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.