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Alagarsamy M, Karuppan S, Amal TC, Markkandan K. Sequencing and analysis of the complete mitochondrial genome of Amrasca biguttula biguttula Ishida, 1913 (Hemiptera: Cicadellidae: Typhlocybinae: Empoascini). Mitochondrial DNA B Resour 2024; 9:725-728. [PMID: 38859916 PMCID: PMC11164192 DOI: 10.1080/23802359.2024.2358958] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Accepted: 05/17/2024] [Indexed: 06/12/2024] Open
Abstract
The complete mitogenome of the cotton leafhopper, Amrasca biguttula biguttula Ishida, 1913, was sequenced and annotated. The mitogenome is 14,474 bp long and contains 37 genes, including 13 protein-coding genes (PCGs), two ribosomal RNA (rRNA) genes, and 22 transfer RNA (tRNA) genes, as well as a control region. The nucleotide composition of the mitogenome is as follows: A, 39.17%; T, 39.3%; C, 11.13%; and G, 10.39%. The total length of the 13 PCGs is 10,496 bp, which encodes 3503 amino acids. All PCGs start with the ATG codon, except for ATA, ATC, GTG, and ATT. Most of the PCGs stop with TGA, and the remaining with CCT, GAA, GGT, TCA, CCA, CTA, TTA, AAA, ATT, or ATA. The phylogenetic tree shows that A. biguttula biguttula belongs to Empoascini of the subfamily Typhlocybinae, but is different from other species within the subfamily.
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Affiliation(s)
| | | | - Thomas Cheeran Amal
- ICAR-Central Institute for Cotton Research, Regional Station, Coimbatore, India
| | - Kesavan Markkandan
- Oneomics Private Limited, Bharathidasan University Technology Park, Tiruchirappalli, India
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Sohi M, Pitesky M, Gendreau J. Analyzing public sentiment toward GMOs via social media between 2019-2021. GM CROPS & FOOD 2023; 14:1-9. [PMID: 36947744 PMCID: PMC10038016 DOI: 10.1080/21645698.2023.2190294] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/24/2023]
Abstract
Genetically modified organisms or GMOs offer significant advantages in food production, including increased yield, decreased pesticide usage, and better disease resistance. However, adoption and public sentiment toward GMOs is highly variable. Without positive sentiment toward GMOs, consumption of GMO-based foods may not have an adequate market for further investment. In order to better understand overall public sentiment toward GMO-based foods, a Boolean search was created using a commercial web-crawling service to collect and analyze public sentiment of GMOs across multiple social media and web-based services from May 1, 2019, to May 31, 2021. The Boolean query identified 2 million mentions of GMOs during the study period. Using the commercial software's sentiment analysis (i.e. classifying mentions as either neutral, negative, or positive), 54% of the mentions were categorized as having a neutral sentiment, 32% as having a negative sentiment, and 14% as having a positive sentiment. Further emotional analysis (classifying posts by the emotion expressed, e.g., disgust, joy, sadness, anger, fear, surprise) produced by the software shows that the majority of the mentions were categorized as expressing a negative emotion: 31% of mentions expressed disgust, 28% joy, 18% sadness, 16% anger, 7% fear, and 1% surprise. Among the various social media sources collected, Twitter was the main source of data, providing 62% of the total 2 million mentions, followed by 14% from news sources and 12% from Reddit. These types of data can be used to better understand trends in sentiment toward GMOs and ultimately play an important role in combating mis-information.
