Could 1)Insects Be Used as Instruments of Biological Warfare-英语课

时间：2018-12-08 作者：英语课 分类：VOA2003（上）-科技先知

英语课

Broadcast: Jan 29, 2003

The use of insects as agents of warfare 1 is not a new idea. In the 2)Biblical story of the 3)Exodus, one of the 4)plagues visited upon the Egyptians was a horde 2 of 5)locusts. In a short-lived program in the mid-20th century, the U.S. Army reared 100 million yellow fever mosquitoes each week for possible use as a biological weapon against enemy troops.

"There are very few examples of where insects were used in the context of weapons of war, and there's almost no examples of where they were effective," Mr. Carey said.

James Carey is a professor of 6)entomology at the University of California, Davis, a specialist in what he calls 'invasion biology.' Although he doesn't consider the potential entomological threat to the United States to be as important as other forms of bioterrorism, he does see a way insects could be used as an economic weapon, targeted at American agriculture. Crop-destroying pests, he said, would be one likely form of attack.

"If you find what they call a 'Class-A pest' like the Mediterranean 3 fruit fly and you have someone with a bottle full of Medflies deliberately 4 planting them in traps, what happens is that it sets in motion the 7)eradication programs, it sets in motion the 8)quarantines so far, because it's very difficult to distinguish between a real outbreak and one that's deliberately planted. So I can see that as the worst nightmare situation," he said.

The 9)screwworm, which can devastate 5 cattle herds 6, is also small enough to carry in a bottle and release onto a ranch 7, triggering an 10)infestation that, if unchecked, could cause serious economic damage.

But according to Ian McDonnell, executive director of the North American Plant Protection Organization, there are myriad 8 systems in place in the United States, as well as Canada and Mexico, that can identify, control and eradicate 9 pests, no matter how they're introduced.

"We certainly rely on surveillance and the ability to rapidly identify the existence of a new pest and that's not restricted to governments. Producers, who are very well in tune 10 with their crop, will be able to identify a new pest situation. We rely on universities and other academic institutions, scientific societies such as the Entomological Society of America, literature reports. So there's a vast array of sources that we count on to identify these new pest situations," Mr. McDonnell said.

In addition, the diversity of American agriculture makes it unlikely that an insect attack on a single commodity could have the 11)catastrophic effect a terrorist group would probably be seeking. Still, entomologist James Carey says he would like to see closer 12)collaboration between medical 13)epidemiologists and invasion biologists in developing a national policy to prepare for pest outbreaks caused by such 14)saboteurs.

"Clearly, you need a short-term program where you're always prepared for these outbreaks, but that's no different than preparing for naturally occurring outbreaks. I think one of the dangers here is for regulatory agencies to start seeing terrorist bogeymen all over the place and attribute these naturally occurring outbreaks to the terrorist planet and so forth," Mr. Carey said.

Yet, even as some entomologists discount the threat of insects being used as weapons, others are working to develop insects for military defense 11 for example, wasps 12 trained to become weapon detectors 13.

"One of the things we've learned is that wasps can be trained to detect numerous odors, and so you can train them to detect odors, like explosives food odors, and perform certain behaviors in response," Jim Tumlinson works for the USDA's Agricultural Research Service, in Gainesville, Florida. His work takes advantage of the wasps' natural feeding responses, such as rubbing their 15)antennas on a spot with food or getting in position to sting their prey 14. Once the wasps learn to associate a particular odor with food, the scientists can watch for those feeding behaviors.

"One of the projects we were working on was to see if we could train wasps to locate explosives that might be in 16)landmines. This project is not complete and there's still a long way to go to develop wasps as detectors of chemicals of various types. But certainly they have the ability to learn we haven't found a chemical yet that they couldn't learn," Mr. Tumlinson said.

Mr. Tumlinson predicts that trained wasps might one day also be used to detect dangerous food contaminants like 17)salmonella and aflotoxin.

In this post 9-11 world, the U.S. government and the farming community are on high-alert to possible sabotage 15 - aware that even in peacetime, they can expect insects will annually 16 do billions of dollars in damage to the nation's crops and livestock 17. If terrorists try to cause similar damage with the deliberate release of a nasty agricultural pest, experts say chances are very good the outbreak would be quickly halted.