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Johnson N, Zhang G, Soble A, Johnson S, Baucom RS. The consequences of synthetic auxin herbicide on plant-herbivore interactions. TRENDS IN PLANT SCIENCE 2023; 28:765-775. [PMID: 36842859 DOI: 10.1016/j.tplants.2023.02.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 02/05/2023] [Accepted: 02/06/2023] [Indexed: 06/17/2023]
Abstract
Although herbicide drift is a common side effect of herbicide application in agroecosystems, its effects on the ecology and evolution of natural communities are rarely studied. A recent shift to dicamba, a synthetic auxin herbicide known for 'drifting' to nontarget areas, necessitates the examination of drift effects on the plant-insect interactions that drive eco-evo dynamics in weed communities. We review current knowledge of direct effects of synthetic auxin herbicides on plant-insect interactions, focusing on plant herbivory, and discuss potential indirect effects, which are cascading effects on organisms that interact with herbicide-exposed plants. We end by developing a framework for the study of plant-insect interactions given drift, highlighting potential changes to plant developmental timing, resource quantity, quality, and cues.
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Affiliation(s)
- Nia Johnson
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Grace Zhang
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Anah Soble
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Stephen Johnson
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Regina S Baucom
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA.
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2
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Sampedro-Guerrero J, Vives-Peris V, Gomez-Cadenas A, Clausell-Terol C. Efficient strategies for controlled release of nanoencapsulated phytohormones to improve plant stress tolerance. PLANT METHODS 2023; 19:47. [PMID: 37189192 PMCID: PMC10184380 DOI: 10.1186/s13007-023-01025-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Accepted: 05/06/2023] [Indexed: 05/17/2023]
Abstract
Climate change due to different human activities is causing adverse environmental conditions and uncontrolled extreme weather events. These harsh conditions are directly affecting the crop areas, and consequently, their yield (both in quantity and quality) is often impaired. It is essential to seek new advanced technologies to allow plants to tolerate environmental stresses and maintain their normal growth and development. Treatments performed with exogenous phytohormones stand out because they mitigate the negative effects of stress and promote the growth rate of plants. However, the technical limitations in field application, the putative side effects, and the difficulty in determining the correct dose, limit their widespread use. Nanoencapsulated systems have attracted attention because they allow a controlled delivery of active compounds and for their protection with eco-friendly shell biomaterials. Encapsulation is in continuous evolution due to the development and improvement of new techniques economically affordable and environmentally friendly, as well as new biomaterials with high affinity to carry and coat bioactive compounds. Despite their potential as an efficient alternative to phytohormone treatments, encapsulation systems remain relatively unexplored to date. This review aims to emphasize the potential of phytohormone treatments as a means of enhancing plant stress tolerance, with a specific focus on the benefits that can be gained through the improved exogenous application of these treatments using encapsulation techniques. Moreover, the main encapsulation techniques, shell materials and recent work on plants treated with encapsulated phytohormones have been compiled.
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Affiliation(s)
- Jimmy Sampedro-Guerrero
- Departamento de Biología, Bioquímica y Ciencias Naturales, Universitat Jaume I, 12071, Castelló de la Plana, Castellón, Spain
| | - Vicente Vives-Peris
- Departamento de Biología, Bioquímica y Ciencias Naturales, Universitat Jaume I, 12071, Castelló de la Plana, Castellón, Spain
| | - Aurelio Gomez-Cadenas
- Departamento de Biología, Bioquímica y Ciencias Naturales, Universitat Jaume I, 12071, Castelló de la Plana, Castellón, Spain.
| | - Carolina Clausell-Terol
- Departamento de Ingeniería Química, Instituto Universitario de Tecnología Cerámica, Universitat Jaume I, 12071, Castelló de la Plana, Castellón, Spain.
