Effects of a biocontrol cocktail from Trichoderma asperellum on earthworms and microbial communities: a mesocosm study

The wine industry is an important socio-economic agricultural sector at an international scale, but the cultivation of grape vine (Vitis vinifera) also involves intensive use of pesticides. Copper sulphate in Bordeaux mixture, used as a fungicide, affects various soil organisms that are essential for proper functioning of agroecosystems. The development of alternative practices to replace copper sulphate is of great importance. Trichoderma asperellum can produce bioactive compounds with antifungal properties. This study compared the effects of: (i) copper sulphate, (ii) a biocontrol cocktail from T. asperellum and (iii) their combination, at different doses, on the biological and physicochemical properties of a vineyard soil in mesocosms. Microbial (respiration, biomass and catabolic diversities of bacterial and fungal communities) and earthworm Aporrectodea caliginosa (biomass, abundance and reproduction) properties were monitored after a 30-day incubation period. The results revealed that the biocontrol cocktail did not show any deleterious effects and even had beneficial effects: at certain doses, the biocontrol cocktail promoted microbial respiration and earthworm weight gain. On the other hand, the harmful impact of copper sulphate was confirmed on microbial biomass, bacterial catabolic activity, together with a change in the microbial catabolic profiles. Furthermore, negative effects were observed from copper sulphate on the reproduction of the earthworms in terms of number of individuals, hatched cocoons and time of cocoon hatching.