Coccinellid abundance in shelterbelts is affected more by adjacent crop type and aphid abundance than vegetation characteristics

Coccinellidae are important natural enemies of agricultural pests in a variety of crops and there is interest in landscape manipulation to enhance coccinellid populations. Here we investigate impacts of non-crop woody vegetation variables, adjacent crop type and abundance of aphid prey on coccinellid abundance in shelterbelts adjacent to vineyards or pasture near Melbourne, Australia. Sixty sites were sampled five times at monthly intervals using yellow sticky traps. The abundance of coccinellids in shelterbelts was influenced to a greater extent by adjacent crop type and aphid abundance rather than vegetation characteristics like canopy flowers. Abundance of some species was 2-5 times higher in riparian shelterbelts while increased litter depth decreased abundance. When the leaf litter depth of shelterbelts was experimentally increased, the abundance of coccinellids decreased, whereas an experimental decrease in porosity tended to have the opposite effect. These findings suggest that coccinellid abundance can be influenced to some extent by characteristics of shelterbelts, but crop type and prey availability is likely to have a relatively larger impact, perhaps reflecting the high movement rates of this group of natural enemies. (C) 2015 Elsevier Inc. All rights reserved.