Interspecific competition affects growth and herbivore damage of Brassica napus in the field
Interspecific competition affects growth and herbivore damage of Brassica napus in the field
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DOI：
10.1023/a:1020377627529
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发表时间：
2002-10-01
期刊：
影响因子：
1.7
通讯作者：
Bergelson, J
中科院分区：
文献类型：
--
作者：
Cipollini, DF;Bergelson, J
资源竞争可以直接影响植物的适合度，也可以通过影响植物在田间遭受的食草动物损伤量间接影响植物的适合度。我们之前发现，竞争可以限制温室盆栽甘蓝型油菜幼苗中防御性胰酶抑制剂的结构性和创伤诱导表达，这表明植物的化学防御能力可能受到田间竞争的限制。在这些结果的指导下，我们调查了竞争是否会影响田间生长以及食草动物和食草动物对甘蓝型油菜植株的危害。我们在7x7m的网格中建立了16个1m(2)的田间地块。将9株两周生的油菜幼苗从温室移栽到每1 m(2)小区。一半的地块没有杂草，一半留下来发展种间杂草竞争对手。六周后，在每一块土地上随机选择三株植物，测量高度、叶片数量、草食动物移走的叶面积以及是否存在蚜虫、潜叶虫和瓢虫卵。与避荫反应的诱导一致，有杂草竞争对手的地块的植株显著高于没有杂草竞争的地块的植株，叶片数量是无杂草的地块的一半。与之竞争的植物也有60%以上的叶面积被食草动物移除，80%以上的叶片带有蚜虫，而同样比例的叶片带有挖叶虫。在这项研究中，杂草竞争对生长、草食动物对叶面积的去除以及田间甘蓝型油菜上蚜虫的存在都有很大的影响。再加上我们证明竞争可以限制胰蛋白酶抑制物活性的表达，这些结果表明资源竞争可能限制植物抵御天敌的能力，导致更大的草食。反过来，竞争植物上食草性的增加可能会加剧竞争对植物适应性的直接影响。
Resource competition can influence plant fitness either directly, or indirectly by influencing the amount of herbivore damage received by plants in the field. We previously found that competition could constrain the constitutive and wound-induced expression of defensive trypsin inhibitors in pot-grown Brassica napus seedlings in the greenhouse, suggesting that the ability of a plant to chemically defend itself could be constrained by competition in the field. Guided by these results, we investigated whether competition would affect growth and the presence of herbivores and herbivore damage on B. napus plants in the field. We established sixteen 1 m(2) plots in the field in a 7 x 7 m grid. Nine two-week-old B. napus seedlings were transplanted from the greenhouse into each 1 m(2) plot. Half of the plots were kept weed-free and half were left to develop interspecific weed competitors. After six weeks, three randomly chosen plants in each plot were measured for height, number of leaves, leaf area removed by herbivores, and the presence of aphids, leaf miners, and eggs of ladybird beetles. Consistent with the induction of the shade-avoidance response, plants in plots with weed competitors were significantly taller and had half as many leaves as plants in weed-free plots. Competing plants also had 60% more leaf area removed by herbivores, an 80% higher proportion of leaves with aphids, and an equal proportion of leaves with leaf miners. In this study, weed competition had dramatic effects on growth, leaf area removal by herbivores, and the presence of aphids on B. napus plants in the field. Together with our demonstration that competition can constrain the expression of trypsin inhibitor activity, these results suggest that resource competition may limit the ability of a plant to defend itself from natural enemies, leading to greater herbivory. In turn, increased herbivory on competing plants could exacerbate the direct effects of competition on plant fitness.