双语阅读：为什么有些人那么招蚊子？

Some people can sit outside all summer long and not suffer from mosquito bites. Others turn into an itchy mess despite bathing in DEET and never leaving the purple glow of the bug zapper.

有些人可以整个夏天坐在户外乘凉却不被蚊子叮咬，而另有一些人即便用含驱蚊胺的沐浴露洗浴、随身带着灭蚊灯，却仍遭蚊子叮咬而奇痒难耐。

It's mostly about the invisible chemical landscape of the air around us. Mosquitoes take advantage of this landscape by using specialized behaviors and sensory organs to find victims by following the subtle chemical traces their bodies leave behind.

这主要是因为我们身体周围空气中肉眼看不见的化学成分。通过特殊习性和感觉器官，蚊子利用这种化学环境，跟踪人体留下的细微化学痕迹找到叮咬对象。

In particular, mosquitoes rely on carbon dioxide to find their hosts. When we exhale, the carbon dioxide from our lungs doesn't immediately blend with the air. It temporarily stays in plumes that mosquitoes follow like breadcrumbs.

具体来说，蚊子能够靠人体释放的二氧化碳找到它们叮咬的对象。当我们呼气时，从肺里呼出的二氧化碳并非立即与空气混合，而是暂时形成类似于面包粉的团块状气流，而蚊子会跟踪这种气流。

"Mosquitoes start orienting themselves to those pulses of carbon dioxide and keep flying upwind as they sense higher concentrations than the normal ambient air contains," said Joop van Loon, an entomologist at Wageningen University in the Netherlands. Using carbon dioxide, mosquitoes can lock onto targets from up to 164 feet (50 meters) away.

荷兰瓦赫宁恩大学的昆虫学家约普·范隆说：“蚊子开始自我定位，跟踪那些二氧化碳气流，并在它们感觉到二氧化碳浓度比正常环境空气的浓度高时保持逆流飞行。”利用二氧化碳，蚊子可以锁定164英尺（约合50米）以外的目标。

Things start getting personal when mosquitoes get about 3 feet (1 meter) away from a group of potential targets. In close quarters, mosquitoes take into account a lot of factors that vary from person to person, including skin temperature, the presence of water vapor and color.

当蚊子飞到离一群潜在目标大约3英尺远时，就开始区分每个人的不同情况。在近距离时，蚊子考虑很多因人而异的因素，包括皮肤温度、水汽的存在和颜色。

Scientists think the most important variable mosquitoes rely on when choosing one person over another are the chemical compounds produced by the colonies of microbes that live on our skin.

科学家们认为，蚊子选择某个特定的人作为叮咬目标依据的一个最重要因素是，皮肤上微生物菌落产生的化学成分。

"Bacteria convert the secretions of our sweat glands into volatile compounds that are taken through the air to the olfactory system on the head of the mosquitoes," Van Loon told Live Science.

范隆告诉美国趣味科学网站说：“细菌把人类汗腺的分泌物变成挥发性混合物，通过空气进入位于蚊子头部的嗅觉系统。”

These chemical bouquets are complex, including upward of 300 different compounds, and they vary from person to person based on genetic variation and environment.

这些混合物的化学气味很复杂，含有300多种成分，而且因为基因差异和环境不同，因人而异。

"If you compare a father and daughter in the same household, there can be differences in the ratios of the chemicals the microbes are making," said Jeff Riffell, an associate professor of biology at the University of Washington who has studied mosquito attraction.

美国华盛顿大学研究蚊子吸引力的生物学副教授杰夫·里费尔说：“即使拿一个家庭里的父亲与女儿做比对，微生物产生的化学物质比例可能也有差异。”

For instance, men with a greater diversity of skin microbes tended to get fewer mosquito bites than men with less diverse skin microbes did, a 2011 study in the journal?PLOS ONE?found. Moreover, men with less diverse microbes tended to have the following bacteria on their bodies: Leptotrichia, Delftia, Actinobacteria Gp3 and Staphylococcus, the researchers said.

譬如，2011年发表在美国《公共科学图书馆·综合》杂志上的一篇研究报告发现，皮肤微生物多样性较高的男性往往比皮肤微生物多样性较低的男性少招蚊子叮咬。而且研究人员称，皮肤微生物多样性较低的男性，他们皮肤上往往有下列几种细菌：纤毛菌、代尔夫特菌、放线菌Gp3和葡萄球菌。

In contrast, men with a diverse array of microbes tended to have the bacteria Pseudomonas and Variovorax on their skin, that study found.

研究发现，相比之下，有多种多样微生物的男性，在他们的皮肤上往往有假单胞菌和贪嗜菌。

Subtle differences in the composition of these chemical bouquets can account for big differences in how many bites a person gets. The composition of those microbial colonies can also vary over time in the same individual, particularly if that person is sick, Riffell said.

这些化学气味成分的细微差异在一个人遭蚊子叮咬时会产生巨大差异。里费尔说，同一个人，这些微生物菌落的组成也可能随时间变化而不同，尤其是在此人生病的时候。

We don't have much control over the microbiomes on our skin, but Riffell did offer some advice based on his research.

我们对皮肤上的微生物没有太多控制权，但里费尔根据他的研究结果给出了一些建议。

"Mosquitoes love the color black," so consider wearing something lighter at your next cookout, he said.

他说，“蚊子喜欢黑色”，因此下次露天烧烤时，可以考虑穿浅色衣物。