Ingwell et al data for high tunnel bee study 2018

<p>Insecticide use and insufficient forage are two of the leading stressors to pollinators in agroecosystems. While these factors have been well-studied individually, the experimental designs do not reflect real-world conditions where insecticide exposure and lack of forage occur simultaneously and could interactively suppress pollinator health. Using outdoor enclosures, we tested the effects of insecticides (imidacloprid + lambda-cyhalothrin) and non-crop forage (clover) in a factorial design, measuring the survival, behavior, and performance of bumble bees (<em>Bombus impatiens</em>), as well as pollination of the focal crop, watermelon. Colony survival was synergistically reduced to 17% in watermelon alone + insecticides (survival was 100% in all other treatments). However, behavioral shifts in foraging were mainly due to insecticides (e.g., 95% reduced visitation rate to watermelon flowers), while impacts on hive performance were primarily driven by clover presence (e.g., 374% increase in number of live eggs). Insecticide-mediated reductions in foraging decreased crop pollination (fruit set) by 32%. Altogether, these data indicate that both insecticides and non-crop forage play integral roles in shaping pollinator health in agricultural landscapes, but the relative importance and interaction of these two factors depend on which aspect of “health” are most valued.</p>