Do cover crops influence beneficial and herbivorous arthropod communities across growing seasons?

Abstract

Cover crops provide multiple ecosystem services in agriculture, yet their influence on arthropod communities remains poorly understood, especially in commercial farming. Despite their potential benefits, it remains unexplored how cover crops affect arthropod community dynamics across multiple growing seasons. We conducted a two-year study across three commercial farms in the Lower Rio Grande Valley, Texas, to examine how cover crops influence arthropod community composition and abundance, whether beneficial arthropods (natural enemies and pollinators) persist into cash-crop phases, and how cover crops affect natural enemy–herbivore relationships. We compared arthropod communities between cover-crop treatments and control plots and tracked responses through subsequent cash-crop phases. We sampled arthropods and classified them into functional groups, including natural enemies, herbivores, and pollinators. Total arthropod abundance declined 45% between years across all treatments, and year-to-year variation exceeded treatment effects for all functional groups. Arthropod community composition differed between sampling years, and year influenced composition more strongly than cover-crop treatment. Natural enemy abundance showed no treatment effects but declined 43% between years and remained stable during transitions from cover crops to cash crops. Pollinator abundance declined 74% between years, with no treatment effects and only minor carryover into the subsequent cash-crop phase. Natural enemies and herbivores correlated positively, with stronger relationships in cash-crop phases than in cover-crop phases. These findings show that temporal variation outweighed management effects, which suggests that cover-crop effectiveness for supporting arthropod communities might depend on environmental conditions, landscape context, and management practices. Multi-year studies are essential to understand how cover crops influence arthropod-mediated ecosystem services in commercial agriculture.