scholarly journals Fitness of Herbicide-Resistant Weeds: Current Knowledge and Implications for Management

Plants ◽  
2019 ◽  
Vol 8 (11) ◽  
pp. 469 ◽  
Author(s):  
Vila-Aiub
Keyword(s):  
Life History ◽  
Herbicide Resistance ◽  
Management Practices ◽  
Current Knowledge ◽  
Resistance Management ◽  
Fitness Cost ◽  
Plant Fitness ◽  
Resistance Mutations ◽  
Fitness Costs ◽  
Wide Range

Herbicide resistance is the ultimate evidence of the extraordinary capacity of weeds to evolve under stressful conditions. Despite the extraordinary plant fitness advantage endowed by herbicide resistance mutations in agroecosystems under herbicide selection, resistance mutations are predicted to exhibit an adaptation cost (i.e., fitness cost), relative to the susceptible wild-type, in herbicide untreated conditions. Fitness costs associated with herbicide resistance mutations are not universal and their expression depends on the particular mutation, genetic background, dominance of the fitness cost, and environmental conditions. The detrimental effects of herbicide resistance mutations on plant fitness may arise as a direct impact on fitness-related traits and/or coevolution with changes in other life history traits that ultimately may lead to fitness costs under particular ecological conditions. This brings the idea that a “lower adaptive value” of herbicide resistance mutations represents an opportunity for the design of resistance management practices that could minimize the evolution of herbicide resistance. It is evident that the challenge for weed management practices aiming to control, minimize, or even reverse the frequency of resistance mutations in the agricultural landscape is to “create” those agroecological conditions that could expose, exploit, and exacerbate those life history and/or fitness traits affecting the evolution of herbicide resistance mutations. Ideally, resistance management should implement a wide range of cultural practices leading to environmentally mediated fitness costs associated with herbicide resistance mutations.

scholarly journals Evaluation of Herbicide-Resistance Status on Populations of Littleseed Canarygrass (Phalaris Minor Retz.) from Southern Greece and Suggestions for their Effective Control

2012 ◽  
Vol 52 (3) ◽  
pp. 308-313 ◽  
Author(s):  
Ilias Travlos
Keyword(s):  
Herbicide Resistance ◽  
Resistance Index ◽  
Acetolactate Synthase ◽  
Effective Control ◽  
Cross Resistance ◽  
Resistance Mutations ◽  
Resistance Level ◽  
Phalaris Minor ◽  
Wide Range ◽  
Southern Greece

Evaluation of Herbicide-Resistance Status on Populations of Littleseed Canarygrass (Phalaris MinorRetz.) from Southern Greece and Suggestions for their Effective ControlIn 2010, a survey was conducted in the wheat fields of a typical cereal-producing region of Greece to establish the frequency and distribution of herbicide-resistant littleseed canarygrass (Phalaris minorRetz.). In total, 73 canarygrass accessions were collected and screened in a field experiment with several herbicides commonly used to control this weed. Most of the weed populations were classed as resistant (or developing resistance) to the acetyl-CoA varboxylase (ACCase)-inhibiting herbicide diclofop, while resistance to clodinafop was markedly lower. The results of the pot experiments showed that some of the canary populations were found to have a very high level of diclofop resistance (resistance index up to 12.4), while cross resistance with other herbicides was also common. The levels of resistance and cross resistance patterns among populations varied along with the different amounts and times of selection pressure. Such variation indicated either more than one mechanism of resistance or different resistance mutations in these weed populations. The population which had the highest diclofop resistance level, showed resistance to all aryloxyphenoxypropinate (APP) herbicides applied and non-ACCase inhibitors. Alternative ACCase-inhibiting herbicides, such as pinoxaden remain effective on the majority of the tested canarygrass populations, while the acetolactate synthase (ALS)-inhibiting herbicide mesosulfuron + iodosulfuron could also provide some solutions. Consequently, there is an opportunity to effectively control canarygrass by selecting from a wide range of herbicides. It is the integration of agronomic practices with herbicide application, which helps in effective management ofP. minorand particularly its resistant populations.

A comparative perspective of knowledge management via social media: India and China

2015 ◽  
Vol 22 (2) ◽  
pp. 93-114 ◽  
Author(s):  
Michelle Liu ◽  
Pramila Rao
Keyword(s):  
Social Media ◽  
Knowledge Management ◽  
Management Practices ◽  
Current Knowledge ◽  
Global Market ◽  
Comparative Perspective ◽  
Content Type ◽  
Wide Range ◽  
Depth Analysis ◽  
India And China

