托福综合写作

📖 阅读文章

The decline of the honeybee population, known as colony collapse disorder (CCD), has been widely attributed to the use of neonicotinoid pesticides. These systemic insecticides are absorbed by plants and contaminate nectar and pollen. First, neonicotinoids impair honeybee navigation and foraging behavior. Studies show that bees exposed to sublethal doses have difficulty finding their way back to the hive, leading to disorientation and colony loss. Second, these pesticides weaken bees' immune systems, making them more susceptible to pathogens such as the deformed wing virus and Nosema fungi. Laboratory experiments have demonstrated higher infection rates in bees fed with neonicotinoid-treated pollen. Third, neonicotinoids reduce queen viability. Research indicates that queen bees exposed to these chemicals produce fewer eggs and have shorter lifespans, which undermines colony reproduction and long-term survival. Therefore, banning neonicotinoids is essential to protect honeybee populations and ensure agricultural pollination.

🎧 听力讲座

The professor challenges the reading's claim that neonicotinoids are the primary cause of CCD. First, while neonicotinoids may affect bee navigation in laboratory settings, field studies have not consistently shown a direct link between pesticide exposure and colony collapse. Many colonies near treated fields remain healthy, suggesting other factors are more critical. Second, the immune suppression argument is overstated. The studies cited in the reading often use unrealistically high doses that do not reflect real-world exposure levels. In contrast, bees in natural environments encounter a mix of stressors, including mites and poor nutrition, which can independently weaken immunity. Third, the queen viability issue is not unique to neonicotinoids; other environmental stressors like Varroa mites and fungal diseases also reduce queen health. Moreover, recent large-scale field trials found no significant difference in colony losses between areas using neonicotinoids and those that did not. Thus, the professor concludes that neonicotinoids are not the primary driver of CCD, and banning them may not solve the problem without addressing other factors like habitat loss and invasive parasites.