Bottom-up effects of glucosinolate variation on aphid colony dynamics in wild cabbage populations
Bottom-up effects of glucosinolate variation on aphid colony dynamics in wild cabbage populations
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DOI：
10.1111/j.1365-2311.2009.01111.x
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发表时间：
2009-10-01
影响因子：
2.2
通讯作者：
Hodgson, Dave
中科院分区：
文献类型：
--
作者：
Newton, Erika;Bullock, James M.;Hodgson, Dave
1.关于自上而下和自下而上对野生食草动物动态进行调控的相对重要性，人们一直在争论。植物产生的次生代谢产物对一些食草动物物种的生存和生长有负面影响，导致自下而上的种群动态调节。食草动物的天敌可能会以植物次生代谢物为线索寻找猎物，但它们的生存和繁殖也会受到次级代谢物通过食物网向上级联的影响。因此，植物化学也可能通过调节自上而下的调控来影响食草动物种群。研究了甘蓝属植物产生的一类次生代谢物脂肪族硫代葡萄糖苷的遗传变异对天然甘蓝种群中甘蓝种群自上而下和自下而上调节的相对重要性的影响。我们控制了天敌对不同硫代葡萄糖苷含量的植物的压力，并监测了蚜虫群体的生长和分散剂的产生。与产生替代脂肪族硫代葡萄糖苷的植物相比，产生黄豆素的植物上的蚜虫群体大小明显较小。天敌数量与种群大小相关，但植物化学表型对天敌丰度没有额外影响。此外，实验中降低天敌压力对麦长管蚜的种群大小和有翼分散器的产量没有影响。我们的结果提供了硫代葡萄糖苷介导的、自下而上调节自然种群中粉状甘蓝蚜群的证据，但我们没有发现自上而下调节的迹象。我们强调，对这些过程的更多研究应该集中在野外的三营养相互作用上。
1. There is an ongoing debate about the relative importance of top-down and bottom-up regulation of herbivore dynamics in the wild. Secondary metabolites, produced by plants, have negative effects on survival and growth of some herbivore species, causing bottom-up regulation of population dynamics. Herbivore natural enemies may use plant secondary metabolites as cues to find their prey, but their survival and reproduction can also be influenced by the upward cascade of secondary metabolites through the food web. Thus plant chemistry might also affect herbivore populations by mediating top-down regulation.2. We investigated the influence of heritable variation in aliphatic glucosinolates, a class of secondary metabolites produced by Brassica plants, on the relative importance of top-down and bottom-up regulation of Brevicoryne brassicae (mealy cabbage aphid) colonies in natural Brassica oleracea (wild cabbage) populations. We manipulated natural enemy pressure on plants differing in their glucosinolate profiles, and monitored aphid colony growth and disperser production.3. Aphid colony sizes were significantly smaller on plants producing sinigrin, compared with plants producing alternative aliphatic glucosinolates. Aphid natural enemy numbers correlated with aphid colony size, but there was no additional effect of the plants' chemical phenotype on natural enemy abundance. Furthermore, experimental reduction of natural enemy pressure had no effect on aphid colony size or production of winged dispersers.4. Our results provide evidence for glucosinolate-mediated, bottom-up regulation of mealy cabbage aphid colonies in natural populations, but we found no indication of top-down regulation. We emphasise that more studies of these processes should focus on tritrophic interactions in the wild.