VOA标准英语2012--Dallas Attacks West Nile Virus by Land, Air
时间：2019-01-13 作者：英语课 分类：VOA标准英语2012年(八月)
Dallas Attacks West Nile Virus by Land, Air
The aerial and ground fumigation 1 programs are blanketing around 1,400 square kilometers of the county, but don't target all mosquitoes.
Laura McGowan, who works with Clarke, the company contracted to carry out the aerial operation, says two local species spread West Nile virus.
“The ones that we are targeting right now are the Culex mosquitoes here in Dallas," she says. "Culex quinquefasciatus and Culex Tarsalis.”
The mosquitoes, known generally together as the Southern House Mosquito, lay eggs in water, which turn to larvae 2 and finally into full-grown flying bloodsuckers.
They come out at dusk each night. So that's when the planes fly and drop a fine mist of a concoction 3 called DUET which, according to McGowan, attracts the mosquitoes and kills them.
“Our average droplet 4 size is smaller in diameter than a human hair, so that is designed to specifically interact with the mosquito biology," she says. "That is how we know we are avoiding non-target insects, by both the time of the day we are applying as well as the size of the droplets 5.”
McGowan says some areas may need to be sprayed two or three times to make sure no significant numbers of mosquitoes or their larvae remain.
But some areas may need only one application, according to the director of Dallas County Health and Human Services.
“Especially if we have not had one positive human case or a positive mosquito pool, one application would be sufficient,” Zachary Thompson says.
Weekend rains halted some of the spraying efforts and left puddles 6 of water where more mosquitoes can breed.
While streams and ponds are perfect breeding grounds for mosquitoes, experts say even a small amount of water on a city street can support larvae.
Local officials are asking people to look for discarded containers that might contain stagnant 7 water that could breed mosquitoes and get rid of them.
McGowan stresses the need for public awareness 8 of the threat and what to do to avoid the disease.
“It only takes one West Nile mosquito to make someone sick," she says. "So we want to make sure people put on personal protection, that they do avoid being out at dusk and dawn, and we are still very early in the West Nile season.”
Measures to fight the spread of West Nile virus will not end until the first good frost subdues 9 mosquitoes, but that could be more than two months from now.
- We think that the fumigation can be done in a large, round metal container. 我们觉得熏蒸过程可以在一个大圆金属容器内进行。 来自辞典例句
- In the northern states fumigation is needed only after insect outbreaks occur. 在北部各州，只在虫害发生后才进行熏蒸。 来自辞典例句
- Larvae are parasitic on sheep.幼虫寄生在绵羊的身上。
- The larvae prey upon small aphids.这种幼虫以小蚜虫为食。
- She enjoyed the concoction of foreign dishes.她喜欢调制外国菜。
- His story was a sheer concoction.他的故事实在是一纯属捏造之事。
- The rate of droplet growth under different conditions can be evaluated.可以计算在不同条件下的云滴增长率。
- The test results showed that increasing droplet size was associated with better stability.试验结果表明，增加液滴尺寸将使稳定性提高。
- Droplets of sweat were welling up on his forehead. 他额头上冒出了滴滴汗珠。 来自辞典例句
- In constrast, exhaled smoke contains relatively large water droplets and appears white. 相反，从人嘴里呼出的烟则包含相当大的水滴，所以呈白色。 来自辞典例句
- The puddles had coalesced into a small stream. 地面上水洼子里的水汇流成了一条小溪。
- The road was filled with puddles from the rain. 雨后路面到处是一坑坑的积水。 来自《简明英汉词典》
- Due to low investment,industrial output has remained stagnant.由于投资少，工业生产一直停滞不前。
- Their national economy is stagnant.他们的国家经济停滞不前。
- There is a general awareness that smoking is harmful.人们普遍认识到吸烟有害健康。
- Environmental awareness has increased over the years.这些年来人们的环境意识增强了。