Purpose – This research paper aims to showcase current knowledge management (KM) practices via social media that is being adopted by organizations in India and China. India and China are considered leading economies in today’s global market. Any understanding of management practices in these countries will help practitioners in doing businesses in these nations. Design/methodology/approach – This conceptual paper analyzes KM practices in India and China using an in-depth analysis of the extant literature to provide a comparative perspective of KM policies in these two economies. This paper has used a wide range of scholarly and non-scholarly databases from ABI Global Inform to Business Source Complete to Google Scholar among others. Findings – This research offers valuable insights into characteristic KM trends followed by Indian and Chinese firms. This paper also highlights different approaches adopted by these two cultures in managing their KM practices. The study also provides hypotheses that can be tested by potential scholars. This paper also offers theoretical models to understand this concept better. Practical implications – This paper also provides implications for practice by identifying guidelines for global managers. These frameworks might serve as preliminary parameters for practitioners planning to establish KM practices in India and China. Originality/value – This paper compares and contrasts KM practices in one of the two largest BRIC (Brazil, Russia, India and China) economies which have not been addressed in the literature before. It also combines two theoretical frameworks from different fields (information technology and human resource management) providing a richer viewpoint on the subject.

Benchmark study on glyphosate-resistant crop systems in the United States. Economics of herbicide resistance management practices in a 5 year field-scale study

2014 ◽  
Vol 70 (12) ◽  
pp. 1924-1929 ◽  
Author(s):  
C Blake Edwards ◽  
David L Jordan ◽  
Michael DK Owen ◽  
Philip M Dixon ◽  
Bryan G Young ◽  
...  
Keyword(s):  
United States ◽  
Herbicide Resistance ◽  
Management Practices ◽  
Resistance Management ◽  
The United States ◽  
Field Scale ◽  
Benchmark Study

scholarly journals Fitness costs of herbicide resistance across natural populations of the common morning glory,Ipomoea purpurea

2015 ◽  
Author(s):  
Megan L. van Etten ◽  
Adam Kuester ◽  
Shu-Mei Chang ◽  
Regina S Baucom
Keyword(s):  
Life History ◽  
Herbicide Resistance ◽  
Natural Populations ◽  
Cumulative Effect ◽  
Morning Glory ◽  
Visual Exploration ◽  
Fitness Costs ◽  
Ipomoea Purpurea ◽  
Life Cycle Stages ◽  
Trade Offs

AbstractAlthough fitness costs associated with plant defensive traits are widely expected, they are not universally detected, calling into question their generality. Here we examine the potential for life history trade-offs associated with herbicide resistance by examining seed germination, root growth, and above-ground growth across 43 naturally occurring populations ofIpomoea purpureathat vary in their resistance to RoundUp®, the most commonly used herbicide worldwide. We find evidence for life history trade-offs associated with all three traits; highly resistant populations had lower germination rates, shorter roots and smaller above-ground size. A visual exploration of the data indicated that the type of trade-off may differ among populations. Our results demonstrate that costs of adaptation may be present at stages other than simply the production of progeny in this agricultural weed. Additionally, the cumulative effect of costs at multiple life cycle stages can result in severe consequences to fitness when adapting to novel environments.

scholarly journals Fitness costs of individual and combined pyrethroid resistance mechanisms, kdr and CYP-mediated detoxification, in Aedes aegypti

2021 ◽  
Vol 15 (3) ◽  
pp. e0009271
Author(s):  
Letícia B. Smith ◽  
Juan J. Silva ◽  
Connie Chen ◽  
Laura C. Harrington ◽  
Jeffrey G. Scott
Keyword(s):  
Aedes Aegypti ◽  
Pyrethroid Resistance ◽  
Resistance Mechanisms ◽  
Fitness Cost ◽  
Adult Longevity ◽  
Cost Ratio ◽  
Resistance Mutations ◽  
Fitness Costs ◽  
Net Reproductive Rate ◽  
Mating Competition

Background Aedes aegypti is an important vector of many human diseases and a serious threat to human health due to its wide geographic distribution and preference for human hosts. A. aegypti also has evolved widespread resistance to pyrethroids due to the extensive use of this insecticide class over the past decades. Mutations that cause insecticide resistance result in fitness costs in the absence of insecticides. The fitness costs of pyrethroid resistance mutations in A. aegypti are still poorly understood despite their implications for arbovirus transmission. Methodology/Principle findings We evaluated fitness based both on allele-competition and by measuring specific fitness components (i.e. life table and mating competition) to determine the costs of the different resistance mechanisms individually and in combination. We used four congenic A. aegypti strains: Rockefeller (ROCK) is susceptible to insecticides; KDR:ROCK (KR) contains only voltage-sensitive sodium channel (Vssc) mutations S989P+V1016G (kdr); CYP:ROCK (CR) contains only CYP-mediated resistance; and CYP+KDR:ROCK (CKR) contains both CYP-mediated resistance and kdr. The kdr allele frequency decreased over nine generations in the allele-competition study regardless of the presence of CYP-mediated resistance. Specific fitness costs were variable by strain and component measured. CR and CKR had a lower net reproductive rate (R0) than ROCK or KR, and KR was not different than ROCK. There was no correlation between the level of permethrin resistance conferred by the different mechanisms and their fitness cost ratio. We also found that CKR males had a reduced mating success relative to ROCK males when attempting to mate with ROCK females. Conclusions/Significance Both kdr and CYP-mediated resistance have a fitness cost affecting different physiological aspects of the mosquito. CYP-mediated resistance negatively affected adult longevity and mating competition, whereas the specific fitness costs of kdr remains elusive. Understanding fitness costs helps us determine whether and how quickly resistance will be lost after pesticide application has ceased.

