Test No. 254: Mason bees (Osmia sp.), Acute Contact Toxicity Test
New OECD Guideline 254 – Mason Bees (Osmia sp.)
Testapi SAS is proud to have actively contributed to the international ring tests during several years, that led to the adoption of the new OECD Guideline No. 254 (acute contact toxicity test on mason bees, Osmia sp.).
We are already working on the first study requests, and capacity 2026 is limited due to the restricted testing window. To secure your slot, we strongly recommend booking well in advance – ideally a year ahead.
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This test guideline 254 is 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.