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Affiliation(s)
- Manreet Sohi
- Department of Computer Science, School of Letters and Science, University of California, Davis, CA, USA
| | - Maurice Pitesky
- Department of Population Health and Reproduction, School of Veterinary Medicine-Cooperative Extension, University of California, Davis, CA, USA
| | - Joseph Gendreau
- Department of Population Health and Reproduction, School of Veterinary Medicine-Cooperative Extension, University of California, Davis, CA, USA
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Orbović V, Ravanfar SA, Achor DS, Shilts T, Ibanez-Carrasco F, Banerjee R, El-Mohtar C, Stelinski LL, Bonning BC. Cry1Ba1-mediated toxicity of transgenic Bergera koenigii and Citrus sinensis to the Asian citrus psyllid Diaphorina citri. FRONTIERS IN INSECT SCIENCE 2023; 3:1125987. [PMID: 38469526 PMCID: PMC10926525 DOI: 10.3389/finsc.2023.1125987] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Accepted: 04/06/2023] [Indexed: 03/13/2024]
Abstract
The Asian citrus psyllid, Diaphorina citri, vectors the bacterial causative agent of citrus greening disease, which has severely impacted citrus production on a global scale. As the current repeated application of chemical insecticides is unsustainable for management of this insect and subsequent protection of groves, we investigated the potential use of the bacteria-derived pesticidal protein, Cry1Ba1, when delivered via transgenic citrus plants. Having demonstrated transformation of the Indian curry leaf tree, Bergera koenigii, for Cry1Ba1 expression for use as a trap plant, we produced transgenic plants of Duncan grapefruit, Citrus paridisi, Valencia sweet orange, Citrus sinensis, and Carrizo citrange, C. sinensis x Poncirus trifoliata, for expression of Cry1Ba1. The presence of the cry1ba1 gene, and cry1ba1 transcription were confirmed. Western blot detection of Cry1Ba1 was confirmed in most cases. When compared to those from wild-type plants, leaf discs from transgenic Duncan and Valencia expressing Cry1Ba1 exhibited a "delayed senescence" phenotype, similar to observations made for transgenic B. koenigii. In bioassays, significant reductions in the survival of adult psyllids were noted on transgenic B. koenigii and Valencia sweet orange plants expressing Cry1Ba1, but not on transgenic Duncan grapefruit or Carrizo citrange. In contrast to psyllids fed on wild type plants, the gut epithelium of psyllids fed on transgenic plants was damaged, consistent with the mode of action of Cry1Ba1. These results indicate that the transgenic expression of a bacterial pesticidal protein in B. koenigii and Valencia sweet orange offers a viable option for management of D. citri, that may contribute to solutions that counter citrus greening disease.
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Affiliation(s)
- Vladimir Orbović
- Citrus Research and Education Center, Institute of Food and Agricultural Sciences (IFAS), University of Florida, Lake Alfred, FL, United States
| | - Seyed Ali Ravanfar
- Citrus Research and Education Center, Institute of Food and Agricultural Sciences (IFAS), University of Florida, Lake Alfred, FL, United States
| | - Diann S. Achor
- Citrus Research and Education Center, Institute of Food and Agricultural Sciences (IFAS), University of Florida, Lake Alfred, FL, United States
| | - Turksen Shilts
- Citrus Research and Education Center, Institute of Food and Agricultural Sciences (IFAS), University of Florida, Lake Alfred, FL, United States
| | - Freddy Ibanez-Carrasco
- Citrus Research and Education Center, Institute of Food and Agricultural Sciences (IFAS), University of Florida, Lake Alfred, FL, United States
| | - Rahul Banerjee
- Entomology and Nematology Department, Institute of Food and Agricultural Sciences (IFAS), University of Florida, Gainesville, FL, United States
| | - Choaa El-Mohtar
- Citrus Research and Education Center, Institute of Food and Agricultural Sciences (IFAS), University of Florida, Lake Alfred, FL, United States
| | - Lukasz L. Stelinski
- Citrus Research and Education Center, Institute of Food and Agricultural Sciences (IFAS), University of Florida, Lake Alfred, FL, United States
