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When are pests most likely to travel？
A．When the airports are next to jungles
B．When there is a lot of food being transported by the airplane
C．When the insects can mate in the new region
D．When the weather is similar in both regions
答案
更多“When are pests most likely to travel？A．When the airports are next to junglesB．When there i”相关的问题
第1题
Humans aren't the only ones to take a summer holiday, a new study has revealed.
Creepy-crawlies, flies, and plants also join the vacation rush by hitching long-haul rides inside airline baggage.
The research reveals that—like people in many countries—June, July, and August are the peak months for long-distance travel.
Jet-Setting Beetles
Previous studies have shown that international flights are a significant factor in unwelcome insect invasion. Some 73 percent of recorded pest interceptions in the U.S., in fact, occur at airports.
Curious to determine when insects pack their bags and where the bugs are most likely to go, Andrew Tatem and Simon Hay of the University of Oxford in England studied global flight patterns for the 12-month period from May 1,2005 to April 30,2006.
Pest travel between far-flung locations is more likely when the weather is similar in both regions, making it easy for the pests to settle into their new home.
The researchers used rainfall, temperature, and humidity data from each region to work out which places linked by the global flight network had the most similar climates at various times of the year.
"Hawaii, with its moderate year-round climate, is a hot spot for pest invasions," Tatem said. "It is linked to a similar climate in Central America in April, Asia in July, and the Caribbean in October."
In general, though, June, July, and August are the peak months for insect travel.
"There are more airports in the Northern Hemisphere, and the major Southern Hemisphere airports tend to be closer to the Equator," Tatem said. "The June-to- August period stood out as the time when, overall, the busiest flight routes connect geographically distant but climatically similar locations."
According to the article, what is the main cause of insect invasions？
A．Changing wind patterns.
B．Unusually hot temperatures.
C．International flights.
D．Changes in agricultural chemicals.
第2题
Since 1939, scientific studies have shown that smoking does great harm to one's health and it will shorten one's life.
Cigarette smoking is believed, by most research workers in the field, a very important cause in the development of the cancer of the lungs and the cancer of the throat and is believed to have much to do with some other kinds of cancers. Cigarette smokers suffer from the illness of the heart more often than those who don't smoke. But strange, yet true, women are thought to be less affected, because when women smoke, they usually don't breathe in the smoke so deeply. Most of doctors and researchers say, "Give up smoking. If you don't smoke--don't start!"
Filters (过滤嘴) are required now to make smoking a bit safer, but they can only reduce, not get rid of, its poison.
But there are still a number of doctors and research workers who are less sure of the effect of cigarette smoking on health. They believe that the cancers of the lungs, the throat and so on may also be caused by air pollution, or chemical poison that is now being used by farmers in large quantities to destroy plant pests and small animals.
______each smoke about 4,195 cigarettes a year.
A．Americans
B．American men
C．American women
D．American aged 18 or more
第3题
IPM is different from the older methods because______.
A．chemical poisons are only used when necessary
B．chemical poisons are used very often
C．pests are completely destroyed
D．farmers do not have to worry about pests
第4题
Insect pests die if they freeze, but many have the ability to become "supercool", remaining alive even when the temperature drops to - 10℃. However, Paul Fields of the Agriculture Canada Research Station in Winnipeg has discovered that the ability of these insects to supercool can be seriously affected by "ice-nucleating-active bacteria". When the bacteria are present, the insects freeze and die at a higher temperature than normal.
Ice-nucleating-active bacteria are found naturally on most plant leaves. They are also grown commercially for use in cloud seeding and in making artificial snow.
Fields added these bacteria to wheat which was stored at a temperature of - 10℃ and contained the rusty grain beetle. He found that when the bacteria accounted for only 10 parts per million of the grain, the beetles' supercooling point rose from - 11.3℃ to - 7.1℃, so more died. At concentrations of 100 ppm or 1000 ppm, the bacteria increased the supercooling point to as high as -6.3℃, which resulted in more than 75 percent of the beetles dying.
Fields also applied the bacteria to two other species of grain beetle, Sitophilus granarius and Oryzaephilus surinamensis, keeping them at - 10℃. He found that more of these beetles also died. First, though, he gradually acclimatized some of the insects to cold, to simulate the increase in tolerance to cold which they normally develop as winter approaches. Fields found that the insects that had been acclimatized were less affected by cold than the beetles that had not been acclimatized, but that more of them still died at - 10℃.
Fields says that the technique of using ice-nucleating-active bacteria leaves no noxious chemical residues and poses little risk to the people who apply the treatment. It is also effective against insects which have become resistant to pesticides.
Which of the following statements about ice-nucleating-active bacteria is true？
A．They may cool the grain to - 10℃.
B．They can weaken the beetles' resistance to coldness.
C．They can be grown on most plant leaves.
D．They are used only in biological researches.
