Data from: Risk assessment of pesticide seed treatment for farmland birds using refined field data

1.Due to reductions in winter food resources, newly sown cereal seeds have become a key component of many bird species’ diet, but these seeds are often treated with pesticides that may cause toxic effects. To complete an appropriate risk assessment, data on treated seed toxicity need to be combined with information about the risk of exposure of birds in the field and the factors that modulate such exposure.
2.We studied the abundance of pesticide-treated seeds available for birds in the field, the pesticides and their concentrations in treated seeds, and the bird species observed in the field that were feeding on these pesticide-treated seeds. The exposure of red-legged partridge to treated winter cereal seeds was characterized through the analysis of crop and gizzard contents of hunted individuals (n=189). Moreover, we measured the contribution of cereal seeds in the autumn–winter diet of partridges in order to assess the potential risk of exposure to pesticide-treated seeds.
3.Density of treated seeds on the soil surface after sowing (11.3 ± 1.2 seeds m−2 in the centre of field and 43.4 ± 5.5 seeds m−2 in the headlands) was enough to provide, in an area between 6 and 50 m2, doses of six active ingredients above those indicating acute (i.e. a dose capable of killing 50% of individuals of a sensitive species) and chronic (no observed effect level) toxicity.
4.Up to 30 bird species were observed consuming treated cereal seeds in recently sown fields. Corn bunting was identified as an appropriate focal passerine species for the risk assessment of pesticide-treated seeds.
5.We found that treated seeds were an important route of pesticide ingestion for red-legged partridge; pesticide residues (six fungicides and two insecticides) were found in 32.3% of crops and gizzards. Cereal seeds represented more than half (53.4 ± 4.3%) of total biomass consumed by partridges from October to February.
6.Synthesis and applications. The field exposure data combined with previous studies about the toxicity to partridges of using pesticide-treated seeds point to an unacceptable risk of this practice to farmland birds. Our results suggest that the prophylactic use of pesticide-coated seeds should be avoided, with the approval of this treatment considered on a case-by-case basis and accompanied with specific measures to minimise risks of adverse effects on avian communities.

1. 由于冬季食物资源减少，新播谷物种子已成为多种鸟类饮食的关键组成部分，但这类种子常经农药处理，可能产生毒性效应。为开展恰当的风险评估，需将处理种子的毒性数据，与野外鸟类的暴露风险及其调控因素的相关信息相结合。
2. 本研究调查了野外可供鸟类取用的经农药处理种子的丰度、处理种子中的农药种类及其浓度，以及野外观测到的取食这类经农药处理种子的鸟类物种。通过对189只狩猎个体的嗉囊（crop）与肌胃（gizzard）内容物进行分析，明确了红腿石鸡（red-legged partridge）暴露于冬季经处理谷物种子的情况。此外，我们还测定了谷物种子在石鸡秋冬季饮食中的占比，以评估其暴露于经农药处理种子的潜在风险。
3. 播种后土壤表层的经处理种子密度（田块中心为11.3±1.2粒·m⁻²，田埂区域为43.4±5.5粒·m⁻²）足以在6至50平方米的范围内，提供6种有效成分（active ingredients）的剂量，超过了急性毒性（acute toxicity，即可杀死敏感物种50%个体的剂量）与慢性毒性（chronic toxicity）的无观察效应水平（no observed effect level, NOEL）阈值。
4. 在新近播种的田块中，共观测到多达30种鸟类取食经处理的谷物种子。黍鹀（corn bunting）被确定为开展经农药处理种子风险评估的适宜焦点雀形目物种。
5. 本研究发现，经处理种子是红腿石鸡摄入农药的重要途径；32.3%的嗉囊与肌胃样本中检出了农药残留（6种杀菌剂（fungicides）与2种杀虫剂（insecticides））。10月至2月期间，谷物种子在石鸡摄入的总生物量中占比超过一半（53.4±4.3%）。
6. 综合与应用：本研究的野外暴露数据结合此前关于经农药处理种子对石鸡毒性的研究表明，该种植方式对农田鸟类存在不可接受的风险。本研究结果提示，应避免预防性使用包衣农药种子；此类处理的审批需遵循个案评估原则，并配套特定措施以最小化其对鸟类群落产生不良影响的风险。