scholarly journals Evaluation of Resistance Development in Bemisia tabaci Genn. (Homoptera: Aleyrodidae) in Cotton against Different Insecticides

Insects ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 996
Author(s):  
Muhammad Zaryab Khalid ◽  
Sohail Ahmed ◽  
Ibrahim Al-ashkar ◽  
Ayman EL Sabagh ◽  
Liyun Liu ◽  
...  
Keyword(s):  
Bemisia Tabaci ◽  
The Other ◽  
Resistance Development ◽  
Susceptible Population ◽  
Low Level ◽  
Development Of Resistance ◽  
Major Pest ◽  
Selection For ◽  
High Level ◽  
Very High

Cotton is a major crop of Pakistan, and Bemisia tabaci (Homoptera: Aleyrodidae) is a major pest of cotton. Due to the unwise and indiscriminate use of insecticides, resistance develops more readily in the whitefly. The present study was conducted to evaluate the resistance development in the whitefly against the different insecticides that are still in use. For this purpose, the whitefly population was selected with five concentrations of each insecticide, for five generations. At G1, compared with the laboratory susceptible population, a very low level of resistance was observed against bifenthrin, cypermethrin, acetamiprid, imidacloprid, thiamethoxam, nitenpyram, chlorfenapyr, and buprofezin with a resistance ratio of 3-fold, 2-fold, 1-fold, 4-fold, 3-fold, 3-fold, 3-fold, and 3-fold, respectively. However, the selection for five generations increased the resistance to a very high level against buprofezin (127-fold), and to a high level against imidacloprid (86-fold) compared with the laboratory susceptible population. While, a moderate level of resistance was observed against cypermethrin (34-fold), thiamethoxam (34-fold), nitenpyram (30-fold), chlorfenapyr (29-fold), and acetamiprid (21-fold). On the other hand, the resistance was low against bifenthrin (18-fold) after selection for five generations. A very low level of resistance against the field population of B. tabaci, at G1, showed that these insecticides are still effective, and thus can be used under the field conditions for the management of B. tabaci. However, the proper rotation of insecticides among different groups can help to reduce the development of resistance against insecticides.

scholarly journals Building Extraction in Very High Resolution Imagery by Dense-Attention Networks

2018 ◽  
Vol 10 (11) ◽  
pp. 1768 ◽  
Author(s):  
Hui Yang ◽  
Penghai Wu ◽  
Xuedong Yao ◽  
Yanlan Wu ◽  
Biao Wang ◽  
...  
Keyword(s):  
Deep Learning ◽  
High Resolution ◽  
Building Extraction ◽  
Learning Networks ◽  
Feature Maps ◽  
Low Level ◽  
High Resolution Imagery ◽  
Very High Resolution Imagery ◽  
High Level ◽  
Very High

Building extraction from very high resolution (VHR) imagery plays an important role in urban planning, disaster management, navigation, updating geographic databases, and several other geospatial applications. Compared with the traditional building extraction approaches, deep learning networks have recently shown outstanding performance in this task by using both high-level and low-level feature maps. However, it is difficult to utilize different level features rationally with the present deep learning networks. To tackle this problem, a novel network based on DenseNets and the attention mechanism was proposed, called the dense-attention network (DAN). The DAN contains an encoder part and a decoder part which are separately composed of lightweight DenseNets and a spatial attention fusion module. The proposed encoder–decoder architecture can strengthen feature propagation and effectively bring higher-level feature information to suppress the low-level feature and noises. Experimental results based on public international society for photogrammetry and remote sensing (ISPRS) datasets with only red–green–blue (RGB) images demonstrated that the proposed DAN achieved a higher score (96.16% overall accuracy (OA), 92.56% F1 score, 90.56% mean intersection over union (MIOU), less training and response time and higher-quality value) when compared with other deep learning methods.

Resistance to Aryloxyphenoxypropionate and Cyclohexanedione Herbicides in Wild Oat (Avena fatua)

Weed Science ◽  
1993 ◽  
Vol 41 (2) ◽  
pp. 232-238 ◽  
Author(s):  
Ian M. Heap ◽  
Bruce G. Murray ◽  
Heather A. Loeppky ◽  
Ian N. Morrison
Keyword(s):  
Dry Matter ◽  
Cross Resistance ◽  
Western Canada ◽  
Wild Oat ◽  
Recommended Dosage ◽  
Susceptible Population ◽  
South Central ◽  
Repeated Applications ◽  
High Level ◽  
Very High

