Sensitivity of non-target arthropods to plant protection products: Could Typhlodromus pyri and Aphidius spp. be used as indicator species?

Abstract

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 ≥ 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 ≥ 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 ≥ 30% on T. pyri without affecting Aphidius sp., 13.7% elicited an adverse lethal or sub-lethal effect ≥ 30% on Aphidius spp. without affecting T. pyri. Among all arthropod species and PPP tested, an adverse effect ≥ 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 sub-lethal 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 ≥ 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.