蜜蜂是怎样避免群体感染病毒的？
Virus-Infected Bees Practice Social Distancing
Bees infected with a virus cut back on interactions within their hive but find it easier to get past sentries at neighboring hives.
If there’s one thing we know about viruses, it’s that they love to spread. The novel coronavirus is happy to use us humans as its host. Other viruses fancy honeybees. But like us, bees fight back.
In the case of one particular virus, called Israeli acute paralysis virus, a study shows that honeybees actually use a form of social distancing to prevent transmitting the infection within their own colony. Of course, not to be outdone, the virus manipulates the bees in a way that spreads the infection to the colony next door. The study is in the Proceedings of the National Academy of Sciences. [Amy C. Geffre et al, Honey bee virus causes context-dependent changes in host social behavior]
Honeybees live in large communities that contain tens of thousands of related individuals in close quarters. So researchers got to wondering, how can bees keep infections from spreading like wildfire?
While a graduate student at the University of Illinois at Champagne-Urbana, Tim Gernat developed an automated system for tracking the behavior of thousands of bees. And he watched what happened when he introduced infected bees into the hive.
Entomologist Adam Dolezal, who worked with Gernat, describes what they saw.
“We found in this study that within their own colony context, when they are interacting with their nest mates, usually their sisters, infected bees experience fewer contact behaviors, fewer mouth-to-mouth feeding contacts than bees who are not infected.”
The researchers also saw the same sort of social avoidance when, instead of infecting the bees with a virus, they artificially activated the bees’ immune system. So, the behavior isn’t driven by the virus, but by the bees’ own immune response. Which Dolezal says makes sense. If honeybees are going to protect their colony and their queen from disease, sick bees need to keep their feelers to themselves.
“They have to. They live in these really large colonies where everybody’s touching each other all the time, they’re all closely related…I joke that honeybees have been doing social distancing for millions of years.”
At the same time, bees are under no pressure to keep infections from spreading to other colonies. And that’s where the virus gains the upper hand. Amy Geffre, who worked on the project as a graduate student, found that the guard bees from other colonies were actually less aggressive toward incoming infected bees than they were to uninfected bees. As a result:
“The infected bees are accepted into the colony at about twice the rate of control bees or immunostimulated bees.”
The virus, it seems, alters the chemicals that bees use to communicate who they are and where they’re from.
“And so we think that one way that the virus could be gaining entry to these other colonies is by changing the bees’ physiology in a way to make it more acceptable to other colonies’ guard bees.”
That’s bad news for beekeepers, who tend to keep tens or even hundreds of hives right next to one another.
“It’s a really ripe situation for bees to be able to move between colonies relatively easily and bring pathogens and parasites along with them.”
Seems ya gotta carefully mind your beeswax—and keep kept colonies healthily, socially distanced.
---from Scientific American
百度翻译:
感染病毒的蜜蜂与社会保持距离
感染病毒的蜜蜂减少了蜂巢内的相互作用，但发现更容易越过邻近蜂巢的哨兵。
如果我们对病毒有一点了解的话，那就是它们喜欢传播。这种新型冠状病毒乐于以人类为宿主。其他病毒喜欢蜜蜂。但和我们一样，蜜蜂也会反击。
在一种叫做以色列急性麻痹病毒的特殊病毒的例子中，一项研究表明蜜蜂实际上使用一种社交距离的形式来防止在自己的蜂群内传播感染。当然，为了不被超越，病毒操纵蜜蜂的方式，传播感染到隔壁的蜂群。这项研究发表在《美国国家科学院院刊》上。[Amy C.Geffre等人，蜜蜂病毒引起宿主社会行为的上下文依赖性变化]
蜜蜂生活在一个大的社区里，在这个社区里有成千上万的相关个体。所以研究人员开始想，蜜蜂如何才能防止感染像野火一样蔓延？
蒂姆·格尔纳特是伊利诺伊大学香槟分校的研究生，他开发了一个自动系统来跟踪成千上万只蜜蜂的行为。他观察了当他把感染的蜜蜂引入蜂巢时发生的事情。
与格尔纳特一起工作的昆虫学家亚当·多莱扎尔描述了他们所看到的。
“我们在这项研究中发现，在它们自己的群体环境中，当它们与巢友（通常是它们的姐妹）互动时，受感染的蜜蜂比未受感染的蜜蜂经历更少的接触行为，更少的口对口喂食接触。”
研究人员也看到了同样的社交回避，他们人工激活蜜蜂的免疫系统，而不是用病毒感染蜜蜂。所以，这种行为不是由病毒驱动的，而是蜜蜂自身的免疫反应。Dolezal说的有道理。如果蜜蜂要保护它们的蜂群和蜂王不受疾病的侵害，病蜂就必须保持自己的触角。
“他们必须这样做。它们生活在这些非常大的蜂群里，每个人都在彼此接触，它们都有着密切的关系……我开玩笑说，蜜蜂已经在社会上疏远了数百万年了。”
同时，蜜蜂没有压力阻止感染扩散到其他蜂群。这就是病毒占上风的地方。作为一名研究生，Amy Geffre参与了这个项目，她发现来自其他蜂群的保卫蜜蜂实际上比未受感染的蜜蜂对传入的受感染蜜蜂的攻击性要小。因此：
“受感染的蜜蜂以大约两倍于对照蜜蜂或免疫刺激蜜蜂的速度进入蜂群。”
这种病毒似乎改变了蜜蜂用来交流它们是谁和从哪里来的化学物质。
“因此，我们认为，病毒进入其他蜂群的一种方式是改变蜜蜂的生理机能，使其更容易被其他蜂群的保卫蜜蜂所接受。”
这对养蜂人来说是个坏消息，他们往往把几十个甚至几百个蜂箱放在一起。
“蜜蜂能够相对容易地在蜂群之间移动，并携带病原体和寄生虫，这是一个非常成熟的情况。”
看来你得小心你的蜂蜡，保持殖民地健康，社会距离。