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是一项重要的生态系统服务（ecosystem service），其受多空间尺度上多种变量的共同影响。在这些变量中，生境和景观尺度的异质性（heterogeneity）是农业生态系统（agroecosystems）中营养级相互作用（trophic interactions）和害虫密度的已知关键驱动因素。然而，试图解析它们在多年生作物系统中相对效应的研究较为匮乏，且关于其对害虫密度及农药施用的影响尚属未知。
2. 我们连续三年在20个葡萄园考察了这两个尺度的异质性对葡萄蛾（欧洲葡萄园最具破坏性的害虫之一）及其生物防治的影响。我们以本地植被管理和周边景观中半自然生境的比例作为生境和景观尺度异质性的代理指标，对葡萄蛾密度进行了长期监测，并评估了鸟类、无脊椎捕食者、寄生性天敌及虫生真菌提供的生物防治服务。
3. 三年间的研究结果显示，葡萄蛾密度主要由本地异质性决定：与部分草地覆盖的葡萄园相比，完全草地覆盖的葡萄园中第一代葡萄蛾幼虫数量显著更少。
4. 尽管存在上述效应，但葡萄蛾的生物防治并非主要受本地植被管理的影响，而是由景观异质性驱动，且这种效应的方向随时间变化。值得注意的是，春季鸟类捕食作用随景观异质性增加而增强，这一效应依赖于本地植被管理；而冬季虫生真菌的侵染率则随景观异质性增加而降低。
5. 综合与应用：我们的结果表明，与生境异质性相关的上行过程（bottom-up processes）对葡萄蛾发生的驱动作用远大于下行过程（top-down processes）。这些结果对葡萄园景观的生态集约化（ecological intensification）具有重要启示。我们发现，维持葡萄园内部完全草地覆盖可将葡萄蛾密度降至常见干预阈值以下；葡萄园周边的景观异质性有助于提升鸟类的生物防治效果，但这一效果依赖于本地植被管理。此外，景观管理对生物防治服务的效应随时间呈现相反趋势，这表明仅通过调控景观异质性的策略可能并非限制葡萄园葡萄蛾密度的最优方案。