Do diverse landscapes provide for effective natural pest control in subtropical rice?. Issue 1 (29th October 2019)

• Record Type: Journal Article
• Authors: Zou, Yi; de Kraker, Joop; Bianchi, Felix J. J. A.; Xiao, Haijun; Huang, Jikun; Deng, Xiangzheng; Hou, Lingling; van der Werf, Wopke
• Editors: Marini, Lorenzo
• Is Part Of: Journal of applied ecology. Volume 57:Issue 1(2020)
• Page Start: 170
• Page End: 180
• Publication Date: 2019-10-29
• Subjects: agroecosystem -- biological pest control -- chemical -- China -- natural enemy -- pest management -- planthopper -- yield; Agriculture -- Periodicals; Biology, Economic -- Periodicals; Agricultural ecology -- Periodicals; Applied ecology -- Periodicals; 577
• DOI: 10.1111/1365-2664.13520
• Languages: English
• ISSNs: 0021-8901

Abstract

Abstract: While the biocontrol potential of natural enemies is well established, it is largely unknown how landscape‐mediated effects on pest and natural enemy communities impact the cascade of biocontrol potential, crop injury, yield and profit, taking into account crop management and surrounding landscape composition. We compared natural biocontrol with chemical control according to local farmers' practice, across the 'full cascade' from natural enemy and pest abundance to crop injury, yield loss, yield and economic performance. This 2‐year study was conducted in 20 rice fields embedded in a gradient of landscapes from crop‐dominated to semi‐natural habitat‐dominated, in subtropical China, the world's largest rice‐producing region. Natural enemies suppressed brown planthopper population growth in unsprayed plots, irrespective of landscape composition. However, crop injury was lower in pesticide treated plots than in unsprayed plots, and yields in sprayed plots were 20% higher than in unsprayed plots. Nevertheless, pesticide applications were only profitable in less than half of the cases when only costs for pesticides were considered, and in less than one third of the cases when costs for pesticides and labour were considered. Synthesis and applications . Our findings question the cost‐effectiveness of current chemical‐based pest management in farming, and highlight opportunities for more ecologically based pest management strategies based on the widespread activity of natural enemies. Pest damage and biocontrol, however, are largely independent from the landscape context, which might be due to the small‐scale character of Chinese rice landscapes. To maintain high levels of biocontrol, conserving this small‐scale character appears more important than increasing the proportion of semi‐natural habitat. Abstract : Our findings question the cost‐effectiveness of current chemical‐based pest management in farming, and highlight opportunities for more ecologically based pest management strategies based on the widespread activity of natural enemies. Pest damage and biocontrol, however, are largely independent from the landscape context, which might be due to the small‐scale character of Chinese rice landscapes. To maintain high levels of biocontrol, conserving this small‐scale character appears more important than increasing the proportion of semi‐natural habitat. Chinese Abstract: 虽然天敌的生物防治潜力已经较为明确, 但是农田景观构成及其农作物管理的综合作用如何影响害虫与天敌的种群群落, 生物防治能力、作物的损失、产量与害虫防治收益等系列的问题仍不清楚。 我们比较了生物防治与农民实施常规化学防治的地块, 围绕天敌与害虫的种群数量, 害虫为害率、产量损失, 收成与经济表现等进行系统分析。本研究在中国亚热带地区, 世界上最大的水稻产区, 选择了20个拥有不同景观构成的稻田生境连续进行了两年的研究, 景观构成从以作物为主到以半自然栖境为主的系列梯度差异。 在无农药区稻田天敌可以显著抑制褐飞虱种群的增长, 生防功能与农田景观背景无显著关联。农民常规喷洒农药防治害虫的区域作物损害率低于无农药区的地块, 前者的产量比后者高20％。尽管如此, 仅考虑农药成本时, 不到一半农户实施的害虫防治措施可获盈利, 若同时考虑农药成本和防治劳动力成本, 则仅有不足三分之一的农户获盈利。 结论与应用。我们的研究结果表明当前农民实施化学防治的行为存在成本投入大和效益不明显的问题, 突显基于合理广泛应用自然天敌进行害虫生态调控策略的机遇。然而, 可能是由于中国小规模稻田景观的特征, 害虫损失和天敌生物防治效率在很大程度上与小规模农田景观背景无显著相关。为保持高水平的生物防治潜力, 适当维护小规模农田景观特征似乎比单纯强调增加半自然生境的比例更为重要。