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

Abstract

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.

Biological impact of harmaline, ricinine and their combined effects with Bacillus thuringiensis on Spodoptera exigua (Lepidoptera: Noctuidae)

“…EC 50 and LC 50 values were determined using log-probit analysis (Grimm et al 2001) and the values were further used in nutritional and enzyme analysis either individually or in combination with Bt and each other (see Sects. "Nutrition analysis" and "Enzyme analysis").…”

Estimating ecotoxicological effects of pesticide drift on nontarget arthropods in field hedgerows

“…In accordance with the guidance document on terrestrial ecotoxicology [11] and the results of the ESCORT 2 workshop [12], T. pyri and A. rhopalosiphi were chosen as representative of nontarget arthropods species for the present study. The toxicological endpoint considered was the LR50 (g/ha) [15], obtained from the European Union Footprint project database (http://sitem.herts.ac.uk/aeru/footprint/) (Table 1).…”

“…This is calculated using the hazard quotient (HQ) approach, following the guidance document on terrestrial ecotoxicology [11] and the results of the ESCORT 2 workshop ([12]; http://www.iobc‐wprs.org/). According to these documents, at Tier I, the HQ is calculated by dividing the crop‐specific application rates (in‐field exposure scenario) or drift rates (off‐field exposure scenario) by the median lethal rate (LR50); the last is the application rate causing 50% mortality of the two test organisms Typhlodromus pyri Scheuten (Acari, Phytoseiidae) and Aphidius rhopalosiphi DeStefani‐Perez (Hymenoptera, Braconidae) chosen as the most sensitive species [13–15]. The off‐field HQ is calculated with the model where AR and MAF are the application rate and multiple application factor [16], respectively; the drift factor (% drift/100) derives from BBA studies [17].…”

An extended laboratory test for evaluating the effects of plant protection products on the parasitic wasp, Aphidius rhopalosiphi (Hymenoptera, Braconidae)

“…Lower replication may be considered for the toxic reference item, if the test facility considers that results between bioassays are consistent. For rate-response studies intended to determine the median lethal rate (LR 50 ), lower replication may also be considered (Grimm et al, 2001), but the experimenter should demonstrate that the data still fit the statistical model being applied to the results.…”

“…However, see Grimm et al (2001) for limitations of this method and a discussion of alternative procedures. In general the rate-response relationship is used to estimate an LR x (i.e.…”