Effects of Red Clover Living Mulch on Arthropod Herbivores and Natural Enemies, and Cucumber Yield

Abstract

Increasing habitat complexity through cover cropping has been proposed as a tactic to reduce herbivore colonization and encourage natural enemies in cropping systems. To test the supposition that cover crops can be used to alter arthropod communities, we compared arthropod communities on cucumber (Cucumis sativus L.; Cucurbitaceae) interplanted with a red clover (Trifolium pratense L.; Fabaceae) living mulch and grown as a monoculture. In 2016 and 2017, visual surveys and yellow sticky card traps were used to estimate numbers of arthropod natural enemies and herbivores in each treatment. Among herbivores, striped cucumber beetles [Acalymma vittatum (Fabricius, 1775); Coleoptera: Chrysomelidae] and melon aphids (Aphis gossypii Glover, 1877; Hemiptera: Aphididae) had lower densities in the presence of red clover. However, populations of spotted cucumber beetle (Diabrotica undecimpunctata howardi Barber, 1947; Coleoptera: Chrysomelidae) had a variable response to red clover. Sticky card captures of natural enemies, including bigeyed bugs (Geocoris spp. Fallén; Hemiptera: Geocoridae), minute pirate bugs (Orius spp. Wolff; Hemiptera: Anthocoridae), and lady beetles (Coleoptera: Coccinellidae), were generally greater in cucumber interplanted with red clover than monoculture. Overall, cucumber yield did not differ between treatments. Findings from this study lend support to the hypothesis that greater habitat complexity can reduce herbivore densities.