Organic Farming and Cover-Crop Management Reduce Pest Predation in Austrian Vineyards

SIMPLE SUMMARY: Global declines in arthropods necessitate a rethinking of current agricultural practices. Organic farming, complex landscapes with high proportions of seminatural habitats and local vineyard management practices such as implementation of flower-rich cover-crop mixtures may be a promising approach to enhance arthropod biodiversity and, thus, natural pest control in viticulture. We examined effects of organic farming, different types of vineyard inter-row vegetation, and landscape composition on natural pest control of a major grapevine pest, the grape berry moth Lobesia botrana, and identified its dominant natural enemies. Surprisingly, natural pest control was reduced by sown cover-crops and organic farming. Interestingly, bush crickets were one of the most dominant natural enemies in the Austrian study region. Negative effects of organic farming in our study are most likely related to high fungicide inputs. Thus, a promising approach to reduce fungicide input and, therefore, promote a more sustainable viticulture may be the implementation of fungus-resistant grape varieties. ABSTRACT: Habitat simplification and intensive use of pesticides are main drivers of global arthropod declines and are, thus, decreasing natural pest control. Organic farming, complex landscapes, and local vineyard management practices such as implementation of flower-rich cover-crop mixtures may be a promising approach to enhance predator abundance and, therefore, natural pest control. We examined the effect of organic versus integrated management, cover-crop diversity in the vineyard inter-rows, and landscape composition on the natural pest control of Lobesia botrana eggs and pupae. Predation of L. botrana pupae was reduced by organic farming and species-poor cover-crops by about 10%. Predation rates of L. botrana eggs did not differ significantly in any of the studied management options. Dominant predators were earwigs (Forficulidae), bush crickets (Tettigoniidae), and ants (Formicidae). Negative effects of organic viticulture are most likely related to the negative nontarget effects on arthropods related to the frequent sulfur and copper applications in combination with the avoidance of strongly damaging insecticides by integrated winegrowers. While a 10% difference in predation rates on a single pest stage is unlikely to have strong practical implications, our results show that the assumed effectiveness of environmentally friendly agriculture needs to be evaluated for specific crops and regions.