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1. Ant Communities and Ecosystem Services in Organic Versus Conventional Agriculture in the U.S. Corn Belt

   https://doi.org/10.1093/ee/nvab105  

   Helms, Jackson A ; Smith, Jamie ; Clark, Stephanie ; Knupp, Kathleen ; Haddad, Nick M ( September 2021 , Environmental Entomology)

   Schmidt-Jeffris, Rebecca A (Ed.)

   Abstract Reducing the use of synthetic fertilizers and pesticides can limit negative impacts of agriculture on insects and is a crucial step towards sustainable agriculture. In the United States, organic agriculture has the potential to reduce greenhouse gas emissions, pollutant runoff, and biodiversity loss in the Midwestern Corn Belt—an area extending over 500,000 km2 devoted to intensive production of corn Zea mays (Linnaeus 1753) (Poales: Poaceae), often in rotation with soy Glycine max (Linnaeus 1753) (Fabales: Fabaceae) or wheat Triticum aestivum (Linnaeus 1753) (Poales: Poaceae). Working in 30-yr-long landscape experiments in this region, we tested for impacts of conventional versus organic agriculture on ant communities (Hymenoptera: Formicidae) and potential ecosystem services they provide. Organic fields supported higher ant diversity and a slightly more species-rich ant assemblage than conventionally managed fields but did not otherwise differ in community composition. Despite similar community composition, organic and conventional fields differed in seasonal patterns of ant foraging activity and potential for natural pest suppression. Conventional plots experienced higher overall ant foraging activity, but with the timing skewed towards late in the growing season such that 75% of ant foraging occurred after crop harvest in a wheat year and was therefore unavailable for pest suppression. Organic fields, in contrast, experienced moderate levels of ant foraging activity throughout the growing season, with most foraging occurring during crop growth. Organic fields thus supported twice as much pest suppression potential as conventional fields. Our results highlight the importance of timing in mediating ecosystem services in croplands and emphasize the value of managing landscapes for multiple services rather than yield alone. 

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2. High‐level field‐evolved resistance to spinosad in Colorado potato beetle, Leptinotarsa decemlineata , in organically managed fields

   https://doi.org/10.1002/ps.6473  

   Schnaars‐Uvino, Kathleen ; Baker, Mitchell B. ( May 2021 , Pest Management Science)

   Organic pest management eschews synthetic pesticides and insecticide resistance is rarely studied in organically managed systems. Spinosad is a biologically based insecticide used widely by both organic and conventional growers. Colorado potato beetle,Leptinotarsa decemlineata, is infamous for its ability to evolve resistance to insecticides. Spinosad resistance was surveyed in conventionally managed fields in eastern New York in 2006. In response to grower reports of spinosad failure on two organic farms in 2009, resistance to spinosad was assayed in both conventionally and organically managed fields the following year, and growers were surveyed for their prior spinosad use.

   In 2006, spinosad resistance measured as median lethal dose (LD₅₀) varied 9.8‐fold among the eight conventional fields sampled and a laboratory susceptible strain. In 2010, the resistance ratios of LD₅₀values relative to a laboratory susceptible strain ranged from 17.5 to 40.6 in conventionally managed fields, and from 128.7 to 5750.3 in organically managed fields, a dramatic increase from 2006 with higher resistance ratios in organically managed fields. Organic growers reported much heavier use of spinosad in the years prior to 2010.

   This is the first report of high‐level resistance to spinosad in Coleopterans. Selection strength due to number of years used and number of applications per season appear to have been the primary factors driving the evolution of resistance to spinosad, highlighting the need for resistance management in organic production, where fewer alternative active ingredients for resistance management are available. © 2021 Society of Chemical Industry.

    

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3. Food production and resource use of urban farms and gardens: a five-country study

   https://doi.org/10.1007/s13593-022-00859-4  

   Dorr, Erica ; Hawes, Jason K. ; Goldstein, Benjamin ; Fargue-Lelièvre, Agnès ; Fox-Kämper, Runrid ; Specht, Kathrin ; Fedeńczak, Konstancja ; Caputo, Silvio ; Cohen, Nevin ; Poniży, Lidia ; et al ( February 2023 , Agronomy for Sustainable Development)

