Differential responses of Orthoptera in vineyards to organic farming, pesticide reduction, and landscape heterogeneity

Abstract

Conservation measures such as those under the European Green Deal aim to counteract the biodiversity loss by increasing the share of organic farming and reducing pesticide use, as well as increasing the proportion of semi-natural habitats (SNH) in agricultural landscapes. Given the large environmental impacts of agriculture, it is important to thoroughly understand effects of such measures on organisms to provide evidence-based and effective implications for conservation. In this study, we analysed how vineyard management, pesticide reduction, and landscape composition affect Orthoptera densities and species composition. Therefore, we sampled herb- and vine-dwelling orthopterans in a paired design of classic and fungus-resistant grape (FRG) varieties in conventionally and organically managed vineyards along a landscape heterogeneity gradient. Here, FRG varieties allowed us to study the effect of 44% reduced pesticide applications under real-world conditions. Total densities of herb-dwelling Orthoptera did not differ between grape varieties in conventional vineyards, but were 2.9 times higher in FRG varieties under organic management. In contrast, total densities of vine-dwelling Orthoptera, mainly driven by the dominant species Phaneroptera falcata, were similar between grape varieties in organic vineyards, but tended to be 1.4 times higher in classic grapes under conventional management. Furthermore, the management system and SNH in a radius of 500 m in the surrounding landscape influenced species composition.