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3
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Grant TJ, Fisher KE, Krishnan N, Mullins AN, Hellmich RL, Sappington TW, Adelman JS, Coats JR, Hartzler RG, Pleasants JM, Bradbury SP. Monarch Butterfly Ecology, Behavior, and Vulnerabilities in North Central United States Agricultural Landscapes. Bioscience 2022; 72:1176-1203. [PMID: 36451972 PMCID: PMC9699720 DOI: 10.1093/biosci/biac094] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/02/2023] Open
Abstract
The North American monarch butterfly (Danaus plexippus) is a candidate species for listing under the Endangered Species Act. Multiple factors are associated with the decline in the eastern population, including the loss of breeding and foraging habitat and pesticide use. Establishing habitat in agricultural landscapes of the North Central region of the United States is critical to increasing reproduction during the summer. We integrated spatially explicit modeling with empirical movement ecology and pesticide toxicology studies to simulate population outcomes for different habitat establishment scenarios. Because of their mobility, we conclude that breeding monarchs in the North Central states should be resilient to pesticide use and habitat fragmentation. Consequently, we predict that adult monarch recruitment can be enhanced even if new habitat is established near pesticide-treated crop fields. Our research has improved the understanding of monarch population dynamics at the landscape scale by examining the interactions among monarch movement ecology, habitat fragmentation, and pesticide use.
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Affiliation(s)
- Tyler J Grant
- Research scientist, Iowa State University, Ames, Iowa
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4
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Ramos SE, Rzodkiewicz LD, Turcotte MM, Ashman TL. Damage and recovery from drift of synthetic-auxin herbicide dicamba depends on concentration and varies among floral, vegetative, and lifetime traits in rapid cycling Brassica rapa. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 801:149732. [PMID: 34438156 DOI: 10.1016/j.scitotenv.2021.149732] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Revised: 08/04/2021] [Accepted: 08/13/2021] [Indexed: 06/13/2023]
Abstract
Herbicides can drift from intended plants onto non-target species. It remains unclear how drift impacts plant functional traits that are important for fitness. To address this gap, we conducted an experiment where fast cycling Brassica rapa plants were exposed to one of three drift concentrations (0.5%, 1%, 10%) of synthetic-auxin dicamba. We evaluated damage to and capacity of floral and vegetative traits to recover as well as lifetime fitness by comparing treated plants to controls. Response to dicamba exposure was concentration-dependent across all traits but varied with trait type. At 0.5% dicamba, three out of five floral traits were affected, while at 1% dicamba, four floral traits and one out of two vegetative traits were negatively impacted. At 10% dicamba all floral and vegetative traits were stunted. Overall, floral traits were more responsive to all dicamba drift concentrations than vegetative traits and displayed a wide range of variation ranging from no response (e.g., pistil length) to up to 84% reduction (ovule number). However, despite floral traits were more affected across the dicamba drift concentrations they were also more likely to recover than the vegetative traits. There was also variation among lifetime traits; the onset of flowering was delayed, and reproductive fitness was negatively affected in a concentration-dependent manner, but the final biomass and total flower production were not affected. Altogether, we show substantial variation across plant traits in their response to dicamba and conclude that accounting for this variation is essential to understand the full impact of herbicide drift on plants and the ecological interactions these traits mediate.
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Affiliation(s)
- Sergio E Ramos
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA.
