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BT corn

Marwa A A Ibrahim, Ebtsam F Okasha
Genetically modified (GM) plants expressing insecticidal traits offer a new strategy for crop protection. GM-corn contains Bacillus thuringiensis (Bt) genes producing delta endotoxins in the whole plant. Diet can influence the characteristics of the gastrointestinal tract altering its function and structure. The aim of this study was to evaluate the effect of GM-corn on the histological structure of jejunal mucosa of adult male albino rat using different histological, immunohistochemical and morphometrical methods...
October 18, 2016: Experimental and Toxicologic Pathology: Official Journal of the Gesellschaft Für Toxikologische Pathologie
Ute Schellenberger, Jarred Oral, Barbara A Rosen, Jun-Zhi Wei, Genhai Zhu, Weiping Xie, Mark J McDonald, David C Cerf, Scott H Diehn, Virginia C Crane, Gary A Sandahl, Jian-Zhou Zhao, Timothy M Nowatzki, Amit Sethi, Lu Liu, Zaiqi Pan, Yiwei Wang, Albert L Lu, Gusui Wu, Lu Liu
The coleopteran insect western corn rootworm (WCR, Diabrotica virgifera virgifera LeConte) is a devastating crop pest in North America and Europe. Although crop plants that produce Bacillus thuringiensis (Bt) proteins can limit insect infestation, some insect populations have evolved to be resistance to Bt proteins. Here we describe an insecticidal protein, designated IPD072Aa, that is isolated from Pseudomonas chlororaphis. Transgenic corn plants expressing IPD072Aa show protection from WCR insect injury under field conditions...
September 22, 2016: Science
Yuwen Zhang, Wei Zhang, Yan Liu, Jianhua Wang, Guoying Wang, Yunjun Liu
Cry1Ie is a kind of Bacillus thuringiensis (Bt) toxin protein which has a different action model than the Cry1Ab and Cry1Ac protein. The transgenic maize expressing Cry1Ie might be commercially used in the near future and it is urgent to develop a method to detect Cry1Ie protein in transgenic plants and their products. To develop an ELISA method, Cry1Ie protein was expressed in Escherichia coli strain Transetta DE3, purified with the Ni-NTA spin columns, and then validated by sequencing. Bioassay results showed that the purified Cry1Ie protein was highly toxic to the Asian corn borer...
November 2016: Analytical and Bioanalytical Chemistry
Yueqin Wang, Yidong Wang, Zhenying Wang, Alejandra Bravo, Mario Soberón, Kanglai He
The Asian corn borer (ACB), Ostrinia furnacalis (Guenée) (Lepidoptera: Crambidae), is the most destructive insect pest of corn in China. Susceptibility to the Cry1F toxin derived from Bacillus thuringiensis has been demonstrated for ACB, suggesting the potential for Cry1F inclusion as part of an insect pest management program. Insects can develop resistance to Cry toxins, which threatens the development and use of Bt formulations and Bt crops in the field. To determine possible resistance mechanisms to Cry1F, a Cry1F-resistant colony of ACB (ACB-FR) that exhibited more than 1700-fold resistance was established through selection experiments after 49 generations of selection under laboratory conditions...
2016: PloS One
Hong-Xing Chen, Rui Yang, Wang Yang, Liu Zhang, Ibrahima Camara, Xue-Hui Dong, Yi -Qing Liu, Wang-Peng Shi
Ostrinia furnacalis (Guenée) and Helicoverpa armigera (Hübner) are the most important pests of maize in China. A laboratory study and a 2-year field study on the efficacy of transgenic maize expressing the Cry1Ac protein BT38 against O. furnacalis and H. armigera were performed. We found that the husks, kernels, and silks of BT38 showed significant efficacy against larvae of O. furnacalis and H. armigera. In the field, when neonate larvae of O. furnacalis and H. armigera were on plants at different growth stages and when levels of leaf-damage or number of damaged silks were used to score efficacy, we found that BT38 showed significant insecticidal efficacy against O...
August 11, 2016: Environmental Science and Pollution Research International
Mike W Dunbar, Matthew E O'Neal, Aaron J Gassmann
Western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), and northern corn rootworm, Diabrotica barberi Smith & Lawrence, are major pests of corn (Zea mays L.). Corn producing Bacillus thuringiensis (Bt) toxins are widely used to manage Diabrotica spp.; however, Bt resistance by D. v. virgifera has led to high levels of feeding injury in the field. We tested whether field history affected root injury and abundance of adult Diabrotica spp. In 2013 and 2014, four types of cornfields were sampled: 1) recently rotated fields, 2) continuous cornfields, 3) fields with a history of injury to Bt corn (past problem fields), and 4) fields with greater than one node of injury to Bt corn at the time of sampling (current problem fields)...
