第二篇：Honey Bees inTrouble （当蜜蜂遇到困难）
原文：
Honey Bees in Trouble
Can native pollinators fill the gap?
A
Recently, ominousheadlines have described a mysterious ailment, colony collapse disorder (CCD),which is wiping out the honeybees that pollinate many crops. Without honeybees,the story goes, fields will be sterile, economies will collapse, and food willbe scarce.
B
But what fewaccounts acknowledge is that what’s at riskis not itself a natural state of affairs. For one thing, in the United States,where CCD was first reported and has had its greatest impacts, honeybees arenot a native species. Pollination in modern agriculture isn’t alchemy, it’sindustry. The total number of hives involved in the U.S. pollination industryhas been somewhere between 2.5 million and 3 million in recent years.Meanwhile, American farmers began using large quantities of organophosphateinsecticides, planted large-scale crop monocultures, and adopted “clean farming” practicesthat scrubbed native vegetation from field margins and roadsides. Thesepractices killed many native bees outright — they’re as vulnerable to insecticides as any agriculturalpest — and made the agricultural landscapeinhospitable to those that remained. Concern about these practices and theireffects on pollinators isn’t new, in her 1962 ecological alarm cry SilentSpring, Rachel Carson warned of a ‘FruitlessFall’ that could result from the disappearanceof insect pollinators.
C
If that ‘Fruitless Fall’ has not — yet — occurred, it may be largely thanks to thehoneybee, which farmers turned to as the ability of wild pollinators to servicecrops declined. The honeybee has been semi-domesticated since the time of theancient Egyptians, but it wasn’t just familiarity that determined thischoice: the bees’ biology is in many ways suited to the kindof agricultural system that was emerging. For example, honeybee hives can beclosed up and moved out of the way when pesticides are applied to a field. Thebees are generalist pollinators, so they can be used to pollinate manydifferent crops. And although they are not the most efficient pollinator ofevery crop, honeybees have strength in numbers, with 20,000 to 100,000 beesliving in a single hive. “Without a doubt, if there was one bee youwanted for agriculture, it would be the honeybee,” says JimCane, of the U.S. Department of Agriculture. The honeybee, in other words, hasbecome a crucial cog in the modern system of industrial agriculture. Thatsystem delivers more food, and more kinds of it, to more places, more cheaplythan ever before. But that system is also vulnerable, because making a farmfield into the photosynthetic equivalent of a factory floor, and pollinationinto a series of continent-long assembly lines, also leaches out some of theresilience characteristic of natural ecosystems.
D
Breno Freitas, anagronomist in Brazil, pointed out that in nature such a high degree ofspecialization usually is a very dangerous game: it works well while all therest is in equilibrium, but runs quickly to extinction at the least disbalance.In effect, by developing an agricultural system that is heavily reliant on asingle pollinator species, we humans have become riskily overspecialised. Andwhen the human-honeybee relationship is disrupted, as it has been by colonycollapse disorder, the vulnerability of that agricultural system begins tobecome clear.In fact, a few wild bees are already being successfully managedfor crop pollination. “The problem is trying to provide nativebees in adequate numbers on a reliable basis in a fairly short number of yearsin order to service the crop,” Jim Cane says. “You’re talking millions of flowers per acre ina two-to three-week time frame, or less, for a lot of crops.” On the other hand, native bees can be much moreefficient pollinators of certain crops than honeybees, so you don’t need as many to do the job. For example, about 750blue orchard bees (Osmia lignaria) can pollinate a hectare of apples oralmonds, a task that would require roughly 50,000 to 150,000 honeybees. Thereare bee tinkerers engaged in similar work in many corners of the world. InBrazil, Breno Freitas has found that Centris tarsata, the native pollinator of wild cashew,can survive in commercial cashew orchards if growers provide a source of floraloils, such as by interplanting their cashew trees with Caribbean cherry. E
In certain places,native bees may already be doing more than they’re gettingcredit for. Ecologist Rachael Winfree recently led a team that looked atpollination of four summer crops (tomato, watermelon, peppers, and muskmelon)at 29 farms in the region of New Jersey and Pennsylvania.
