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 protection products to the non‐target arthropods Typhlodromus pyri (Acari: Phytoseiidae) and Aphidius rhopalosiphi (Hymenoptera: Aphidiidae) are limit tests designed to compare a single‐use rate of the product with a water control. The suitability of these test systems for generating dose‐response data 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 method, a logistic regression, a generalised Probit analysis, and the moving average‐angle method in order to calculate the LR50‐values (application rate killing 50 % of the exposed organisms). The fit of the models, the precision of the resulting LR50 values, and the required minimum number of replicates were compared. In 85 % of the studies, at least one of the statistical methods led to satisfactory results. The moving average‐angle method was the most widely applicable method. The results show that the existing guidelines can be used to perform dose‐response tests. Implications for risk assessment are discussed.