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https://www.readbyqxmd.com/read/28627124/cross-resistance-to-purified-bt-proteins-bt-corn-and-bt-cotton-in-a-cry2ab2-corn-resistant-strain-of-spodoptera-frugiperda
#1
Fei Yang, David L Kerns, Graham P Head, Paula Price, Fangneng Huang
BACKGROUND: Gene-pyramiding by combining two or more dissimilar Bt proteins into a crop has been used to delay insect resistance. The durability of gene-pyramiding can be reduced by cross-resistance. Fall armyworm, Spodoptera frugiperda, is a major target pest of the Cry2Ab2 protein used in pyramided Bt corn and cotton. Here, we provide the first experimental evaluation of cross-resistance in S. frugiperda selected with Cry2Ab2 corn to multiple Bt sources including purified Bt proteins, Bt corn and Bt cotton...
June 19, 2017: Pest Management Science
https://www.readbyqxmd.com/read/28623231/cry6aa1-a-bacillus-thuringiensis-nematocidal-and-insecticidal-toxin-forms-pores-in-planar-lipid-bilayers-at-extremely-low-concentrations-and-without-the-need-of-proteolytic-processing
#2
Eva Fortea, Vincent Lemieux, Léna Potvin, Vimbai Chikwana, Samantha Griffin, Thimothy Hey, David McCaskill, Kenneth Narva, Sek Yee Tan, Xiaoping Xu, Vincent Vachon, Jean-Louis Schwartz
Cry6Aa1 is a Bacillus thuringiensis (Bt) toxin active against nematodes and corn rootworm insects. Its 3-D molecular structure, which has been recently elucidated, is unique among those known for other Bt toxins. Typical three-domain Bt toxins permeabilise receptor-free planar lipid bilayers (PLBs) by forming pores at doses in the 1-50 μg/ml range. Solubilisation and proteolytic activation are necessary steps for PLB permeabilisation. In contrast to other Bt toxins, Cry6Aa1 formed pores in receptor-free bilayers at doses as low as 200 pg/ml in a wide range of pH (5...
June 16, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28596570/an-alcaligenes-strain-emulates-bacillus-thuringiensis-producing-a-binary-protein-that-kills-corn-rootworm-through-a-mechanism-similar-to-cry34ab1-cry35ab1
#3
Nasser Yalpani, Dan Altier, Jennifer Barry, Adane Kassa, Timothy M Nowatzki, Amit Sethi, Jian-Zhou Zhao, Scott Diehn, Virginia Crane, Gary Sandahl, Rongjin Guan, Brad Poland, Claudia Perez Ortega, Mark E Nelson, Weiping Xie, Lu Liu, Gusui Wu
Crops expressing Bacillus thuringiensis (Bt)-derived insecticidal protein genes have been commercially available for over 15 years and are providing significant value to growers. However, there remains the need for alternative insecticidal actives due to emerging insect resistance to certain Bt proteins. A screen of bacterial strains led to the discovery of a two-component insecticidal protein named AfIP-1A/1B from an Alcaligenes faecalis strain. This protein shows selectivity against coleopteran insects including western corn rootworm (WCR)...
June 8, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28590421/characterization-of-asian-corn-borer-resistance-to-bt-toxin-cry1ie
#4
Yueqin Wang, Jing Yang, Yudong Quan, Zhenying Wang, Wanzhi Cai, Kanglai He
A strain of the Asian corn borer (ACB), Ostrinia furnacalis (Guenée), has evolved >800-fold resistance to Cry1Ie (ACB-IeR) after 49 generations of selection. The inheritance pattern of resistance to Cry1Ie in ACB-IeR strain and its cross-resistance to other Bt toxins were determined through bioassay by exposing neonates from genetic-crosses to toxins incorporated into the diet. The response of progenies from reciprocal F₁ crosses were similar (LC50s: 76.07 vs. 74.32 μg/g), which suggested the resistance was autosomal...
