we present a synthesis of our recent insights on the efficacy of kaolin against D. suzukii as well as on the chemical and sensory properties of the wines vinified from kaolin treated grapes. In autumn 2016, kaolin (Surround WP®) was applied in 23 field trials on various cultivars located in various winegrowing regions of Switzerland. Overall, kaolin achieved an average efficiency of 54 % and no significant differences could be observed between kaolin applications at 1 % and 2 % with 56.8 % and 57.1 % efficacy, respectively. At the higher concentration, the preventive and curative strategy were also nearly as effective with efficacies at 67.4 % and 50.3 %, respectively. In addition, a field experiment was set up on the red grape cultivar 'Mara' in 2015. This experiment revealed that three applications of kaolin at 1 % or 2 % did neither affect fermentation nor the usual chemical properties of kaolin treated wines compared to the untreated control. However, aluminum concentration within wines increased with the applied dosage of kaolin but the measured aluminum levels were 38-times lower than the maximal German threshold of 8 mg·L-1. Moreover, tasters were also not able to distinguish the aroma and the taste of wines processed from kaolin treated grapes from the untreated control. We therefore conclude that kaolin applications are effective against D. suzukii and do not cause any major risks to the environment, to wine quality and to human health

Influence of processed Halyomorpha halys bugs on the aroma and taste of 'Chardonnay' and 'Merlot' musts and wines

Native to East Asia, the invasive brown marmorated stink bug (Halyomorpha halys) was accidentally introduced into Switzerland around 2004 and is now spreading all over Europe. This pentatomid is highly polyphagous and attacks vegetables, field and tree crops as well as soft fruits. Moreover, all development stages of H. halys are found in vineyards, suggesting that grapevine is also a host plant for this insect. Nonetheless, its actual effects on European wine production is unclear. As such, we studied the impact of processed H. halys on the aroma and taste of grape musts and wines. We artificially contaminated 'Chardonnay' and 'Merlot' grapes with up to ten H. halys nymphs and adults per kg grapes directly before the vintage was crushed. In the freshly pressed must, the addition of 1 living bug/kg grapes did not affect the olfactory sensation of the 'Chardonnay' juice. However, the aroma and taste of 'Chardonnay' and 'Merlot' musts contaminated with 3 to 10 H. halys individuals/kg grapes could be distinguished from the uncontaminated control juices and were perceived as vegetal and woody. Yet after bottling, the different wines with 0 to 10 H. halys individuals/kg grapes could no longer be differentiated from each other in 2-out-of-5 discrimination tests. Amongst 17 rated organoleptic descriptors to characterise the sensory profile of the four 'Chardonnay' wines, only two showed significant differences; the colour intensity increased and wines’ finesse decreased with the number of added bugs. For the three 'Merlot' wines, none of the 21 organoleptic descriptors of the sensory profiles differed significantly. In addition, winegrowers did not dislike H. halys contaminated 'Chardonnay' and 'Merlot' wines compared to their uncontaminated controls one year after bottling. It therefore seems that the molecules responsible for the off-flavours in contaminated musts volatilise to a large part during the fermentation process. Our results consequently indicate that a contamination of the vintage with H. halys has the potential to alter the quality of grape musts and potentially grape juices but that there is little risk for influencing the taste of processed wines. Nonetheless, we recommend monitoring the development of H. halys in vineyards in order to anticipate quantitative and qualitative problems at harvest

Impact of processed earwigs and their faeces on the aroma and taste of 'Chasselas' and 'Pinot Noir' wines

The abundance of the European earwig Forficula auricularia L. (Dermaptera, Forficulidae) in European vineyards increased considerably over the last few years. Although earwigs are omnivorous predators that prey on viticultural pests such as grape moths, they are also known to erode berries and to transfer fungal spores. Moreover, they are suspected to affect the human perception of wines both directly by their processing with the grapes and indirectly by the contamination of grape clusters with their faeces. In this study we artificially contaminated grapes with F. auricularia adults and/or their faeces and determined the impact on aroma and taste of white 'Chasselas' and red 'Pinot noir' wines. Whereas the addition of five living adults/kg grapes affected the olfactory sensation of 'Chasselas' wines only marginally, 0.6 gram of earwig faeces/kg grapes had a strong effect on colour, aroma and the general appreciation of 'Chasselas' wines. Faeces-contaminated wines were less fruity and less floral, the aroma was described as faecal and they were judged to be of lower quality. The contamination of 'Pinot noir' grapes with four different densities of living earwig adults (e.g. 0, 5, 10 and 20 individuals/kg grapes) showed that only wines contaminated with more than 10 earwigs/kg grapes smelled and tasted significantly different than the uncontaminated control wine. Earwig-contaminated 'Pinot noir' wines were judged to be of lower quality. The descriptors “animal”, “reductive”, “vegetal”, “acidic”, “bitter” and “tannic” characterised their sensory perception. In conclusion, our results show that there is a real risk of wine contamination by F. auricularia. In particular, earwig faeces and earwig adults at densities above a threshold of 5 to 10 individuals/kg grapes have the potential to reduce the quality of wines. The evolution of earwig populations in vineyards should therefore be monitored carefully in order to anticipate problems during vinification.

The capabilities approach and worker wellbeing

Recently, scholars have attempted to apply the capabilities approach, as advanced by Amartya Sen, to the realm of labour. They argue that it provides a philosophical justification for a ‘development’ approach to labour regulation, supports the design of policies that promote workers’ wellbeing and validates the institution of worker participation mechanisms. For labour proponents, this is an exciting prospect. This article argues that despite its promise for expanding workers’ capabilities, certain ambiguities potentially impede the approach’s utility, particularly in developing countries. We suggest ways in which it can be refined and developed to better serve the interests of labour in these contexts, notably by promoting collective and not merely individual capabilities