Honey bees prefer moderate sublethal concentrations of acetamiprid and experience increased mortality

Abstract

Acetamiprid, a prevalent neonicotinoid residue in honey, poses long-term risks to honey bee health even at sublethal concentrations. Despite this, the chronic lethal effects across a bee's full adult life stage and the influence of acetamiprid at environmentally relevant concentrations on food preferences in honey bees remain uncertain. By conducting a long-term survival monitoring, we found that bees chronically exposed to 0.75 mg/L acetamiprid exhibited a greater mortality compared to those exposed to the highest concentration (3 mg/L) when given a choice between acetamiprid-treated syrup and nontreated pollen. Bees exposed to 0.75 mg/L acetamiprid consumed less pollen and higher amounts of treated syrups compared to the control and 3 mg/L treatment, indicating a preference for moderate sublethal concentrations. To refine our understanding, we tested a range of additionally extended acetamiprid concentrations (0, 0.1, 0.5, 1, and 5 mg/L) using various food-choice assays. The findings indicated no consumption bias and revealed a significant dose-response relationship concerning reduced survival at concentrations exceeding 0.5 mg/L of acetamiprid in the no-choice assay, while manifesting a highest preference for 0.5 mg/L concentration in the two-choice and five-choice assays. This study underscores the hidden risk of acetamiprid threatening bees through foraging preferences on specific range of concentrations.