小海雀能散发天然驱蚊剂

A bird species found in some parts of Western Alaska is believed to emit a natural mosquito repellent with properties similar to DEET, the key ingredient in many commercial repellents.

Hector Douglas, a University of Alaska Fairbanks researcher, said he made the discovery in the feathers of the crested auklet after applying a little scientific intuition and sacrificing some of his own blood.

"It's perhaps an example of how there are natural products in nature that have the potential to be utilized," Douglas said.

Clues to the crested auklet's unique ability to repel mosquitoes and pests like ticks and lice was apparent the first time Douglas encountered the creature, one of four auklet species in Alaska. He had been dropped at Kiska Island in the Aleutians to conduct research for the U.S. Fish and Wildlife Service.

The birds feed en masse on zooplankton in the ocean and return as a group, 1 million strong. As they began landing, the first clue was right under his nose.

"It was literally like stepping into a Dr. Seuss story," Douglas said. "The birds would come down and have this citrus smell and they're landing on the rocks all around you and they have these elaborate social interactions. It was pretty peculiar, the first time it happened."

He noticed the birds had little trouble with ticks compared to other species of auklets and seabirds.

The citrus smell reminded him of a research paper he'd read about birds that rubbed citrus peels in their feathers to help ward off pests, which at best are nuisances and at worst carry disease.

It wasn't until years later, however, when he was studying auklets on St. Lawrence Island in the Bering Sea where mosquitoes are more prevalent that he began to see the compound's effect on the airborne pests.

To test his theory, he went into the laboratory with a few auklet feathers. An analysis showed him the chemicals that make up the auklet's "odorant." Most are available commercially.

He then tested their repellent properties using mosquitoes specially bred at a research lab in Florida for their aggressive tendencies. Douglas dabbed test samples on filter paper, attached that paper to his hand, then put it in a cage with hungry mosquitoes.

It was clear the auklet samples kept mosquitoes away.

"They soon give up trying to land and rest on the side of the cage," Douglas said. "It's a similar reaction to DEET and other repellants. It overwhelms their sensory systems."

Douglas detailed his findings in a "Journal of Medical Entomology" paper. The research is part of his doctoral thesis. He said he was unsure if it will lead to something like a commercial repellant.

"It has potential, but at the same time you'd have to do further research to find out if it's safe to use on the skin," he said.

冠毛小海雀能散发出天然的驱蚊剂

美国研究人员日前表示，栖息在美国阿拉斯加州一些地区的冠毛小海雀可以释放出一种天然的驱蚊物质，其性质与避蚊胺相类似。

据报道，阿拉斯加费尔班克斯大学的研究员赫克托。道格拉斯表示，他在冠毛小海雀（crested auklet）的羽毛上发现了这种驱蚊物质。

第一次和冠毛小海雀（阿拉斯加4种小海雀之一）相遇时，它们这种能够驱退蚊子、虱子等害虫的独一无二的本领就已经明显地展露出来。道格拉斯曾在阿留申群岛的吉斯卡岛上负责关于美国鱼类和野生动物保护的研究。

冠毛小海雀以海里的浮游生物为食，在进食完毕后，它们会以很大的群体一起返回。当开始着陆时，展示这种特殊本领的第一个线索就在道格拉斯鼻子下面显现出来了。道格拉斯说，这种鸟会带着一种柑橘般的气味降落到你周围的岩石上……那个场面非常奇特。

道格拉斯注意到，和其它小海雀和海鸟相比，冠毛小海雀在对待扁虱这个问题上似乎没有什么困难。而这种柑橘气味则提醒他想起了曾经看过的一篇关于鸟类的研究报告。该报告阐述的是鸟类通过摩擦柑橘等水果的果皮，以帮助自己免受小虫的骚扰。而这些小虫会给鸟类带来很多麻烦，严重时还能传播疾病。

然而，直到几年后道格拉斯在白令海的圣劳伦斯岛上研究小海雀时，他才开始注意到这种有着柑橘般气味的物质对蚊子的功效。在圣劳伦斯岛上，蚊子的数量更为普遍。为了验证自己的理论，道格拉斯带着几根冠毛小海雀的羽毛走进了实验室，分析结果显示出了构成冠毛小海雀身上“有味东西”的化学成分，其中的大部分都是商业上可以用到的。

而后，道格拉斯又使用在佛罗里达一个实验室中特别培养的蚊子，进行了驱蚊性的测试。道格拉斯将试验样本涂在滤纸上，再将滤纸放在自己手上，然后把手伸入一个装有饥饿蚊子的小笼子里。很明显的是，这种从冠毛小海雀身上提取的试验样本成功地将蚊子“拒之在外”。道格拉斯说，这些蚊子很快放弃了试图要叮咬我的念头，而且都停留在笼子的一边。这和使用避蚊胺以及其它驱蚊剂的效果差不多，它对蚊子的感觉系统起了作用。

报道说，这项研究是道格拉斯博士论文的一部分，但目前他也尚不确定这项研究是否会催生某种类似商业驱蚊剂的东西。他说，虽然具有这方面的潜力，但是同时也要进行更为深入的研究，以确定它对人类皮肤是否安全。