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Effects of insecticides on freshwater invertebrate communities of small streams in soy-production regions of South America.

机译：杀虫剂对南美大豆产区小溪淡水无脊椎动物群落的影响。

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摘要

In this dissertation, I examined the occurrence of insecticides in streams in intensive soy production regions of South America, and their effects on invertebrate communities. Recently soy has become a major export crop in South America, and the insecticides used are highly toxic to aquatic invertebrates. I adapted the Species at Risk pesticide index (SPEARpesticides), which was developed in Europe to assess effects of pesticide contamination in agricultural streams. I then explored the relative importance of insecticides in comparison to other agricultural stressors, and the potential for riparian buffers to mitigate pesticide transport and impacts. My study sites were on small streams adjacent to agricultural fields in four soy production regions: two regions in the Argentine Pampas (La Plata-Magdalena and Arrecifes), and one region each in the Atlantic forest habitat of Brazil and Paraguay.;Commonly used insecticides were detected at high frequencies in all three countries, and pyrethroids insecticides were the most likely to occur at acutely toxic concentrations. Samples with highest toxicity were collected from streams with riparian buffer width less than 20 m, and buffer width was the most important predictor variable in explaining insecticide levels. I evaluated the toxicity of the four most commonly detected insecticides to Hyalella curvispina, a freshwater amphipod that is widespread in South America. The lowest LC50 values were found for the pyrethroid insecticides lambda-cyhalothrin and cypermethrin, followed by chlorpyrifos and alpha-endosulfan.;After adapting the SPEARpesticides index for local invertebrate communities in the Argentina streams, I found that SPEARpesticides was the only response metric that was significantly correlated with insecticide levels. Multiple regression showed that insecticide toxicity was the most important stressorin explaining variability in the SPEARpesticide index.;I then evaluated the relative importance of insecticides and other agricultural stressors on invertebrate communities in Atlantic Forest streams. Although buffer widths in Brazil streams were negatively correlated with insecticide concentrations, and had a moderate importance in mitigating effects on some sensitive taxa, insecticides had little importance in explaining variability in invertebrate communities. The forested riparian buffer zones are likely to have mitigated the effects of pesticides on stream invertebrate communities in these regions.
机译：在本文中，我研究了南美集约化大豆生产地区溪流中杀虫剂的发生及其对无脊椎动物群落的影响。最近，大豆已成为南美的主要出口作物，所用杀虫剂对水生无脊椎动物具有剧毒。我采用了在欧洲开发的用于评估农药污染对农业生产影响的物种危险农药指数（SPEARpesticides）。然后，我探索了与其他农业胁迫源相比杀虫剂的相对重要性，以及河岸缓冲带减轻农药运输和影响的潜力。我的研究地点位于四个大豆生产地区与农田相邻的小溪上：阿根廷潘帕斯州的两个地区（拉普拉塔-马格达莱纳和阿雷西费斯），巴西和巴拉圭的大西洋森林栖息地各一个地区;常用的杀虫剂在这三个国家中均以高频率检测到了拟除虫菊酯类杀虫剂，并且其毒性极高。从河岸缓冲带宽度小于20 m的溪流中收集毒性最高的样品，缓冲带宽度是解释杀虫剂含量最重要的预测变量。我评估了四种最常检测到的杀虫剂对Hyalella curvispina（一种在南美广泛分布的淡水两栖动物）的毒性。拟除虫菊酯类杀虫剂氟氯氰菊酯和氯氰菊酯的最低LC50值，其次是毒死LC和α-硫丹;在将SPEARpesticides指数适应阿根廷河流中的无脊椎动物群落之后，我发现SPEARpesticides是唯一的响应指标与杀虫剂水平显着相关。多元回归分析表明，杀虫剂毒性是解释SPEARpesticide指数变化的最重要压力源；然后我评估了杀虫剂和其他农业胁迫源对大西洋森林溪流无脊椎动物群落的相对重要性。尽管巴西河流中的缓冲带宽度与杀虫剂浓度呈负相关，并且在减轻对某些敏感类群的影响方面具有中等重要性，但杀虫剂对于解释无脊椎动物群落的变异性并不重要。森林上的河岸缓冲区可能减轻了农药对这些地区河流无脊椎动物群落的影响。

著录项

  • 作者

    Hunt, Elizabeth Shirin.;

  • 作者单位

    University of California, Berkeley.;

  • 授予单位 University of California, Berkeley.;
  • 学科 Environmental science.;Ecology.;Toxicology.;Agriculture.;Aquatic sciences.
  • 学位 Ph.D.
  • 年度 2016
  • 页码 134 p.
  • 总页数 134
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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