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Biotechnology and insect management in field crop agroecosystems.

机译：田间作物农业生态系统中的生物技术和昆虫管理。

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摘要

Since the introduction of genetically modified crops in 1996, the majority of grain growers in the US have adopted the technology (e.g., currently about 93% of the US soybean acreage is genetically modified for glyphosate resistance). Initially, these transgenic crops were expected to increase yields and simplify farming by reducing pesticide applications. Indeed, the widespread adoption of insect-resistant crops modified to express Bacillus thuringiensis (Bt) toxins has improved yield by reducing injury caused by lepidopteran pest species. In addition to these yield increases, these crops have also reduced insecticide usage, and populations of some target pest species to historical lows. Whereas, the implementation of herbicide resistant crops has not improved yield; instead, widespread adoption of glyphosate-resistant crops and subsequent overuse of glyphosate in these systems has selected for 16 of the 25 glyphosate-resistant weed species worldwide, which has resulted in increased herbicide usage. To combat this resistance epidemic, the agricultural industry has developed crops resistant to dicamba and 2,4-D, two synthetic auxin herbicides that are highly volatile and prone to causing non-target damage.;My research with genetically modified crops had two foci. One involved assessing non-target effects of the herbicide dicamba on insects and their communities. Because herbicides are the dominant pesticide applied in agroecosystems, herbicides may pose significant ecotoxicological risks to non-target plants and insects. To understand these risks, we used a combination of field- and laboratory-based experiments exploring direct and indirect effects of dicamba on aphids, caterpillars, and bees. The other focus evaluated efficacy and value of transgenic, insect-resistant field-corn hybrids for controlling two target caterpillar species, European corn borer (ECB), (Ostrinia nubilalis [Hubner]) and corn earworm (CEW) (Helicoverpa zea [Boddie]. Over three years, we performed large scale field trials with Bt and non-Bt corn hybrids at 29 locations across Pennsylvania. We also worked with moth capture data from the PestWatch pheromone trapping network (pestwatch.psu.edu) and GIS mapping software to determine if the number of moths captured, or land-use variables related to in-field damage from caterpillars.;Despite limited usage, the herbicides dicamba and 2,4-D commonly cause herbicide-drift damage to non-target plants. Now with dicamba and 2,4-D primed to be more widely used in association with pending transgenic crop varieties, there is a pressing need to understand the influence of these synthetic auxin herbicides on insects and their communities. To understand the effects of dicamba on two common lepidopteran species, we applied several sub-lethal, drift-level rates of dicamba to soybean (Glycine max L.) and nodding plumeless thistle (Carduus nutans L.) and evaluated on dosed plants growth and