Landscape simplification increases the risk of infestation by the polyphagous pest Helicoverpa armigera for walnut, a novel marginal host

文献类型： 外文期刊

第一作者： Yang, Long

作者： Yang, Long;Liu, Haining;Pan, Yunfei;Li, Haiqiang;Lu, Yanhui;Li, Haiqiang

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关键词： Adaptive evolution; Helicoverpa armigera; Landscape diversity; Marginal host; Polyphagous herbivore; Weed cover

期刊名称：LANDSCAPE ECOLOGY （ 影响因子：5.043； 五年影响因子：5.586 ）

ISSN： 0921-2973

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收录情况： SCI

摘要： Context Plant diversity can sometimes determine the distribution of pests in ecosystems, but the effects of plant diversity at local and landscape scales on the occurrence of pests on novel marginal hosts are still unknown. Objectives We explored the direct effects of plant diversity at local and landscape scales on the colonization of the marginal host walnut by Helicoverpa armigera (Lepidoptera: Noctuidae). Methods We surveyed and compared the occurrence (and damage) of H. armigera in walnut orchards embedded in simple vs. diverse landscapes, and with weeds or without weed cover. The surrounding landscape composition and weed communities in walnut orchards were also investigated to shed light on the mechanisms driving H. armigera responses. Results Diverse landscapes were associated with lower densities of overwintering adult H. armigera, first generation eggs and larvae, as well as with lower infestation rates of walnut fruits. Weed presence in walnut orchards had no significant effects on the abundance of H. armigera adults or eggs, but was associated with higher larvae densities in orchards, in both simple and diverse landscapes. The effect of within-orchard weed cover on larvae was stronger in diverse landscapes. Conclusions Our study demonstrated that landscape composition coupled with local orchard ground cover vegetation mediated the occurrence of H. armigera on a marginal host walnut. Monoculture production increases walnut's exposure to the pest and may accelerate its evolutionary adaptation to this poor host; weed cover in individual orchards may increase larval density by providing floral resources for adults.

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[1]Landscape simplification increases the risk of infestation by the polyphagous pest Helicoverpa armigera for walnut, a novel marginal host. Yang, Long,Liu, Haining,Pan, Yunfei,Li, Haiqiang,Lu, Yanhui,Li, Haiqiang.

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