| | - Lacey D Rzodkiewicz
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Martin M Turcotte
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Tia-Lynn Ashman
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
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5
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Sánchez-Bayo F. Indirect Effect of Pesticides on Insects and Other Arthropods. TOXICS 2021; 9:177. [PMID: 34437495 PMCID: PMC8402326 DOI: 10.3390/toxics9080177] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 07/26/2021] [Accepted: 07/27/2021] [Indexed: 12/04/2022]
Abstract
Pesticides released to the environment can indirectly affect target and non-target species in ways that are often contrary to their intended use. Such indirect effects are mediated through direct impacts on other species or the physical environment and depend on ecological mechanisms and species interactions. Typical mechanisms are the release of herbivores from predation and release from competition among species with similar niches. Application of insecticides to agriculture often results in subsequent pest outbreaks due to the elimination of natural enemies. The loss of floristic diversity and food resources that result from herbicide applications can reduce populations of pollinators and natural enemies of crop pests. In aquatic ecosystems, insecticides and fungicides often induce algae blooms as the chemicals reduce grazing by zooplankton and benthic herbivores. Increases in periphyton biomass typically result in the replacement of arthropods with more tolerant species such as snails, worms and tadpoles. Fungicides and systemic insecticides also reduce nutrient recycling by impairing the ability of detritivorous arthropods. Residues of herbicides can reduce the biomass of macrophytes in ponds and wetlands, indirectly affecting the protection and breeding of predatory insects in that environment. The direct impacts of pesticides in the environment are therefore either amplified or compensated by their indirect effects.
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Affiliation(s)
- Francisco Sánchez-Bayo
- School of Life and Environmental Sciences, The University of Sydney, Eveleigh, NSW 2015, Australia
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6
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Nakajima K, Miyashita T. Close association between grasshopper and plant communities in suburban secondary grasslands and the indicator value of grasshoppers for conservation. LANDSCAPE AND ECOLOGICAL ENGINEERING 2021. [DOI: 10.1007/s11355-021-00447-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Larval pesticide exposure impacts monarch butterfly performance. Sci Rep 2020; 10:14490. [PMID: 32879347 PMCID: PMC7468139 DOI: 10.1038/s41598-020-71211-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 08/05/2020] [Indexed: 12/18/2022] Open
Abstract
The long-term decline of monarch butterflies has been attributed to loss of their milkweed (Asclepias sp.) host-plants after the introduction of herbicide-tolerant crops. However, recent studies report pesticide residues on milkweed leaves that could act as a contributing factor when ingested as part of their larval diet. In this study, we exposed monarch larvae to six pesticides (insecticide: clothianidin; herbicides: atrazine, S-metolachlor; fungicides: azoxystrobin, pyraclostrobin, trifloxystrobin) on their primary host-plant, A. syriaca. Each was tested at mean and maximum levels reported from published analyses of milkweeds bordering cropland and thus represent field-relevant concentrations. Monarch lethal and sub-lethal responses were tracked over their complete development, from early instar larvae to adult death. Overall, we found no impact of any pesticide on immature development time and relatively weak effects on larval herbivory or survival to adulthood. Comparatively stronger effects were detected for adult performance; namely, a 12.5% reduction in wing length in response to the fungicides azoxystrobin and trifloxystrobin. These data collectively suggest that monarch responses to host-plant pesticides are largely sublethal and more pronounced in the adult stage, despite exposure only as larvae. This outcome has important implications for risk assessment and the migratory success of monarchs in North America.
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Iriart V, Baucom RS, Ashman TL. Herbicides as anthropogenic drivers of eco-evo feedbacks in plant communities at the agro-ecological interface. Mol Ecol 2020; 30:5406-5421. [PMID: 32542840 DOI: 10.1111/mec.15510] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2019] [Revised: 04/27/2020] [Accepted: 05/29/2020] [Indexed: 12/16/2022]
Abstract
Herbicides act as human-mediated novel selective agents and community disruptors, yet their full effects on eco-evolutionary dynamics in natural communities have only begun to be appreciated. Here, we synthesize how herbicide exposures can result in dramatic phenotypic and compositional shifts within communities at the agro-ecological interface and how these in turn affect species interactions and drive plant (and plant-associates') evolution in ways that can feedback to continue to affect the ecology and ecosystem functions of these assemblages. We advocate a holistic approach to understanding these dynamics that includes plastic changes and plant community transformations and also extends beyond this single trophic level targeted by herbicides to the effects on nontarget plant-associated organisms and their potential to evolve, thereby embracing the complexity of these real-world systems. We make explicit recommendations for future research to achieve this goal and specifically address impacts of ecology on evolution, evolution on ecology and their feedbacks so that we can gain a more predictive view of the fates of herbicide-impacted communities.
