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Acute Oral and Contact Toxicity to the Bumblebee, Bombus terrestris L.

Bumblebees (Bombus terrestris L.) can be affected by pesticide residues on plants, via oral and contact intake, in the course of application during farming practice. As the proposed use pattern of pesticides indicates a possible exposure of bumblebees, this study shall be useful for the registration of the pesticide in question.

Study Design

Test organisms

The test is conducted with adult female Bombus terrestris worker bees from a commercial bumblebee company.

Course of the test

At first the bumblebees are collected form the nest under red light without the use of anaesthetics. After that the bumblebees are kept in test units. Differentiation into treatment groups are carried out visually by body size. Each bumblebee is weighed individually after anesthetization with CO2. Before application the bees are acclimatised to the test conditions for 12 - 24 hours (25 °C, 60 %).

In the oral test bees are starved for 2 - 4 hours and then fed with treated or untreated feeding solution for a period not exceeding 6 hours via syringes. The exact food uptake is calculated by the syringe weight before and after the application period.

In the contact test the bees are exposed to the test item by dorsal application of a 5 µL droplet on the bumblebee thorax.

The test is regularly finished after 48 hours. In case of delayed mortality onset the test can be prolonged up to 96 hours.

Assessments

  • Mortality: Number of dead bees after 4 (±0.5 h) hours (first day), 24 and 48 (±2 h) hours, (72 and 96 (±2 h) hours, if prolonged).
  • Behavioural abnormalities: Signs of intoxication are recorded throughout the trial (e.g. affected, moribund, cramps)
  • Food uptake (oral test): The exact uptake of treated food is calculated.

 

Validity criteria

Control and reference item groups ensure that the test results show high accuracy and trueness. Each test is reliably validated by the following criteria:

  • Mortality in the control group: ≤ 10 % at test end
  • Mortality in the reference item group: ≥ 50 % at test end

Endpoints

LD50; NOED

Guidelines and Literature

  • Van der Steen (2001): Review of the methods to determine hazards and toxicity of pesticides to bumblebees
  • OECD 213: OECD Guideline for the Testing of Chemicals, Honeybees, Acute Oral Toxicity Test, (adopted 21st September 1998)
  • OECD 214: OECD Guideline for the Testing of Chemicals, Honeybees, Acute Contact Toxicity Test, (adopted 21st September 1998)
  • Current recommendations of the non-Apis ring test group (2014)