October 2016: Journal of Economic Entomology
Rebecca A Schmidt-Jeffris, Anders S Huseth, Brian A Nault
European corn borer, Ostrinia nubilalis (Hübner), is a major pest of processing snap bean because larvae are contaminants in pods. The incidence of O. nubilalis-contaminated beans has become uncommon in New York, possibly because widespread adoption of Bt field corn has suppressed populations. Snap bean fields located where Bt corn has been intensively grown in space and time may be at lower risk for O. nubilalis than fields located where Bt corn is not common. To manage O. nubilalis infestation risk, growers determine insecticide application frequency in snap bean based on pheromone-trapping information in nearby sweet corn fields; adult activity is presumed equivalent in both crops...
July 24, 2016: Journal of Economic Entomology
Lanzhi Han, Xingfu Jiang, Yufa Peng
Many lines of insect-resistant genetically modified (IRGM) corn and rice containing Bacillus thuringiensis (Bt) insecticidal genes have been developed and undergone different environmental biosafety assessments stages in China, showing robust application prospects. The potential of targeted pests to develop resistance to Bt crops is widespread, which threatens the sustainable utility of IRGM corn and rice. In this study, the potential risks of target pest complexes developing resistance to IRGM corn and rice are evaluated...
June 2016: Current Opinion in Insect Science
C A Blanco, W Chiaravalle, M Dalla-Rizza, J R Farias, M F García-Degano, G Gastaminza, D Mota-Sánchez, M G Murúa, C Omoto, B K Pieralisi, J Rodríguez, J C Rodríguez-Maciel, H Terán-Santofimio, A P Terán-Vargas, S J Valencia, E Willink
Transgenic crops producing Bacillus thuringiensis- (Bt) insecticidal proteins (Bt crops) have provided useful pest management tools to growers for the past 20 years. Planting Bt crops has reduced the use of synthetic insecticides on cotton, maize and soybean fields in 11 countries throughout Latin America. One of the threats that could jeopardize the sustainability of Bt crops is the development of resistance by targeted pests. Governments of many countries require vigilance in measuring changes in Bt-susceptibility in order to proactively implement corrective measures before Bt-resistance is widespread, thus prolonging the usefulness of Bt crops...
June 2016: Current Opinion in Insect Science
Ana M Vélez, Neetha Nanoth Vellichirammal, Juan Luis Jurat-Fuentes, Blair D Siegfried
The Cry1Fa protein from the bacterium Bacillus thuringiensis (Bt) is known for its potential to control lepidopteran pests, especially through transgenic expression in maize and cotton. The maize event TC1507 expressing the cry1Fa toxin gene became commercially available in the United States in 2003 for the management of key lepidopteran pests including the European corn borer, Ostrinia nubilalis, and the fall armyworm, Spodoptera frugiperda. A high-dose/refuge strategy has been widely adopted to delay evolution of resistance to event TC1507 and other transgenic Bt crops...
June 2016: Current Opinion in Insect Science
Aaron J Gassmann
Western corn rootworm is a serious pest of maize. Beginning in 2003, management of western corn rootworm included transgenic maize that produces insecticidal toxins derived from the bacterium Bacillus thuringiensis (Bt). The first Bt maize hybrids produced Cry3Bb1, but additional Bt toxins have since been introduced, including eCry3.1Ab, mCry3A and Cry34/35Ab1. Laboratory selection experiments found that western corn rootworm could develop resistance to all types of Bt maize following three to seven generations of selection...
June 2016: Current Opinion in Insect Science
Brad S Coates
Transgenic plants that express Bacillus thuringiensis (Bt) crystal (Cry) protein toxins (Bt crops) effectively control feeding by the European corn borer, Ostrinia nubilalis, although documented resistance evolution among a number of species in both the laboratory and field has heightened concerns about the durability of this technology. Research has provided major insights into the mutations that alter Bt toxin binding receptor structure and function within the midgut of Lepidoptera that directly impacts the efficacy of Bt toxins, and potentially leads to the evolution of resistance to Bt crops in the field...
June 2016: Current Opinion in Insect Science
Sek Yee Tan, Murugesan Rangasamy, Haichuan Wang, Ana María Vélez, James Hasler, David McCaskill, Tao Xu, Hong Chen, Jessica Jurzenski, Matthew Kelker, Xiaoping Xu, Kenneth Narva, Blair D Siegfried
The western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte, is an important maize pest throughout most of the U.S. Corn Belt. Bacillus thuringiensis (Bt) insecticidal proteins including modified Cry3Aa and Cry34/35Ab1 have been expressed in transgenic maize to protect against WCR feeding damage. To date, there is limited information regarding the WCR midgut target sites for these proteins. In this study, we examined whether a cadherin-like gene from Diabrotica virgifera virgifera (DvvCad; GenBank accession # EF531715) associated with WCR larval midgut tissue is necessary for Cry3Aa or Cry34/35Ab1 toxicity...