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Affiliation(s)
- Veronica Iriart
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Regina S Baucom
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan, USA
| | - Tia-Lynn Ashman
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
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9
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Gutiérrez Y, Ott D, Scherber C. Direct and indirect effects of plant diversity and phenoxy herbicide application on the development and reproduction of a polyphagous herbivore. Sci Rep 2020; 10:7300. [PMID: 32350369 PMCID: PMC7190834 DOI: 10.1038/s41598-020-64252-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Accepted: 12/27/2019] [Indexed: 01/15/2023] Open
Abstract
Widespread application of synthetic pesticides and loss of plant diversity are regarded as significant drivers of current global change. The effects of such phenomena on insect performance have been extensively studied separately, yet the interactions of these two drivers have been poorly explored. Here, we subjected the polyphagous grasshopper Pseudochorthippus parallelus (Zetterstedt, 1821) to a full-lifecycle field experiment with 50 cages containing experimental plant communities differing in grass species richness (2 vs. 8 grass species), half of them treated with a phenoxy herbicide commonly employed to control broadleaf plants in grasslands. We measured plant elemental content as a proxy for plant physiology, and a wide range of insect traits in both female and male grasshoppers. In females, grass diversity increased herbivory, insect nitrogen content and egg load, while herbicide reduced herbivory but increased the number of offspring, likely mediated by altered plant community composition. In males, grass diversity also increased herbivory, had positive effects on fat body, muscle volume and lifespan, and negative effects on body mass. Herbicide negatively affected herbivory in both females and males. Overall, plant diversity and herbicides may shift resource allocation in generalist terrestrial insect herbivores, indicating complex and unexpected effects of human-induced environmental change.
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Affiliation(s)
- Yeisson Gutiérrez
- Institute of Landscape Ecology, University of Münster, 48149, Münster, Germany.
| | - David Ott
- Institute of Landscape Ecology, University of Münster, 48149, Münster, Germany
| | - Christoph Scherber
- Institute of Landscape Ecology, University of Münster, 48149, Münster, Germany
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Tooker JF, O'Neal ME, Rodriguez-Saona C. Balancing Disturbance and Conservation in Agroecosystems to Improve Biological Control. ANNUAL REVIEW OF ENTOMOLOGY 2020; 65:81-100. [PMID: 31923378 DOI: 10.1146/annurev-ento-011019-025143] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Disturbances associated with agricultural intensification reduce our ability to achieve sustainable crop production. These disturbances stem from crop-management tactics and can leave crop fields more vulnerable to insect outbreaks, in part because natural-enemy communities often tend to be more susceptible to disturbance than herbivorous pests. Recent research has explored practices that conserve natural-enemy communities and reduce pest outbreaks, revealing that different components of agroecosystems can influence natural-enemy populations. In this review, we consider a range of disturbances that influence pest control provided by natural enemies and how conservation practices can mitigate or counteract disturbance. We use four case studies to illustrate how conservation and disturbance mitigation increase the potential for biological control and provide co-benefits for the broader agroecosystem. To facilitate the adoption of conservation practices that improve top-down control across significant areas of the landscape, these practices will need to provide multifunctional benefits, but should be implemented with natural enemies explicitly in mind.
