The effect of cover crop residue and reduced tillage on natural enemies, herbivores, and weed seeds in acorn squash (Cucurbita pepo var. turbinata)

Acorn squash (Cucurbita pepo var. turbinata) is one of the most widely grown crops in the North Central US, yet it is also one of the most likely to face pest pressure and biological control deficits. Promoting biological control services requires habitat and resources to increase the abundance and efficacy of natural enemies, which are often lacking in conventional agroecosystems. We hypothesized that the use of a winter rye cover crop and reduced tillage within an acorn squash field would increase beneficial insect abundance and diversity while decreasing insect pest pressure. Tillage (moldboard plow or strip-till) and cover crop (winter rye or bare) treatments were applied to an acorn squash field in Michigan in a split plot design with six replications in the 2014 growing season. Insects were sampled visually and with pitfall traps. Weed seed predation was estimated by evaluating the disappearance of commonly occurring weed seeds from deployed arenas. The effects of reduced tillage and cover crops on key natural enemy and herbivore abundances and weed seed predation were evaluated using generalized linear mixed models and non metric multidimensional scaling. Reduced tillage and mulching postively affected natural enemy abundance. Ultimately, this work could lead to an increased understanding of conditions favorable to beneficial insect activity on growers’ farms, thus reducing pesticide inputs and increasing acorn squash yield and profitability.