   There is a lack of data on resources used and food produced at urban farms. This hampers attempts to quantify the environmental impacts of urban agriculture or craft policies for sustainable food production in cities. To address this gap, we used a citizen science approach to collect data from 72 urban agriculture sites, representing three types of spaces (urban farms, collective gardens, individual gardens), in five countries (France, Germany, Poland, United Kingdom, and United States). We answered three key questions about urban agriculture with this unprecedented dataset: (1) What are its land, water, nutrient, and energy demands? (2) How productive is it relative to conventional agriculture and across types of farms? and (3) What are its contributions to local biodiversity? We found that participant farms used dozens of inputs, most of which were organic (e.g., manure for fertilizers). Farms required on average 71.6 L of irrigation water, 5.5 L of compost, and 0.53 m² of land per kilogram of harvested food. Irrigation was lower in individual gardens and higher in sites using drip irrigation. While extremely variable, yields at well-managed urban farms can exceed those of conventional counterparts. Although farm type did not predict yield, our cluster analysis demonstrated that individually managed leisure gardens had lower yields than other farms and gardens. Farms in our sample contributed significantly to local biodiversity, with an average of 20 different crops per farm not including ornamental plants. Aside from clarifying important trends in resource use at urban farms using a robust and open dataset, this study also raises numerous questions about how crop selection and growing practices influence the environmental impacts of growing food in cities. We conclude with a research agenda to tackle these and other pressing questions on resource use at urban farms.

    

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4. The success of a habitat specialist biological control agent in the face of disturbance

   https://doi.org/10.1002/ecs2.4050  

   Kishinevsky, Miriam ; Ives, Anthony R. ( April 2022 , Ecosphere)

   Natural enemies that can use multiple habitats are thought to better withstand disturbances in agricultural systems than natural enemies that are habitat specialists. This is because habitat generalists have populations in multiple habitats that can serve as sources of immigrants into an agricultural crop following a disturbance. In contrast, the dynamics of habitat specialists are tightly coupled with those of one agricultural crop. Nonetheless, some habitat specialists are successful in highly disturbed environments. To test how the magnitude of within‐field disturbance affects biological control agents, we conducted a large‐scale field manipulation in alfalfa fields and monitored the response of pea aphids, habitat‐generalist predators, a habitat‐specialist parasitoid (Aphidius ervi), and hyperparasitoids ofA. ervi. The manipulation involved three treatments: harvesting normally (intermediate disturbance); spraying insecticide immediately after harvesting (high disturbance); and harvesting in strips (low disturbance). As a group, the habitat‐generalist predator species showed a range of responses to disturbances, from no response to decreases in abundance in the high‐disturbance treatment, indicating differences in their response to the density of pea aphids following disturbances. Surprisingly, percentage parasitism by the habitat‐specialist parasitoid was little affected by experimental disturbance manipulations. Furthermore, two of the four hyperparasitoids ofA. erviwere negatively affected by the magnitude of disturbance, suggesting that disturbance could have an indirect positive effect onA. ervi. These results suggest that a habitat specialist can overcome the detrimental effects of disturbances without using alternative habitats. In addition, disturbance can sometimes benefit biological control agents by disproportionally negatively affecting their enemies from the fourth trophic level.

    

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5. A new critical social science research agenda on pesticides

   https://doi.org/10.1007/s10460-023-10492-w  

   Mansfield, Becky ; Werner, Marion ; Berndt, Christian ; Shattuck, Annie ; Galt, Ryan ; Williams, Bryan ; Argüelles, Lucía ; Barri, Fernando Rafael ; Ishii, Marcia ; Kunin, Johana ; et al ( August 2023 , Agriculture and Human Values)

   Abstract The global pesticide complex has transformed over the past two decades, but social science research has not kept pace. The rise of an enormous generics sector, shifts in geographies of pesticide production, and dynamics of agrarian change have led to more pesticide use, expanding to farm systems that hitherto used few such inputs. Declining effectiveness due to pesticide resistance and anemic institutional support for non-chemical alternatives also have driven intensification in conventional systems. As an inter-disciplinary network of pesticide scholars, we seek to renew the social science research agenda on pesticides to better understand this suite of contemporary changes. To identify research priorities, challenges, and opportunities, we develop the pesticide complex as a heuristic device to highlight the reciprocal and iterative interactions among agricultural practice, the agrochemical industry, civil society-shaped regulatory actions, and contested knowledge of toxicity. Ultimately, collaborations among social scientists and across the social and biophysical sciences can illuminate recent transformations and their uneven socioecological effects. A reinvigorated critical scholarship that embraces the multifaceted nature of pesticides can identify the social and ecological constraints that drive pesticide use and support alternatives to chemically driven industrial agriculture. 

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