June 7, 2017: Toxins
https://www.readbyqxmd.com/read/28535300/magnitude-and-allele-frequency-of-cry1f-resistance-in-field-populations-of-the-fall-armyworm-lepidoptera-noctuidae-in-brazil
#5
O F Santos-Amaya, C S Tavares, J V C Rodrigues, T C Souza, N Rodrigues-Silva, R N C Guedes, A P Alves, E J G Pereira
Bacillus thuringiensis (Bt) corn producing the Cry1F protein was the first highly efficacious Bt corn deployed against the fall armyworm Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) in Brazil, but reduced efficacy of this technology against the fall armyworm has been reported in some regions of the country. Here, we surveyed Cry1F resistance allele frequency and susceptibility of eight S. frugiperda populations collected in 2013 from non-Bt fields in different regions of Brazil. In F1 screen experiments, the overall frequency of the Cry1F resistance alleles in Brazilian populations was estimated at 0...
May 23, 2017: Journal of Economic Entomology
https://www.readbyqxmd.com/read/28492498/assessment-of-inheritance-and-fitness-costs-associated-with-field-evolved-resistance-to-cry3bb1-maize-by-western-corn-rootworm
#6
Aubrey R Paolino, Aaron J Gassmann
The western corn rootworm, Diabrotica virgifera virgifera LeConte, is among the most serious insect pests of maize in North America. One strategy used to manage this pest is transgenic maize that produces one or more crystalline (Cry) toxins derived from the bacterium Bacillus thuringiensis (Bt). To delay Bt resistance by insect pests, refuges of non-Bt maize are grown in conjunction with Bt maize. Two factors influencing the success of the refuge strategy to delay resistance are the inheritance of resistance and fitness costs, with greater delays in resistance expected when inheritance of resistance is recessive and fitness costs are present...
May 11, 2017: Toxins
https://www.readbyqxmd.com/read/28484967/biotic-potential-and-life-table-of-helicoverpa-armigera-h%C3%A3-bner-lepidoptera-noctuidae-from-three-brazilian-regions
#7
I F Silva, E L L Baldin, A Specht, D R Sosa-Gómez, V F Roque-Specht, R Morando, S V Paula-Moraes
This study aimed to evaluate the biotic potential and life table of individuals of Helicoverpa armigera (Hübner) from different host plants (citrus, corn, and cotton) and Brazilian states (São Paulo, Distrito Federal, and Bahia) in artificial diet, under laboratory conditions (25 ± 1°C, 70 ± 10% RH, 14 h photophase). The longevity, pre-, post- and oviposition periods, fecundity, and fertility of 15 mating pairs per origin were evaluated. We also compared the reproductive parameters of each group of insects (São Paulo (SP), Distrito Federal (DF), and Bahia (BA)), including the net reproductive rate (Ro), mean generation time (T), intrinsic rate of increase (r m), and finite rate of increase (λ)...
May 8, 2017: Neotropical Entomology
https://www.readbyqxmd.com/read/28481307/histopathological-effects-of-bt-and-tcda-insecticidal-proteins-on-the-midgut-epithelium-of-western-corn-rootworm-larvae-diabrotica-virgifera-virgifera
#8
Andrew J Bowling, Heather E Pence, Huarong Li, Sek Yee Tan, Steven L Evans, Kenneth E Narva
Western corn rootworm (WCR, Diabrotica virgifera virgifera LeConte) is a major corn pest in the United States, causing annual losses of over $1 billion. One approach to protect against crop loss by this insect is the use of transgenic corn hybrids expressing one or more crystal (Cry) proteins derived from Bacillus thuringiensis. Cry34Ab1 and Cry35Ab1 together comprise a binary insecticidal toxin with specific activity against WCR. These proteins have been developed as insect resistance traits in commercialized corn hybrids resistant to WCR feeding damage...