Assessing Fitness Costs from a Herbicide-Resistance Management Perspective: A Review and Insight

Weed Science ◽  
2018 ◽  
Vol 67 (2) ◽  
pp. 137-148 ◽  
Author(s):  
Eshagh Keshtkar ◽  
Roohollah Abdolshahi ◽  
Hamidreza Sasanfar ◽  
Eskandar Zand ◽  
Roland Beffa ◽  
...  
Keyword(s):  
Herbicide Resistance ◽  
Weed Management ◽  
Genetic Background ◽  
Management Practices ◽  
Evolutionary Ecology ◽  
Resistance Management ◽  
Single Population ◽  
Herbicide Resistant ◽  
Scientific Disciplines ◽  
Cost Studies

AbstractIn recent years, herbicide resistance has attracted much attention as an increasingly urgent problem worldwide. Unfortunately, most of that effort was focused on confirmation of resistance and characterization of the mechanisms of resistance. For management purposes, knowledge about biology and ecology of the resistant weed phenotypes is critical. This includes fitness of the resistant biotypes compared with the corresponding wild biotypes. Accordingly, fitness has been the subject of many studies; however, lack of consensus on the concept of fitness resulted in poor experimental designs and misinterpretation of the ensuing data. In recent years, methodological protocols for conducting proper fitness studies have been proposed; however, we think these methods should be reconsidered from a herbicide-resistance management viewpoint. In addition, a discussion of the inherent challenges associated with fitness cost studies is pertinent. We believe that the methodological requirements for fitness studies of herbicide-resistant weed biotypes might differ from those applied in other scientific disciplines such as evolutionary ecology and genetics. Moreover, another important question is to what extent controlling genetic background is necessary when the aim of a fitness study is developing management practices for resistant biotypes. Among the methods available to control genetic background, we suggest two approaches (single population and pedigreed lines) as the most appropriate methods to detect differences between resistant (R) and susceptible (S) populations and to derive herbicide-resistant weed management programs. Based on these two methods, we suggest two new approaches that we named the “recurrent single population” and “recurrent pedigreed lines” methods. Importantly, whenever the aim of a fitness study is to develop optimal resistance management, we suggest selecting R and S plants within a single population and evaluating all fitness components from seed to seed instead of measuring changes in the frequency of R and S alleles through multigenerational fitness studies.

scholarly journals Linking System-Wide Impacts of RNA Polymerase Mutations to the Fitness Cost of Rifampin Resistance in Pseudomonas aeruginosa

mBio ◽  
2014 ◽  
Vol 5 (6) ◽  
Author(s):  
Qin Qi ◽  
Gail M. Preston ◽  
R. Craig MacLean
Keyword(s):  
Antibiotic Resistance ◽  
Genetic Basis ◽  
Molecular Mechanisms ◽  
Fitness Cost ◽  
Resistance Mutations ◽  
Fitness Costs ◽  
Content Type ◽  
Genome Wide ◽  
Rifampin Resistance ◽  
The Cost

ABSTRACTFitness costs play a key role in the evolutionary dynamics of antibiotic resistance in bacteria by generating selection against resistance in the absence of antibiotics. Although the genetic basis of antibiotic resistance is well understood, the precise molecular mechanisms linking the genetic basis of resistance to its fitness cost remain poorly characterized. Here, we examine how the system-wide impacts of mutations in the RNA polymerase (RNAP) generpoBshape the fitness cost of rifampin resistance inPseudomonas aeruginosa. Rifampin resistance mutations reduce transcriptional efficiency, and this explains 76% of the variation in fitness amongrpoBmutants. The pleiotropic consequence ofrpoBmutations is that mutants show altered relative transcript levels of essential genes. We find no evidence that global transcriptional responses have an impact on the fitness cost of rifampin resistance as revealed by transcriptome sequencing (RNA-Seq). Global changes in the transcriptional profiles ofrpoBmutants compared to the transcriptional profile of the rifampin-sensitive ancestral strain are subtle, demonstrating that the transcriptional regulatory network ofP. aeruginosais robust to the decreased transcriptional efficiency associated withrpoBmutations. On a smaller scale, we find that rifampin resistance mutations increase the expression of RNAP due to decreased termination at an attenuator upstream fromrpoB, and we argue that this helps to minimize the cost of rifampin resistance by buffering against reduced RNAP activity. In summary, our study shows that it is possible to dissect the molecular mechanisms underpinning variation in the cost of rifampin resistance and highlights the importance of genome-wide buffering of relative transcript levels in providing robustness against resistance mutations.IMPORTANCEAntibiotic resistance mutations carry fitness costs. Relative to the characteristics of their antibiotic-sensitive ancestors, resistant mutants show reduced growth rates and competitive abilities. Fitness cost plays an important role in the evolution of antibiotic resistance in the absence of antibiotics; however, the molecular mechanisms underlying these fitness costs is not well understood. We applied a systems-level approach to dissect the molecular underpinnings of the fitness costs associated with rifampin resistance inP. aeruginosaand showed that most of the variation in fitness cost can be explained by the direct effect of resistance mutations on the enzymatic activity of the mutated gene. Pleiotropic changes in transcriptional profiles are subtle at a genome-wide scale, suggesting that the gene regulatory network ofP. aeruginosais robust in the face of the direct effects of resistance mutations.

