Maj Rundlof remembers the moment she changed her mind about neonicotinoids-the world's most widely used pesticides （杀虫剂）.In December 2013，in her office at Lund University in Sweden,she and postdoc Georg Andersson were looking at data from their latest study.It was designed to test what would happen to bees if they fed on crops treated with neonicotinoids. "I didn't expect to see any effect at all,to be honest," says Rundlof.
Hives of honeybees weren't greatly affected by the chemicals in crops,the study suggested.But the data on bumblebees told a different story.Bumblebee colonies that hadn't fed on the treated crops looked normal：they were packing on weight to survive the winter.But in the colonies exposed to neonicotinoids,the growth chart was a flat line.
When the Swedish study was published in April 2015，it made headlines around the world.It was the first to show that neonicotinoids-known as neonics-could harm bees in a real-world farming situation.Bee populations are declining in many parts of the globe,a worrying sign for the crops and wild plants that rely on these bees for their survival.Parasites （寄生虫），disease and shrinking food resources are all prime suspects.But a link to neonics has become a major flashpoint.
Even before Rundlof's results were revealed,the European Union had placed heavy restrictions on three most widely used neonics in flowering crops-plants that might be attractive to bees-among rising concerns that the chemicals might harm pollinators（传粉者）.But farmers,the agrochemical industry and some scientists pointed out that these were based on limited evidence,gathered mostly from lab tests.
Since Rundlof's paper,studies showing real-world evidence of harm from pesticides in the field have been mounting-and environmental organizations have demanded wide-ranging bans.Regulatory agencies will soon decide what to do about neonics,which have a global market worth more than US 1.5 billion per year.This month,the EU's European Food Safety Authority is due to complete a reevaluation of evidence for restricting neonics；the EU will then need to decide what action to take.France has passed a law that would ban neonics in 2018.
But industry groups and some scientists say the evidence still isn't conclusive.The picture is complicated：some studies show harm to some bees in some circumstances,while others find no harm.The results seem to be affected by many factors,including the species of bee and the kinds of crops involved.Scientists working on the question say any new study is instantly picked at by advocates on both sides.Even the results of the largest study on the matter,funded by the agrochemical industry,failed to produce a consensus.It's likely that political or regulatory decisions will settle the matter before opposing parties agree.



Maj Rundlof's study suggests that ______ .

A. neonicotinoids are linked to bee decline
B. bumblebees are threatened with cold winter
C. honeybees are at no risk from neonicotinoids
D. neonicotinoids are harmful to bees as expected

Why does the decline of bee populations raise much concern？ ______

A. Disease has caused the lack of food resources.
B. Flowering crops with neonics are appealing to bees.
C. Bees play a leading role in limiting the number of parasites.
D. Bee populations are crucial to the survival of crops and wild plants.

According to the passage,we know that ______ .

A. the EU is to further assess the harm of neonicotinoids
B. evidence of harm to bees from pesticides is sufficient
C. the EU has already banned the use of neonicotinoids
D. more and more studies prove pesticides are harmful to bees

The last paragraph is mainly about ______ .

A. the battle against the widespread use of neonicotinoids
B. the debate about the harm done by neonicotinoids to bees
C. factors of influence on the present situation of bees
D. doubts about current political or regulatory systems