Sweden scientists study on God: mosquito simply bed place chicken? -Insect repellent, mosquito, malaria-IT information
On how to prevent malaria, scientists are racked his brain. More recently, from Sweden and Ethiopian researchers propose a new method for preventing malaria: bed chicken, or disguised as a chicken.
People already know that malaria spread by mosquitoes is the main media, effective insect repellent DEET is an important part of combating malaria. Sweden people Paul Hermann Miller invented the to address of malaria made an outstanding contribution to the DTT was awarded the Nobel Prize, but later it was found that DTT has a huge damage to the environment and gave up. Since then people have been looking for a safe and effective method of DEET, anti-insect repellent and mosquito nets is the main method.
Sweden University (Swedish University of Agricultural Sciences), chemical ecologist Rickard Ignell led a team of researchers recently had a brain hole opening of the experiment. Researchers at the high incidence of malaria in the three villages of Ethiopia and caught thousands of mosquito, of which the vast majority (98.5%) are Arab mosquitoes (Anopheles arabiensis)-a most mosquitoes to spread malaria in Africa South of the Sahara desert. They analysis has these mosquito smoking of blood, found in indoor capture of mosquito smoking of most (69%) is people of blood, next is cattle (18%), and goat (3.3%) and sheep (2%); outdoor capture of mosquito smoking of is most is is cattle (63%|) of blood, then is people (20%), and goat (5%) and sheep (2.6%) of blood. Strange thing is, whether it's indoor or outdoor capture mosquitoes, are rarely found in the blood (only in the thousands of mosquitoes found a mosquito outdoor chicken blood). You know, in these three villages near the site of the mosquito, has approximately 6700, 10000, 3,200 chickens, 850 480 sheep and goats, they could be mosquitos prey.
: Why do mosquitoes don't like chicken? This group of scientists suspect mosquitoes with a strong sense of smell, chickens who probably smells like mosquitoes to avoid them. So they gathered samples of animal body parts and found only chicken feathers out of taste has a repellent effect (so, on insect repellent, with a feather when the token is very reliable). Researchers then analyzed using gas chromatography and mass spectrometry instruments cattle, sheep and chicken odour molecules. They found some of the odorant molecules, such as limonene (limonene), nonanal (nonanal) and sulcatone is shared by these animals, chicken-specific odour molecules there are six, including known molecule has four, hexadecane,naphthalene,isobutyl butanoate and TRANS-limonene oxide, respectively, there are two through gas chromatography and mass spectrometry analysis.
Next, the researchers synthesized these compounds unique to chickens, used to test the mosquito's response: as the dose increases, mosquitoes has been responding more strongly-Arab ones do escape from these molecules.
So, is it true that these molecules can protect humans from mosquito bites? Researchers recruited a group of volunteers, volunteers in the nets as "human bait" to attract mosquitoes. Researchers in the nets on the plug-in mosquito, mosquito traps next to have a distributed little bottles of the above four kinds of odorant molecules (below). As a control, they are still a group of volunteers nets outside of a live chicken. Experimental results show that both chicken odor molecules and the chickens can keep mosquitoes away from mosquito traps, and those smells other mosquito traps can catch more mosquitoes.
? Researchers used pictures of odor molecules do mosquito experiment, the picture on the left is using chicken odor molecules, the figure on the right is the use of a live chicken. Pictures from the study's original paper.
"We were surprised to find the chicken body odour can drive away mosquitoes. The study found that for the first time the mosquitoes would specifically avoid an animal, and this behavior is mediated by scent signals. "Professor Ignell in the United Kingdom the independent newspaper (The Independent) said in a report.
But why do mosquitoes will repel chickens smell it?
Researchers now have no definite answer, but some conjecture. Unlike with cattle and sheep, chicken is a master catch insects, prey on mosquitoes and other insects, which could make mosquitoes evolved ability to avoid the chicken. In other words, radiates the smell of chicken for mosquitoes may be a red flag. If this is true, maybe we can go to research other predators have mosquito repellent odor molecules.
It is interesting, in this research analysis of chicken-specific odor molecules, two had been reported in those is not easy to be detected by mosquitoes bite humans, there are two known natural insect repellent.
Researchers are now considering chicken-with disguised as these molecules make insect repellent to prevent malaria, they also called on the whole considered similar ideas in the field of malaria. After all, the resistance of mosquitoes to insecticides is getting worse now.