Resistance to aryloxyphenoxypropionate and cyclohexanedione herbicides was identified in four wild oat populations from western Canada. Populations UM1, UM2, and UM3 originated from northwestern Manitoba and UM33 from south-central Saskatchewan. Field histories indicated that these populations were exposed to repeated applications of diclofop-methyl and sethoxydim over the previous 10 yr. The populations differed in their levels and patterns of cross-resistance to these and five other acetyl-CoA carboxylase inhibitors (ACCase inhibitors). UM1, UM2, and UM3 were resistant to diclofop-methyl, fenoxaprop-p-ethyl, and sethoxydim. In contrast, UM33 was resistant to the aryloxyphenoxy propionate herbicides but not to sethoxydim. The dose of sethoxydim required to reduce growth of UM1 by 50% was 150 times greater than for a susceptible population (UM5) or UM33 based on shoot dry matter reductions 21 d after treatment. This population differed from UM2 and UM3 that had R/S ratios of less than 10. In the field UM1 also exhibited a very high level of resistance to sethoxydim. In contrast to susceptible plants that were killed at the recommended dosage, shoot dry matter of resistant plants treated at eight times the recommended dosage was reduced by only 27%. In growth chamber experiments none of the four populations was cross-resistant to herbicides from five different chemical families.

Confirmation and characterization of cyhalofop-butyl–resistant Chinese sprangletop (Leptochloa chinensis) populations from China

Weed Science ◽  
2020 ◽  
Vol 68 (3) ◽  
pp. 253-259
Author(s):  
Yajun Peng ◽  
Lang Pan ◽  
Ducai Liu ◽  
Xiaomei Cheng ◽  
Guolan Ma ◽  
...  
Keyword(s):  
Resistance Index ◽  
Resistance Mechanisms ◽  
The Other ◽  
Susceptible Population ◽  
Acetyl Coenzyme A ◽  
Target Site Resistance ◽  
High Level ◽  
Acetyl Coenzyme A Carboxylase ◽  
Grass Weed

AbstractChinese sprangletop [Leptochloa chinensis (L.) Nees] is one grass weed severely affecting rice (Oryza sativa L.) growth in paddies in China. Cyhalofop-butyl is the main herbicide used to control grass weeds in Chinese paddy fields, especially for controlling L. chinensis; however, L. chinensis has evolved resistance to cyhalofop-butyl due to continuous and extensive application. To investigate cyhalofop-butyl resistance levels and mechanisms in L. chinensis in some of the Chinese rice areas, 66 field populations were collected and treated with cyhalofop-butyl. Of these tested populations, 10 showed a high level of resistance to cyhalofop-butyl; the 50% effective dose ranged within 108.4 to 1,443.5 g ai ha−1 with resistance index values of 9.1 to 121.8 when compared with the susceptible population. Acetyl-coenzyme A carboxylase genes (ACCase) of susceptible and all 10 resistant populations were amplified and sequenced. Among them, Ile-1781-Leu, Trp-2027-Cys, Trp-2027-Ser, and Ile-2041-Asn mutations were found in five resistant populations. No known resistance-related mutations were found in the other five resistant populations, indicating that resistance to cyhalofop-butyl in these populations was likely to be endowed by non–target site resistance mechanisms. Notably, the Ile-1781-Leu and Trp-2027-Cys substitutions have previously been reported, but this is the first report of Trp-2027-Ser and Ile-2041-Asn mutations in L. chinensis. Furthermore, three derived cleaved amplified polymorphic sequence methods were developed to rapidly detect these mutations in L. chinensis.

Positive association between resistance to Bacillus thuringiensis and overwintering survival of cabbage loopers, Trichoplusia ni (Lepidoptera: Noctuidae)

2008 ◽  
Vol 98 (3) ◽  
pp. 317-322 ◽  
Author(s):  
V. Caron ◽  
J.H. Myers
Keyword(s):  
Bacillus Thuringiensis ◽  
Trichoplusia Ni ◽  
Positive Association ◽  
Pest Species ◽  
Development Of Resistance ◽  
Trade Offs ◽  
Major Pest ◽  
Selection For ◽  
Overwintering Survival ◽  
Lepidoptera Noctuidae

AbstractDevelopment of resistance to insecticides has generally been associated with fitness costs that may be magnified under challenging conditions. Lepidopterans which are resistant to the biopesticide Bacillus thuringiensis subsp. kurstaki (Btk) have been shown to have reduced fitness, such as lower survival when subjected to overwintering stress. Recently, resistance to Btk has been found in some populations of Trichoplusia ni Hübner in greenhouses in British Columbia. This situation provides an opportunity to investigate potential trade-offs between overwintering survival and insecticide resistance in a major pest species. Here, we assess the survival and eventual fecundity of Btk resistant and susceptible T. ni pupae exposed to cool temperatures. Contrary to our expectations, resistant T. ni had higher overwintering survival than susceptible individuals. This is the first account of a potential advantage associated with Btk resistance. Resistant and susceptible moths had reduced fecundity and smaller progeny after cold exposure compared to controls, and this may counteract the survival advantage. Nevertheless, it seems unlikely that this is sufficient to select out the resistant phenotype in the presence of strong selection for resistance and in the absence of immigration of susceptible moths. The appearance of resistance without evidence of a trade-off in overwintering survival presents a major challenge to management in production greenhouses.

