Semi-natural areas adjacent to vineyards increase the abundance of Hymenoptera parasitoids in a hill wine-growing area of Northern Italy

Hymenoptera parasitoid communities were studied using Malaise traps in a hill wine-growing area of Northern Italy, dominated by extensive viticulture. Parasitoid abundance data were correlated with landscape composition around vineyards using geospatial analysis. A remarkable parasitoid fauna, comprising 71 taxa across families and subfamilies, was recorded, with Ichneumonidae (18%), Diapriidae (14%), Braconidae (11%), Mymaridae (9%), and Scelionidae (8%) being the most represented. Semi-natural habitats within 200 m were strongly associated with the abundance of several Hymenoptera taxa, including five families and six subfamilies. Lobesia botrana (EGVM) infestation was negatively correlated with the proportion of semi-natural habitats within 200 m, while parasitisation was not correlated with any of the landscape metrics tested at 200, 500, or 1000 m (vineyards and orchards, semi-natural, anthropised areas, and meadows and arable crops). Parasitoids emerged from collected EGVM larvae belonged to the genus Diadegma (Ichneumonidae, Campopleginae). These results highlight the importance of nearby semi-natural habitats as refuges for parasitoid diversity in viticultural landscapes. Integrating spatial scale with the ecological requirements of target taxa is crucial for promoting conservation strategies that support specific functional groups, in this case Hymenoptera parasitoids.