scholarly journals Biochemical Basis of Cyfluthrin and DDT Resistance in Anopheles stephensi (Diptera: Culicidae) in Malarious Area of Iran

2018 ◽  
Author(s):  
Mohammad Amin Gorouhi ◽  
Mohammad Ali Oshaghi ◽  
Hassan Vatandoost ◽  
Ahmad Ali Enayati ◽  
Ahmad Raeisi ◽  
...  
Keyword(s):  
Anopheles Stephensi ◽  
Indian Subcontinent ◽  
Management Strategies ◽  
Resistance Management ◽  
Cytochrome P450s ◽  
Enzyme Assays ◽  
Biochemical Basis ◽  
Development Of Resistance ◽  
Ddt Resistance

Background: Anopheles stephensi is a key urban malaria vector in the Indian subcontinent and Middle East includ­ing south and southeast of Iran. Wide application of insecticides resulted in resistance of this species to various insec­ticides in these regions. This study was conducted to reveal the role of metabolic mechanisms in the development of resistance in An. stephensi to DDT and cyfluthrin. Methods: Field mosquito specimens were collected from Chabahar Seaport, southeast corner of Iran, in 2015. Insec­ticide susceptibility and enzyme assays were conducted as recommended by WHO. Results: Mean enzyme ratios were 3.95 and 3.04 for α- esterases and 2.40 and 1.97 for β- esterases in the DDT and cyfluthrin- resistant populations correspondingly compared with the susceptible strain. The GSTs enzyme mean ac­tivity ratios were 5.07 and 2.55 in the DDT and cyfluthrin- resistant populations compared with the susceptible beech strain. The cytochrome p450s enzyme ratios were 1.11 and 1.28 in the DDT and cyfluthrin- resistant populations respectively compared with the susceptible beech strain. Conclusion: Metabolic mechanisms play a crucial role in the development of DDT and cyfluthrin resistance in An. stephensi, therefore, further evaluation of the mechanisms involved as well as implementation of proper insecticide resistance management strategies are recommended.

scholarly journals Investigation of DDT resistance mechanisms in Anopheles funestus populations from northern and southern Benin reveals a key role of the GSTe2 gene

2020 ◽  
Vol 19 (1) ◽  
Author(s):  
Genevieve M. Tchigossou ◽  
Seun M. Atoyebi ◽  
Romaric Akoton ◽  
Eric Tossou ◽  
Djegbe Innocent ◽  
...  
Keyword(s):  
Burkina Faso ◽  
Gene Expression Analysis ◽  
Management Strategies ◽  
Resistance Management ◽  
Anopheles Funestus ◽  
Resistance Mechanisms ◽  
Polymorphism Analysis ◽  
Ddt Resistance ◽  
Southern Benin

Abstract Background Understanding the molecular basis of insecticide resistance in mosquito, such as Anopheles funestus, is an important step in developing strategies to mitigate the resistance problem. This study aims to assess the role of the GSTe2 gene in DDT resistance and determine the genetic diversity of this gene in An. funestus. Methods Gene expression analysis was performed using microarrays and PCR while the potential mutation associated with resistance was determined using sequencing. Results Low expression level of GSTe2 gene was recorded in Burkina-Faso samples with a fold change of 3.3 while high expression (FC 35.6) was recorded in southern Benin in Pahou (FC 35.6) and Kpome (FC 13.3). The sequencing of GSTe2 gene in six localities showed that L119F-GSTe2 mutation is almost getting fixed in highly DDT-resistant Benin (Pahou, Kpome, Doukonta) and Nigeria (Akaka Remo) mosquitoes with a low mutation rate observed in Tanongou (Benin) and Burkina-Faso mosquitoes. Conclusion This study shows the key role of the GSTe2 gene in DDT resistant An. funestus in Benin. Polymorphism analysis of this gene across Benin revealed possible barriers to gene flow, which could impact the design and implementation of resistance management strategies in the country.

scholarly journals Independent Emergence of Resistance to Seven Chemical Classes of Fungicides in Botrytis cinerea

