2022 article
Pest species respond differently to farm field size
Kennedy, G. G., & Huseth, A. S. (2022, September 27). PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, Vol. 119.
MeSH headings : Animals; Arthropods / physiology; Farms; Insect Control; Insecta / physiology; Insecticides
open access via doi.org (publisher)
UN Sustainable Development Goal Categories
2. Zero Hunger
(Web of Science)
13. Climate Action
(Web of Science)
15. Life on Land
(Web of Science)
Source: Web Of Science
Added: September 5, 2023
Agriculture faces numerous challenges relating to population growth and environmental quality. Strategies to address these challenges are expected to involve a redesign of agricultural production systems to increase productivity and sustainability (1, 2). Notably, changing how cropland is structured within agroecosystems is one redesign opportunity that could have multiple sustainability benefits. Agroecosystems are a complex arrangement of crop and noncrop habitats that support a diverse array of arthropods relevant to sustainable crop production, including pests, natural enemies, and pollinators. Farmers and ecologists have long known that the arrangement and abundance of crops have local impacts on pest infestations, leading to the idea that manipulation of cropland structure could alleviate pressure by pests, promote biological control, and reduce pesticide use (3–7). One aspect of this is that concentrated crop production, either size of fields planted to a single crop or prevalence of a single crop in the landscape, will result in more pest problems. Rosenheim et al. (8), in PNAS, tested this concept using a large, multicrop dataset collected from different agricultural systems to investigate whether the size of fields planted to a single crop or the amount of a crop in the surrounding landscape is positively related to pest abundance. Their key finding is the absence of a consistent relationship between pest abundance and the area of host crop at either the field or the landscape scale. They found negative, neutral, and positive relationships, suggesting that pests vary in their response to crop abundance at both the field and landscape scales (Fig. 1). The results provide a compelling argument that the relationship between pest pressure and the extent of host crop production is context dependent. This suggests that predicting the effect of crop abundance on the intensity of pest problems will require accounting for the ways in which individual pest species interact with their habitats, as well as the effects of landscape composition and configuration on their natural enemies. The results are important not only because of their relevance to the sustainable intensification of agricultural production systems but also because there has been a longstanding acceptance in the agroecological literature that increasing field size in agricultural monocultures is positively related to pest infestation levels, crop loss, and pesticide use (3, 5, 7, 9). The conceptual framework underlying this putative relationship is based largely on two ecological concepts: the resource concentration hypothesis and the natural enemies hypothesis (10, 11). The former predicts that population densities of specialist herbivores will be higher in large monocultures of their host plants than in diverse stands. The latter suggests reduced biological control of herbivores in large pure stands because these monocultures do not provide suitable habitat and resources for natural enemies. However, the generalization of these concepts to agricultural systems across broad spatial scales and the idea that large-scale monocultures intensify pest problems lacks rigorous theoretical or empirical support (8). Field studies in agricultural crops, primarily involving small plots, as well as studies in natural systems and modeling studies have shown that the effects of increasing field size on pest population density can be inconsistent (12–17). Rosenheim et al. (8) took advantage of existing data compiled by independent crop advisors or farm staff during regular sampling of pest populations or crop injury to inform decisions regarding pesticide applications. The dataset comprised >20,000 field-year observations spanning Fig. 1. The size of arthropod pest populations sampled in different annual and perennial crops were related to the size of the agricultural field and the abundance of the same crop in the surrounding landscape. Results showed that different arthropod species responded positively (pest 1) or negatively (pest 3) or had no relationship at all (pest 2) to the size of agricultural fields. Species tended to have similar trends at different spatial scales of crop production.