The widespread use of neonicotinoid pesticides has been linked to the decline of bee populations, but recent research suggests that these chemicals may also pose a significant threat to bird species. Three main arguments support this concern. First, neonicotinoids are highly persistent in the environment. They remain in soil and water for months or even years after application, and they can be taken up by plants, including wildflowers and trees that birds rely on for food. Second, these pesticides reduce the abundance of insects, which are a critical food source for many bird species, especially during the breeding season when chicks require protein-rich diets. A decline in insect prey could lead to reduced chick survival and lower overall bird populations. Third, direct exposure to neonicotinoids through contaminated seeds or water may cause sublethal effects in birds, such as impaired navigation, reduced feeding behavior, and weakened immune responses, which could ultimately affect their reproductive success and migratory patterns. Given these points, it is urgent to reconsider the widespread use of neonicotinoids to protect avian biodiversity.
🎧 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。
The lecture challenges the reading’s claims about neonicotinoids harming bird populations. While the reading emphasizes environmental persistence, the professor points out that neonicotinoid concentrations in soil and water typically drop to negligible levels within a few weeks, and birds are unlikely to ingest harmful amounts through plants because the chemicals are mostly present in roots and seeds, not in fruits or leaves that birds commonly eat. Regarding the reduction of insects, the professor acknowledges that neonicotinoids can kill pests, but argues that they are often applied at low doses that do not eliminate all insects; moreover, many bird species are generalist feeders and can switch to alternative prey, such as spiders or seeds, when insect numbers are temporarily low. Finally, the lecture casts doubt on the sublethal effects by citing a major field study that found no significant differences in the health, breeding success, or migration of birds living near treated fields compared to those in untreated areas. The professor concludes that while neonicotinoids should be used responsibly, the evidence does not support the claim that they are a major driver of bird declines.
📝 写作提示 Summarize the points made in the lecture, being sure to explain how they cast doubt on the specific points made in the reading passage.