However, Professor Ignell said chemicals used in their camouflage not yet finalized. He told the Scientific American (Scientific American) says, not without humor in an interview: "the ideal situation would be that we put them in a bottle and sent out, you don't have to pay even a dime--which of course is impossible. But there is an equally effective way, it is a chicken in the House, so that mosquitoes will reduce, this is probably the cheapest way. ”
瑞典科学家神研究：驱蚊只需床头放只鸡？ - 驱蚊,防蚊,疟疾 - IT资讯
关于如何预防疟疾，科学家们可谓是绞尽了脑汁。最近，来自瑞典和埃塞尔比亚的研究人员提出一个预防疟疾的新方法：床头放只鸡，或伪装成一只鸡。
人们早已知道由蚊子是传播疟疾的主要媒介，如何有效地驱蚊避蚊是防治疟疾的重要一环。瑞典人Paul Hermann Miller因为发明了为解决疟疾作出卓越贡献的DTT而被授予诺贝尔奖，但后来人们发现DTT对环境有巨大的破坏而放弃了。此后人们一直在寻找安全有效的避蚊方法，灭蚊剂和蚊帐是目前主要的方法。
瑞典农业大学（Swedish University of Agricultural Sciences）的化学生态学家Rickard Ignell领导的一个研究小组最近做了一个脑洞大开的实验。研究人员先在疟疾高发的埃塞尔比亚的三个村庄中捉了几千只蚊子，这其中绝大部分（98.5%）都是阿拉伯疟蚊（Anopheles arabiensis）——一种在撒哈拉沙漠以南的非洲传播疟疾最厉害的蚊子。他们分析了这些蚊子吸食的血液，发现在室内捕捉的蚊子吸食的大部分（69%）是人的血液，接下来是牛（18%）、山羊（3.3%）和绵羊（2%）；室外捕捉的蚊子吸食的则大部分是是牛（63%|）的血液，然后是人（20%）、山羊（5%）和绵羊（2.6%）的血液。奇怪的是，无论是室内还是室外捕捉的蚊子，都极少发现鸡的血液（在几千只蚊子里仅仅发现了一只室外的蚊子吸食了鸡的血液）。要知道，在这三个村庄捕蚊的地点附近，有大约6700人、10000头牛、3200只鸡、850只山羊和480只绵羊，他们都有可能是蚊子的捕食对象。
蚊子为什么不喜欢鸡呢？这群科学家猜测，蚊子具有极强的嗅觉，鸡的身上也许有什么气味让蚊子避开它们。于是，他们收集了这些动物身体各部位的样本，发现只有鸡的羽毛散发出来的味道有驱蚊的效果（这样看来，在驱蚊这件事上，拿着鸡毛当令箭还是挺靠谱的）。接着研究人员使用气象色谱和质谱仪器分析了牛、羊和鸡散发的气味分子。他们发现有一些气味分子，比如苧烯（limonene）、壬醛（nonanal）和sulcatone是这些动物共有的，鸡所特有的气味分子有六种，其中已知的分子有四种，分别为hexadecane，naphthalene，isobutyl butanoate和trans-limonene oxide，还有两种无法通过气象色谱和质谱仪器分析出来。
接下来，研究人员人工合成了鸡身上所特有的这些化合物，用来测试蚊子的反应：随着剂量的增加，蚊子的反应也更强烈——阿拉伯疟蚊确实会逃避这些分子。
那么，这些分子是否真的能让人类免受蚊虫叮咬呢？研究人员招募了一些志愿者，让志愿者在蚊帐中作为“人肉诱饵”吸引蚊子。研究人员在蚊帐外挂上捕蚊器，捕蚊器旁还有一个散发以上四种气味分子的小瓶子（下图）。作为对照，他们还在一组志愿者的蚊帐外放了一只活鸡。实验的结果显示：无论是鸡的气味分子还是活鸡都能让蚊子远离捕蚊器，而那些散发着其它气味的捕蚊器可以捉到更多的蚊子。
▲研究者用各种气味分子做捕蚊实验的照片，左图是使用鸡的气味分子，右图是使用一只活鸡。图片来源于该研究的原始论文。
“我们惊讶地发现鸡身上散发的气味可以驱离蚊子。这项研究第一次发现了疟蚊会特异性地避开某种动物，而这种行为是由气味信号介导的。”Ignell教授在英国《独立报》（The Independent）的报道中说。
但是，蚊子为何会排斥鸡的气味呢？
研究者们现在还没有确切的答案，但有一些猜想。与牛和羊不一样，鸡是捉虫高手，捕食蚊子和其他昆虫，这可能使得蚊虫在进化中获得了躲避鸡的能力。也就是说，鸡身上散发出来的气味对蚊虫来说可能是一个危险的信号。如果这个猜想是正确的，也许我们可以去研究蚊虫的其它天敌是否也有能够驱蚊的气味分子。
有趣的是，在这项研究分析出的鸡特有的气味分子中，有两种曾经被报道过可以在那些不易被蚊子叮咬的人身上检测到，还有两种是已知的天然驱虫分子。
研究者们现在正在考虑把人伪装成鸡——用这些气味分子做成驱蚊剂以预防疟疾，他们也呼吁整个疟疾防治领域考虑类似的思路。毕竟，现在蚊子对杀虫剂的抗药性越来越严重了。
不过，Ignell教授表示他们的化学伪装剂还未最终完成。他在接受《科学美国人》（Scientific American）采访时不无幽默地说：“最理想的状况是我们把这些气味装在瓶子里然后送出去，你们一分钱也不用给——这当然是不可能的。不过有一个同样有效的方法，那就是在家里放一只鸡，这样蚊虫就会减少，这恐怕是最便宜的方法了。”