Effect of Weedy Backgrounds on Colonization of Collards by Green Peach Aphid,Myzus persicae1, and Its Major Predators

Insect colonization of collards in contiguous weedy and weed-free plots was monitored in 1978 and 1979. Green peach aphids, Myzus persicae (Sulzer) preferentially invaded weed-free collards and developed higher densities thereon. Numbers of Chrysopa oculata (Say), Coccinellidae, and Syrphidae were higher in plots in which weeds were uncut, despite lower aphid densities. When weeds were trimmed to 10 cm maximum height, predators became more numerous on weedless collards. Predator response were generally inefficient, especially when overall aphid densities were low.