2015 ◽  
Vol 105 (4) ◽  
pp. 424-432 ◽  
Author(s):  
Dolores Fernández-Ortuño ◽  
Anja Grabke ◽  
Xingpeng Li ◽  
Guido Schnabel
Keyword(s):  
United States ◽  
Botrytis Cinerea ◽  
Target Genes ◽  
Management Strategies ◽  
Resistance Management ◽  
Monitoring Program ◽  
Gene Mutations ◽  
The United States ◽  
Gray Mold ◽  
Development Of Resistance

Gray mold, caused by the fungal pathogen Botrytis cinerea, is one of the most destructive diseases of small fruit crops and control is largely dependent on the application of fungicides. As part of a region-wide resistance-monitoring program that investigated 1,890 B. cinerea isolates from 189 fields in 10 states of the United States, we identified seven isolates (0.4%) from five locations in four different states with unprecedented resistance to all seven Fungicide Resistance Action Committee (FRAC) codes with single-site modes of action including FRAC 1, 2, 7, 9, 11, 12, and 17 registered in the United States for gray mold control. Resistance to thiophanate-methyl, iprodione, boscalid, pyraclostrobin, and fenhexamid was based on target gene mutations that conferred E198A and F200Y in β-tubulin, I365N/S in Bos1, H272R/Y in SdhB, G143A in Cytb, and T63I and F412S in Erg27. Isolates were grouped into MDR1 and MDR1h phenotypes based on sensitivity to fludioxonil and variations in transcription factor mrr1. MDR1h isolates had a previously described 3-bp deletion at position 497 in mrr1. Expression of ABC transporter atrB was increased in MDR1 isolates but highest in MDR1h isolates. None of the isolates with seven single resistances (SR) had identical nucleotide variations in target genes, indicating that they emerged independently. Multifungicide resistance phenotypes did not exhibit significant fitness penalties for the parameters used in this study, but MDR1h isolates produced more sclerotia at low temperatures and exhibited increased sensitivity to salt stress. In this study we show that current resistance management strategies have not been able to prevent the geographically independent development of resistance to all seven site-specific fungicides currently registered for gray mold control in the United States and document the presence of MDR1h in North America.

scholarly journals Challenges with managing insecticide resistance in agricultural pests, exemplisfied by the whitefly Bemisia tabaci

1998 ◽  
Vol 353 (1376) ◽  
pp. 1757-1767 ◽  
Author(s):  
I. Denholm ◽  
M. Cahill ◽  
T. J. Dennehy ◽  
A. R. Horowitz
Keyword(s):  
Insecticide Resistance ◽  
Bemisia Tabaci ◽  
Management Strategies ◽  
Resistance Management ◽  
Chemical Diversity ◽  
Breeding Cycle ◽  
Agricultural Pests ◽  
Management Options ◽  
Development Of Resistance ◽  
Significant Achievement

For many key agricultural pests, successful management of insecticide resistance depends not only on modifying the way that insecticides are deployed, but also on reducing the total number of treatments applied. Both approaches benefit from a knowledge of the biological characteristics of pests that promote or may retard the development of resistance. For the whitefly Bemisia tabaci (Gennadius), these factors include a haplodiploid breeding system that encourages the rapid selection and fixation of resistance genes, its breeding cycle on a succession of treated or untreated hosts, and its occurrence on and dispersal from high–value crops in greenhouses and glasshouses. These factors, in conjunction with often intensive insecticide use, have led to severe and widespread resistance that now affects several novel as well as conventional control agents. Resistance–management strategies implemented on cotton in Israel, and subsequently in south–western USA, have nonetheless so far succeeded in arresting the resistance treadmill in B. tabaci through a combination of increased chemical diversity, voluntary or mandatory restrictions on the use of key insecticides, and careful integration of chemical control with other pest–management options. In both countries, the most significant achievement has been a dramatic reduction in the number of insecticide treatments applied against whiteflies on cotton, increasing the prospect of sustained use of existing and future insecticides.

Fungicide Resistance—Lessons for Herbicide Resistance Management?

