Mechanisms of predator accumulation in a mixed crop system

Publisher Website
Google Scholar
Abstract
1. In a previous study, Orius tristicolor (White), a generalist predator of soft‐bodied insects and mites, invaded patches with a mixed plant assemblage at a faster rate than it did single‐species stands. This study was designed to determine experimentally the underlying mechanisms of predator movement patterns that cause more intense colonization of crop mixtures.2. Plots were established in a randomized complete block design. Treatments reflected different components of mixed crop patches: species richness, plant density, colour contrast, structural complexity, and volatile plant compounds.3. O. tristicolor colonists were more abundant on squash intercropped with corn and cowpea than in squash monocultures even though early season prey densities were similar. Initial accumulation of the generalist predator was also higher in densely planted monocultures and in monocultures with artificially enhanced structural complexity than in normally‐spaced squash monocultures.4. Therefore, mechanisms underlying rates of predator colonization in a stand initially depended upon aspects of plant architecture and density and were independent of prey density and plant diversity. O. tristicolor densities at the end of the colonization period, however, were greater on squash (Cucurbita pepo L.) in polyculture than in any other treatment.5. These results suggest that attributes of the vegetation can influence the colonization rates of interacting organisms on different trophic levels and thus can alter predator‐prey interactions and the development of community structure.