Epigeal collembola in arable fields: their ecology in relation to the effects of pesticides

The ecology of arable springtails (Collembola) was investigated in relation to pesticide exposure and recovery. Lepidocyrtus spp., Isotomurus spp., Bourletiella hortensis, Isotoma viridis, and I. Notabilis overwintered as surface-active adults within fields where they could potentially be exposed to pesticide deposition at a time when little or no crop cover was present. Sminthurus viridis and Sminthurinus elegans overwintered as eggs in the field soil, where exposure to sprayed winter pesticide applications would be expected to be lower than for surface-active species. The eggs of S. viridis, S. elegans and B. hortensis from field soils were resistant to periods of drought, although resistance varied among species. This study provided the first evidence for drought tolerance in eggs of S. viridis, S. elegans and B. hortensis in northern European arable habitats; viable eggs survived a four-month period of simulated drought in the laboratory. Drought resistance of some species is likely to alter the community composition in fields and hence affect the availability of vulnerable species for monitoring pesticide non-target effects.S. elegans, S. viridis and I. viridis dispersed into arable fields from an adjacent hedgerow, providing the first evidence that hedgerows may be important sources for collembolan recolonisation of arable fields. B. hortensis, Isotomurus spp. and Lepidocyrtus spp. were found to recover from population sources within the field itself. Certain species including B. hortensis, Isotomurus spp. and E. multifasciata were consistently found in the vicinity of hedgerows and may be unlikely to be true arable field species, and hence of limited use in studies monitoring pesticide effects.Collembolan abundance and community composition were compared in fields managed under organic, conventional and integrated regimes to assess the effects of farming systems. Differences in community composition were identified among regimes, although no individual species or species assemblage was indicative of any of the farming management systems.