Variation in Herbivore Population Sizes: The Effects of Host Quality, Host Genotype, Natural Enemies and the Formation of Demes

小行星9309298 瘿蝇 无齿目 Borrichiae， 在海牛雏菊顶端分生组织形成的虫瘿中内部发育， 博里基亚 frutescens。 幼虫以一种专性真菌为食，这种真菌在虫瘿腔中产生。 沿着佛罗里达中西部海岸， B。 frutescens 只有在小的障壁岛和小的“弃土”岛以及邻近沿海内水道的地方才能找到。岛屿之间的虫瘿密度变化多达2 - 3个数量级。 这可能是因为：（1）某些海牛肝菌斑不适合虫瘿（即质量差或遗传抗性），（2）有些地方未能被虫瘿发现，（3）有些地方鼓励天敌的高水平攻击，或（4）在某些岛屿上，虫瘿已局部适应现有的宿主斑（即同类形成）。 通过三组试验评估了植物克隆、天敌攻击水平、瘿蚊扩散和当地适应对瘿蚊种群动态的重要性：（1）无瘿植物在地点之间的相互移植，（2）有瘿植物在地点之间的相互移植和（3）在共同花园中保持一年以消除母体影响的植物的相互移植。这个系统将使过去很少可能的研究能够了解控制四个营养级系统的因素。 在更实际的层面上，这个项目可能会确定为什么一些补丁或基因型的海牛眼是抗破坏性草食性昆虫，而其他人没有的原因。 这一点很重要，因为这种植物和其他几种沿海和沙丘植物遭受高比率的攻击，由擦伤昆虫。 了解其不同的攻击率背后的原因可能会大大有助于选择最抗虫的物种和基因型的沼泽和海滩恢复项目。

9309298 Stiling The gall fly, Asphondylia borrichiae, develops internally in galls which form at the apical meristems of sea oxeye daisy, Borrichia frutescens. Larvae feed on an obligate fungus which they initiate in the gall cavity. Along the west central coast of Florida, local populations of B. frutescens are found only on small barrier islands and small "spoil" islands and adjacent to the intracoastal waterway. Gall densities between islands vary by as much as 2 3 orders of magnitude. This could be because: (1) some patches of sea oxeye are unsuitable for galls (i.e of poor quality or genetically resistant), (2) some sites fail to be discovered by the files, (3) some sites encourage high levels of attack by natural enemies or (4) on some islands, gall files have become locally adapted to existing host patches (i.e. deme formation). Three sets of experiments will assess the importance of plant clone, attack levels of natural enemies and gall fly dispersal and local adaptation on gall midge population dynamics: (1) reciprocal transplants of gall free plants between sites, (2) reciprocal transplant of galled plants between sites and (3) reciprocal transplant of plants that have been maintained in a common garden for one year to remove maternal effects. %%% This system will allow research that has rarely been possible in the past understand the factors controlling a four trophic level system. On a more practical level, this project may identify the reasons why some patches or genotypes of sea oxeye are resistant to damaging herbivorous insects while others are not. This is important because this plant and several other coastal and dune plants suffer high rates of attack by galling insects. Understanding the reasons behind their different rates of attack may greatly aid in selecting the most insect resistant species and genotypes for marsh and beach restoration projects.