survival of H. zea and Vanessa cardui (L.) larvae, respectively. In the laboratory with several rates of dicamba, we also performed direct toxicity bioassays on the two caterpillar species. Dicamba was not directly toxic to larvae of either species, and H. zea showed no negative effects when feeding upon soybeans dosed with dicamba. I did, however, detect significant negative, indirect effects of higher rates of dicamba on V. cardui larval and pupal mass, thistle biomass, and total plant nitrogen. Notably, in the absence of caterpillars, thistle biomass was not related to dicamba dose, suggesting that the additional herbivore stress was necessary to reveal costs of sub-lethal exposure to dicamba.;We also evaluated whether drift-level doses of dicamba on soybeans can influence soybean aphids and the soybean insect community. We found that when soybean aphid populations were high, population densities started to decrease on plants dosed with rates above 0.56 g/ha (particle drift levels). When aphid population densities were low, however, we did not find any relationship between dicamba dose and aphid populations. During field studies, we found evidence that as dicamba dose increased populations of ants, mirids, nabids, spiders, opiliones, Orius, and lathridids increased; these largely predaceous taxa may have responded to changes in plant structure caused by herbicide injury. (Abstract shortened by UMI.).
机译：自1996年引入转基因作物以来，美国大多数谷物种植者都采用了该技术（例如，目前约有93％的美国大豆种植面积经过了转基因改造，以抗草甘膦）。最初，这些转基因作物有望通过减少农药施用量来提高产量并简化耕作。实际上，通过修饰表达苏云金芽孢杆菌（Bt）毒素的抗虫作物得到了广泛采用，通过减少鳞翅目害虫物种造成的伤害提高了产量。除了增加产量外，这些作物还减少了杀虫剂的使用，并使某些目标害虫物种的数量降至历史最低水平。鉴于实施除草剂抗性作物并没有提高产量；相反，抗草甘膦作物的广泛采用以及随后在这些系统中过度使用草甘膦已为全球25种抗草甘膦杂草物种中的16种选择，这导致除草剂的使用增加。为了抵抗这种抗药性流行，农业已经开发出了对麦草畏和2,4-D（两种合成的生长素除草剂）具有抗性的作物，这两种植物生长素除草剂挥发性高，容易造成非目标性伤害。其中一项涉及评估除草剂麦草畏对昆虫及其群落的非目标作用。由于除草剂是在农业生态系统中使用的主要农药，因此除草剂可能会对非目标植物和昆虫造成重大的生态毒理风险。为了了解这些风险，我们结合了野外试验和实验室试验，研究了麦草畏对蚜虫，毛虫和蜜蜂的直接和间接作用。另一个重点评估了转基因，抗虫的田间玉米杂交种对两种目标毛虫物种（欧洲玉米bore（ECB），欧O（Ostrinia nubilalis [Hubner]）和玉米ear（CEW）（Helicoverpa zea [Boddie]）的控制效果和价值。在过去三年中，我们在宾夕法尼亚州的29个地点对Bt和非Bt玉米杂交种进行了大规模田间试验，还使用了来自PestWatch信息素捕获网络（pestwatch.psu.edu）和GIS测绘软件的蛾子捕获数据确定飞蛾的数量，还是与毛虫对田间破坏相关的土地利用变量；尽管使用量有限，麦草畏和2,4-D通常会给非目标植物造成除草剂漂移损害。麦草畏和2,4-D已准备好广泛用于即将出现的转基因作物品种，因此迫切需要了解这些合成的生长素除草剂对昆虫及其群落的影响。麦草畏在两个常见的鳞翅目物种上，我们将数种半致死性，漂移水平的麦草畏应用于大豆（Glycine max L.）和点头无羽蓟（Carduus nutans L.），并评估了定剂量的H. zea植物生长和存活和Vanessa cardui（L.）的幼虫。在几倍麦草畏的实验室中，我们还对两种毛虫进行了直接毒性生物测定。麦草畏对这两种物种的幼虫均无直接毒性，并且当饲喂饲喂麦草畏的大豆时，H。zea没有显示出负面影响。但是，我确实发现了较高的麦草畏含量对V. cardui幼虫和p质量，蓟生物量以及植物总氮具有显着的负面，间接影响。值得注意的是，在没有毛毛虫的情况下，蓟生物量与麦草畏剂量无关，这表明额外的草食动物胁迫对于揭示亚致命性麦草畏暴露的成本是必要的。影响大豆蚜虫和大豆昆虫群落。我们发现，当大豆蚜虫种群数量很高时，剂量超过0.56 g / ha（颗粒漂移水平）的植物的种群密度开始下降。但是，当蚜虫种群密度低时，我们未发现麦草畏剂量与蚜虫种群之间有任何关系。在田间研究中，我们发现有证据表明，随着麦草畏剂量的增加，蚂蚁，mi虫，纳比斯，蜘蛛，阿片酮，奥里乌斯和立足动物的种群也增加了。这些主要是早先的分类单元可能对除草剂损伤引起的植物结构变化有反应。 （摘要由UMI缩短。）。

著录项

  • 作者

    Bohnenblust, Eric.;

  • 作者单位

    The Pennsylvania State University.;

  • 授予单位 The Pennsylvania State University.;
  • 学科 Biology Entomology.;Agriculture Agronomy.
  • 学位 Ph.D.
  • 年度 2014
  • 页码 267 p.
  • 总页数 267
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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