Efficacy of a ciprofloxacin/amikacin combination against planktonic and biofilm cultures of susceptible and low-level resistant Pseudomonas aeruginosa

2019 ◽  
Vol 74 (11) ◽  
pp. 3252-3259 ◽  
Author(s):  
Anaïs Soares ◽  
Kévin Alexandre ◽  
Fabien Lamoureux ◽  
Ludovic Lemée ◽  
François Caron ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Bacterial Biofilm ◽  
The Other ◽  
Clinical Strain ◽  
Bacterial Reduction ◽  
Low Level ◽  
Mechanical Dispersion ◽  
Resistant Mutants ◽  
High Level

Abstract Background Eradicating bacterial biofilm without mechanical dispersion remains a challenge. Combination therapy has been suggested as a suitable strategy to eradicate biofilm. Objectives To evaluate the efficacy of a ciprofloxacin/amikacin combination in a model of in vitro Pseudomonas aeruginosa biofilm. Methods The antibacterial activity of ciprofloxacin and amikacin (alone, in combination and successively) was evaluated by planktonic and biofilm time–kill assays against five P. aeruginosa strains: PAO1, a WT clinical strain and three clinical strains overexpressing the efflux pumps MexAB-OprM (AB), MexXY-OprM (XY) and MexCD-OprJ (CD), respectively. Amikacin MIC was 16 mg/L for XY and ciprofloxacin MIC was 0.5 mg/L for CD. The other strains were fully susceptible to ciprofloxacin and amikacin. The numbers of total and resistant cells were determined. Results In planktonic cultures, regrowth of high-level resistant mutants was observed when CD was exposed to ciprofloxacin alone and XY to amikacin alone. Eradication was obtained with ciprofloxacin or amikacin in the other strains, or with the combination in XY and CD strains. In biofilm, bactericidal reduction after 8 h followed by a mean 4 log10 cfu/mL plateau in all strains and for all regimens was noticed. No regrowth of resistant mutants was observed whatever the antibiotic regimen. The bacterial reduction obtained with a second antibiotic used simultaneously or consecutively was not significant. Conclusions The ciprofloxacin/amikacin combination prevented the emergence of resistant mutants in low-level resistant strains in planktonic cultures. Biofilm persister cells were not eradicated, either with monotherapy or with the combination.

Wild Mustard (Brassica kaber) Resistance to Ethametsulfuron But Not to Other Herbicides

1996 ◽  
Vol 10 (4) ◽  
pp. 847-850 ◽  
Author(s):  
G. Mark Jeffers ◽  
John T. O'Donovan ◽  
Linda M. Hall
Keyword(s):  
Dry Weight ◽  
The Other ◽  
Controlled Environment ◽  
Susceptible Population ◽  
Initial Frequency ◽  
Wild Mustard ◽  
Resistant Population ◽  
Imidazolinone Herbicides ◽  
Brassica Kaber ◽  
Very High

In 1993, a wild mustard population growing in a canola crop near Wetaskiwin, AB was poorly controlled by ethametsulfuron after only one previous use of the herbicide. Controlled environment experiments were conducted to compare the response of this suspected resistant population (R) with that of a known susceptible population (S) collected near Vegreville, AB to increasing rates of ethametsulfuron, metsulfuron, chlorsulfuron, thifensulfuron, HOE 075032, imazamethabenz, imazethapyr, metribuzin, and 2,4-D. The R wild mustard population was highly resistant to ethametsulfuron, slightly resistant to low rates of metsulfuron but not resistant to any of the other herbicides tested. This suggests that the mechanism of resistance may differ from that reported for other sulfonylurea and imidazolinone herbicides. Since resistance was documented after only 2 yr of ethametsulfuron use, the initial frequency of resistance to this herbicide in wild mustard populations may be very high. Dry weight of untreated plants did not differ significantly between the S and R populations suggesting little or no differences in competitiveness between them.

scholarly journals Stepwise Upregulation of the Pseudomonas aeruginosa Chromosomal Cephalosporinase Conferring High-Level β-Lactam Resistance Involves Three AmpD Homologues

