The indirect effect of seminatural habitats on pest suppression has been widely studied in agricultural landscapes. By contrast, the role of crop diversity on pest suppression by predators has seldom been explored, particularly using molecular gut-content analysis (MGCA). In addition, differences between early- and late-season effects of landscape complexity on pest control, crucial to ensure season-long control, have received little attention. During 2014 and 2015, we investigated the effect of agricultural landscape complexity and crop diversity on cereal leaf beetle (CLB, Oulema melanoplus) predation early in the season using sentinel egg cards and late in the season by assessing larval predation using MGCA. Early-season CLB egg predation and late-season abundance of Nabis americoferus and coccinellids in wheat fields were positively correlated with amount of woodland habitat in these landscapes. Contrary to our predictions, crop diversity had negative associations with the late-season frequency of larval predation and the abundance of N. americoferus. Predator diversity and the abundance of Hippodamia lady beetles had negative associations with CLB abundance, highlighting the significant contribution of some generalist predators to CLB suppression. Our results suggest that the proportion of woodland and a few major crops (e.g., canola and non-cereal crops), rather than crop diversity, are associated with higher predation at different temporal scales. Overall, our results suggest that a habitat management strategy could be implemented to adjust the crop rotation regime to add the right kind of crop diversity in the landscape to support the natural control of CLB.

半自然栖息地对害虫抑制的间接影响已在农业景观中得到广泛研究。相比之下，很少探索作物多样性对捕食者抑制害虫的作用，特别是使用分子肠道含量分析（MGCA）。此外，景观复杂性对害虫控制的早期和晚期影响之间的差异，对于确保长期控制至关重要，很少受到关注。在 2014 年和 2015 年期间，我们调查了农业景观复杂性和作物多样性对谷物叶甲虫 (CLB, Oulema melanoplus ) 在季节早期使用哨兵蛋卡和在季节后期通过使用 MGCA 评估幼虫捕食的影响。Nabis americoferus的早季CLB卵捕食和晚季丰度麦田中的瓢虫和这些景观中的林地栖息地数量呈正相关。与我们的预测相反，作物多样性与幼虫捕食的晚季频率和美洲猪笼草的丰度呈负相关。捕食者的多样性和Hippodamia的丰度瓢虫与 CLB 丰度呈负相关，突出了一些通才捕食者对 CLB 抑制的显着贡献。我们的研究结果表明，林地和一些主要作物（例如油菜和非谷物作物）的比例，而不是作物多样性，与不同时间尺度的更高捕食率有关。总体而言，我们的研究结果表明，可以实施栖息地管理策略来调整作物轮作制度，以在景观中添加正确的作物多样性，以支持 CLB 的自然控制。