Data from: Grape moth density in Bordeaux vineyards depends on local habitat management despite effects of landscape heterogeneity on their biological control

1. Biological control of crop pests is a major ecosystem service affected by several variables acting at multiple spatial scales. Among these variables, heterogeneity at the habitat and landscape scales are known key drivers of trophic interactions and pest density in agroecosystems. However, studies that try to disentangle their relative effects in perennial cropping systems are scarce and nothing is known about their impacts on insect pest density and pesticide applications.

2. We examined the effect of heterogeneity at these two scales on grape moths, one of the most damaging insect pests in European vineyards, and their biological control in 20 vineyards during three consecutive years. We used local vegetation management and the proportion of semi-natural habitats in the surrounding landscape as proxies of heterogeneity at the habitat and landscape scales. Grape moth density was measured over time, as well as biological control services provided by different groups: birds, invertebrate predators, parasitoids and entomopathogenic fungi.

3. Over the 3 years, grape moth density was mainly determined by local heterogeneity, with significantly fewer larvae of the first generation established in vineyards with full compared to partial grass cover.

4. Despite these effects, biological control of grape moths was not primarily affected by local vegetation management but by landscape heterogeneity, and the direction of this effect varied over time. Notably, predation by birds increased with landscape heterogeneity in spring, depending on local vegetation management, while attacks by pathogenic fungi decreased with landscape heterogeneity during winter.

5. Synthesis and applications. Our results suggest that bottom-up processes related to habitat heterogeneity drive grape moth occurrence much more than top-down processes. These results have important implications for the ecological intensification of vineyard landscapes. We found that maintaining full grass cover within vineyards reduced grape moth density to a level below common intervention thresholds. Landscape heterogeneity in the close vicinity of vineyards contributed to improved biological pest control by birds, but depended on local vegetation management. Moreover, opposing effects of landscape management on biological pest control services over time revealed that strategies based only on manipulating landscape heterogeneity might not be the optimal option to limit grape moth density in vineyards.

1. 作物害虫的生物防治（biological control）是一项受多空间尺度下多种变量影响的重要生态系统服务（ecosystem service）。其中，生境异质性（habitat heterogeneity）与景观异质性（landscape heterogeneity）是农业生态系统（agroecosystems）中营养级互作（trophic interactions）与害虫种群密度（pest density）的关键驱动因子。然而，目前针对多年生种植系统（perennial cropping systems）中二者相对作用的解析研究较为匮乏，且尚无关于其对害虫种群密度与农药施用（pesticide applications）影响的相关报道。
2. 本研究连续三年对20个葡萄园展开调查，旨在探究这两类尺度下的异质性对葡萄蛀果蛾（grape moth）及其生物防治的影响。我们以本地植被管理模式与周边景观中半自然生境（semi-natural habitats）占比，分别作为生境与景观尺度异质性的替代指标。本研究定期监测了葡萄蛀果蛾的种群密度，同时评估了鸟类、无脊椎捕食者（invertebrate predators）、寄生性天敌（parasitoids）以及昆虫病原真菌（entomopathogenic fungi）等不同类群所提供的生物防治服务。
3. 三年监测结果显示，葡萄蛀果蛾的种群密度主要由生境异质性决定：相较于部分覆草的葡萄园，全覆草葡萄园中第一代幼虫的定植量显著更低。
4. 尽管存在上述影响，但葡萄蛀果蛾的生物防治并非主要受本地植被管理调控，而是取决于景观异质性，且该效应的作用方向随时间发生变化。值得注意的是，春季鸟类捕食作用随景观异质性的提升而增强，且这一关系依赖于本地植被管理模式；而冬季昆虫病原真菌的侵染率则随景观异质性的提升而下降。
5. 研究结论与应用启示：本研究结果表明，与生境异质性相关的上行调控过程（bottom-up processes）对葡萄蛀果蛾种群发生的驱动作用远强于下行调控过程（top-down processes）。上述结果对葡萄园景观的生态集约化（ecological intensification）具有重要指导意义。我们发现，在葡萄园内维持全覆草模式，可将葡萄蛀果蛾的种群密度降至常规干预阈值以下。葡萄园周边邻近区域的景观异质性，可通过鸟类提升害虫生物防治效果，但该效应依赖于本地植被管理模式。此外，景观管理对害虫生物防治服务的影响随时间呈现截然相反的趋势，这表明仅通过调控景观异质性的策略，或许并非限制葡萄园葡萄蛀果蛾种群密度的最优方案。