Assessing delayed and acute toxicity of five formulated fungicides to Osmia lignaria Say and Apis mellifera

The delayed and acute toxicity of benomyl (Benlate(R)), captan (Captan 50WP), iprodione ( Rovral.), propiconazole ( Orbit.), and neem oil ( Trilogy.) to two crop pollinators, A. mellifera and O. lignaria, was evaluated. Survival after contact and oral single exposure to high doses of the pesticides was compared to survival of controls with the dosing vehicle. LD50 values at 24, 48 and 72 h from exposure were determined. Contact and oral exposure to benomyl and iprodione did not affect survival of any of the two species. Contact exposure to neem oil affected survival of A. mellifera. Orally administered propiconazole showed delayed and acute toxicity to both species. Captan severely limited survival of O. lignaria. The tested fungicides seemed to be safe to both bee species at the recommended rates, with the exception of captan to O. lignaria. To our knowledge, this is the first complete contact and oral toxicity test on an Osmia species.