Living Mulch Strips as Habitats for Beneficial Insects in the Production of Cucurbits

Abstract

Effects of cover crops managed as living mulch habitats on populations of cucumber beetles Acalymma vittatum Fabricius and Diabrotica undecimpunctata howardi (Barber) (Coleoptera: Chrysomelidae) and arthropod predators were assessed at the Virginia Tech Kentland experimental farm and a local farmer's field in 1994 and 1995. In 1994, spring-planted strips of two living mulch mixtures, oats/vetch (Arvena sativa/Vicia atropurpurea) and oats/white clover (A. sativa/Trifoliium repens), and straw mulch between rows of cucumber cv. Pointsett and an heirloom pumpkin cultivar were compared to non-mulched plots in a randomized complete-block design. Counts of the predator Pennsylvania leatherwing, Chauliognathus pennsylvanicus (Coleoptera: Cantharidae) on yellow sticky traps were 2.7 to 10 times greater in living mulch treatments, compared to plots with cucurbits alone or with straw mulch (P = 0.0040 in 1994 and P = 0.0085 in 1995). In 1995, counts of Harpalus spp. (Coleoptera: Carabidae) in buckwheat Fagopyrum esculentum (Moench) living mulch treatments were twice those in the plots with the crop alone, and cucumber beetle counts were 60% lower (P = 0.0165) in the mulched habitats. Crop yields were depressed in living mulch treatments, but a twin-row planting system (5:3 crop: habitat ratio) with buckwheat gave yields 4.8 times greater than the single-row system (3:5 crop: habitat ratio) initially used in 1994. These yields were 72% of yields in the control using conventional practices. These results indicate that strip cropping has the potential to maintain cucumber beetle populations below threshold levels, but that more management research is needed to obtain economically viable yields.