Relative impacts of gypsy moth outbreaks and insecticide treatments on forest resources and ecosystem: An experimental approach

Gypsy moth outbreaks cause severe defoliation in Holarctic forests, both in North America where it is invasive, and in its native range in Eurasia. Severe defoliation can hamper timber production and impact ecological communities and processes. Aerial insecticide applications are regularly performed in outbreak areas to mitigate economic losses. These operations can be financially costly and harmful to non-target species and may disrupt species interaction networks. However, replicated studies of the relative impacts of gypsy moth outbreaks and insecticide application on forest growth and animal communities are rare and have yet to be carried out in the species' indigenous range.

Here, we review the pathways in which gypsy moth outbreaks and the chemical control of these outbreaks affect forest ecosystems. We then present an experimental design established in South Central Germany in early 2019, aiming to study the ecological and economic consequences of gypsy moth eruptions and insecticide application in oak forests. The study's full factorial design comprises forest stands with high and low defoliation risk, either treated with tebufenozide or left unsprayed, within 12 experimental blocks. Measurements of forest growth and structure, tree mortality, gypsy moth density, and composition of lepidopteran, bird, bat, ground beetle, and canopy arthropod communities will be conducted for several years.

One-year intensive monitoring of gypsy moth populations and damage across the selected sites showed substantial differences in population density between plots with high and low defoliation risk and high efficacy of tebufenozide in suppressing gypsy moth populations in treated plots. In the first year of the experiment, gypsy moth density and defoliation in predicted outbreak plots differed strongly, confirming the importance of using many replicates and blocking to control spatial heterogeneity. The experiment will be running continuously during the coming years to produce short- and medium-term economic and ecological data to improve our understanding and management of gypsy moth outbreaks.

Methods
One-year monitoring of gypsy moth population and defoliation during an outbreak in German oak forests. Data collected from March to August 2019 at all life-stages of the gypsy moth (egg, larva, pupa, imago). Details on the sampling methods and timing and processing of the various data are provided in the associated article.

舞毒蛾（Gypsy moth）的暴发会对全北界森林造成严重的脱叶危害，无论其作为入侵物种的北美分布区，还是其原生分布的欧亚大陆区域均受其影响。严重的脱叶危害会阻碍木材生产，并对生态群落及生态过程造成负面影响。为减轻经济损失，暴发区域通常会开展航空施药作业，但此类作业不仅经济成本高昂，还会对非靶标物种造成危害，甚至可能破坏物种互作网络。然而，针对舞毒蛾暴发与施药对森林生长及动物群落的相对影响开展的重复研究十分匮乏，且在该物种的原生分布区内尚未有相关研究开展。

本研究首先梳理了舞毒蛾暴发及其化学防治手段对森林生态系统的作用途径。随后介绍了2019年初在德国中南部建立的实验设计，该实验旨在探究栎林内舞毒蛾暴发与施药行为所带来的生态与经济后果。本研究采用完全析因设计，在12个实验区组内设置高、低脱叶风险林分，分别施以虫酰肼（tebufenozide）处理或不进行施药。研究将连续多年开展森林生长与结构、树木死亡率、舞毒蛾种群密度，以及鳞翅目、鸟类、蝙蝠、步甲和冠层节肢动物群落组成的监测工作。

对选定样地开展的为期一年的舞毒蛾种群与危害密集监测结果显示，高、低脱叶风险样地间的种群密度存在显著差异，且虫酰肼处理样地对舞毒蛾种群的抑制效果优异。实验第一年，预测暴发样地内的舞毒蛾种群密度与脱叶程度差异显著，证实了通过设置大量重复样地与区组来控制空间异质性的重要性。本实验将在未来数年持续开展，以获取短期与中期的经济及生态数据，从而加深我们对舞毒蛾暴发的认知，并优化其防控管理策略。

## 方法
针对德国栎林暴发期的舞毒蛾种群与脱叶危害开展了为期一年的监测。监测数据采集于2019年3月至8月，覆盖舞毒蛾的所有生活史阶段（卵、幼虫、蛹、成虫）。各类数据的采样方法、时序安排与处理细节详见相关研究论文。