August 2016: Insect Biochemistry and Molecular Biology
J P F Bentivenha, E L L Baldin, T E Hunt, S V Paula-Moraes, E E Blankenship
The western bean cutworm Striacosta albicosta (Smith), the fall armyworm Spodoptera frugiperda (J. E. Smith), and the corn earworm Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae) are among the major lepidopteran pests of maize in the United States, belonging to the same guild and injuring the reproductive tissues of this crop. Here, intraguild competition of these lepidopterans on non-Bt maize was evaluated through survival analysis of each species under laboratory and field conditions. Competition scenarios were carried out in arenas containing maize silk or ear tissue, using larvae on different stadium of development...
August 2016: Environmental Entomology
F P F Reay-Jones, R T Bessin, M J Brewer, D G Buntin, A L Catchot, D R Cook, K L Flanders, D L Kerns, R P Porter, D D Reisig, S D Stewart, M E Rice
Blended refuge for transgenic plants expressing Bacillus thuringiensis (Bt) toxins has been approved in the northern United States as a resistance management strategy alternative to a structured refuge. A three-year study (2012-2014) was conducted with 54 trials across nine states in the southern United States to evaluate plant injury from lepidopteran pests of corn and yield in a corn hybrid expressing Cry1F × Cry1Ab × Vip3Aa20 (Pioneer Brand Optimum Leptra) planted as a pure stand and in refuge blends of 5, 10, and 20% in both early and late plantings...
August 2016: Journal of Economic Entomology
Aaron J Gassmann, Ram B Shrestha, Siva R K Jakka, Mike W Dunbar, Eric H Clifton, Aubrey R Paolino, David A Ingber, B Wade French, Kenneth E Masloski, John W Dounda, Coy R St Clair
Western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), is a serious pest of corn in the United States, and recent management of western corn rootworm has included planting of Bt corn. Beginning in 2009, western corn rootworm populations with resistance to Cry3Bb1 corn and mCry3A corn were found in Iowa and elsewhere. To date, western corn rootworm populations have remained susceptible to corn producing Bt toxin Cry34/35Ab1. In this study, we used single-plant bioassays to test field populations of western corn rootworm for resistance to Cry34/35Ab1 corn, Cry3Bb1 corn, and mCry3A corn...
August 2016: Journal of Economic Entomology
Siva R K Jakka, Ram B Shrestha, Aaron J Gassmann
The evolution of resistance and cross-resistance threaten the sustainability of genetically engineered crops that produce insecticidal toxins derived from the bacterium Bacillus thuringiensis (Bt). Western corn rootworm, Diabrotica virgifera virgifera LeConte, is a serious pest of maize and has been managed with Bt maize since 2003. We conducted laboratory bioassays with maize hybrids producing Bt toxins Cry3Bb1, mCry3A, eCry3.1Ab, and Cry34/35Ab1, which represent all commercialized Bt toxins for management of western corn rootworm...
2016: Scientific Reports
Elane Fishilevich, Ana M Vélez, Nicholas P Storer, Huarong Li, Andrew J Bowling, Murugesan Rangasamy, Sarah E Worden, Kenneth E Narva, Blair D Siegfried
The western corn rootworm (WCR), Diabrotica virgifera virgifera, is the most important pest of corn in the US Corn Belt. Economic estimates indicate that costs of control and yield loss associated with WCR damage exceed $US 1 billion annually. Historically, corn rootworm management has been extremely difficult because of its ability to evolve resistance to both chemical insecticides and cultural control practices. Since 2003, the only novel commercialized developments in rootworm management have been transgenic plants expressing Bt insecticidal proteins...
September 2016: Pest Management Science
Sarah N Zukoff, Anthony L Zukoff, Ryan W Geisert, Bruce E Hibbard
Corn fields planted with plant-incorporated Bacillus thuringiensis (Bt) proteins must have a portion of the field planted with non-Bt, isoline, plants that serve as a refuge for susceptible insects. In the Corn Belt, refuge seeds are now blended in the bag with Bt seeds for corn hybrids containing two or more toxins targeted toward the western corn rootworm, Diabrotica virgifera virgifera LeConte. Syngenta's corn hybrid, Agrisure Duracade, containing the eCry3.1Ab (event 5307) and mCry3a (event MIR604) rootworm-targeted toxins were registered as a seed blend in 2014...
August 2016: Journal of Economic Entomology
Oscar F Santos-Amaya, Clébson S Tavares, João Victor C Rodrigues, Silverio O Campos, Raul Narciso C Guedes, Analiza P Alves, Eliseu José G Pereira
BACKGROUND: The presence of fitness costs of resistance to Bacillus thuringiensis (Bt) insecticidal proteins in insect populations may delay or even reverse the local evolution of insect resistance to Bt transgenic crops, deserving rigorous investigation. Here we assessed the fitness costs associated with Cry1Fa resistance in two fall armyworm strains [Spodoptera frugiperda (Lepidoptera: Noctuidae)] derived from field collections in different Brazilian regions and further selected in the laboratory for high levels of resistance to Cry1Fa using leaves of TC1507 corn...
May 5, 2016: Pest Management Science
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