Ecological toxicity reduction of dinotefuran to honeybee: New perspective from an enantiomeric level

In last decade, there has been a concerted effort to reduce the potential threats of honeybees' population due to exposure to neonicotinoid pesticides. A new perspective was put forward to reduce the potential ecological toxicity of neonicotinoid dinotefuran to honeybee in terms of an enantiomeric level in the study. Toxicity of dinotefuran was enantioselective, and S-dinotefuran was 41.1- to 128.4-fold more toxic than R-dinotefuran to honeybee Apis mellifera (Apis mellifera Linnaeus), whereas R-dinotefuran exhibited comparative insecticidal activities (1.7-2.4 times) to typical sucking pests Aphis gossypii and Apolygus hicorum compared to racemic mixtures. Our data suggested that use of R-dinotefuran could have a good efficacy in controlling target pests while minimizing hazard to honeybees. The mechanism for chiral specific toxicity to honeybee was further characterized by electrophysiological studies and molecular docking. S-dinotefuran appears to be more toxic by binding to alpha 8 subunit of nAChR of Apis mellifera. The alpha 8 also have a more stable, functional binding cavity to S-dinotefuran with a higher binding score of 7.15, primarily due to an extensive hydrogen bond network. Therefore, new chiral products with a high proportion of or an enantiomeric pure R-dinotefuran are recommended to achieve effective pests control reducing hazard to honeybee populations.

在过去十年中，人们齐心协力降低蜜蜂因接触新烟碱类杀虫剂而面临的潜在种群威胁。该研究从对映体层面提出了一种新的视角，以降低新烟碱类杀虫剂呋虫胺对蜜蜂的潜在生态毒性。呋虫胺的毒性具有对映选择性，对于西方蜜蜂（Apis mellifera Linnaeus），S - 呋虫胺的毒性是R - 呋虫胺的41.1 - 128.4倍，而与外消旋混合物相比，R - 呋虫胺对典型的刺吸式害虫棉蚜（Aphis gossypii）和绿盲蝽（Apolygus lucorum）表现出相当的杀虫活性（1.7 - 2.4倍）。我们的数据表明，使用R - 呋虫胺在控制目标害虫的同时，能够将对蜜蜂的危害降至最低。通过电生理研究和分子对接进一步明确了对蜜蜂手性特异性毒性的机制。S - 呋虫胺似乎通过与西方蜜蜂烟碱型乙酰胆碱受体的α8亚基结合而具有更强的毒性。α8亚基对S - 呋虫胺还具有更稳定、功能性的结合腔，结合分数更高，为7.15，这主要是由于广泛的氢键网络。因此，建议使用含有高比例或对映体纯的R - 呋虫胺的新手性产品，以实现有效的害虫控制，同时降低对蜜蜂种群的危害。