1. Ecological intensification in croplands aims to enhance biodiversity‐based ecosystem services, helping to increase yield while reducing agricultural environmental impacts. Identifying ecological intensification tools of wide applicability and easily implemented by farmers is, therefore, an imperative. Here, we verify the efficiency of provisioning artificial nest boxes for insectivorous birds to reinforce pest biological control in apple orchards.
2. The study was conducted in 24 cider‐apple orchards in Asturias (NW Spain) over 3 years. We compared the effect of insectivorous birds between orchards with and without nest boxes occupied by different bird species, through insectivory estimates based on attack on a sentinel pest and measurements of arthropod abundance in apple trees. We also identified preys that birds of different species captured to feed nestlings.
3. Bird occupancy of nest boxes was widespread, ranging 25.0%–33.3% each year. Great tit was the dominant species, followed by blue tit and, occasionally, common redstart.
4. Predation pressure on apple pests increased in orchards with nest boxes, as judged by the increased proportion of sentinel models attacked by birds (34.9% increase in 2018 and 41.1% in 2019), decreased biomass of tree‐dwelling arthropods (−51.7%) and reduced probability of apple pest occurrence (from 57% to 40%), compared to orchards without nest boxes.
5. Nesting species showed different predatory roles in apple orchards. Fewer attacks on sentinel pests but lower arthropod biomass was associated with blue tit rather than great tit. Besides, blue tit fed nestlings at a faster rate and included in their diet a higher proportion of apple pests than great tit, which preyed mostly on other herbivorous insects.
6. Synthesis and applications. We demonstrated the usefulness of nest boxes for insectivorous birds in enhancing biological control of apple pests at a regional scale, identifying tit species as complementary predators of apple pests and herbivores. From the farmers' perspective, providing nest boxes in orchards may represent an efficient, easy to implement, cheap and attractive measure of ecological intensification, compatible with other actions fostering biodiversity in croplands.

中文翻译：

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增强苹果园中的生态系统服务：巢箱可增强食虫鸟类对害虫的控制

1. 耕地的生态集约化旨在增强基于生物多样性的生态系统服务，帮助增加产量同时减少对农业环境的影响。因此，必须确定具有广泛适用性并易于农民实施的生态集约化工具。在这里，我们验证了为食虫性鸟类提供人工巢箱以加强苹果园中害虫生物防治的效率。
2. 这项研究历时3年，在阿斯图里亚斯（西班牙西北部）的24个苹果酒果园中进行。我们通过基于对前哨害虫的侵袭和苹果树节肢动物丰度测量的食虫估计，比较了有无鸟巢的果园间食虫鸟的影响。我们还确定了捕食不同物种的鸟类捕食雏鸟的猎物。
3. 巢箱中的鸟类占有率很高，每年在25.0％至33.3％之间。大山雀是主要物种，其次是蓝山雀，偶尔还有常见的红尾start。
4. 巢箱果园中苹果害虫的捕食压力增加，这可以通过鸟类攻击的前哨模型比例增加（2018年增加34.9％，2019年增加41.1％），树栖节肢动物的生物量减少（-51.7％）和与没有巢箱的果园相比，减少了苹果虫害发生的可能性（从57％降低到40％）。
5. 套种在苹果园中表现出不同的掠食作用。对前哨害虫的攻击较少，但节肢动物生物量较低与蓝雀而不是大山雀有关。此外，蓝山雀以更快的速度喂食雏鸟，并且在饮食中包含的苹果害虫比例比大山雀要高，大山雀主要捕食其他草食性昆虫。
6. 综合与应用。我们证明了巢箱对食虫鸟类在增强苹果害虫在区域范围内的生物防治中的作用，确定山雀物种是苹果害虫和食草动物的互补天敌。从农民的角度来看，在果园中提供巢箱可能是一种有效，易于实施，廉价且具有吸引力的生态集约化措施，与其他促进农田生物多样性的行动相适应。