理工类考试备考资料AB级：阅读理解the Bees Gone
Scientists who study insects have a real mystery on their hands. All across the country， honeybees are leaving their hives and never returning. Researchers call this phenomenon colony-collapse1 disorder. According to surveys of beekeepers across the country， 25 to 40 percent of the honeybees in the United States have vanished from their hives since last fall. So far， no one can explain why.
Colony collapse is a serious concern because bees play an important role in the production of about one-third of the foods we eat. As they feed， honeybees spread pollen from flower to flower. Without this process， a plant can’t produce seeds or fruits.
Now， a group of scientists and beekeepers have teamed up to try to figure out what’s causing the alarming collapse of so many colonies. By sharing their expertise in honeybee behavior， health， and nutrition， team members hope to find out what’s contributing to the decline and to prevent bee disappearances in the future.
It could be that disease is causing the disappearance of the bees. To explore that possibility， Jay Evans， a researcher at the United States Department of Agriculture (USDA) Bee Research Laboratory2， examines bees taken from colonies that are collapsing. “We know what s healthy bee should look like on the inside， and we can look for physical signs of disease，” he says. And bees from collapsing colonies don’t look very healthy. “Their stomachs are worn down， compared to the stomachs of healthy bees，” Evans says. It may be that a parasite is damaging the bees’ digestive organs. Their immune systems may not be working as they should. Moreover， they have high levels of bacteria inside their bodies.
Another cause of colony-collapse disorder may be certain chemicals that farmers apply to kill unwanted insects on crops， says Jerry Hayes， chief bee inspector for the Florida Department of Agriculture3. Some studies， he says， suggest that a certain type of insecticide affects the honeybee’s nervous system (which includes the brain) and memory. “It seems like honeybees are going out and getting confused about where to go and what to do，” he says.
If it turns out that a disease is contributing to colony collapse， bees’ genes could explain why some colonies have collapsed and others have not. In any group of bees there are many different kinds of genes. The more different genes a group has， the higher the group’s genetic diversity. So far scientists haven’t determined the role of genetic diversity in colony collapse， but it’s a promising theory， says Evans.
词汇：
honeybee n. 蜜蜂 parasite n. 寄生虫；寄生生物
hive n. 蜂巢； 蜂箱 digestive adj. 消化的
pollen n. 花粉 immune adj. 免疫的
beekeeper n. 养蜂人 insecticide n. 杀虫剂
expertise n. 专门知识，专长 diversity n. 多样性
注释：
1. colony-collapse：群体瘫痪。Colony有“殖民地”的意思，在此意为： a group of the same kind of animals， plants， or one-celled organisms living or growing together. 一群生活或生长在一起的同种动物、植物或单细胞有机体。
2. the United States Department of Agriculture (USDA) Bee Research Laboratory：美国农业部蜜蜂研究实验室。
3. the Florida Department of Agriculture：佛罗里达农业局。佛罗里达是美国东南部的一个州，濒临大西洋和墨西哥湾。