Use of standard toxicity tests with Typhlodromus pyri and Aphidius rhopalosiphi to establish a dose-response relationship

The existing standardised test systems for assessing the toxicity of crop p rotection products to the non-target arthropods Typhlodromus pyri (Acari: P hytoseiidae) and Aphidius rhopalosiphi (Hymenoptera: Aphidiidae) are limit tests designed to compare a single-use rate of the product with a water con trol. The suitability of these test systems for generating dose-response da ta as required for refined ecotoxicological risk assessment was evaluated. Data on dose-response toxicity of crop protection products to T pyri and A rhopalosiphi were generated under worst-case laboratory and to T pyri under extended laboratory conditions and analysed using the standard Probit meth od, a logistic regression, a generalised Probit analysis, and the moving av erage-angle method in order to calculate the LR50-values (application rate killing 50 % of the exposed organisms). The fit of the models, the precisio n of the resulting LR50, values, and the required minimum number of replica tes were compared. In 85 % of the studies, at least one of the statistical methods led to satisfactory results. The moving average-angle method was th e most widely applicable method. The results show that the existing guideli nes can be used to perform dose-response tests. Implications for risk asses sment are discussed.