Test No. 254: Mason bees (Osmia sp.), Acute Contact Toxicity Test

This test guideline describes a laboratory test method, designed to assess the acute contact toxicity of test chemicals to adult solitary bees. It is based principally on the OECD guidelines for the testing of chemicals 214 and 246. Adult female solitary bees are exposed to a range of doses of the test chemical dissolved in an appropriate carrier, by direct application to the dorsal side of thorax. The test duration is 48 h (or up to 96 h, if ongoing mortality makes prolongation necessary) and bees are fed ad libitum with sugar solution throughout the test. Mortality is recorded daily and compared with control values. The results are analysed in order to calculate the LD50 at 48 h, as well as at 72 h and 96 h if the duration of the study is extended. Sublethal effects, if any, should also be recorded.