May 8, 2017: Toxins
https://www.readbyqxmd.com/read/28430986/field-trial-performance-of-herculex-xtra-cry34ab1-cry35ab1-and-smartstax-cry34ab1-cry35ab1-cry3bb1-hybrids-and-soil-insecticides-against-western-and-northern-corn-rootworms-coleoptera-chrysomelidae
#9
K D Johnson, L A Campbell, M D Lepping, D M Rule
Western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), and northern corn rootworm, Diabrotica barberi Smith and Lawrence (Coleoptera: Chrysomelidae), are important insect pests in corn, Zea mays L. For more than a decade, growers have been using transgenic plants expressing proteins from the bacterium Bacillus thuringiensis (Bt) to protect corn roots from feeding. In 2011, western corn rootworm populations were reported to have developed resistance to Bt hybrids expressing Cry3Bb1 and later found to be cross-resistant to hybrids expressing mCry3A and eCry3...
June 1, 2017: Journal of Economic Entomology
https://www.readbyqxmd.com/read/28369407/nitrogen-rate-effects-on-cry3bb1-and-cry3bb1-cry34-35ab1-expression-in-transgenic-corn-roots-resulting-root-injury-and-corn-rootworm-beetle-emergence
#10
T M Leaf, K R Ostlie
Nitrogen (N) application rates have been recommended historically for maximum economic yield of corn (Zea mays L.), but not for optimal expression or impacts of Bt (Bacillus thuringiensis Berliner) Cry protein(s) on target insects. This study explored the need to adjust N rates to optimize expression of corn rootworm-active Bt (Bt-RW) protein(s) in a single and a pyramided trait hybrid and resulting impacts on beetle emergence and root injury, under field conditions. The experiment featured a factorial treatment arrangement in a split-plot randomized complete block design with six N rates as the main plots and three hybrids (MON88017 expressing Cry3Bb1, MON88017 x DAS-59122 expressing Cry3Bb1 + Cry34/35Ab1, and a non-Bt-RW hybrid) as the subplots...
June 1, 2017: Journal of Economic Entomology
https://www.readbyqxmd.com/read/28358336/patterns-of-gene-expression-in-western-corn-rootworm-diabrotica-virgifera-virgifera-neonates-challenged-with-cry34ab1-cry35ab1-and-cry34-35ab1-based-on-next-generation-sequencing
#11
Haichuan Wang, Seong-Il Eyun, Kanika Arora, Sek Yee Tan, Premchand Gandra, Etsuko Moriyama, Chitvan Khajuria, Jessica Jurzenski, Huarong Li, Maia Donahue, Ken Narva, Blair Siegfried
With Next Generation Sequencing technologies, high-throughput RNA sequencing (RNAseq) was conducted to examine gene expression in neonates of Diabrotica virgifera virgifera (LeConte) (Western Corn Rootworm, WCR) challenged with individual proteins of the binary Bacillus thuringiensis insecticidal proteins, Cry34Ab1 and Cry35Ab1, and the combination of Cry34/Cry35Ab1, which together are active against rootworm larvae. Integrated results of three different statistical comparisons identified 114 and 1300 differentially expressed transcripts (DETs) in the Cry34Ab1 and Cry34/35Ab1 treatment, respectively, as compared to the control...
March 30, 2017: Toxins
https://www.readbyqxmd.com/read/28334330/survivorship-of-z-pheromone-race-european-corn-borer-lepidoptera-crambidae-on-a-range-of-host-plants-varying-in-defensive-chemistry
#12
Kelsey E Fisher, Charles E Mason, J Lindsey Flexner, Judith Hough-Goldstein, John H McDonald
The European corn borer, Ostrinia nubilalis (Hübner), was introduced in North America in the early 1900s and became a major pest of corn. After its introduction, it was found on > 200 other plant hosts, but corn remained its primary host. Early life history studies indicated that European corn borer had the potential of a wide host range. For nearly 80 yr before the introduction of Bt corn, the European corn borer was a major pest of corn in North America. This study investigated the growth and survivorship of the Z-pheromone race European corn borer on a range of hosts that vary in defensive chemistries and historic degree of infestation to better understand the current host plant range of Z-pheromone race of O...