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Affiliation(s)
- John F Tooker
- Department of Entomology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA;
| | - Matthew E O'Neal
- Department of Entomology, Iowa State University, Ames, Iowa 50011, USA;
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11
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Direct and Indirect Effects of Herbicides on Insect Herbivores in Rice, Oryza sativa. Sci Rep 2019; 9:6998. [PMID: 31061412 PMCID: PMC6502833 DOI: 10.1038/s41598-019-43361-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2018] [Accepted: 04/17/2019] [Indexed: 11/09/2022] Open
Abstract
Densities of insect pests in agricultural communities may be affected by herbicides commonly used for weed management via several routes. First, herbicides may cause direct mortality to insects present both during and immediately following application. Second, herbicides may induce plant defenses that increase resistance to insect herbivores. Third, herbicides may alter the quantity and composition of weed populations, which in turn may change the structure of insect communities found subsequently in the crop. This study was designed to investigate the effects of an array of herbicides on the densities of several major pests found in rice in the southern United States. These pests included the rice water weevil, Lissorhoptrus oryzophilus Kuschel (Coleoptera: Curculionidae), the rice stinkbug, Oebalus pugnax (Fabricius) (Hemiptera: Pentatomidae), and a stemborer complex comprised of three lepidopteran species (Lepidoptera: Crambidae). Insects directly exposed to herbicides experienced high mortality; while those fed leaf material that had been exposed to herbicides did not. Herbicide application did not significantly increase resistance in rice to subsequent herbivore infestation. Results provided modest support for the third hypothesis represented by positive correlations between weed densities and insect pest densities.
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12
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Babu A, Reisig DD, Walgenbach JF, Heiniger RW, Everman W. Influence of Weed Manipulation in Field Borders on Brown Stink Bug (Hemiptera: Pentatomidae) Densities and Damage in Field Corn. ENVIRONMENTAL ENTOMOLOGY 2019; 48:444-453. [PMID: 30810746 DOI: 10.1093/ee/nvz016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Indexed: 06/09/2023]
Abstract
Brown stink bug, Euschistus servus (Say), is a damaging pest of corn, Zea mays L. (Cyperales: Poaceae), in the southeastern United States. In North Carolina, during the spring, winter-planted wheat, Triticum aestivum L. (Cyperales: Poaceae), serves as the earliest available crop host, and E. servus seems to prefer this crop over seedling corn. In the absence of wheat in the agroecosystem, weeds serve as a bridge host for a portion of overwintered E. servus populations until they move to corn and other subsequent crops. Our objective was to reduce densities of E. servus in corn by manipulating the weedy field borders with mowing and applications of dicamba herbicide. During the study, multiple species of stink bugs (n =16) were found associated with weed plots. However, E. servus was the predominant (>94%) stink bug species in the corn. In this farmscape, density of E. servus adults in the unmanaged weed plots began declining around the second week of May, followed by an increase in density in adjacent corn plots. This movement coincided with the seedling growth of corn. In 2016, applications of dicamba in the weedy field border resulted in a lower density of E. servus in herbicide-treated weed plots compared with untreated plots. Despite this difference, manipulations of weeds did not lead to any significant changes in density of E. servus adults in corn. Further evidence suggested that a prominent external source of E. servus, other than field-bordering weeds, in the farmscape was likely driving densities in corn.
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Affiliation(s)
- Arun Babu
- Department of Entomology and Plant Pathology, North Carolina State University, Plymouth, NC
| | - Dominic D Reisig
- Department of Entomology and Plant Pathology, North Carolina State University, Plymouth, NC
| | - James F Walgenbach
- Department of Entomology and Plant Pathology, North Carolina State University, Mills River, NC
| | - Ronnie W Heiniger
- Department of Crop and Soil Sciences, North Carolina State University, Plymouth, NC
| | - Wesley Everman
- Department of Crop and Soil Sciences, North Carolina State University, Raleigh, NC
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13
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Freydier L, Lundgren JG. Unintended effects of the herbicides 2,4-D and dicamba on lady beetles. ECOTOXICOLOGY (LONDON, ENGLAND) 2016; 25:1270-1277. [PMID: 27282375 DOI: 10.1007/s10646-016-1680-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 05/23/2016] [Indexed: 06/06/2023]
Abstract
Weed resistance to glyphosate and development of new GM crops tolerant to 2,4-dichlorophenoxyacetic acid (2,4-D) and dicamba is expected to lead to increased use of these herbicides in cropland. The lady beetle, Coleomegilla maculata is an important beneficial insect in cropland that is commonly used as an indicator species in safety evaluations of pesticides. Here, we examined the lethal and non-lethal effects of 2,4-D and dicamba active ingredients and commercial formulations to this lady beetle species, and tested for synergistic effects of the herbicides. Second instars of lady beetles were exposed to an experimental treatment, and their mortality, development, weight, sex ratio, fecundity, and mobility was evaluated. Using similar methods, a dose-response study was conducted on 2,4-D with and without dicamba. The commercial formulation of 2,4-D was highly lethal to lady beetle larvae; the LC90 of this herbicide was 13 % of the label rate. In this case, the "inactive" ingredients were a key driver of the toxicity. Dicamba active ingredient significantly increased lady beetle mortality and reduced their body weight. The commercial formulations of both herbicides reduced the proportion of males in the lady beetle population. The herbicides when used together did not act synergistically in their toxicity toward lady beetles versus when the chemistries were used independently. Our work shows that herbicide formulations can cause both lethal and sublethal effects on non-target, beneficial insects, and these effects are sometimes driven by the "inactive" ingredients. The field-level implications of shifts in weed management practices on insect management programs should receive further attention.
