Evaluation of a solvent, a suspension agent, and a surfactant for use in non-Apis bee toxicity tests

Toxicity testing with bumble bees and solitary bees has increased in the last ten years, and the regulatory requirements in some regions are driving the development of standardized methods. For example, in 2017 the guidelines for acute contact and oral tests with bumble bees (OECD 246 and OECD 247) were finalized after an extensive evaluation and validation of the methods via multiple laboratories. Acute contact and oral tests with solitary bees (Osmia spp.) and a chronic oral test with bumble bees have gone through a similar validation process, although guidelines are still pending, and currently there is an ongoing validation process for a chronic oral assay for solitary bees (Osmia spp.). Through a series of tests for validation and adaptation purposes with North American species of bumble bees and solitary bees, we’ve evaluated the effects of a solvent, a suspension agent, and a surfactant, which may be necessary to deliver a test material via direct topical application or to maintain solubility via feeding solution. We identified which of these materials and what concentrations are safe to use as carriers of test materials in toxicity test with non-Apis bees, specifically Bombus impatiens, Osmia lignaria, O. cornifrons, and Megachile rotundata. Our findings show additional methods that can be used to solubilized or suspend test materials and add tools in a toolbox for the testing of chemicals to non-Apis bees.