Objective of the study

This study is designed to assess the length of time over which field-weathered foliar residues remain toxic to worker honeybees. The results of this test can be used to define the need for further evaluation, in particular in a step-wise procedure for evaluating the risks of pesticides to bees, based on sequential progression from laboratory toxicity tests to semi-field and field experiments.

Circumstances under which the study is recommended to be required

Data are recommended only when the formulation contains one or more active ingredients with an acute LD50 of < 11 μg / bee as determined in the honeybee acute contact study, and the use pattern(s) indicate(s) that honeybees may be exposed to the pesticide. This study may not be required in situations where bees are not likely to be exposed, including (but not limited to): food storage in enclosed spaces; soil applications with non-systemic pesticides (except granules, which may release dust if drilled); non-systemic dipping treatments for transplanted crops and bulbs, non-systemic rodenticidal baits; use in greenhouses without bees as pollinators.

Test organism

The study is conducted with adult worker honeybees (Apis mellifera).

Test substance

End-use product

Typical endpoints of the study

• Mortality
• Sub-lethal effects (e.g. on behaviour)
• RT₂₅ (hours) (= residual time resulting in 25% mortality after 24 hours exposure of the bees

Test guidelines

The following test guidelines may be used for determination of the toxicity of residues on foliage:

• US EPA Ecological Effects Test Guidelines. 850.3030: Honey bee toxicity of residues on foliage.  
• US EPA Ecological Effects Test Guidelines. OCSPP 850.3000: Background and special considerations – Tests with terrestrial beneficial insects, invertebrates and microorganisms. 
• COLOSS BEEBOOK Vol I: Standard methods for toxicology research in Apis mellifera.