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Non-target arthropod testing with the parasitic wasp (Aphidius rhopalosiphi)

The acute toxicity of adult Aphidius rhopalosiphi will be measured in the laboratory via contact on treated glass surfaces, barely seedlings or treated leaves, respectively, compared to a water treated control and to a reference item. Additionally, an assessment for significant sublethal effects will be made (parasitisation activity). If possible the LR50 value for mortality effects will be calculated.

Study Design

Test organisms

The parasitic wasp Aphidius rhopalosiphi is recommended as one of the most sensitive standard species for non-target arthropod regulatory testing for plant protection products (Candolfi et al. 2001).

Course of the test

Exposure will last for 48 hours with assessments after 2, 24 and 48 hours. At 48 hours, for treatment groups where the corrected mortality is less than 50 %, female wasps will be removed and their reproductive capacity will be assessed by confining them individually over untreated barley plants infested with the host cereal aphids, Rhopalosiphum padi. The adult parasitoids are removed after 24 hours and the aphid-infested plants left for a further 10 - 12 days before the numbers of aphid mummies that had developed will be assessed.

Tailor-made study designs

The study can also be performed in an aged residue design. For this study type plants will be treated under field conditions and the treated leaves will be transferred to the lab after aging of a determined time period. The course of the test is the same as described above.

Endpoints

Mortality of exposed parasitoids; if possible LR50: lethal rate producing 50 % mortality after 48 h of exposure. Additionally reproductive capacity for female survivors.

Guidelines and Literature

  • Mead-Briggs M.A., Brown K., Candolfi M.P., Coulson M.J.M., Miles M., Moll M., Nienstedt K., Schuld M., Ufer A. & McIndoe E. 2000: A laboratory test for evaluating the effects of plant protection products on the parasitic wasp, Aphidius rhopalosiphi (DeStephani-Perez) (Hymenoptera, Braconidae). In M.P. Candolfi, S. Blümel, R. Forster, F.M. Bakker, C. Grimm, S.A. Hassan, U. Heimbach, M.A. Mead-Briggs, B. Reber, R. Schmuck and H. Vogt (eds.) 2000: Guidelines to evaluate side-effects of plant protection products to non-target arthropods. IOBC/WPRS, Gent, pp 13-25
  • Mead-Briggs M.A., Moll M., Grimm C., Schuld M., Ufer A. & Walker H. 2010: An extended laboratory test for evaluating the effects of plant protection products on the parasitic wasp, Aphidius rhopalosiphi (Hymenoptera, Braconidae). BioControl 55:329-338