scholarly journals Experimental Methods for Estimation of Plant Fitness Costs Associated with Herbicide-Resistance Genes

Weed Science ◽  
2015 ◽  
Vol 63 (SP1) ◽  
pp. 203-216 ◽  
Author(s):  
Martin M. Vila-Aiub ◽  
Pedro E. Gundel ◽  
Christopher Preston
Keyword(s):  
Herbicide Resistance ◽  
Resistance Genes ◽  
Experimental Methods ◽  
Plant Fitness ◽  
Fitness Costs ◽  
Weed Species ◽  
Adaptive Traits ◽  
Herbicide Treatments ◽  
Survival And Reproduction ◽  
Selection Of

Since the beginning of agriculture, crops have been exposed to recurrent invasion by weeds that can impose severe reductions in crop quality and yield. There have been continuing efforts to reduce the impacts of weeds on production. More than 40 yr ago, overreliance on herbicide technology to reduce weed infestations resulted in the selection of adaptive traits that enabled weed survival and reproduction under herbicide treatments (Délye et al. 2007; Powles and Yu 2010; Vila-Aiub et al. 2008). As a result, herbicide resistance in > 200 weed species has evolved worldwide (Heap 2013; Powles 2008).

scholarly journals Rethinking Outreach: Collaboration Is Key for Herbicide-Resistance Management

Weed Science ◽  
2016 ◽  
Vol 64 (SP1) ◽  
pp. 655-660 ◽  
Author(s):  
Amy Asmus ◽  
Jill Schroeder
Keyword(s):  
Herbicide Resistance ◽  
Management Practices ◽  
Interdisciplinary Collaboration ◽  
Resistance Management ◽  
Information Delivery ◽  
Effective Resistance ◽  
Herbicide Resistant

Effective outreach is critical to achieving success in managing herbicide-resistant weeds. Interdisciplinary collaboration is needed to adapt information delivery and to engage communities to address the herbicide-resistance problem. Weed scientists must partner with the production community to adapt herbicide-resistance practices for local needs, to work collaboratively with state and regional stakeholders to create effective resistance-management practices, and to provide an overarching national message as to the causes of, and solutions to, resistance.

Survey of rice weed management and public and private consultant characteristics in Southern Brazil

2019 ◽  
Vol 34 (3) ◽  
pp. 351-356 ◽  
Author(s):  
Bruno de Lima Fruet ◽  
Aldo Merotto ◽  
André da Rosa Ulguim
Keyword(s):  
Herbicide Resistance ◽  
Weed Management ◽  
Management Practices ◽  
Resistance Management ◽  
Weedy Rice ◽  
Herbicide Application ◽  
Public And Private ◽  
Rice Farmers ◽  
Survey Results ◽  
Imidazolinone Herbicides

AbstractIdentification of common weeds is fundamental in determining adequate recommendations for management practices. The aim of this study was to identify the patterns of weed management adopted by rice farmers and the perspectives of consultants who work in flooded rice areas in Rio Grande do Sul (RS) State, Brazil. Fifty-three public and 50 private consultants who worked with rice in RS in 2017 and 2018 were interviewed. Data were analyzed by descriptive statistics. Both weedy rice and Echinochloa sp. occurred and escaped more often from chemical control because they remained in the field until harvest in 59% of the area. According to consultants, the main reasons for reduced weed control were related to herbicide resistance and late herbicide application. Fifty-six percent of farmers used imidazolinone herbicides at rates that were greater than those indicated on the label for POST application. The consultants’ main challenges were weed escapes, resistance management, and guidelines on herbicide rates. Survey results show that the use of herbicide rates above label recommendations and consultants’ work on control of weed escapes are directly related to the high occurrence of herbicide resistance.

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