Concerns regarding the potential of pesticides to harm terrestrial non-target arthropod populations have led to the increased use of ecotoxicological test systems for terrestrial Non-target Arthropod risk assessment. Whilst some useful guidance on terrestrial invertebrate test systems is available, there are significant gaps in guidance for terrestrial non-target arthropod exposure estimates. The typical exposure in the standard test systems is by application of the test substance at the field rate (i. e. gram substance per hectare field) on to a two dimensional surface. However, under field conditions such a spray deposit will be diluted over the total available 3-Dimensional plant and soil surface. The recommendation is to use published leaf area index and crop interception values to standardize terrestrial dilution factors, which can then be used to predict exposure on a 3-Dimensional plant surface. Based on average crop/time specific LAI data for 26 crops, a surrogate off-crop dilution factor of 12 was calculated which can be used to convert 2-Dimensional spray drift exposure to 3-Dimensional off-crop plant surface exposure. Another significant terrestrial exposure guidance gap is how to calculate predicted environmental concentrations (PECs) for multiple application products. Based on spray interval and half-life data from 32 representative multiple application plant protection products, the typical worst-case PECs for accumulation of residues were calculated after up to 8 applications. These data showed that Multiple Application Factors (MAFs = accumulated PEC/initial PEC), increased from 1 to 3.5 after 1 to 8 applications, respectively. Finally, overall 90th percentile spray deposit values have been proposed for deriving off-crop multiple applications PECs (1 to 8 applications) based on published spray drift data. The recommended equations for terrestrial exposure assessment include the use of:-application rate, the 90th percentile drift value, the multiple application factors (MAF) and the standard dilution factor (for 3-Dimensional plant surface). This proposed terrestrial non-target arthropod exposure scheme is comparable with other first tier exposure assessment schemes eg aquatic exposure assessment.

This paper is a guidance document for side-effect testing with plant protection products on non-target arthropods under semi-field and field conditions. The principles, methods, endpoints and interpretation of non-target arthropod semi-field and field trials which should be conducted for registration of plant protection products in the European Union are presented and discussed. The recommendations presented reflect the opinions of the experts from authority, academia, industry and consulting which participated at the IOBC (International Organisation of Biological Control), BART (Beneficial Arthropod Regulatory Testing) group and EPPO (European Plant Protection Organisation) Joint Initiative workshop held in Versailles (France) on the 25–26 October, 1999.

The EU Plant Protection Product Directive 91/414/EEC recommends the EPPO/CoE Arthropod Natural Enemies Risk Assessment Scheme for guidance on how to conduct risk assessments for terrestrial non-target arthropods. This scheme is currently in the process of being revised by EPPO/ CoE. A major change will be the recommendation for the generation and use of ’Dose Response’ toxicity data instead of limit test data. In addition, the revised EPPO/CoE Non-target Arthropods Risk Assessment Scheme will replace the current arbitrary 30% threshold trigger value applied to limit test data, with a Hazard Quotient (HQ; = Ratio Application Rate/LC50 on Glass)), comparable to the successful approach adopted in the EPPO/CoE ’Honeybee Risk Assessment Scheme’. However, in order for this new approach to be implemented under 91/414/EEC, an appropriate regulatory HQ trigger value needs to be derived. Such an HQ trigger value has been established by calculating HQ values for the 2 recommended sensitive indicator species (T pyri andAphidius) for a wide range of products and validating opposite robust semi-field/field data. This validation indicated that an HQ trigger value of ≥ 12 forT pyri and ≥ 8 forAphidius spp., should be used to trigger higher-tier risk assessment and/or higher-tier testing for non-target arthropods. As these trigger values were validated with realistic semi-field/ field data they apply for both lethal and sub-lethal effects as well as single and multiple application scenarios. Due to the worst case assumptions used in this HQ validation analysis, no further uncertainty factors need to be applied for in-crop risk assessment. Whilst a small amount of uncertainty exists regarding the comparative sensitivity ofT pyri andAphidius spp. for off-crop non-target arthropod guilds of arthropods, this is balanced by the fact that the off-crop exposure assessment used in the HQ derivation, is at least an order of magnitude higher than that realistically likely in the field. This HQ approach and trigger value is an appropriate and conservative tool for tier 1 risk assessment, which should reduce the number of false positive results leading to unnecessary higher-tier testing.

Data on the sensitivity of nine non-target arthropod families to 95 plant protection products (PPP), including herbicides, fungicides, insecticides and plant growth regulators, tested using currently established laboratory methods were analyzed. The data presented were supplied by 11 agro-chemical companies and were generated for regulatory purposes. All the studies were performed in compliance with Good Laboratory Practice (GLP) standards. For the analysis of the relative sensitivity to PPP, the measurement endpoints in each arthropod study performed were separated into lethal (mortality) and sub-lethal effects (e.g. oviposition, hatching rate, food consumption). Differences in sensitivity among arthropod species to the same PPP, the relative sensitivity of arthropod species among PPP tested, and the potential use of the more sensitive species as indicator species for regulatory testing purposes are discussed.Pooling the data for all PPP tested provided a ranking of the sensitivity of the arthropod species using the currently available test systems. Typhlodromus pyri and Aphidius spp., showed the greatest sensitivity to PPP (76.8% and 67.4% of the PPP tested eliciting lethal or sub-lethal effects greater than or equal to 30% to T. pyri and Aphidius spp., respectively). All other species tested were of intermediate sensitivity with approximately 10.5% and 55% of the PPP tested eliciting lethal or sub-lethal effects greater than or equal to 30%. Ranking of the arthropod species tested, in order of decreasing sensitivity and based on a combination of both lethal and sub-lethal endpoints, follows: T. pyri, Aphidius spp., Coccinella septempunctata, Orius spp., Pardosa spp., Episyrphus balteatus, Chrysoperla carnea, P. cupreus and A. bilineata.Of the 95 PPP evaluated, 23.2% elicited an adverse lethal or sub-lethal effect greater than or equal to 30% an T. pyri without affecting Aphidius sp., 13.7% elicited an adverse lethal or sub-lethal effect greater than or equal to 30% on Aphidius spp. without affecting I: pyri. Among all arthropod species and PPP tested, an adverse effect greater than or equal to 30% on a sub-lethal endpoint was observed in 10% to 20% of the studies without an adverse effect on mortality. For E. balteatus, C. carnea, P. cupreus and A. bilineata, the percentage of PPP eliciting adverse; effects on sublethal parameters was always higher than the percentage of PPP showing effects on mortality.With a combination of both lethal and sub-lethal parameters as the assessment endpoints, if a PPP elicited an adverse effect greater than or equal to 30% on any of the arthropod species tested, an adverse effect also was observed in either T. pyri and Aphidius spp. in 95.8% of the cases. Similar results were obtained if fungicides and herbicides were considered separately (96.0% and 94.1%, respectively). These results indicate that the potential of an arthropod species to be adversely affected following exposure to a PPP under worst-case exposure conditions can be effectively predicted by determining the lethal and sub-lethal effects of the PPP on the two sensitive species, T. pyri and Aphidius spp. (C) 1999 Elsevier Science Ltd. All rights reserved.