Influence of Winter Cover Crop Mulch on Arthropods in a Reduced Tillage Cucurbit System

Winter cover crop mulches can diversify agricultural habitats and provide a range of benefits for crop production and pest management. Here we report the influence of strip tilled winter cover crop mulches on arthropod abundance in organic vegetable plots. Crookneck squash (Cucurbita pepo L.; Cucurbitales: Cucurbitaceae) was direct seeded into mowed and strip tilled barley (Hordeum vulgare L.; Poales: Poaceae), crimson clover (Trifolium incarnatum L.; Fabales: Fabaceae), a barley + crimson clover mixture, or a no-cover crop control. Arthropods on squash plants were assessed weekly using visual counts. Seed predation was assessed using weed seed arenas. In 2013, mixed species cover crops produced the most ground cover, fewest weeds, and largest squash plants, but herbivore and predator abundance were not correlated with any of those factors. In 2014, mixed species cover crops again produced the most ground cover and fewest weeds, but the largest squash plants were found in no-cover crop control plots, which also had the highest herbivore abundance per plant. Predator and herbivore abundance were positively correlated with squash plant size in 2014. There were no differences in seed predation across treatments. Differences in ground cover biomass and weed presence between the 2 yr may have contributed to differences in squash plant quality and subsequent herbivore abundance between seasons. Results suggest that arthropods on plants responded largely indirectly to cover crops through host plant quality. Results are interpreted in light of overall costs and benefits of cover cropping.