Ball Olivier J P, Coudron Thomas A, Tapper Brian A, Davies Elizabeth, Trently David, Bush Lowell P, Gwinn Kimberly D, Popay Alison J
AgResearch, Grasslands Research Centre, Private Bag 11008, Palmerston North, New Zealand.
J Econ Entomol. 2006 Aug;99(4):1462-73. doi: 10.1603/0022-0493-99.4.1462.
Three grass host species--tall fescue, Festuca arundinacea Schreber; meadow fescue, Festuca pratensis Hudson; and perennial ryegrass, Lolium perenne L.--each infected with a number of different Neotyphodium endophyte isolates, were investigated for their effects on fall armyworm, Spodoptera frugiperda (J.E. Smith). Alkaloid profiles varied among associations. Choice and no-choice tests comparing feeding and early development of S. frugiperda larvae on endophyte-infected and endophyte-free leaf blade material were performed. Endophyte-mediated resistance to S. frugiperda was greatest in meadow fescue and weakest in tall fescue. Some endophyte isolates, particularly in perennial ryegrass and meadow fescue, had a major effect on feeding and development of S. frugiperda, whereas others had no effect or were only weakly efficacious. In tall fescue, some associations deterred S. frugiperda from feeding in choice tests but had no effect on development, whereas larvae reared on other associations weighed significantly more than control larvae fed endophyte-free grass. It was concluded that the deleterious consequences of endophyte infection were easily masked by other factors in tall fescue. Relative leaf age had no effect on feeding preferences in the three host species. Chemical analysis of herbage from the plants used, and results from a no-choice study using spiked artificial diets, failed to individually implicate any of the major known alkaloids (peramine, lolitrem B, ergovaline, and lolines) in the observed effects on S. frugiperda. Hypotheses explaining these observations, and their impact on creating desirable grass-endophyte associations for use in pastures, are discussed.
研究了三种禾本科寄主植物——高羊茅（Festuca arundinacea Schreber）、草地羊茅（Festuca pratensis Hudson）和多年生黑麦草（Lolium perenne L.），它们各自感染了多种不同的内生真菌新种Neotyphodium，研究其对草地贪夜蛾（Spodoptera frugiperda (J.E. Smith)）的影响。不同组合之间的生物碱谱各不相同。进行了选择试验和无选择试验，比较了草地贪夜蛾幼虫在感染内生真菌和未感染内生真菌的叶片材料上的取食情况和早期发育情况。内生真菌介导的对草地贪夜蛾的抗性在草地羊茅中最强，在高羊茅中最弱。一些内生真菌分离株，特别是多年生黑麦草和草地羊茅中的分离株，对草地贪夜蛾的取食和发育有重大影响，而其他分离株则没有影响或效果微弱。在高羊茅中，一些组合在选择试验中阻止了草地贪夜蛾取食，但对其发育没有影响，而在其他组合上饲养的幼虫体重明显高于以未感染内生真菌的草为食的对照幼虫。得出的结论是，在高羊茅中，内生真菌感染的有害后果很容易被其他因素掩盖。相对叶龄对这三种寄主植物的取食偏好没有影响。对所用植物的牧草进行化学分析，以及使用添加人工饲料的无选择研究结果，均未能单独证明任何一种已知的主要生物碱（麦角酰胺、洛里曲霉毒素B、麦角缬氨酸和黑麦草碱）对草地贪夜蛾的观察效应有影响。讨论了解释这些观察结果的假设，以及它们对创建用于牧场的理想草-内生真菌组合的影响。
