Supporting Data: Refocusing Risk: An Updated Approach for Safeguarding Pollinators

While science and policy have advanced in characterizing pesticide ‘risk’, these indices remain unvalidated and disconnected from environmental risk assessment (ERA). Here, we identify and validate pesticide risk thresholds by connecting landscape-scale pesticide risk and colony-level outcomes in the bee species <i>Bombus terrestris</i> to provide: (1) a basis for post-approval pesticide monitoring with feedback to ERA, and (2) a suggestion for how to facilitate simplified, yet realistic and protective, pesticide approval process.</p><p><br></p><p dir="ltr"><b>Study design</b></p><p dir="ltr">We conducted a semi-field experiment with 120 <i>Bombus terrestris</i> colonies (Biobest Biological Systems, Belgium), allocated to twelve treatments based on initial colony weight.

Colonies, all containing a natal queen and 25–40 workers, were fed pesticide-treated sugar syrup and pollen, housed in ventilated boxes at the edge of a red clover field, and allowed to forage naturally after initial exposure. Colony growth was monitored weekly as a proxy for worker force and brood production, foraging activity was recorded via repeated 10-minute observations, and reproductive output was assessed at the end of six weeks by dissecting colonies to count worker, male, and queen cocoons.