| | - Bryony C. Bonning
- Entomology and Nematology Department, Institute of Food and Agricultural Sciences (IFAS), University of Florida, Gainesville, FL, United States
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Santiago-González JC, Kerns DL, Head GP, Yang F. A Modified F2 Screen for Estimating Cry1Ac and Cry2Ab Resistance Allele Frequencies in Helicoverpa zea (Lepidoptera: Noctuidae). JOURNAL OF ECONOMIC ENTOMOLOGY 2023; 116:289-296. [PMID: 36610074 DOI: 10.1093/jee/toac181] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Indexed: 05/30/2023]
Abstract
Evaluating the frequency of resistance alleles is important for resistance management and sustainable use of transgenic crops that produce insecticidal proteins from Bacillus thuringiensis. Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae) is a major crop pest in the United States that has evolved practical resistance to the crystalline (Cry) proteins in Bt corn and cotton. The standard F2 screen for estimating resistance allele frequency does not work well for H. zea because successful single-pair matings are rare. In this study, we developed and implemented a modified F2 screen for H. zea that generates F1 progeny by crossing three laboratory susceptible female moths with one feral male moth instead of single-pair crosses. During 2019-2020, we used this modified method to establish 192 F2 families from 623 matings between susceptible females and feral males from Arkansas, Louisiana, Mississippi, and Tennessee. From each F2 family, we screened 128 neonates against discriminating concentrations of Cry1Ac and Cry2Ab in diet overlay bioassays. Based on these discriminating concentration bioassays, families were considered positive for resistance if at least five larvae survived to second instar, including at least one to third instar. The percentage of positive families was 92.7% for Cry1Ac and 38.5% for Cry2Ab, which yields an estimated resistance allele frequency (with 95% confidence interval) of 0.722 (0.688-0.764) for Cry1Ac and 0.217 (0.179-0.261) for Cry2Ab. The modified F2 screen developed and implemented here may be useful for future resistance monitoring studies of H. zea and other pests.
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Affiliation(s)
| | - David L Kerns
- Department of Entomology, Texas A&M University, College Station, TX, USA
| | | | - Fei Yang
- Department of Entomology, Texas A&M University, College Station, TX, USA
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Reisig D, Buntin GD, Greene JK, Paula-Moraes SV, Reay-Jones F, Roberts P, Smith R, Taylor SV. Magnitude and Extent of Helicoverpa zea Resistance Levels to Cry1Ac and Cry2Ab2 across the Southeastern USA. INSECTS 2023; 14:262. [PMID: 36975947 PMCID: PMC10058025 DOI: 10.3390/insects14030262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 02/27/2023] [Accepted: 03/02/2023] [Indexed: 06/18/2023]
Abstract
After resistance is first detected, continued resistance monitoring can inform decisions on how to effectively manage resistant populations. We monitored for resistance to Cry1Ac (2018 and 2019) and Cry2Ab2 (2019) from southeastern USA populations of Helicoverpa zea. We collected larvae from various plant hosts, sib-mated the adults, and tested neonates using diet-overlay bioassays and compared them to susceptible populations for resistance estimates. We also compared LC50 values with larval survival, weight and larval inhibition at the highest dose tested using regression, and found that LC50 values were negatively correlated with survival for both proteins. Finally, we compared resistance rations between Cry1Ac and Cry2Ab2 during 2019. Some populations were resistant to Cry1Ac, and most were resistant to CryAb2; Cry1Ac resistance ratios were lower than Cry2Ab2 during 2019. Survival was positively correlated with larval weight inhibition for Cry2Ab. This contrasts with other studies in both the mid-southern and southeastern USA, where resistance to Cry1Ac, Cry1A.105, and Cry2Ab2 increased over time and was found in a majority of populations. This indicates that cotton expressing Cry proteins in the southeastern USA was at variable risk for damage in this region.
