Falk Michael A, Lindroth Richard L, Keefover-Ring Ken, Raffa Kenneth F
Department of Entomology, University of Wisconsin-Madison, 1630 Linden Dr., Madison, WI, 53706, USA.
Wisconsin DATCP, 2811 Agriculture Drive, Madison, WI, 53718, USA.
Oecologia. 2018 Jun;187(2):471-482. doi: 10.1007/s00442-018-4160-0. Epub 2018 May 23.
Empirical studies indicate that host-tree bud break will likely advance faster than spring-folivore egg hatch in response to predicted increases in temperature. How these phenological shifts will affect herbivory will depend on temporal patterns of foliar traits that occur during leaf expansion, and their effects on folivore performance. Through fine-scale time series sampling of newly flushed trembling aspen (Populus tremuloides) foliage, we observed a previously unknown peak in phenolic glycoside concentrations that coincides with the emergence of sensitive neonates of gypsy moths and rapidly declines soon after bud break. The magnitude and duration of the initial post-bud break peak in phenolic glycosides varied substantially among genotypes. In contrast, foliar nitrogen concentrations declined at a more uniform rate among genotypes throughout leaf expansion. In addition, leaf toughness remained uniformly low throughout these periods of phytochemical change, and did not rise or vary substantially among genotypes until after anticipated windows of climate change-induced shifts between bud break and egg hatch had elapsed. Controlled manipulation of intervals between gypsy moth egg hatch and aspen bud break generated differences in larval performance among hatch cohorts and host genotypes that corresponded with changes in foliar phenolic glycoside and nitrogen concentrations. These findings indicate that the effects of climate change-induced phenological shifts on herbivory will differ among host plant genotypes, and that genetic variation in foliar chemical patterns will strongly influence this heterogeneity.
实证研究表明，随着预计气温升高，寄主树木的芽萌发可能比春季食叶动物的卵孵化提前得更快。这些物候变化将如何影响食草作用，将取决于叶片扩展过程中叶片性状的时间模式，以及它们对食叶动物表现的影响。通过对新长出的颤杨（Populus tremuloides）叶片进行精细尺度的时间序列采样，我们观察到酚糖苷浓度出现了一个前所未知的峰值，这与舞毒蛾敏感幼虫的出现同时发生，并且在芽萌发后不久迅速下降。酚糖苷在芽萌发后的初始峰值的大小和持续时间在不同基因型之间有很大差异。相比之下，在整个叶片扩展过程中，不同基因型的叶片氮浓度以更均匀的速率下降。此外，在这些植物化学变化期间，叶片韧性一直保持在较低水平，直到气候变化导致的芽萌发和卵孵化之间的预期时间窗口过去之后，才在不同基因型之间出现大幅上升或变化。对舞毒蛾卵孵化和杨树芽萌发之间的间隔进行控制操作，导致不同孵化群体和寄主基因型的幼虫表现产生差异，这些差异与叶片酚糖苷和氮浓度的变化相对应。这些发现表明，气候变化引起的物候变化对食草作用的影响在寄主植物基因型之间会有所不同，并且叶片化学模式的遗传变异将强烈影响这种异质性。
