OECD Ecotoxicology Update: Bumblebees, Earthworms, and Algae
OECD Ecotoxicology Update: Bumblebees, Earthworms, and Algae
On the 2nd of July 2026, the OECD adopted three updated Test Guidelines relevant to Section 9 ecotoxicology assessments for plant protection products.
OECD TG 255 gives bumblebees (Bombus spp.) their own validated chronic oral toxicity test whereby adult workers are housed individually and fed a treated sucrose solution over a 10-day exposure period. This complements the acute oral and contact studies already available for bumblebees, broadening the assessment beyond honeybees alone. It’s reasonable to expect Member States to start requiring this study, particularly as data requirements are revisited going forward.
OECD TG 256 formally replaces ISO 11268-3:1999 and de Jong et al. (RIVM 2006) as the field-testing standard for earthworm communities. It offers three possible test designs : dose-response, mixed, and NOEC/NOER, each with its own combination of application rates and plot replicates, alongside a considerably more structured statistical approach for analysing abundance and biomass data, and a firm expectation of soil residue analytics alongside the biological sampling. The added rigour is welcome, but it will likely push the cost and complexity of these studies upward compared to the current approach.
OECD TG 201, the freshwater alga and cyanobacteria growth inhibition test, has also been revised. Several recommended strains have been renamed to match current taxonomy (e.g. Navicula pelliculosa is now Mayamaea permitis) and the diatom Mayamaea permitis is newly added as a recommended test species. The Guideline also clarifies how the mean coefficient of variation of section-by-section specific growth rates should be calculated, with the formal definition now in Annex 1 and a worked example in Annex 6.
Together, these three updates mark a step forward for the ecotoxicological data package supporting plant protection product registrations.
If you need support for study commissioning and study monitoring for plant protection products, please do not hesitate to contact the experts at Kerona info@kerona.ie