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Affiliation(s)
- Dominic Reisig
- Department of Entomology, The Vernon James Center, North Carolina State University, Plymouth, NC 27962, USA
| | - G. David Buntin
- Department of Entomology, University of Georgia, Tifton, GA 31793, USA
| | - Jeremy K. Greene
- Department of Plant and Environmental Sciences, Clemson University, Blackville, SC 29817, USA
| | | | - Francis Reay-Jones
- Department of Plant and Environmental Sciences, Clemson University, Blackville, SC 29817, USA
| | - Phillip Roberts
- Department of Entomology, University of Georgia, Tifton, GA 31793, USA
| | - Ron Smith
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL 36849, USA
| | - Sally V. Taylor
- Department of Entomology, Virginia Polytechnic Institute and State University, Suffolk, VA 23437, USA
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Zhuang Y, Sharif Y, Zeng X, Chen S, Chen H, Zhuang C, Deng Y, Ruan M, Chen S, Weijian Z. Molecular cloning and functional characterization of the promoter of a novel Aspergillus flavus inducible gene ( AhOMT1) from peanut. FRONTIERS IN PLANT SCIENCE 2023; 14:1102181. [PMID: 36844094 PMCID: PMC9947529 DOI: 10.3389/fpls.2023.1102181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Accepted: 01/06/2023] [Indexed: 06/18/2023]
Abstract
Peanut is an important oil and food legume crop grown in more than one hundred countries, but the yield and quality are often impaired by different pathogens and diseases, especially aflatoxins jeopardizing human health and causing global concerns. For better management of aflatoxin contamination, we report the cloning and characterization of a novel A. flavus inducible promoter of the O-methyltransferase gene (AhOMT1) from peanut. The AhOMT1 gene was identified as the highest inducible gene by A. flavus infection through genome-wide microarray analysis and verified by qRT-PCR analysis. AhOMT1 gene was studied in detail, and its promoter, fussed with the GUS gene, was introduced into Arabidopsis to generate homozygous transgenic lines. Expression of GUS gene was studied in transgenic plants under the infection of A. flavus. The analysis of AhOMT1 gene characterized by in silico assay, RNAseq, and qRT-PCR revealed minute expression in different organs and tissues with trace or no response to low temperature, drought, hormones, Ca2+, and bacterial stresses, but highly induced by A. flavus infection. It contains four exons encoding 297 aa predicted to transfer the methyl group of S-adenosyl-L-methionine (SAM). The promoter contains different cis-elements responsible for its expression characteristics. Functional characterization of AhOMT1P in transgenic Arabidopsis plants demonstrated highly inducible behavior only under A. flavus infection. The transgenic plants did not show GUS expression in any tissue(s) without inoculation of A. flavus spores. However, GUS activity increased significantly after inoculation of A. flavus and maintained a high level of expression after 48 hours of infection. These results provided a novel way for future management of peanut aflatoxins contamination through driving resistance genes in A. flavus inducible manner.
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Affiliation(s)
- Yuhui Zhuang
- Center of Legume Plant Genetics and Systems Biology, College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, China
- College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Yasir Sharif
- Center of Legume Plant Genetics and Systems Biology, College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Xiaohong Zeng
- Center of Legume Plant Genetics and Systems Biology, College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Suzheng Chen
- Center of Legume Plant Genetics and Systems Biology, College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Hua Chen
- Center of Legume Plant Genetics and Systems Biology, College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Chunhong Zhuang
- Center of Legume Plant Genetics and Systems Biology, College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Ye Deng
- Center of Legume Plant Genetics and Systems Biology, College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, China
| | | | | | - Zhuang Weijian
- Center of Legume Plant Genetics and Systems Biology, College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, China
