Primary parasitoid species, usually Hymenopteran wasp species, contribute to pest regulation services in agroecosystems by parasitizing crop pests and reducing their abundance. However, this positive effect can be limited if primary parasitoids themselves are parasitized by secondary parasitoids, also known as hyperparasitoids. These trophic dynamics that influence pest regulation take place within the context of changes to agricultural landscape structure including loss of natural habitat and landscape simplification. Therefore, there is great interest in understanding how landscape structure influences pest, primary parasitoid, and hyperparasitoid dynamics. We investigated how the structure of agricultural landscapes in Southern Quebec affects primary and hyperparasitism rates of soybean aphid (Aphis glycines). We found that pests, primary parasitoids, and hyperparasitoids responded in contrasting ways to landscape structure. While aphid abundances and hyperparasitoid rates increased with increasing distance-from-forest in soybean fields and as the proportion of forest in the surrounding landscape decreased, primary parasitoid rates showed the opposite trends. Relationships with forest fragment size and isolation were complex, with contrasting positive, negative, and neutral effects across the three groups. Finally, wider fields consistently had lower aphid abundances, primary parasitoid rates, and hyperparasitoid rates. Our results highlight the complexity of the trophic dynamics that underlie pest regulation and how changes to landscape structure can lead to conflicting and contradictory effects on pest regulation.

初级寄生物种，通常是膜翅目黄蜂物种，通过寄生作物害虫并减少其丰度，为农业生态系统中的害虫调控服务做出贡献。但是，如果初级寄生蜂本身被次级寄生蜂（也称为超寄生蜂）寄生，则这种积极影响可能会受到限制。这些影响害虫调控的营养动态发生在农业景观结构变化的背景下，包括自然栖息地的丧失和景观的简化。因此，了解景观结构如何影响害虫、初级寄生蜂和超寄生蜂动力学具有极大的兴趣。我们调查了魁北克南部的农业景观结构如何影响大豆蚜虫（甘氨酸蚜虫）的初级和超寄生率）。我们发现害虫、初级寄生蜂和超寄生蜂对景观结构的反应方式截然不同。虽然蚜虫丰度和高寄生率随着大豆田距森林距离的增加以及周围景观中森林比例的减少而增加，但初级寄生率显示出相反的趋势。与森林碎片大小和隔离的关系很复杂，三组之间的正面、负面和中性影响形成鲜明对比。最后，更广阔的田地始终具有较低的蚜虫丰度、初级寄生率和超寄生率。我们的研究结果强调了作为害虫调控基础的营养动力学的复杂性，以及景观结构的变化如何导致对害虫调控的相互矛盾的影响。