Evaluating the vulnerability of arthropod ecosystem service providers to pesticide exposure

Protecting arthropod species that deliver pest control and pollination services in agricultural landscapes requires methods that account for exposure, toxicological sensitivity and capacity for population recovery. We developed a trait-based vulnerability framework for representative above-ground arthropod families occurring in European crops and combined it with chemical-specific acute contact toxicity data to produce family-level, scenario-dependent vulnerability indices. Trait information describing habitat use, feeding guild, life cycle (breeding phenology and voltinism and dispersal mode was used to calculate a partial vulnerability index based on exposure and recovery. These trait scores were then integrated with measures of acute contact toxicity, expressed as lethal application rates, to derive chemical-specific vulnerability estimates under two exposure scenarios (canopy spray and soil contact). Trait-only screening identified many ground-associated predators (notably several spider families, ground beetles and rove beetles), certain parasitoid wasps and several Diptera as having higher vulnerability related to exposure and limited recovery relative to common regulatory test species. Adding toxicity data produced compound-dependent re-ranking. For a subset of insecticides, families such as ground beetles, ladybirds, certain parasitoids, pteromalid wasps, lacewings and some moths exhibited higher overall vulnerability than the standard surrogates. Canopy exposure produced slightly higher mean vulnerability overall, while soil exposure increased vulnerability of several ground-dwelling families. Data gaps in toxicological coverage and reliance on family-level trait aggregation constrain full implementation. We conclude that a tiered approach that uses trait-based screening to prioritise taxa for targeted toxicological testing will improve ecological relevance of risk assessment and better safeguard arthropod-mediated ecosystem services in agricultural systems.