The decline of the honeybee population, a phenomenon known as colony collapse disorder (CCD), has been attributed by many researchers to the widespread use of neonicotinoid pesticides. These systemic insecticides, applied to crops, are absorbed by plants and contaminate nectar and pollen. A 2012 study by the Harvard School of Public Health found that sublethal doses of imidacloprid, a common neonicotinoid, led to a significant increase in hive abandonment, a hallmark of CCD. Furthermore, neonicotinoids impair the bee's navigational abilities, as demonstrated by a 2016 field study showing that exposed foragers were less likely to return to their hives. Additionally, these pesticides weaken the bee's immune system, making them more susceptible to pathogens like the deformed wing virus. Thus, the evidence strongly implicates neonicotinoids as the primary driver of CCD.
🎧 听力讲座
🎯 模拟考试环境：先点「播放讲座」听完内容，再作答。听力原文默认隐藏。
While the reading suggests neonicotinoids are the main cause of colony collapse disorder, the lecture challenges this claim. First, the Harvard study’s findings have been criticized for methodological flaws—the hives were fed sugar water laced with imidacloprid, which is not how bees encounter the pesticide in nature. In real agricultural settings, bees are exposed to a cocktail of chemicals, and the doses are often lower than those used in the study. Second, the lecture points out that a more significant factor is the Varroa destructor mite, an ectoparasite that has been devastating bee colonies worldwide. Research shows that mite infestation, not pesticides, correlates more strongly with colony losses. For instance, beekeepers who effectively control mites see far fewer colony collapses, regardless of neonicotinoid use. Finally, the immune-weakening effect is not unique to neonicotinoids; malnutrition due to monoculture farming and habitat loss also suppresses bee immunity. Therefore, the lecture concludes that neonicotinoids are not the sole or even primary cause, but rather one of many stressors in a complex problem.
📝 Instrucciones de escritura Summarize the points made in the lecture, being sure to explain how they cast doubt on the specific points made in the reading passage.
📊 TOEFL Integrated Writing Rubric
Content Accuracy: Accurately capture the relationship between lecture and reading
Information Completeness: Cover all key counter-arguments from the lecture
Structure & Coherence: Logical organization and progression
Language Use: Grammar, vocabulary, expression accuracy
Scored 0-30 based on holistic scoring (original 0-5, scaled to 30).
