Aphid (Homoptera: Aphididae) accumulation and distribution near fences designed for cabbage fly (Diptera: Anthomyiidae) exclusion

Summary

Aphids accumulate near exclusion fences designed to intercept Delia radicum (L.) movement into fields. Aphid accumulations increase with fence height, but are not affected by fence overhang length. Overall aphid levels are higher in small (4.3 x 4.3 m) enclosed plots than in unenclosed plots. Enclosing large (38 x 38 m) plots does not alter overall aphid catches, but does alter aphid distribution within enclosures. In large enclosures aphid accumulations are higher at enclosure perimeters than interiors, with the highest accumulations near enclosure corners. This concentric distribution is not observed in unfenced areas, and is not altered by the addition of a trap crop inside an enclosure.