USDA, Agricultural Research Service, Bee Research Lab, BARC-East Bldg. 306, 10300 Baltimore Ave., Beltsville, MD, 20705, USA.
Department of Entomology, University of Maryland, College Park, MD, USA.
Sci Rep. 2021 Apr 26;11(1):8989. doi: 10.1038/s41598-021-88649-y.
Transmission routes impact pathogen virulence and genetics, therefore comprehensive knowledge of these routes and their contribution to pathogen circulation is essential for understanding host-pathogen interactions and designing control strategies. Deformed wing virus (DWV), a principal viral pathogen of honey bees associated with increased honey bee mortality and colony losses, became highly virulent with the spread of its vector, the ectoparasitic mite Varroa destructor. Reproduction of Varroa mites occurs in capped brood cells and mite-infested pupae from these cells usually have high levels of DWV. The removal of mite-infested pupae by worker bees, Varroa Sensitive Hygiene (VSH), leads to cannibalization of pupae with high DWV loads, thereby offering an alternative route for virus transmission. We used genetically tagged DWV to investigate virus transmission to and between worker bees following pupal cannibalisation under experimental conditions. We demonstrated that cannibalization of DWV-infected pupae resulted in high levels of this virus in worker bees and that the acquired virus was then transmitted between bees via trophallaxis, allowing circulation of Varroa-vectored DWV variants without the mites. Despite the known benefits of hygienic behaviour, it is possible that higher levels of VSH activity may result in increased transmission of DWV via cannibalism and trophallaxis.
传播途径会影响病原体的毒力和遗传特性，因此，全面了解这些途径及其对病原体传播的贡献，对于理解宿主-病原体相互作用和设计防控策略至关重要。变形翅膀病毒（DWV）是一种主要的蜜蜂病毒病原体，与蜜蜂死亡率和蜂群损失增加有关，随着其载体——寄生性螨虫瓦螨的传播，其毒力变得非常高。瓦螨在封盖的幼虫巢房中繁殖，而这些细胞中受螨虫侵害的蛹通常携带高水平的 DWV。工蜂通过清除受螨虫侵害的蛹，即瓦螨敏感卫生行为（VSH），导致高 DWV 负荷的蛹被蜂群自相残杀，从而为病毒传播提供了另一种途径。我们使用遗传标记的 DWV，在实验条件下研究了受螨虫侵害的蛹被工蜂自相残杀后，病毒向工蜂的传播和在工蜂之间的传播。我们证明，感染 DWV 的蛹被自相残杀会导致工蜂体内高水平的这种病毒，然后通过蜜食在蜜蜂之间传播，从而在没有螨虫的情况下循环传播瓦螨传播的 DWV 变体。尽管已知卫生行为具有益处，但更高水平的卫生行为活动可能会通过自相残杀和蜜食导致 DWV 的传播增加。