1995 ◽  
Vol 9 (4) ◽  
pp. 840-849 ◽  
Author(s):  
Tobin L. Peever ◽  
Michael G. Milgroom
Keyword(s):  
Disease Control ◽  
Fungicide Resistance ◽  
Rapid Development ◽  
Management Strategies ◽  
Experimental Studies ◽  
Resistance Management ◽  
Pathogenic Fungi ◽  
Systemic Fungicides ◽  
Development Of Resistance ◽  
Pathogen Populations

Resistance to agricultural fungicides has increaséd dramatically in the past twenty years, following the introduction of systemic fungicides. Disease control failures associated with fungicide resistance have occurred with many classes of fungicides and in many genera of plant-pathogenic fungi. In some cases, resistance evolved extremely rapidly making the chemicals ineffective for disease control only a few years after they were introduced.The rapid development of resistance to systemic fungicides has led to efforts to develop strategies to avoid or delay the evolution of fungicide resistance in plant pathogen populations. Despite a widespread interest in managing fungicide resistance, very few experimental studies have been performed to elucidate the important factors controlling resistance development. Most fungicide resistance studies have consisted of anecdotal field observations which have rarely been followed up with experimentation. In order to understand what factors affect the evolution of resistance, and to use this information to design effective resistance management strategies, more experimental studies are required.

scholarly journals Various Levels of Cross-Resistance toBacillus sphaericus Strains in Culex pipiens(Diptera: Culicidae) Colonies Resistant to B. sphaericusStrain 2362

2001 ◽  
Vol 67 (11) ◽  
pp. 5049-5054 ◽  
Author(s):  
Christina Nielsen-LeRoux ◽  
D. Raghunatha Rao ◽  
Jittawadee Rodcharoen Murphy ◽  
Alexandre Carron ◽  
T. R. Mani ◽  
...  
Keyword(s):  
Culex Pipiens ◽  
Mosquito Control ◽  
Management Strategies ◽  
Resistance Management ◽  
Bacillus Sphaericus ◽  
Cross Resistance ◽  
Low Level ◽  
Control Programs ◽  
Development Of Resistance ◽  
Level Resistance

ABSTRACT We studied the cross-resistance to three highly toxicBacillus sphaericus strains, IAB-59 (serotype H6), IAB-881 (serotype H3), and IAB-872 (serotype H48), of four colonies of theCulex pipiens complex resistant to B. sphaericus 2362 and 1593, both of which are serotype H5a5b strains. Two field-selected highly resistant colonies originating from India (KOCHI, 17,000-fold resistance) and France (SPHAE, 23,000-fold resistance) and a highly resistant laboratory-selected colony from California (GeoR, 36,000-fold resistance) showed strong cross-resistance to strains IAB-881 and IAB-872 but significantly weaker cross-resistance to IAB-59 (3- to 43-fold resistance). In contrast, a laboratory-selected California colony with low-level resistance (JRMM-R, 5-fold resistance) displayed similar levels of resistance (5- to 10-fold) to all of the B. sphaericusstrains tested. Thus, among the mosquitocidal strains of B. sphaericus we identified a strain, IAB-59, which was toxic to several Culex colonies that were highly resistant to commercial strains 2362 and 1593. Our analysis also indicated that strain IAB-59 may possess other larvicidal factors. These results could have important implications for the development of resistance management strategies for area-wide mosquito control programs based on the use of B. sphaericus preparations.

scholarly journals The Usefulness of Fungicide Mixtures and Alternation for Delaying the Selection for Resistance in Populations of Mycosphaerella graminicola on Winter Wheat: A Modeling Analysis

2013 ◽  
Vol 103 (7) ◽  
pp. 690-707 ◽  
Author(s):  
P. H. F. Hobbelen ◽  
N. D. Paveley ◽  
R. P. Oliver ◽  
F. van den Bosch
Keyword(s):  
Winter Wheat ◽  
Management Strategies ◽  
Resistance Management ◽  
Mycosphaerella Graminicola ◽  
Decay Rates ◽  
Response Curves ◽  
Resistance Risk ◽  
Modes Of Action ◽  
Development Of Resistance ◽  
Concurrent Use

