The Impact of Microbial and Botanical Insecticides on Grape Berry Moths and Their Effects on Secondary Pests and Beneficials

According to the European Directive 2009/128/EC and the subsequent provisions activated in member states, conventional pesticides should be progressively replaced by “non-chemical tools and/or measures”. The identification of reliable alternatives to pesticides is crucial to achieve this objective. A European project (PURE) was funded to investigate this topic with reference to annual and perennial crops. In this framework, a number of natural insecticides, in particular microbial and botanical ones (Bacillus thuringiensis ssp. kurstaki, Beauveria bassiana, azadirachtin, pyrethrins and spinosad) were selected to test their effectiveness against grape berry moths, the key pests in most European vineyards. Trials were conducted in 2011 and 2012 in two experimental vineyards located in Italy (Tuscany and Veneto regions), following a randomized block design. Additional investigations were carried out in the Veneto region during 2013. Trial results stressed the high performance of spinosad and B. thuringiensis in controlling berry moth densities and the related damage. The use of B. bassiana mixed with B. thuringiensis did not significantly improve the impact of B. thuringiensis alone. Azadirachtin, and especially pyrethrins, proved to be less effective on berry moths than previous insecticides. The use of selected insecticides caused side-effects on a number of secondary pests, in particular leafhoppers. In 2011, densities of Empoasca vitis were higher in spinosad-treated plots probably because of a reduced egg parasitization rate. One year later, the population density of Zygina rhamni was higher in the plots treated with spinosad or pyrethrins. This trend was confirmed on spinosad-treated plots in the last experimental year. At the same time, spinosad and pyrethrins significantly reduced the predatory mite populations compared to other treatments. The use of these insecticides in viticulture is discussed in the framework of organic viticulture and Integrated Pest Management (IPM).