2006 ◽  
Vol 50 (5) ◽  
pp. 1780-1787 ◽  
Author(s):  
Carlos Juan ◽  
Bartolomé Moyá ◽  
José L. Pérez ◽  
Antonio Oliver
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Resistance Mechanisms ◽  
Natural Resistance ◽  
Wild Type ◽  
Triple Mutant ◽  
Major Threat ◽  
Development Of Resistance ◽  
One Step ◽  
High Level ◽  
Very High

ABSTRACT Development of resistance to the antipseudomonal penicillins and cephalosporins mediated by hyperproduction of the chromosomal cephalosporinase AmpC is a major threat to the successful treatment of Pseudomonas aeruginosa infections. Although ampD inactivation has been previously found to lead to a partially derepressed phenotype characterized by increased AmpC production but retaining further inducibility, the regulation of ampC in P. aeruginosa is far from well understood. We demonstrate that ampC expression is coordinately repressed by three AmpD homologues, including the previously described protein AmpD plus two additional proteins, designated AmpDh2 and AmpDh3. The three AmpD homologues are responsible for a stepwise ampC upregulation mechanism ultimately leading to constitutive hyperexpression of the chromosomal cephalosporinase and high-level antipseudomonal β-lactam resistance, as shown by analysis of the three single ampD mutants, the three double ampD mutants, and the triple ampD mutant. This is achieved by a three-step escalating mechanism rendering four relevant expression states: basal-level inducible expression (wild type), moderate-level hyperinducible expression with increased antipseudomonal β-lactam resistance (ampD mutant), high-level hyperinducible expression with high-level β-lactam resistance (ampD ampDh3 double mutant), and very high-level (more than 1,000-fold compared to the wild type) derepressed expression (triple mutant). Although one-step inducible-derepressed expression models are frequent in natural resistance mechanisms, this is the first characterized example in which expression of a resistance gene can be sequentially amplified through multiple steps of derepression.

scholarly journals First Glimpse

1999 ◽  
Vol 121 (09) ◽  
pp. 68-70
Author(s):  
John DeGaspari
Keyword(s):  
Visible Light ◽  
Leading Edge ◽  
The Other ◽  
Light Spectrum ◽  
Substantial Cost ◽  
Infrared Band ◽  
Testing Protocol ◽  
High Level ◽  
To Receive ◽  
Very High

The Next Generation Space Telescope (NGST) will incorporate leading-edge technology in construction, optics, and deployment. NGST will be composed of a large sunshield and lightweight mirror, which will be deployed in space. Both are depicted in this rendering by TRW Space and Electronic Group. Over the next two years, the teams, one led by Lockheed Martin Missiles & Space, Sunnyvale, CA, and the other led by TRW Space and Electronic Group in Redondo Beach, California, and including Ball Aerospace and Technologies Corp., Boulder, CO, will tackle some daunting engineering challenges. The new telescope will pick up where the Hubble telescope leaves off. Hubble observes objects that are still in the visible light spectrum. NGST will investigate objects that are much more distant in space and will need to be sensitive to the infrared band. The testing protocol is going to receive a very high level of attention during this upcoming phase one effort, because it is one of the substantial cost elements of a program of this nature.

scholarly journals JSOX: A Justly Simple Objectization for XML

2014 ◽  
Author(s):  
Steven J. DeRose
Keyword(s):  
The Other ◽  
Low Level ◽  
Other Hand ◽  
High Level ◽  
Cross Language

XML can be as easy to work with as JSON. However, this has not been obvious until now. JSON is easy because it supports only datatypes that are already native to Javascript and uses the same syntax to access them (such as [1:10], ["x"], and “.” notation). XML, on the other hand, supports additional datatypes, and is most commonly handled via SAX or DOM, both of which are low-level and meant to be cross-language. Typical developers want high-level access that feels “native” in the language they are using. These shortcomings have little or nothing to do with XML, and can be remedied by a different API. Software that demonstrates this is presented and described. It uses Python's richer set of abstract datatypes (such as tuples and sets), and provides native Python style syntax with richer semantics than JSON or Javascript.

Categorization

2020 ◽  
pp. 27-37
Author(s):  
Stephen K. Reed
Keyword(s):  
Baby Boomers ◽  
The Other ◽  
Social Categories ◽  
Elbow Angle ◽  
Low Level ◽  
High Level ◽  
Selection Of

Categories reduce the complexity of the environment, are the means by which objects are identified, reduce the need for constant learning, allow for the selection of an appropriate action, and support the organization of objects and events. The most typical members of categories share attributes with the other members of the category. Prototypes are the central members. Hierarchies are composed of subordinate (desk lamp), basic (lamp), and superordinate (furniture) categories. Social categories such as “ baby boomers” classify people but may be associated with misleading stereotypes. Action categories include event boundaries that mark the transition between actions. They are organized into low-level (elbow angle) and high-level (pouring milk) actions.

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