首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
A man-made chemical that attracts male gypsy moths by duplicating the natural attractant of female gypsy moths has been patented
A man-made chemical that attracts male gypsy moths by duplicating the natural attractant of female gypsy moths has been patented
admin
2013-01-12
42
问题
A man-made chemical that attracts male gypsy moths by duplicating the natural attractant of female gypsy moths has been patented as No. 3,018,219.
Dr. Martin Jacobson of Silver Spring, Md., assigned patent rights to the U. S. Government as represented by the Secretary of Agriculture. The chemical can be used to detect gypsy moth infestations, as well as to control the insects.
The gypsy moth does serious damage to forest and shade trees in New England and eastern New York State. The caterpillars, or larvae, of gypsy moths eat the leaves of trees, often causing death by a single attack. Losses of hardwood trees have been estimated at tens of millions of dollars from a 20-year study.
Gypsy moths were prevented from spreading to other U. S. forest areas by using the natural attractant of the female to detect infestations, then spraying with chemicals such as DDT to kill the insects.
Since the lure could previously be obtained only by clipping the last two abdominal segments of the virgin female moth, extracting the segments with benzene and then processing to stabilize the chemical, the procedure was expensive. Another difficulty was that, as the gypsy moth population declined, it became increasingly hard to obtain the females needed for lure production.
Dr. Jacobson overcame both these difficulties by discovering a synthetic method for making the female’s attractant chemical. The chemical is known as 12-acetoxy-l-hydroxycis-9- octadecene. It is so potent that the fraction of a drop produced by the female is 200,000 times more than the amount needed to catch a mate. The synthetic chemical is also very powerful--it works in amounts about equivalent to one drop in a box car.
The flightless female gypsy moth mates only once a year and, as soon as she does, an enzyme switches off production of the sex attractant. The winged male, however, call mate several times and it is because of this that the chemical is being used for pest control.
By using a mixture of attractant and DDT in traps lined with a sticky substance, enough males can be caught to reduce the gypsy moth population substantially.
Prior to Dr. Jacobson’s synthetic drug, scientists found difficulty in controlling the pest because ______.
选项
A、the natural drug was unavailable
B、female moths hid from the scientists
C、extracting the natural drug involved a complicated process
D、the gypsy moth population declined
答案
C
解析
在雅各布森博土的合成药物出现之前,科学家们发现很难控制这种害虫,因为提取天然的药物需要一个复杂的过程。根据第五段,以往获得引诱剂的唯一方法是剪掉未授精而产卵的雌性舞毒蛾腹部的最后两个体节,拔出含有苯的体节,然后进行加工,从而达到使药物稳定的目的,其过程要付出很大的代价。
转载请注明原文地址:https://kaotiyun.com/show/3p9O777K
0
考博英语
相关试题推荐
Thecarswere______becauseitwasimpossibletogoanyfurtherinthefog.
Hewill______resigninviewofthecompletefailureoftheresearchproject.
Genetherapyandgene-baseddrugsaretwowayswecouldbenefitfromourgrowingmasteryofgeneticscience.Buttherewillbeo
Genetherapyandgene-baseddrugsaretwowayswecouldbenefitfromourgrowingmasteryofgeneticscience.Buttherewillbeo
Becauseacirclehasnobeginningorend,theweddingringisasymboloflove.
Vitaminsareorganiccompoundsnecessaryinsmallamountsinthedietforthenormalgrowthandmaintenanceoflifeofanimals,
AtfirstIguesseditwasanairplane,butIsoonchangedmymindbecauseitremainedstaticinsteadofmovinglikeaplane.
Agoodmodernnewspaperisanextraordinarypieceofreading.Itisremarkablefirstforwhatitcontains:therangeofnewsfro
Exactlywherewewillstandinthelongwaragainstdiseasebytheyear2050isimpossibletosay.(111)Butifdevelopmentsin
Whatwecallnatureis,______,thesumofthechangesmadebyallthevariouscreaturesandnaturalforcesintheirintricate
随机试题
正常二尖瓣瓣口面积约为
卫生人力管理包括哪几方面
肺炎球菌的主要致病作用在于
A、利福平B、喹诺酮类C、青霉素D、抗菌谱E、红霉素抑制细菌DNA回旋酶的药物是
水泵机组的各台机组运行时间为带额定负荷连续运行24h(含无故障停机)或7天内累计运行48h(含全站机组联合运行小时数),全部机组联合运行时间一般为6h,且机组无故障停机次数不少于3次。执行机组运行时间确有困难时,可由验收委员会或上级主管部门根据具体情况适当
某小学一节课结束后,任课老师抱着学生刚交的作业本离开教室,一名未交作业的学生急忙追赶,不慎摔倒在地,将门牙摔掉一颗。在此事件中应承担主要责任的是()
①科学家们知道,研究和理解海洋动物的独特语言,需要______年累月的时间。②严厉打击社会上的黑社会性质的恶势力,______它们滋生的土壤,是公安机关义不容辞的责任。③他听到了群众大声的______,仍头也不回地走到车里。填入划横
甲盗窃了农民王某的一个手提包,发现包里有大量现金和一把手枪。甲将真情告诉乙,并将手枪交给乙保管,乙将手枪藏在家里。关于本案,下列说法正确的是()
Onedayalltheempolyeesofaveryfamouscompanyreachedtheirofficeandallsawabigsignonthemaindoorwhichsaidthis:
Whydon’tpeoplejustsaywhattheymean?Thereasonisthatconversationalpartnersarenotmodemsdownloadinginformationin
最新回复
(
0
)