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Affiliation(s)
- Laurène Freydier
- Agrocampus Ouest, 65 rue de Saint-Brieuc, CS 842015, 35042, Rennes Cedex, France
| | - Jonathan G Lundgren
- North Central Agricultural Research Laboratory, USDA-ARS, Brookings, SD, 57006, USA.
- Ecdysis Foundation, 46958 188th Street, Estelline, SD, 57234, USA.
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Bohnenblust EW, Vaudo AD, Egan JF, Mortensen DA, Tooker JF. Effects of the herbicide dicamba on nontarget plants and pollinator visitation. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2016; 35:144-51. [PMID: 26184786 DOI: 10.1002/etc.3169] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Revised: 05/19/2015] [Accepted: 07/14/2015] [Indexed: 05/22/2023]
Abstract
Nearly 80% of all pesticides applied to row crops are herbicides, and these applications pose potentially significant ecotoxicological risks to nontarget plants and associated pollinators. In response to the widespread occurrence of weed species resistant to glyphosate, biotechnology companies have developed crops resistant to the synthetic-auxin herbicides dicamba and 2,4-dichlorophenoxyacetic acid (2,4-D); and once commercialized, adoption of these crops is likely to change herbicide-use patterns. Despite current limited use, dicamba and 2,4-D are often responsible for injury to nontarget plants; but effects of these herbicides on insect communities are poorly understood. To understand the influence of dicamba on pollinators, the authors applied several sublethal, drift-level rates of dicamba to alfalfa (Medicago sativa L.) and Eupatorium perfoliatum L. and evaluated plant flowering and floral visitation by pollinators. The authors found that dicamba doses simulating particle drift (≈1% of the field application rate) delayed onset of flowering and reduced the number of flowers of each plant species; however, plants that did flower produced similar-quality pollen in terms of protein concentrations. Further, plants affected by particle drift rates were visited less often by pollinators. Because plants exposed to sublethal levels of dicamba may produce fewer floral resources and be less frequently visited by pollinators, use of dicamba or other synthetic-auxin herbicides with widespread planting of herbicide-resistant crops will need to be carefully stewarded to prevent potential disturbances of plant and beneficial insect communities in agricultural landscapes.
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Affiliation(s)
- Eric W Bohnenblust
- Department of Entomology, The Pennsylvania State University, University Park, Pennsylvania, USA
| | - Anthony D Vaudo
- Department of Entomology, The Pennsylvania State University, University Park, Pennsylvania, USA
| | - J Franklin Egan
- Pasture Systems and Watershed Management Research Unit, USDA Agricultural Research Service, University Park, Pennsylvania, USA
| | - David A Mortensen
- Department of Plant Science, The Pennsylvania State University, University Park, Pennsylvania, USA
| | - John F Tooker
- Department of Entomology, The Pennsylvania State University, University Park, Pennsylvania, USA
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