Oddie Melissa A Y, Dahle Bjørn, Neumann Peter
Vetsuisse Faculty/University of Bern, Institute of Bee Health, Bern, Switzerland.
Norwegian University of Life Sciences, Department of Animal and Aquacultural Sciences, Ås, Norway.
PeerJ. 2017 Oct 24;5:e3956. doi: 10.7717/peerj.3956. eCollection 2017.
Managed, feral and wild populations of European honey bee subspecies, , are currently facing severe colony losses globally. There is consensus that the ectoparasitic mite , that switched hosts from the Eastern honey bee to the Western honey bee , is a key factor driving these losses. For >20 years, breeding efforts have not produced European honey bee colonies that can survive infestations without the need for mite control. However, at least three populations of European honey bees have developed this ability by means of natural selection and have been surviving for >10 years without mite treatments. Reduced mite reproductive success has been suggested as a key factor explaining this natural survival. Here, we report a managed population in Norway, that has been naturally surviving consistent infestations for >17 years.
Surviving colonies and local susceptible controls were evaluated for mite infestation levels, mite reproductive success and two potential mechanisms explaining colony survival: grooming of adult worker bees and Varroa Sensitive Hygiene (VSH): adult workers specifically detecting and removing mite-infested brood.
Mite infestation levels were significantly lower in surviving colonies and mite reproductive success was reduced by 30% when compared to the controls. No significant differences were found between surviving and control colonies for either grooming or VSH.
Our data confirm that reduced mite reproductive success seems to be a key factor for natural survival of infested colonies. However, neither grooming nor VSH seem to explain colony survival. Instead, other behaviors of the adult bees seem to be sufficient to hinder mite reproductive success, because brood for this experiment was taken from susceptible donor colonies only. To mitigate the global impact of , we suggest learning more from nature, i.e., identifying the obviously efficient mechanisms favored by natural selection.
欧洲蜜蜂亚种的养殖蜂群、野生蜂群和流浪蜂群目前在全球范围内正面临着严重的蜂群损失。人们普遍认为，外寄生螨从东方蜜蜂转移到西方蜜蜂身上，是导致这些损失的关键因素。20多年来，育种工作一直未能培育出无需控制螨虫就能在感染情况下存活的欧洲蜜蜂蜂群。然而，至少有三群欧洲蜜蜂通过自然选择获得了这种能力，并且在不进行螨虫防治的情况下存活了10多年。螨虫繁殖成功率降低被认为是解释这种自然存活现象的关键因素。在此，我们报告了挪威一个养殖的蜂群，该蜂群在持续感染的情况下自然存活了17年以上。
对存活的蜂群和当地易感对照蜂群进行评估，以确定螨虫感染水平、螨虫繁殖成功率以及解释蜂群存活的两种潜在机制：成年工蜂的梳理行为和瓦螨敏感卫生行为（VSH），即成年工蜂专门检测并清除感染螨虫的幼虫。
与对照蜂群相比，存活蜂群的螨虫感染水平显著降低，螨虫繁殖成功率降低了30%。在梳理行为或VSH方面，存活蜂群和对照蜂群之间未发现显著差异。
我们的数据证实，螨虫繁殖成功率降低似乎是感染蜂群自然存活的关键因素。然而，梳理行为和VSH似乎都无法解释蜂群的存活。相反，成年蜜蜂的其他行为似乎足以阻碍螨虫的繁殖成功，因为本实验中的幼虫仅取自易感供体蜂群。为减轻瓦螨对全球的影响，我们建议更多地向自然界学习，即识别自然选择所青睐的明显有效的机制。