June 1, 2017: Journal of Economic Entomology
https://www.readbyqxmd.com/read/28326506/influence-of-calcareous-soil-on-cry3bb1-expression-and-efficacy-in-the-field
#13
David S Wangila, Arnubio Valencia J, Haichuan Wang, Blair D Siegfried, Lance J Meinke
Greater than expected injury by western corn rootworm (WCR) (Diabrotica virgifera virgifera LeConte) to Cry3Bb1 expressing maize hybrids (Zea mays L.) has been reported in southwestern Nebraska. Affected areas of some fields are often associated with high pH calcareous soils where maize growth is poor and iron chlorosis is common. As part of a comprehensive study to understand potential causes of unexpected injury, experiments were conducted during 2013 and 2014 to ascertain whether the calcareous soil conditions and associated poor maize growth negatively affect the expression of Cry3Bb1...
June 2017: Transgenic Research
https://www.readbyqxmd.com/read/28186125/responses-of-the-cutworm-spodoptera-litura-lepidoptera-noctuidae-to-two-bt-corn-hybrids-expressing-cry1ab
#14
Shu Yinghua, Du Yan, Chen Jin, Wei Jiaxi, Wang Jianwu
To examine the responses of the secondary lepidopteran pest Spodoptera litura to two Bacillus thuringiensis (Bt) corn hybrids [5422Bt1 (Event Bt11), 5422CBCL (MON810)] expressing Cry1Ab, larval bioassays with Cry1Ab toxin, corn leaves or kernels and bagging on corn plants were conducted. The results showed that larvae displayed a similar performance when fed kernels, but not leaves of 5422Bt1, 5422CBCL and their near-isogenic non-Bt corn (5422). Significantly higher Cry1Ab amounts were detected in larvae fed leaves than kernels of both Bt hybrids, with different molecular weights of protein band in plants (72 and 90 kDa for 5422Bt1 and 5422CBCL, respectively), gut contents (65 kDa), feces (50 kDa), which indicated that larvae had lower ingestion, higher degradation and excretion of Cry1Ab when fed kernels not leaves of both Bt hybrids...
February 10, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28073978/effects-of-bt-corn-and-egg-density-on-western-corn-rootworm-coleoptera-chrysomelidae-adult-emergence-and-estimation-of-effective-bt-dose
#15
L A Campbell, P L Prasifka, N P Storer, D M Rule, W H Hendrix
Since 2003, rootworm-protected transgenic corn has been commercially deployed in the United States as a principal method of control of western corn rootworm, Diabrotica virgifera virgifera LeConte. Durability of this technology depends partly on larval mortality ("dose") exerted by the traits, but density-dependent mortality can confound calculations of dose. Research reported here examined the effects of density-dependent mortality on adult emergence and estimates of trait dose. At sites in Illinois and Indiana, western corn rootworm eggs were infested at four densities on non-Bt corn and at a single density on corn hybrids with transgenic events MON 88017 (VT Triple PRO), DAS-59122-7 (Herculex Insect Protection), and MON 88017 × DAS-59122-7 (SmartStax corn)...
April 1, 2017: Journal of Economic Entomology
https://www.readbyqxmd.com/read/28073976/effects-of-carriers-emulsifiers-and-biopesticides-for-direct-silk-treatments-on-caterpillar-feeding-damage-and-ear-development-in-sweet-corn
#16
P J Westgate, B B Schultz, R V Hazzard
In the northeastern United States, control of Lepidopteran pests of sweet corn, particularly corn earworm [Helicoverpa zea (Boddie)], is difficult using organic methods. The direct application of corn oil and Bacillus thuringiensis (Bt) to corn silk has been shown to reduce ear damage from corn earworm in past studies; these studies sought to optimize this method by evaluating additional carrier and biopesticide mixtures that comply with the United States Federal Insecticide, Fungicide, and Rodenticide Act and National Organic Standards...