第5题
听力原文： Scientists have observed that plants themselves produce many poisonous chemicals for defense against insects. But insects have developed ways of dealing with them and,in fact,have been eating plants for about 250 million years.Now insects are using these same mechanisms to deal with man-made poisons-insecticide.This is why resistance of insects to insecticide has developed so rapidly.What should be done？Scientists studyilg the problem suggest that farmers use less insecticide.At the moment,famlers regularly spray crops as a precaution against problems that are caused by large numbers of pests.They should,instead,spray only where pests have actually been seen.Secondly,farmers could use a combination of two or three jnsecticide at once.To survive,the insects would need to become resistant to two or more poisons at the same time.The most surprising suggestion,perhaps,perhaps,is that,at certain times of the year,famers should actually try to attract new insects onto the crops they are trying to protect.The new insects will mate with those which survived from a certain kind of insecticide and will lessen the latter's resistance to it.
Scientists hope that these and other measures will postpone the day when farmers and scientists will have to stand by while new super bugs which may be resistant to all our poisons invade our farms and devour our crops.
(30)
A．There are 250 million plants eaten by insects.
B．There are fewer plants than 250 million years ago.
C．They have their way of guarding against insects.
D．They have a better immune system than before.
第6题
听力原文： Scientists have discovered that plants themselves produce many poisonous chemicals for defense against insects. But insects have developed ways of dealing with them and, in fact, have been eating plants for about 250 million years. Now insects are using these same mechanisms to deal with man-made poisons—insecticides. This is why resistance of insects to insecticides has developed so rapidly.
What should be done？ Scientists studying the problem suggest that farmers use less insecticides. At the moment, farmers regularly spray crops as a precaution against problems that are caused by large numbers of pests. They should, instead, spray only where pests have actually been seen. Secondly, farmers could use a combination of two or three insecticides at once. To survive, the insects would need to become resistant to two or more insecticides at the same time.
The most surprising suggestion, perhaps, is that at certain times of the year, farmers should actually try to attract insects onto the crops they are trying to protect. The new insects will mate with those which survived from a certain kind of insecticide and will lessen the latter's resistance to it.
Scientist hope that these and other measures will postpone the day when farmers and scientists will have to stand by while new super-bugs which may be resistant to all poisons invade our farms and devour our crops.
What have scientists discovered about plants and insects？
A．Plants produce many poisonous chemicals for defense against insects.
B．Insects develop ways of dealing with natural poisonous chemicals but not man-made ones.
C．Farmers must spray plants all the time.
D．Farmers must use different brands of insecticides.
第7题
What should be done？ Scientists studying the problem suggest that farmers use less insecticides. At the moment, farmers regularly spray crops as a precaution against problems that are caused by large numbers of pests. They should, instead, spray only where pests have actually been seen. Secondly, farmers could use a combination of two or three insecticides at once. To survive, the insects would need to become resistant to two or more insecticides at the same time.
The most surprising suggestion, perhaps, is that at certain times of the year, farmers should actually try to attract new insects onto the crops they are trying to protect. The new insects will mate with those which survived from a certain kind of insecticide and will lessen the latter's resistance to it.
Scientists hope that these and other measures will postpone the day when farmers and scientists will have to stand by while new super-bugs which may be resistant to all poisons invade our farms and devour our crops.
(33)
A．Insects have developed some sort of resistance to man-made poisons.
B．Insects have been eating plants for about 250 million years.
C．Farmers sometimes use a combination of two or three insecticides at once.
D．New insects mate with insecticide-surviving insects.
第8题
Rattlers come in a variety of sizes—from about two feet in length to over six feet. At the end of the rattler' s tail it is a set of rings. These make up the rattle. When the snake is alarmed, the tail shakes, causing a warning noise to be transmitted a considerable distance.
Rattlers may be found in nearly all states and in some Canadian provinces. However, most of them arc more at home in dry places, such as the western United States and Mexico. Rocky, isolated areas are favorite places for rattlers to lodge. They may be seen mornings and evenings sunning on rocky ledges. In the heat of the day they seek out a shelter from the sun under rocks or in holes.
The rattlesnake is in some ways a friend to humans. This statement contradicts some common views of these creatures. The harmful poisonous fluid released in a rattler' s bite kills small animals—and may kill or cause sickness in people. However, rattlers are competitors with owls and hawks for mice and rats. Many of these pests have been the losers in a clash with a rattlesnake in its quest for food. Thus the rattler helps control the numbers of mice and rats.
How can you avoid a rattlesnake bite.'？ A few principles have been given by experienced people of the outdoors. First, do not run through high grass in rattlesnake country. You might surprise a snake that is otherwise minding its own business. A slow walk insures ample time for the snake to slide away or proclaim its presence.
Although these snakes are very mobile, they will not chase you. If you hear a rattle, back up and walk away slowly. Do not run ! The snake may have a friend or relative in the area who would resent being stepped on as you dash away.
Second, consider your wearing apparel, particularly footwear. Snake fangs have occasionally pierced thick, western boots. However, such footwear offers much more protection than the usual shoes.
Finally, when chimbing, look before you reach or step. Rattlers like to lie on rocky ledges. Although you intended to grab a rock rather than a rattler, the surprised snake may not understand.
Years ago, people usually believed that ______.
A．rattlesnakes had a magic power
B．It was impossible for rattlesnakes to hold human beings under a spell
C．rattlesnakes would never attack human beings even if they were provoked
D．rattlesnakes would attack human beings even with no provocation
第9题
What do most senior citizens care when they are getting older？
A．Money.
B．Safety.
C．Family.
D．Health.
第10题
