The relative merits of field and boundary habitats for conservation biocontrol.

Abstract

Densities of boundary overwintering generalist predators within fields were estimated from their overwintering densities within such features. Their density was lower than that for those found emerging within fields, but numbers peaked in May compared to July for field overwintering species. Exclusion studies revealed that aerially dispersing beneficial invertebrates alone provided effective cereal aphid control although ground dispersing predators contributed to a small extent. Widening field margins had no impact on cereal aphid control.