墨尔本PTE素材库——Pesticides Act as Honeybee Contraceptives

墨尔本PTE素材库——Pesticides Act as Honeybee Contraceptives

中文批注

本段Podcast介绍了科学家通过一个实验发现了造成美国大量蜜蜂减少的元凶。录音中包含大量科学词汇，长度也适中，是一段非常好的Re-tell Lecture的练习素材。大家可以试试先不要看批注，总结本段录音的内容，复述主要要点。这段视频最重要的关注点就是：

• What is the cause of bee loss in the U.S. and how?

简单来说造成蜜蜂减少的元凶是neonicotinoid pesticides（烟碱类杀虫剂），会导致雄蜂发生不育。科学家们是通过对20组蜂巢的研究发现，烟碱类杀虫剂会导致雄蜂寿命变短，从而减少了其能够交配的时间。同时，能够活下来的雄蜂精子也会大幅度减少，从而导致不育。最终整体的表现就是蜜蜂数量的下降。

澳大利亚语言学院整理的墨尔本PTE素材库，旨在帮助各位PTE考生整理一些可以用作PTE考试题型练习的素材，可以帮助大家提升dictation、re-tell lecture、Summarize  spoken text 等等题型的能力哦！PTE市面上的素材并不多，练习的题目也不多，所以AIL整理的这些PTE素材库，真的是帮助非常大的哦！

【Key Vocabulary】

concentration n. 浓度，集中，浓缩

insecticide n. 杀虫剂

sperm n. 精子

beekeeper n. 养蜂人

culprit n. 犯人，元凶

parasitic adj. 寄生的

neonicotinoid n. 新烟碱

reproductive adj. 生殖的

entomologist n. 昆虫学家

genetically adv. 遗传学地，从遗传学角度

collaborator n. 合作者

drone n. 雄蜂

Full Transcript

Pesticides Act as Honeybee Contraceptives

By Christopher Intagliata

Environmental concentrations of certain insecticides slashed honeybee drones’ living sperm counts. Christopher Intagliata reports.

Over the last year, beekeepers in the U.S. lost nearly half their honeybee hives. And there are a lot of suspected culprits for this so-called beepocalypse—from parasitic mites, to viruses, to simple land use changes. But a study out earlier this year pointed to another possibility: poor sperm quality among the drone bees, leading to colony crashes. And now another group of researchers may have found a reason for the subpar sperm: neonicotinoid pesticides. These substances contain chemicals similar to nicotine and affect insect nervous systems.

“So for the drones that were exposed to pesticides during development, it appears there were more dead sperm in their reproductive tracts.” Geoff Williams, an entomologist at the University of Bern in Switzerland and Agroscope, a Swiss federal research facility.

Williams and his colleagues studied the effects of two neonicotinoid pesticides on honeybee drones, genetically assigned to mate with queens. “They’ve got really big eyes so they can identify these queens flying through the air. They eat and have sex. Or try to have sex at least.”

But in 20 honeybee hives Williams and his collaborators found that those drones exposed to standard environmental levels of the pesticides were shorter-lived, thus having fewer opportunities to mate. And even if the drones did survive, they had nearly 40 percent fewer living sperm than did control bees—meaning the pesticides were acting like honeybee contraceptives. The study appears in the Proceedings of the Royal Society B. [Lars Straub et al., Neonicotinoid insecticides serve as inadvertent insect contraceptives]

Williams says pesticides are just one of many factors assaulting bees. But it looks like the way farmers treat some crops could adversely affect the pollinators those crops also rely on.

(Source: http://www.scientificamerican.com/podcast/episode/pesticides-act-as-honeybee-contraceptives/)\