Data from: Natural vegetation benefits synergistic control of the three main insect and pathogen pests of fruit crop in southern Africa

1. Most studies of the potential for natural habitat to improve agricultural productivity have been conducted in transformed, temperate regions, but little is known of the importance of agroecosystem services in biodiverse developing countries. 2. Natural vegetation may promote the density and/or diversity of natural enemies of crop pests, but the strength of the effect varies, and few studies directly measure concurrent impacts on pest density. Considering multiple pest species within the same agroecosystem may help explain why some pests are more affected than others by landscape complexity. Here, we investigated multiple pest species (three species of Tephritidae fruit fly, leaf galling flies and pathogenic fungi Fusarium spp.) and their enemies in cultivated mango Mangifera indica, in north-eastern South Africa. 3. The density of generalist Tephritidae fruit flies increased with distance from natural vegetation during harvesting months, and predation rate of pupae sharply decreased from ~50% at the edge with natural vegetation to 0% at 250 m into the crop. Parasitism rates of the cryptic, gall-forming fly increased with proximity to natural vegetation, but pest density was unrelated to distance from natural vegetation. Incidence of the fungal pathogen disease increased with distance from natural vegetation, possibly due to decreased predation of commensal mites. 4. Although the relationship with distance to natural vegetation was significant for all species considered, the strength of this relationship varied across pest species and type of natural enemy studied, suggesting the benefits of natural vegetation depend on each natural enemy species' ability to disperse into the agricultural environment. 5. Synthesis and applications. Our results suggest that natural vegetation is a net source of natural enemies in a region of South Africa that still contains much of its natural biodiversity. However, the decline in natural enemies, and increase in pests, with distance from natural habitat indicates that this biocontrol is limited by natural enemy dispersal. In landscapes like these that are still dominated by natural habitat, conservation biocontrol can still be improved by management aimed at providing corridors of key plants and habitat elements into the crops, to facilitate natural enemy dispersal.

1. 现有关于自然栖息地提升农业生产潜力的研究，大多集中于经人为改造的温带区域，但对于生物多样性丰富的发展中国家而言，其农业生态系统服务的重要性仍鲜为人知。
2. 天然植被可提升作物害虫天敌的种群密度与/或物种多样性，但其作用强度存在差异，且鲜有研究直接量化其对害虫密度的同步影响。若聚焦同一农业生态系统内的多种害虫物种，则有助于解释为何部分害虫受景观复杂性的影响程度高于其他害虫。本研究针对南非东北部栽培杧果（Mangifera indica）生境中的多种害虫（3种实蝇科（Tephritidae）果蝇、叶瘿蝇及镰孢菌属（Fusarium spp.）病原真菌）及其天敌展开了调查。
3. 在收获季，广食性实蝇科果蝇的种群密度随与天然栖息地距离的增加而升高，其蛹的捕食率则从天然栖息地边缘的约50%急剧下降至农田内250米处的0%。隐匿性虫瘿形成蝇类的寄生率随与天然栖息地距离的拉近而升高，但该类害虫的密度与距天然栖息地的距离并无关联。病原真菌病害的发病率随与天然栖息地距离的增加而上升，这可能与共生螨的捕食作用减弱有关。
4. 尽管所有研究对象的种群与距天然栖息地的距离均存在显著关联，但该关联的强度因害虫物种及天敌类群的不同而存在差异，这表明天然植被的益处取决于各天敌物种向农田环境扩散的能力。
5. 结论与应用。本研究结果表明，在仍保留大量自然生物多样性的南非区域内，天然植被是天敌种群的净来源。然而，天敌种群密度随与天然栖息地距离增加而下降、害虫种群密度随之上升的现象，说明该生物防治作用受限于天敌的扩散能力。在这类仍以天然栖息地为主的景观中，仍可通过构建关键植物与栖息地要素廊道以连通农田的管理手段，优化保护型生物防治，从而促进天敌的自然扩散。