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An important ecosystem service in agriculture is the regulation of pests. However, modern agricultural practices often disrupt natural enemies that provide these services. Adopting Integrated Pest Management (IPM) can conserve natural enemies that protect crop yield and reduce production costs, but surprisingly few field studies have experimentally demonstrated at production scale that IPM improves biological control. We evaluated an integrated system that combined a specialty crop (watermelon as the target crop) surrounded by a field crop (corn) on commercial-level plots to compare IPM based on pest action thresholds with Conventional Pest Management (CPM) that relied on preventative or "insurance" pesticide applications with insecticide-treated seedings and calendar-scheduled insecticide applications to manage insect pests. Over two years at multiple sites, we measured the abundance of key pests (striped cucumber beetle (SCB) Acalymma vittatum Fabricius in watermelon and western corn rootworm Diabrotica virgifera virgifera LeConte in corn, generalist predators (spiders), and non-pest prey (Collembola), as well as field predation estimated with surrogate prey. In watermelon, the abundance of SCB, spiders, Collembola, and field predation was three times or greater on average in IPM compared to CPM field plots where the pest action threshold was rarely reached regardless of treatment. In the surrounding corn, abundances across trophic levels were similar between plots planted with either neonicotinoid-treated or untreated seeds. This study demonstrates how indiscriminate use of insecticides as a pest management strategy can directly (in watermelon) and indirectly (in the surrounding corn) disrupt the benefit of natural enemies and non-pest prey, and mask regulatory ecosystem services otherwise available in commercial crop production.
Grijalva et al. (Fri,) studied this question.