Spatial scale of benefits from adjacent woody vegetation on natural enemies within vineyards

Abundance of predators in crops can be increased by augmenting the adjacent non-crop vegetation, with associated environmental benefits from reduced chemical inputs and landscape conservation. Fine-scale spatial analysis is required to assess the extent to which non-crop benefits extend into farmed areas. We used explicit spatial mapping to investigate benefits of woody vegetation in two vineyards. The abundance of canopy-dwelling predators and predation/parasitism rates was measured at two vineyards with woody vegetation on one margin. Grids were sampled monthly across two summer growing seasons and stability of spatial patterns determined for consecutive months for each season and between seasons. At these two locations small parasitoids and several species of ladybird beetles from the vine canopy exhibited spatial patterning, with regions of high and low abundance and activity, aggregated in rows near to woody vegetation. Aggregations varied in temporal stability, with some persisting throughout the season. When predation and parasitism of sentinel eggs of a moth pest were non-randomly distributed, levels were higher in vine rows closer to the woody vegetation and significantly associated with a known egg parasitoid and ladybird beetles. This study demonstrated predators and parasitoids had non random and stable distributions at two vineyards. Increased abundance of both Coccinellidae and parasitoids was seen over similar distances: extending approximately 40 m from the vegetated edge. Increase in parasitism and predation extended a similar distance in from the vegetation. These results suggest management of vineyards where non-crop vegetation can be used to increase numbers and impact of beneficials, with recommendations for planting woody vegetation a minimum of 50 m from vineyard edges. (C) 2012 Elsevier Inc. All rights reserved.