文獻來源：Jane U. Jepsen, Snorre B. Hagen, Stein-Rune Karlsen, and Rolf A. Ims. 2009. Phase-dependent outbreak dynamics of geometrid moth linked to host plant phenology. Proc R Soc B 276: 4119-4128. [link]
植食性昆蟲的同步大發生機制尚未被確認，但一直被認為是由氣候驅使的「莫倫效應」(Moran effects)所引起。然而，寄主植物與幼蟲的物候之間相關的程度，對許多在春季取食的昆蟲幼蟲而言，在生長與存活方面相當重要；推測物候上的吻合/不吻合所驅使的「莫倫效應」可能有如同步化的驅動者。
作者選在北歐芬諾斯堪地亞的北方白樺木森林，分析由週期性的尺蛾幼蟲大發生所造成、與階段有關的( phase-dependent )空間動態，觀察期間為2000–2008之間最近幾次的大暴發。作者使用人造衛星產生的時間序列，比較蛾幼蟲造成的落葉傳染和整個地區生長季節開始初期，以調查落葉模式和大發生傳播之間的關係。此外，為了評估蛾與其寄主植物之間物候吻合的程度是否可能是「莫倫效應」背後的機制，作者測試在於落葉與生長季的初始之間、是否存在與階段有關的(phase-dependent )統一性在空間同步的樣式。
區域空間同步落葉的強度與落葉傳播的樣式都和階段(phase）具有高度相關。與傳染階段和崩潰階段相較，大發生的初始階段具有極高地區性同步落葉和長距離傳播的特徵。落葉傳染的最佳描述模型是二尺度階層性的傳播模型，可能是由於落葉傳染受到兩種不同空間尺度的動力驅使。與階段有關的空間同步之樣式對落葉及生長季的開始，均具有統一性。此結果推測春季物候的時間對白樺林蛾類的大發生在大尺度的同步化上扮演了重要角色。
Abstract
Climatically driven Moran effects have often been invoked as the most likely cause of regionally synchronized outbreaks of insect herbivores without identifying the exact mechanism. However, the degree of match between host plant and larval phenology is crucial for the growth and survival of many spring-feeding pest insects, suggesting that a phenological match/mismatch-driven Moran effect may act as a synchronizing agent.
We analyse the phase-dependent spatial dynamics of defoliation caused by cyclically outbreaking geometrid moths in northern boreal birch forest in Fennoscandia through the most recent massive outbreak (2000–2008). We use satellite-derived time series of the prevalence of moth defoliation and the onset of the growing season for the entire region to investigate the link between the patterns of defoliation and outbreak spread. In addition, we examine whether a phase-dependent coherence in the pattern of spatial synchrony exists between defoliation and onset of the growing season, in order to evaluate if the degree of matching phenology between the moth and their host plant could be the mechanism behind a Moran effect.
The strength of regional spatial synchrony in defoliation and the pattern of defoliation spread were both highly phase-dependent. The incipient phase of the outbreak was characterized by high regional synchrony in defoliation and long spread distances, compared with the epidemic and crash phase. Defoliation spread was best described using a two-scale stratified spread model, suggesting that defoliation spread is governed by two processes operating at different spatial scale. The pattern of phase-dependent spatial synchrony was coherent in both defoliation and onset of the growing season. This suggests that the timing of spring phenology plays a role in the large-scale synchronization of birch forest moth outbreaks.
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