Review of available evidence regarding the vulnerability of off‐crop non‐target arthropod communities in comparison to in‐crop non‐target arthropod communities

Abstract

EFSA is revising and updating the Ecotoxicology Guidance Document on Terrestrial Risk Assessment of Pesticides (SANCO/10329/2002). For this purpose an overview of available scientific information on several topics is needed. The aim of the current literature survey was to collect and summarize the published scientific literature on (1) the composition of non-target arthropod species that occur in and outside crops, (2) their vulnerability to pesticides and (3) their potential to recover from a pesticide impact. The survey was aimed at all major groups of non-target arthropods occurring in and outside crops. In order to collect relevant literature on-line searches in various databases were carried out in December 2011 and January 2012. The searches addressed two types of scientific information: (1) publications with the results of ecotoxicological field studies in which the effects of pesticides on in-field and off-field communities of non-target arthropod communities are investigated, and (2) publications with the results of ecological studies that describe and compare the composition of in-crop and off-crop communities of non-target arthropods. The literature searches initially yielded over 1,500 articles for which the abstracts were screened, but the number of suitable papers that was finally reviewed was less than 100. The taxonomic groups for which sufficient information was found were ground beetles (Carabidae), rove beetles (Staphylinidae), spiders (Aranea), hoverflies (Syrphidae) springtails (Collembola) and bugs (Heteroptera). Most studies of these groups were conducted in Europe and for the larger part in cereals. Types of off-crop habitats varied greatly (hedgerows, flower strips, grass edges, trees, etc.). For these taxonomic groups, the number of species and their abundance was higher in the off-crop habitat than in the crop. Most species were only found in one or a few studies, indicating that geographic location and specific crop and off-crop habitat are important factors determining the species composition. For other important non-target arthropod taxonomic groups, no suitable studies were found to evaluate in- and off-crop differences in species composition and abundance. These taxonomic groups include grasshoppers, butterflies, isopods, lady beetles, bees and wasps. The available literature was not suitable or contained very little information to assess the sensitivity to pesticides and recovery and thus the vulnerability of individual species from a pesticide impact in the field. Therefore an additional approach, vulnerability analysis based on species traits, was used. The analysis was done for a selection of thirteen species that represent the mentioned dominant taxonomic groups. This vulnerability analysis showed that for insecticides, herbicides and fungicides, the average vulnerability of typical off-crop species was higher than that of typical in-crop species. The average vulnerability of species that occur in both habitats was intermediate. The difference between off-crop and in-crop species can be explained by differences in exposure and especially recovery. In-crop species are less exposed (for instance because they breed out of the pesticide spraying season) and have a greater capacity to disperse, migrate and reproduce. It is plausible that such species are more typical of in-crop habitats because they are better adapted to the varying circumstances and frequent disturbances that occur within arable fields. In the same vulnerability analysis, the two current non-target arthropod standard test species, the parasitic wasp Aphidius rhopalosiphi and the predatory mite Typhlodromus pyri, were found to be the least vulnerable of all species analysed