Winfree’s team identified 54 species of wild bees that visitedthese crops, and found that wild bees were the most important pollinators inthe system: even though managed honeybees were present on many of the farms,wild bees were responsible for 62 percent of flower visits in the study. Inanother study focusing specifically on watermelon, Winfree and her colleaguescalculated that native bees alone could provide sufficient pollination at 90percent of the 23 farms studied. By contrast, honeybees alone could providesufficient pollination at only 78 percent of farms.
F
“The region I work in is not typical of theway most food is produced,” Winfree admits. In the Delaware Valley,most farms and farm fields are relatively small, each farmer typically grows a varietyof crops, and farms are interspersed with suburbs and other types of land usewhich means there are opportunities for homeowners to get involved in bee conservation,too. The landscape is a bee-friendly patchwork that provides a variety ofnesting habitat and floral resources distributed among different kinds ofcrops, weedy field margins, fallow fields, suburban neighborhoods, and seminatural habitat like old woodlots, all at a relatively small scale. In otherwords, “pollinator friendly” farming practices would not only aid pollination ofagricultural crops, but also serve as a key element in the over allconservation strategy for wild pollinators, and often aid other wild species aswell. Of course, not all farmers will be able to implement all of thesepractices. And researchers are suggesting a shift to a kind of polyglotagricultural system. For some small-scale farms, native bees may indeed be allthat’s needed. For larger operations, a suite ofmanaged bees — with honeybees filling the generalist roleand other, native bees pollinating specific crops — could be augmented by free pollination services fromresurgent wild pollinators. In other words, they’re saying,we still have an opportunity to replace a risky monoculture with somethingdiverse, resilient, and robust.
判断4：
27 In the UnitedStates, farmers use honeybees in a large scale over the past few
years. No
NG 28 Cleanfarming practices would be harmful to farmers’ health.
NG 29 The blueorchard bee is the most efficient pollinator for every crop.
YES 30 It isbeneficial to other local creatures to protect native bees.
选择5：
31 The example ofthe ‘Fruitless Fall’ underlines the writer’s pointabout
A needs for usingpesticides.
B impacts oflosing insect pollinators.
C vulnerabilitiesof native bees.
D benefits inbuilding more pollination industries.
32 Why canhoneybees adapt to the modern agricultural system?
A The honeybeescan pollinated more crops efficiently.
B The bees aresemi-domesticated since ancient times.
C Honeybeehives can be protected from pesticides.
D The ability ofwild pollinators using to serve crops declines.
33 The writermentions factories and assembly lines to illustrate
A one drawbackof the industrialised agricultural system.
B a low cost inmodern agriculture.
C the role ofhoneybees in pollination.
D what a highyield of industrial agriculture.
34 In the 6thparagraph, Winfree’s experiment proves that
A honeybees canpollinate various crops.
B there are manytypes of wild bees as the pollinators.
C wild bees canincrease the yield to a higher percentage.
D wild beeswork more efficiently as a pollinator than honeybees in certain
cases.
35 What does thewriter want to suggest in the last paragraph?
A the importanceof honeybees in pollination
B the adoptionof different bees in various sizes of agricultural system
C the comparisonbetween the intensive and the rarefied agricultural system
D the reason whyfarmers can rely on native pollinators
配对5：
36 Headlines ofcolony collapse disorder state that B
37 Viewpoints ofFreitas manifest tha t F
38 Examples ofblue orchard bees have shown that E
39 Centris tarsatais mentioned to exemplify that A
40 One finding ofthe research in Delaware Valley is that D
A nativepollinators can survive when a specific plant is supplied.
B it would causesevere consequences to both commerce and agriculture.
C honeybees cannot be bred.
D someagricultural landscapes are favourable in supporting wild bees.
E a large scale ofhoneybees are needed to pollinate.
F an agriculturalsystem is fragile when relying on a single pollinator.
答案：
27.No 28.NG 29.NG 30.YES 31.B 32.C 33.A
34.D 35.B 36.B 37.F 38.E 39.A 40.D
第三篇：新材料塑料包装（Nature works for Nature Works TM PLA）
原文：
A
A dozen years ago, scientists at Cargill got the idea of converting lactic acid made from corn into plastic while examining possible new uses for materials produced from corn wet milling processes. In the past, several efforts had been made to develop plastics from lactic acid, but with limited success. Achieving this technological breakthrough didn’t come easily, but in time the efforts did succeed. A fermentation and distillation process using com was designed to create a polymer suitable for a broad variety of applications.