A fungicide resistance model (reported and tested previously) was amended to describe the development of resistance in Mycosphaerella graminicola populations in winter wheat (Triticum aestivum) crops in two sets of fields, connected by spore dispersal. The model was used to evaluate the usefulness of concurrent, alternating, or mixture use of two high-resistance-risk fungicides as resistance management strategies. We determined the effect on the usefulness of each strategy of (i) fitness costs of resistance, (ii) partial resistance to fungicides, (iii) differences in the dose-response curves and decay rates between fungicides, and (iv) different frequencies of the double-resistant strain at the start of a treatment strategy. Parameter values for the quinine outside inhibitor pyraclostrobin were used to represent two fungicides with differing modes of action. The effectiveness of each strategy was quantified as the maximum number of growing seasons that disease was effectively controlled in both sets of fields. For all scenarios, the maximum effective lives achieved by the use of the strategies were in the order mixtures ≥ alternation ≥ concurrent use. Mixtures were of particular benefit where the pathogen strain resistant to both modes of action incurred a fitness penalty or was present at a low initial frequency.

Moderating Role of Learning Strategies Between Meta-Cognitive Awareness and Study Habits Among University Students

2019 ◽  
Vol 34 (Spring 2019) ◽  
pp. 215-231
Author(s):  
Mussarat J. Khan ◽  
Seemab Rasheed
Keyword(s):  
Regression Analysis ◽  
Resource Management ◽  
University Students ◽  
Learning Strategies ◽  
Management Strategies ◽  
Cognitive Strategies ◽  
Study Habits ◽  
Good Reliability ◽  
Cognitive Awareness

The purpose of present study is to examine the role of learning strategies as moderator between meta-cognitive awareness and study habits among university students. Sample comprises of 200 students (100 male students and 100 female students) of various universities of Islamabad and Rawalpindi with age ranging from 18-25 years. In order to assess study variables questionnaires were used included Meta-Cognitive Awareness Inventory (Schraw & Dennison, 1994) measuring two-components of meta-cognition that are knowledge and regulation of cognition. Study habits demonstrated by the students were measured by the Study Habits Inventory (Wrenn, 1941). Motivated Strategies for Learning Questionnaire (Pintrich, Smith, Garcia, & McKeachie, 1991) which includes motivation and learning strategies scales. In the present study, only the learning strategies section was utilized, which measures the cognitive strategies and resource management strategies. Results revealed positive correlation between research instruments and are also having good reliability. Regression analysis reflected that meta-cognitive awareness predicts study habits among university students. Regression analysis also suggested that learning strategies including resource management strategies and cognitive strategies significantly moderates the relationship between meta-cognitive awareness and study habits. It is also explored gender differences on learning strategies, meta-cognitive awareness and study habits. Future implications of the study were also discussed.

BİLGİ YÖNETİMİ UYGULAMALARI KAPSAMINDA İNSAN KAYNAKLARI YÖNETİMİNDE MEYDANA GELEN DEĞİŞİMLER

2013 ◽  
Vol 1 (1) ◽  
pp. 83
Author(s):  
Ozan Büyükyılmaz
Keyword(s):  
Knowledge Management ◽  
Human Resources ◽  
Performance Management ◽  
Management Practices ◽  
Human Resources Management ◽  
Management Strategies ◽  
Resources Management ◽  
Management Philosophy ◽  
Management Processes

The development and expansion of knowledge management as an important management philosophy has a significant impact on human resources management as well as on organization as a whole. In this context, knowledge management processes have been used as a strategic tool within human resources management.Therefore, functions of human resources management must adapt itself to this change. The purpose of this study is to determine the role of human resources management in the management of knowledge and to reveal the effects of knowledge management practices on the functions of human resources byexamining the relationship between human resources and knowledge management. In this context, a theoretical investigation was conducted. It has been determined that significant changes occurred on the functions of human resources management such as selection and recruitment, performance management, remuneration and reward, training and development within the framework of the knowledge management strategies.

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