PLoS One：研究证实蜜蜂可对抗真菌 自我医疗

美国北卡罗莱纳州立大学的一项研究显示，当蜂群感染上有害的真菌时，蜜蜂会“自我治疗”，采集更多数量的抗真菌植物树脂，以抵挡真菌的侵袭。

相关论文3月29日在线发表于《公共科学图书馆.综合》（PLoS ONE），论文的主要作者北卡州立大学昆虫系的博士后研究员迈克尔 西蒙妮-芬斯特隆（Michael Simone-Finstrom）说，让工蜂耗费精力采集这些树脂，演化出这种行为应该是由于其利大于弊。

野生蜜蜂通常会在蜂巢中铺上一层蜂胶，这是一种有抗真菌和抗细菌作用的植物树脂和蜡的混合物。家养蜜蜂也会使用蜂胶来填补蜂巢中的缝隙。研究人员发现，当面对真菌威胁时，蜜蜂采集的蜂胶数量平均会急剧增长45%以上。与此同时，蜜蜂还会移走被真菌寄生感染将会成为真菌孢子的蜜蜂幼虫。

研究人员知道蜂胶是一种有效的抗真菌剂，因为他们把一些蜂胶提取物抹在蜂巢后发现，蜂胶提取物能够显著降低真菌感染率。

当蜂巢感染上无害真菌时，蜂群的蜂胶采集量并没有上涨，它们的处理办法只是移走真菌孢子。因此很明显，蜜蜂有时可以区分有害真菌和无害真菌。

不过，这种“自我医疗”的行为仍有局限性。当蜂群感染上病原菌时，尽管蜂胶也有抗细菌作用，但是它们的蜂胶采集量并没有很大提升。芬斯特隆表示，蜂胶数量有些许增多，但是没有那么显著。他们接下来计划接着研究这项内容。

对养蜂人来说，这是一个可以学习的经验。以前美国的养蜂人更喜欢不怎么采集蜂胶的蜂群，因为蜂胶粘稠且不方便操作，但是我们现在知道了，蜂群的这个特征值得提倡，因为蜂胶似乎能给蜜蜂提供天然的防御。（生物谷 bioon.com）

doi:10.1371/journal.pone.0034601
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Increased Resin Collection after Parasite Challenge: A Case of Self-Medication in Honey Bees?

Michael D. Simone-Finstrom, Marla Spivak

The constant pressure posed by parasites has caused species throughout the animal kingdom to evolve suites of mechanisms to resist infection. Individual barriers and physiological defenses are considered the main barriers against parasites in invertebrate species. However, behavioral traits and other non-immunological defenses can also effectively reduce parasite transmission and infection intensity. In social insects, behaviors that reduce colony-level parasite loads are termed “social immunity.” One example of a behavioral defense is resin collection. Honey bees forage for plant-produced resins and incorporate them into their nest architecture. This use of resins can reduce chronic elevation of an individual bee's immune response. Since high activation of individual immunity can impose colony-level fitness costs, collection of resins may benefit both the individual and colony fitness. However the use of resins as a more direct defense against pathogens is unclear. Here we present evidence that honey bee colonies may self-medicate with plant resins in response to a fungal infection. Self-medication is generally defined as an individual responding to infection by ingesting or harvesting non-nutritive compounds or plant materials. Our results show that colonies increase resin foraging rates after a challenge with a fungal parasite (Ascophaera apis: chalkbrood or CB). Additionally, colonies experimentally enriched with resin had decreased infection intensities of this fungal parasite. If considered self-medication, this is a particularly unique example because it operates at the colony level. Most instances of self-medication involve pharmacophagy, whereby individuals change their diet in response to direct infection with a parasite. In this case with honey bees, resins are not ingested but used within the hive by adult bees exposed to fungal spores. Thus the colony, as the unit of selection, may be responding to infection through self-medication by increasing the number of individuals that forage for resin.