The current pesticide risk assessment paradigm may not adequately protect solitary bees as it focuses primarily on the honey bee (Apis mellifera). The alfalfa leafcutting bee (Megachile rotundata) is a potential surrogate species for use in pesticide risk assessment for solitary bees in North America. However, the toxicity of potential toxic reference standards to M. rotundata will need to be determined before pesticide risk assessment tests (tier I trials) can be implemented. Therefore, we assessed the acute topical toxicity and generated LD50 values for three insecticides: dimethoate (62.08 ng a.i./bee), permethrin (50.01 ng a.i./bee), and imidacloprid (12.82 ng a.i/bee). The variation in the mass of individual bees had a significant but small effect on these toxicity estimates. Overall, the toxicity of these insecticides to M. rotundata were within the 10-fold safety factor currently used with A. mellifera toxicity estimates from tier I trials to estimate risk to other bee species. Therefore, tier I pesticide risk assessments with solitary bees may not be necessary, and efforts could be directed to developing more realistic, higher-tier pesticide risk assessment trials for solitary bees.

中文翻译：

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用于一级农药风险评估的三种杀虫剂的接触毒性


目前的农药风险评估范式可能无法充分保护独居蜜蜂，因为它主要关注蜜蜂（Apis mellifera）。苜蓿切叶蜂（Megachile rotundata）是北美独居蜂农药风险评估的潜在替代物种。然而，在实施农药风险评估测试（一级试验）之前，需要确定潜在毒性参考标准对 M. rotundata 的毒性。因此，我们评估了三种杀虫剂的急性局部毒性并生成了 LD50 值：乐果（62.08 ng ai/蜜蜂）、氯菊酯（50.01 ng ai/蜜蜂）和吡虫啉（12.82 ng ai/蜜蜂）。个体蜜蜂质量的变化对这些毒性估计有显着但很小的影响。总体而言，这些杀虫剂对 M. rotundata 的毒性在目前使用的 10 倍安全系数范围内，该安全系数与一级试验中的意大利蜜蜂毒性估计值一起使用，以估计对其他蜂种的风险。因此，可能没有必要对独居蜂进行一级农药风险评估，可以致力于为独居蜂开发更现实、更高层次的农药风险评估试验。