In temperate forests within Europe, early-flushing (EF) deciduous trees are often heavily infested by early spring leaf-eating Lepidoptera, while late-flushing (LF) trees are better protected in a phenological manner against such heavy infestations, as spring moth larvae begin to appear before their bud burst. The associational effects of EF trees on LF ones are only poorly known. We studied whether or not the infestation of LF trees by spring Lepidoptera can be affected by EF ones if they grow in the immediate vicinity. We compared spring assemblages of leaf-eating larvae of Lepidoptera on LF Quercus cerris L. with those on EF Q. pubescens Willd. in several microhabitats in Slovakia, Central Europe. Larvae were collected from mature and young trees. Mature trees sampled were growing: (1) in a closed-canopy forest; (2) in small groups; or (3) as a lone tree. Forest and tree groups are both constituted by oak species. Tree groups and lone trees were 20–50 m distant from forest edges. Young trees were growing (1) under mature Q. pubescens trees in a forest or (2) as a lone tree within forest gaps or near the edges. In the closed-canopy forest where LF trees (Q. cerris) were surrounded by EF ones (Q. pubescens), the caterpillars on mature LF trees were in abundance, almost as on mature EF ones. The species composition of larval assemblages on the two oak species was similar. In contrast, on small groups and on lone trees, the lepidopteran larvae were significantly less abundant on LF trees than EF ones. In the case of young trees, the abundance of larvae and their composition assemblages on both oaks were comparable in the forest. In the open habitat, LF trees were less infested by larvae than EF ones and the assemblages of moth larvae differed between the two. Our results reveal the effect (associational susceptibility) of EF trees on LF ones when growing in a close vicinity. It means that the phenological protection of LF trees may not be sufficient if they grow close to or are surrounded by EF ones.

中文翻译：

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春毛虫对早红树和晚红树的侵染：邻近树木的关联效应

在欧洲的温带森林中，早春 (EF) 落叶树经常受到早春食叶鳞翅目昆虫的严重侵扰，而晚红 (LF) 树木在物候学方面受到更好的保护，以免受春蛾幼虫等严重侵扰在它们的花蕾破裂之前开始出现。EF 树对 LF 树的关联影响知之甚少。我们研究了春季鳞翅目对 LF 树的侵染是否会受到 EF 树的影响，如果它们在附近生长。我们比较了 LF Quercus cerris L. 和 EF Q. pubescens上鳞翅目鳞翅目幼虫的春季组合威尔德。在中欧斯洛伐克的几个小栖息地。从成熟和幼树收集幼虫。采样的成熟树木生长：（1）在封闭的树冠林中；(2) 小团体；或 (3) 作为一棵孤树。森林和树群均由橡树种构成。树群和孤树距离林缘20-50 m。幼树生长 (1) 在森林中成熟的Q. pubescens树下或 (2) 作为森林间隙或边缘附近的孤树。在 LF 树 ( Q. cerris ) 被 EF树( Q. pubescens)，成熟的 LF 树上的毛虫数量很多，几乎和成熟的 EF 树上的毛虫一样。两种橡树种上幼虫组合的物种组成相似。相比之下，在小群体和孤树上，LF 树上的鳞翅目幼虫明显少于 EF 树。就幼树而言，森林中两种橡树上幼虫的数量及其组成组合的数量相当。在开阔的栖息地，LF 树比 EF 树受幼虫侵扰少，并且两者之间的蛾幼虫组合不同。我们的结果揭示了 EF 树在附近生长时对 LF 树的影响（关联敏感性）。这意味着如果 LF 树靠近或被 EF 树包围，它们的物候保护可能不够充分。