April 1, 2017: Journal of Economic Entomology
https://www.readbyqxmd.com/read/28060922/cry3bb1-resistant-western-corn-rootworm-diabrotica-virgifera-virgifera-leconte-does-not-exhibit-cross-resistance-to-dvsnf7-dsrna
#17
William Moar, Chitvan Khajuria, Michael Pleau, Oliver Ilagan, Mao Chen, Changjian Jiang, Paula Price, Brian McNulty, Thomas Clark, Graham Head
BACKGROUND AND METHODOLOGY: There is a continuing need to express new insect control compounds in transgenic maize against western corn rootworm, Diabrotica virgifera virgifera (LeConte) (WCR). In this study three experiments were conducted to determine cross-resistance between the new insecticidal DvSnf7 dsRNA, and Bacillus thuringiensis (Bt) Cry3Bb1; used to control WCR since 2003, with field-evolved resistance being reported. Laboratory susceptible and Cry3Bb1-resistant WCR were evaluated against DvSnf7 dsRNA in larval diet-incorporation bioassays...
2017: PloS One
https://www.readbyqxmd.com/read/28006032/evaluation-of-bt-corn-with-pyramided-genes-on-efficacy-and-insect-resistance-management-for-the-asian-corn-borer-in-china
#18
Fan Jiang, Tiantao Zhang, Shuxiong Bai, Zhenying Wang, Kanglai He
A Bt corn hybrid (AcIe) with two Bt genes (cry1Ie and cry1Ac) was derived by breeding stack from line expressing Cry1Ie and a line expressing Cry1Ac. Efficacy of this pyramided Bt corn hybrid against the Asian corn borer (ACB), Ostrinia furnacalis, was evaluated. We conducted laboratory bioassays using susceptible and resistant ACB strains fed on artificial diet or fresh plant tissues. We also conducted field trials with artificial infestations of ACB neonates at the V6 and silk stages. The toxin-diet bioassay data indicated that mixtures of Cry1Ac and Cry1Ie proteins had synergistic insecticidal efficacy...
2016: PloS One
https://www.readbyqxmd.com/read/27907051/battle-in-the-new-world-helicoverpa-armigera-versus-helicoverpa-zea-lepidoptera-noctuidae
#19
José P F Bentivenha, Silvana V Paula-Moraes, Edson L L Baldin, Alexandre Specht, Ivana F da Silva, Thomas E Hunt
The corn earworm Helicoverpa zea (Boddie) and the old world bollworm Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) are allopatric species and occur in important agricultural crops. In maize, both species tend to infest the ear. The introduction of H. armigera in Brazil has created a new scenario, where these Helicoverpa species might cohabit and interact with one another, affecting the prevalence of each species in the agroecosystem, integrated pest management, and insect resistance management. In this study, larval occurrence and proportion of these species in maize was assessed in three regions of Brazil during three crop seasons...
2016: PloS One
https://www.readbyqxmd.com/read/27782120/genetic-hitchhiking-and-resistance-evolution-to-transgenic-bt-toxins-insights-from-the-african-stalk-borer-busseola-fusca-noctuidae
#20
P Campagne, C Capdevielle-Dulac, R Pasquet, S J Cornell, M Kruger, J-F Silvain, B LeRü, J Van den Berg
Since transgenic crops expressing Bacillus thuringiensis (Bt) toxins were first released, resistance evolution leading to failure in control of pests populations has been observed in a number of species. Field resistance of the moth Busseola fusca was acknowledged 8 years after Bt maize was introduced in South Africa. Since then, field resistance of this corn borer has been observed at several locations, raising questions about the nature, distribution and dynamics of the resistance trait. Using genetic markers, our study identified four outlier loci clearly associated with resistance...
April 2017: Heredity
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