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(28-01) A synoptic quantitative approach for evaluating exposure of non-target invertebrate communities to pesticide drift. Tones, Stephen*,1, Ellis, Stephen2, Oakley, Jonathan3, 1 ADAS, Exeter, UK2 ADAS, Malton, UK3 ADAS, Hereford, UK ABSTRACT- Tiered regulatory tests on non-target arthropods are designed to minimise the approval of pesticides harmful to naturally occurring arthropods, but the extent to which they overestimate exposure is unknown. From a literature review, 72 invertebrate species were chosen to represent the main taxonomic, ecological and behavioural groups of field margin invertebrates in the UK. Aphidius rhopalosiphi, Typhlodromus pyri, and four tier-2 species were included. Eleven biotic determinants of exposure were identified. Information was compiled from the literature, and used to calculate a decimal exposure factor for each determinant (maximum value 1, minimum 10-4) for each species. By multiplying the exposure factors for different determinants together, aggregate indices were derived for exposure to off-crop drift by direct contact, residual contact, or feeding. Species were ranked by index. The possible effects of invertebrate size, mobility, and behavioural responses to sub-lethal doses of pesticides were tested using contrasting assumed values. All tier-1 and tier-2 test species are small, and all are predators or parasites. Many field margin invertebrates are much larger than the test species, and many are herbivores or detrivores. Most of the 72 species had exposure indices several orders of magnitude less than the maximum of 1 (equivalent to exposure in the tier-1 bioassay). Exposure indices differed by up to nine orders of magnitude between the most exposed and the least exposed species. Exposure rankings for direct and residual contact were sensitive to changes in the assumed exposure factors for body size. A. rhopalosiphi ranked between first and 50th, and T. pyri between first and 66th. If size and trophic group are important, it may be advisable to include a large herbivorous species in tiered tests. Further research is proposed on the influence of invertebrate size and some other factors on exposure. Key words: pesticide, exposure, non-target, invertebrate |
