Researchers Make Surprising Discovery about Ancient Mosquitoes

Researchers Make Surprising Discovery about Ancient Mosquitoes

研究人员关于古老蚊子的惊人发现

【原文听力】

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　　By John Russell

　　10 December 2023

　　Hundreds of thousands of people worldwide are killed every year by malaria and other diseases that are spread through mosquito bites.

　　Female mosquitoes are responsible for these deadly bites because they have a special mouth design that male mosquitoes do not have.

　　But it has not always been that way. Researchers said they have discovered the oldest-known fossils of mosquitoes - two males located in pieces of an ancient orange-colored substance known as amber.

　　The male mosquitoes date to 130 million years ago. They were found near the modern town of Hammana in Lebanon. To researchers' surprise, the male mosquitoes had long mouthparts seen now only in females.

　　Dany Azar is a researcher at the Chinese Academy of Sciences' Nanjing Institute of Geology and Paleontology and Lebanese University. Azar said they were clearly blood-eaters. The lead writer of the study, recently published in Current Biology, added, "This discovery is a major one in the evolutionary history of mosquitoes."

　　The two fossilized mosquitoes, both representing the same species that has died off, are similar in size and appearance to modern mosquitoes. However, the mouthparts used for getting blood are shorter than in today's female mosquitoes.

　　Study co-writer André Nel of the National Museum of Natural History of Paris described the finding as "quite surprising."

　　The special anatomy of the two mosquitoes was beautifully saved in the fossils. Both insects had sharp and triangle-shaped jaw anatomy and a long structure with tooth-like elements.

　　The researchers said they suspect that mosquitoes evolved from insects that did not consume blood. They think that the mouthparts that were developed for getting blood meals were originally used to pierce plants to get nutritious fluids.

　　Plant evolution may have affected the differences in feeding between male and female mosquitoes. At the time when these two mosquitoes became stuck in tree sap that eventually became amber, flowering plants were beginning to spread for the first time.

　　From the findings, Azar said that all early mosquitoes, both male and female, were bloodsucking. And male mosquitoes lost the ability later.

　　The researchers said while these are the oldest mosquito fossils, mosquitoes probably appeared millions of years earlier. They noted that molecular evidence suggests mosquitoes developed from about 200 million to 145 million years ago.

　　There are more than 3,500 species of mosquitoes worldwide, found everywhere except Antarctica. Some species spread diseases such as malaria, yellow fever, Zika fever, dengue and others. The World Health Organization says more than 400,000 people die annually from malaria - a parasitic infection - mostly children under age 5.

　　I'm John Russell.

　　Will Dunham reported on this story for Reuters. John Russell adapted it for VOA Learning English.

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　　作者：John Russell

　　2023年12月10日

　　每年全球有数十万人死于疟疾和其他通过蚊子叮咬传播的疾病。

　　雌性蚊子对这些致命的叮咬负有责任，因为它们有一种雄性蚊子所没有的特殊口部设计。

　　但情况并非一直如此。研究人员表示，他们发现了已知最古老的蚊子化石——两只雄性蚊子，位于被称为琥珀的古老橙色物质的碎片中。

　　这两只雄性蚊子的化石可以追溯到1.3亿年前。它们在现代黎巴嫩的哈马纳镇附近被发现。令研究人员惊讶的是，这些雄性蚊子具有现在只在雌性蚊子中看到的长口器。

　　Dany Azar是中国科学院南京地质古生物研究所和黎巴嫩大学的一名研究员。Azar说，他们显然是吸血的。这项研究的主要作者在《当前生物学》最近发表的文章中补充说，“这个发现在蚊子的进化历史中是一个重大的发现。”

　　这两只化石化的蚊子都代表了同一种已经灭绝的物种，它们的大小和外观与现代蚊子相似。然而，用于吸血的口器比今天的雌性蚊子短。

　　研究的合著者，巴黎自然历史博物馆的André Nel描述这个发现为“相当令人惊讶”。

　　这两只蚊子的特殊解剖结构在化石中得到了完美的保存。两只昆虫都有锐利的三角形颚部解剖结构和一个带有类似牙齿的元素的长结构。

　　研究人员表示，他们怀疑蚊子是从不吸血的昆虫进化而来的。他们认为，用于获取血液食物的口器最初是用来刺穿植物获取营养液体的。

　　植物的进化可能影响了雄性和雌性蚊子之间的饮食差异。当这两只蚊子被困在最终变成琥珀的树脂中时，开花植物正开始首次传播。

　　从这些发现中，Azar表示，所有的早期蚊子，无论雄性还是雌性，都是吸血的。而雄性蚊子后来失去了这种能力。

　　研究人员表示，虽然这些是最古老的蚊子化石，但蚊子可能在数百万年前就已经出现。他们指出，分子证据表明蚊子从大约2亿年到1.45亿年前开始发展。

　　全球有超过3500种蚊子，除了南极洲，其他地方都有。有些种类会传播如疟疾、黄热病、寨卡热、登革热等疾病。世界卫生组织表示，每年有超过40万人死于疟疾（一种寄生虫感染），大多数是5岁以下的儿童。

　　我是约翰·罗素。

　　这个故事是由路透社的Will Dunham报道的，约翰·罗素为VOA学习英语进行了改编。

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　　本故事中的词汇

　　fossil – n. 来自古代生物（如叶子、骨骼或足迹）的东西，

　　evolution – n. 一种观点，认为植物和动物之间的差异是由于在很长一段时间内通过自然过程发生的变化，

　　species – n. 一组相似并能繁殖后代的动物或植物，

　　anatomy -- n. 构成生物的各个部分，

　　pierce -- v. 在某物上打洞或穿透某物，

　　sap – n.植物内部的水状汁液，用于运输植物的食物。