Insecticide overuse in crop production systems often results in detrimental effects on predators and parasitoids, which regulate important insect pests. The natural enemies are also unable to survive in monocrop landscapes with the absence of shelter or food sources. Diversified vegetation, especially with flowering plants, can enhance natural enemy abundance and diversity, thus strengthening biological control, enabling farmers to reduce insecticides. In this study, we conserved bund vegetation and manipulated the existing rice landscapes with flowering plants to provide food and shelter for the biological control agents. Our study revealed significant positive relationships between predator densities and bund plant diversity. The abundance of predators significantly increased in the eco-engineered plots, especially at the flowering peaks compared to the insecticide-treated and control plots, while parasitoids were more diverse in both the eco-engineered and control plots. There were no significant differences in planthopper and leafhopper densities among the treatments during the rice early and maximum tillering stages, suggesting effective natural control of these herbivore pests in the eco-engineered plots at the early rice-growing season. However, at the heading stage relatively higher planthopper and leafhopper populations in the control and eco-engineered plots than in the insecticide-sprayed plots were recorded, suggesting perhaps the need for insecticide interventions if exceeding the threshold at this time. Our study indicates that manipulating the habitats surrounding the rice fields to enhance natural enemies is a sustainable practice in rice production as it can enhance the natural suppression of pests and thus reducing the need for insecticide.

中文翻译：

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多样化的外滩植被与开花植物相结合可增强捕食者数量和早季害虫防治

作物生产系统中杀虫剂的过度使用通常会对捕食者和寄生蜂造成不利影响，而这些捕食者和寄生蜂是重要的害虫。在没有庇护所或食物来源的情况下，天敌也无法在单一作物景观中生存。多样化的植被，尤其是开花植物，可以增强天敌的丰度和多样性，从而加强生物防治，使农民能够减少杀虫剂。在这项研究中，我们保护了堤岸植被，并用开花植物操纵现有的水稻景观，为生物防治剂提供食物和住所。我们的研究揭示了捕食者密度与外滩植物多样性之间的显着正相关关系。在生态工程地块中捕食者的数量显着增加，与经杀虫剂处理的地块和对照地块相比，尤其是在开花高峰期，而生态工程地块和对照地块的寄生蜂种类更丰富。水稻早期和最大分蘖期各处理间飞虱和叶蝉密度没有显着差异，表明在水稻生长季节早期生态工程地块中这些食草动物害虫的有效自然控制。然而，在抽穗期，控制和生态工程地块中的飞虱和叶蝉种群数量相对高于杀虫剂喷洒地块，这表明如果此时超过阈值，可能需要进行杀虫剂干预。