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Louisiana State University

LSU Master's Theses

Theses/Dissertations

Resistance

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Marker-Trait Association Mapping Of Sorghum Mosaic Virus Resistance In Sugarcane, Chenie Zamora Apr 2022

Marker-Trait Association Mapping Of Sorghum Mosaic Virus Resistance In Sugarcane, Chenie Zamora

LSU Master's Theses

Mosaic is a potentially devastating disease of sugarcane that had severe economic impact on Louisiana’s sugarcane industry in the 1920’s and has caused periodic problems ever since. The disease is vectored by migrating aphids that transmit Sugarcane mosaic virus (SCMV) and Sorghum mosaic virus (SrMV) in a non-persistent manner. Mosaic in Louisiana is currently caused by strains of SrMV. Mosaic has been controlled primarily by developing resistant cultivars. Recently, mosaic was detected in some near-commercial clones in the cultivar selection program. This prompted extensive screening of breeding program parent populations that detected infiltration of susceptibility and revealed the need for …


Insecticide Resistance Management Approaches And Naturally Derived Toxicants For The Control Of Fall Armyworm, Spodoptera Frugiperda, Sarah Mccomic Nov 2020

Insecticide Resistance Management Approaches And Naturally Derived Toxicants For The Control Of Fall Armyworm, Spodoptera Frugiperda, Sarah Mccomic

LSU Master's Theses

Spodoptera frugiperda, the fall armyworm (FAW), is a major agricultural pest causing billions of dollars in damage annually to staple crops. Agricultural losses stemming from this pest continues to increase as resistance to commercialized insecticide classes evolves and spreads. Considering this, novel chemistries with new modes of action as well as novel resistance management strategies need to be developed to achieve continued control of FAW populations. This project consisted of two main goals. First, we aimed to develop a neurophysiological assay to enable a more precise understanding of pyrethroid and organophosphate resistance at the level of the nerve. We …


Fitness Costs And Inheritance Of Bt Cry2ab2 Resistance In Fall Armyworm, Spodoptera Frugiperda (J.E. Smith), Binod Acharya Jan 2017

Fitness Costs And Inheritance Of Bt Cry2ab2 Resistance In Fall Armyworm, Spodoptera Frugiperda (J.E. Smith), Binod Acharya

LSU Master's Theses

Evolution of resistance in target pest populations is a major threat to the sustainability of transgenic crops expressing Bacillus thuringiensis (Bt) proteins. Fall armyworm, Spodoptera frugiperda (J.E. Smith), is a cross-crop target pest of Bt corn, Bt cotton, and Bt soybean. This pest, thus far, is the only target pest species that has developed field resistance to Bt crops in multiple areas across countries. Cry2Ab2 is a common Bt protein expressed in transgenic corn and cotton targeting lepidopteran pests including S. frugiperda. The objective of this study was to characterize fitness costs and inheritance of Cry2Ab2 resistance in S. frugiperda. …


Screening For Resistance To Sugarcane Brown Rust With Controlled Conditions Inoculation, Mavir Carolina Avellaneda Barbosa Jan 2014

Screening For Resistance To Sugarcane Brown Rust With Controlled Conditions Inoculation, Mavir Carolina Avellaneda Barbosa

LSU Master's Theses

Brown rust, caused by Puccinia melanocephala, is an important disease of sugarcane. Breeding for host plant resistance is the primary control measure. Screening for resistance has relied on rating the severity of symptoms caused by natural infection; however, erratic results make this method problematic. A method accomplishing both infection and disease expression under controlled conditions could avoid the problems associated with resistance evaluations under natural infection. Inoculation of seedlings was evaluated to determine whether it could provide accurate resistance ratings in cross appraisal, and inoculation under controlled conditions was evaluated for the potential to accurately determine resistance reactions in clones …


Resistance Of Fall Armyworm, Spodoptera Frugiperda (J.E. Smith) To Bacillus Thuringiensis, Ying Niu Jan 2014

Resistance Of Fall Armyworm, Spodoptera Frugiperda (J.E. Smith) To Bacillus Thuringiensis, Ying Niu

LSU Master's Theses

The fall armyworm, Spodoptera frugiperda (J.E. Smith), is a target pest of Bacillus thuringiensis (Bt) corn in North and South America. In this study, multiple tests were conducted in the laboratory and greenhouse to 1) determine the susceptibility of two field populations of S. frugiperda collected from Florida (FL) and Puerto Rico (PR) to purified Cry1F protein and Bt corn leaf tissue and 2) evaluate larval survival of and plant injury by Cry1F-susceptible, -resistant, and –heterozygous genotypes of S. frugiperda on whole plants of transgenic corn containing single and pyramided Bt genes. Corn hybrids evaluated in this study included five …


Yogurt Cultures Survive Upon Exposure To Two Antimicrobials And Streptococcus Thermophilus St-M5 Acquired Resistance To Both Antimicrobials, Maria Carolina Vives Habeych Jan 2012

Yogurt Cultures Survive Upon Exposure To Two Antimicrobials And Streptococcus Thermophilus St-M5 Acquired Resistance To Both Antimicrobials, Maria Carolina Vives Habeych

LSU Master's Theses

Different antimicrobials are added in the manufacturing of dairy products such as flavored yogurts and processed cheese. Potassium Metabisulfite (PM) and Potassium Nitrite (PN) have been reported to have antimicrobial effect on pathogenic microorganisms such as Clostridium botulinum and Listeria monocytogenes. Yogurt is known for its health benefits, due to the presence of cultured bacteria. PM and PN are not commonly used in the dairy industry hence it would be interesting to study their influence in yogurt culture bacteria. The objectives of this study were: 1. to elucidate the influence of PM and PN at various concentrations, on the growth …


Association Of Esterases In Resistance To Naled And Resmethrin In The Southern House Mosquito, Culex Quinquefasciatus, Jennifer R. Gordon Jan 2010

Association Of Esterases In Resistance To Naled And Resmethrin In The Southern House Mosquito, Culex Quinquefasciatus, Jennifer R. Gordon

LSU Master's Theses

The vector-competency and its affinity for humans make C. quinquefasciatus an important target of mosquito abatement programs. Whenever such control programs are implemented, protocols to monitor frequencies and mechanisms of resistance to the insecticides used are necessary to optimize the efficacy of the management strategy and to slow development of resistance to the insecticides used. In the current study, susceptibilities to the two adulticides used by EBRMARC (naled and resmethrin) were monitored using field-collected mosquitoes and a topical and contact bioassay, respectively. My hypothesis was that esterase-mediated enhanced metabolism conferred resistance to both insecticides in populations of C. quinquefasciatus from …