The impact of intercropping squash with non-crop vegetation borders on the above-ground arthropod community

Abstract

The influence of intercropping strips of non-crop vegetation on the above-ground arthropod community was assessed, including natural enemy populations and interference with pest colonization in an adjacent yellow squash crop (Cucurbita pepo L.). Four non-crop border treatments were evaluated including: sorghum × sudangrass hybrid (Sorghum bicolor (L.) Moench × S. sudanense (Piper) Stapf); pigeon pea, (Cajanus cajan (L.) (Millsp.); the native weed complex; and a bare ground control. Border treatments were established on both sides of experimental plots containing 'Early Crookneck' squash. Sticky cards, pitfall traps, pan traps, and in situ counts were used to assess differences in the arthropod community within each of the border treatments and the adjacent squash crop. Natural enemies were most abundant in the native weed complex and pigeon pea borders; however, the spill-over of natural enemies into the neighboring crop was only observed in 2008, when predatory Coleoptera were most abundant in both the sorghum-sudangrass treatment and adjacent squash. Border crops did not influence the movement of thrips and whiteflies; however, in situ aphid counts were lower on squash bordered by sorghum-sudangrass than in the control. Flea beetles (Altica spp.) were consistently most abundant in the bare ground border, but many arthropod groups were unaffected by the treatments. None of the border treatments could prevent a heavy infestation of melonworm (Diaphania hyalinata L.), which defoliated and killed many of the squash plants.