B
As an agricultural based firm, Cargill had taken this product as far as it could by 1997. The company needed a partner with access to plastics markets and polymerization capabilities, and began discussions with The Dow Chemical Company. The next step was the formation of the joint venture that created Cargill Dow LLC. Cargill Dow’s product is the world’s first commercially available plastic made from annually renewable resources such as com:Nature Works PLA is a family of packaging polymers (carbon-based molecules) made from non-petroleum based resources.Ingeo is a family of polymers for fibers made in a similar manner.
C
By applying their unique technology to the processing of natural plant sugars, Cargill Dow has created a more environmentally friendly material that reaches the consumer in clothes, cups, packaging and other products. While Cargill Dow is a stand-alone business, it continues to leverage the agricultural processing, manufacturing and polymer expertise of the two parent companies in order to bring the best possible products to market.
D
The basic raw materials for PLA are carbon dioxide and water. Growing plants, like com take these building blocks from the atmosphere and the soil. They are combined in the plant to make carbohydrates (sucrose and starch) through a process driven by photosynthesis. The process for making Nature Works PLA begins when a renewable resource such as corn is milled, separating starch from the raw material. Unrefined dextrose, in turn, is processed from the starch.
E
Cargill Dow turns the unrefined dextrose into lactic acid using a fermentation process similar to that used by beer and wine producers. This is the same lactic acid that is used as a food additive and is found in muscle tissue in the human body. Through a special condensation process, a lactide is formed. This lactide is purified through vacuum distillation and becomes a polymer (the base for NatureWorks PLA) that is ready for use through a solvent-free melt process. Development of this new technology allows the company to “harvest” the carbon that living plants remove from the air through photosynthesis. Carbon is stored in plant starches, which can be broken down into natural plant sugars. The carbon and other elements in these natural sugars are then used to make NatureWorks PLA.
F
Nature Works PLA fits all disposal systems and is fully compostable in commercial composting facilities. With the proper infrastructure, products made from this polymer can be recycled back to a monomer and re-used as a polymer. Thus, at the end of its life cycle, a product made from Nature Works PLA can be broken down into its simplest parts so that no sign of it remains.
G
PLA is now actively competing with traditional materials in packaging and fiber applications throughout the world; based on the technology’s success and promise, Cargill Dow is quickly becoming a premier player in the polymers market. This new polymer now competes head-on with petroleum-based materials like polyester. A wide range of products that vary in molecular weight and crystallinity can be produced, and the blend of physical properties of PLA makes it suited for a broad range of fiber and packaging applications. Fiber and non-woven applications include clothing, fiberfill, blankets and wipes. Packaging applications include packaging films and food and beverage containers.
H
As Nature Works PLA polymers are more oil- and grease-resistant and provide a better flavor and aroma barrier than existing petroleum-based polymers, grocery retailers are increasingly using this packaging for their fresh foods. As companies begin to explore this family of polymers, more potential applications are being identified. For example, PLA possess two properties that are particularly useful for drape fabrics and window furnishings. Their resistance to ultraviolet light is particularly appealing as this reduces the amount of fading in such fabrics, and their refractive index is low, which means fabrics constructed from these polymers can be made with deep colors without requiring large amounts of dye. In addition, sportswear makers have been drawn to the product as it has an inherent ability to take moisture away from the skin and when blended with cotton and wool, the result is garments that are lighter and better at absorbing moisture.
I
PLA combines inexpensive large-scale fermentation with chemical processing to produce a value-added polymer product that improves the environment as well. The source material for PLA is a natural sugar found in plants such as com and using such renewable feedstock presents several environmental benefits. As an alternative to traditional petroleum-based polymers, the production of PLA uses 20%-50% less fossil fuel and releases a lower amount of greenhouse gasses than comparable petroleumbased plastic; carbon dioxide in the atmosphere is removed when the feedstock is grown and is returned to the earth when the polymer is degraded. Because the company is using raw materials that can be regenerated year after year, it is both cost competitive and environmentally responsible.
答案：
27.B 28. C 29. F 30. A
31. starch 32. fermentation 33. condensation 34. ploymer
35. B 36. C 37. A 38. D 39. A 40. C
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发表于 2019-12-10 11:14:18
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