期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2022
卷号：119
期号：37
DOI：10.1073/pnas.2208813119
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Significance
Economies of scale in agricultural production continue to promote shifts to larger monocultural plantings of crop plants. Contrary to widely accepted views on resource concentration in monocultures, we find that larger field sizes do not consistently amplify the severity of arthropod pest impacts. Although smaller fields may enhance biodiversity and augment many ecosystem services, including pollination, our analysis shows that simply downsizing the scale of agriculture will not consistently ameliorate pest impacts. Additional work on pest and natural enemy overwintering and movement biology is needed to understand why larger field sizes can amplify, reduce, or have no effect on pest severity across different pest-crop systems.
Increasing diversity on farms can enhance many key ecosystem services to and from agriculture, and natural control of arthropod pests is often presumed to be among them. The expectation that increasing the size of monocultural crop plantings exacerbates the impact of pests is common throughout the agroecological literature. However, the theoretical basis for this expectation is uncertain; mechanistic mathematical models suggest instead that increasing field size can have positive, negative, neutral, or even nonlinear effects on arthropod pest densities. Here, we report a broad survey of crop field-size effects: across 14 pest species, 5 crops, and 20,000 field years of observations, we quantify the impact of field size on pest densities, pesticide applications, and crop yield. We find no evidence that larger fields cause consistently worse pest impacts. The most common outcome (9 of 14 species) was for pest severity to be independent of field size; larger fields resulted in less severe pest problems for four species, and only one species exhibited the expected trend of larger fields worsening pest severity. Importantly, pest responses to field size strongly correlated with their responses to the fraction of the surrounding landscape planted to the focal crop, suggesting that shared ecological processes produce parallel responses to crop simplification across spatial scales. We conclude that the idea that larger field sizes consistently disrupt natural pest control services is without foundation in either the theoretical or empirical record.
