Data from: Landscape simplification reduces classical biological control and crop yield

Agricultural intensification resulting in the simplification of agricultural landscapes is known to negatively impact the delivery of key ecosystem services such as the biological control of crop pests. Both conservation and classical biological control may be influenced by the landscape context in which they are deployed; yet studies examining the role of landscape structure in the establishment and success of introduced natural enemies and their interactions with native communities are lacking. In this study, we investigated the relationship between landscape simplification, classical and conservation biological control services and importantly, the outcome of these interactions for crop yield. We showed that agricultural simplification at the landscape scale is associated with an overall reduction in parasitism rates of crop pests. Additionally, only introduced parasitoids were identified, and no native parasitoids were found in crop habitat irrespective of agricultural landscape simplification. Pest densities in the crop were lower in landscapes with greater proportions of semi natural habitats. Furthermore, farms with less semi-natural cover in the landscape and consequently, higher pest numbers, had lower yields than farms in less agriculturally dominated landscapes. Our study demonstrates the importance of landscape scale agricultural simplification in mediating the success of biological control programs and highlights the potential risks to native natural enemies in classical biological control programs against native insects. Our results represent an important contribution to an understanding of the landscape-mediated impacts on crop yield which will be essential to implementing effective policies that simultaneously conserve biodiversity and ecosystem services.

众所周知，农业集约化导致农业景观简化，会对作物害虫生物防治等关键生态系统服务（ecosystem services）的供给产生负面影响。保护生物防治（conservation biological control）与经典生物防治（classical biological control）均可能受其实施所处的景观背景影响；然而目前尚缺乏针对景观结构在引入天敌（introduced natural enemies）定殖与成功建立过程中所发挥的作用，以及其与本地群落间相互作用的相关研究。本研究探讨了景观简化、经典生物防治与保护生物防治服务之间的关联，尤为重要的是，还分析了这些相互作用对作物产量的影响。研究结果表明，景观尺度上的农业简化与作物害虫寄生率的整体下降存在关联。此外，本次研究仅检测到引入的寄生性天敌（parasitoids），无论农业景观是否简化，作物生境中均未发现本地寄生性天敌。半自然生境（semi-natural habitats）占比更高的景观中，作物内的害虫密度更低。此外，景观内半自然覆被占比较低、因此害虫数量更多的农场，其作物产量要低于农业占比更低的景观中的农场。本研究证实了景观尺度农业简化在调控生物防治项目成效中的重要性，并揭示了针对本地昆虫的经典生物防治项目可能对本地天敌构成的潜在风险。本研究结果有助于深化对景观介导的作物产量影响机制的理解，这对于制定能够同时保护生物多样性与生态系统服务的有效政策至关重要。