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Santiago-González JC, Kerns DL, Yang F. Resistance Allele Frequency of Helicoverpa zea to Vip3Aa Bacillus thuringiensis Protein in the Southeastern U.S. INSECTS 2023; 14:161. [PMID: 36835730 PMCID: PMC9958976 DOI: 10.3390/insects14020161] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Revised: 01/23/2023] [Accepted: 02/03/2023] [Indexed: 06/18/2023]
Abstract
Helicoverpa zea is a major target pest of Bt crops expressing Cry and/or Vip3Aa proteins in the U.S.A. Widespread practical resistance of H. zea to the Cry1 and Cry2 proteins makes Vip3Aa the only effective Bt protein against this pest. Understanding the frequency of resistance alleles against Vip3Aa in field populations of H. zea is crucial for resistance management and the sustainability of Vip3Aa technology. Using a modified F2 screen method by crossing susceptible laboratory female moth with feral male moth of H. zea, we successfully screened a total of 24,576 neonates from 192 F2 families of H. zea collected from Arkansas, Louisiana, Mississippi, and Tennessee during 2019-2020. We found five F2 families containing ≥3rd instar survivors on the diagnostic concentration of 3.0 µg/cm2 Vip3Aa39. Dose-response bioassays confirmed the high levels of Vip3Aa resistance in these F2 families, with an estimated resistance ratio of >909.1-fold relative to the susceptible strain. The estimated resistance allele frequency against Vip3Aa in H. zea for these four southern states is 0.0155 with a 95% CI of 0.0057-0.0297. These data should provide critical information for understanding the risks of Vip3Aa resistance in H. zea and help design appropriate resistance management strategies for the sustainability of the Vip3Aa technology.
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Gassmann AJ, Reisig DD. Management of Insect Pests with Bt Crops in the United States. ANNUAL REVIEW OF ENTOMOLOGY 2023; 68:31-49. [PMID: 36170641 DOI: 10.1146/annurev-ento-120220-105502] [Citation(s) in RCA: 25] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Genetically engineered corn and cotton that produce insecticidal toxins derived from the bacterium Bacillus thuringiensis (Bt) have been used to manage insect pests in the United States and elsewhere. In some cases, this has led to regional suppression of pest populations and pest eradication within the United States, and these outcomes were associated with reductions in conventional insecticides and increased profits for farmers. In other instances, pests evolved resistance to multiple Bt traits, compromising the capacity of Bt crops to manage pests and leading to increased feeding injury to crops in the field. Several aspects of pest biology and pest-crop interactions were associated with cases where pests remained susceptible versus instances where pests evolved resistance. The viability of future transgenic traits can be improved by learning from these past outcomes. In particular, efforts should be made to delay resistance by increasing the prevalence of refuges and using integrated pest management.
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Affiliation(s)
- Aaron J Gassmann
- Department of Plant Pathology, Entomology and Microbiology, Iowa State University, Ames, Iowa, USA;
| | - Dominic D Reisig
- Department of Entomology and Plant Pathology, North Carolina State University, Plymouth, North Carolina, USA
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Yang F, Kerns DL, Little N, Brown SA, Stewart SD, Catchot AL, Cook DR, Gore J, Crow WD, Lorenz GM, Towles T, Tabashnik BE. Practical resistance to Cry toxins and efficacy of Vip3Aa in Bt cotton against Helicoverpa zea. PEST MANAGEMENT SCIENCE 2022; 78:5234-5242. [PMID: 36053801 DOI: 10.1002/ps.7142] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2022] [Revised: 08/14/2022] [Accepted: 08/23/2022] [Indexed: 06/15/2023]
Abstract
BACKGROUND Crops genetically engineered to make insect-killing proteins from Bacillus thuringiensis (Bt) have revolutionized management of some pests. However, the benefits of such transgenic crops are reduced when pests evolve resistance to Bt toxins. We evaluated resistance to Bt toxins and Bt cotton plants using laboratory bioassays and complementary field trials focusing on Helicoverpa zea, one of the most economically important pests of cotton and other crops in the United States. RESULTS The data from 235 laboratory bioassays demonstrate resistance to Cry1Ac, Cry1Fa, and Cry2Ab occurred in most of the 95 strains of H. zea derived from Arkansas, Louisiana, Mississippi, Tennessee, and Texas during 2016 to 2021. Complementary field data show efficacy decreased for Bt cotton producing Cry1Ac + Cry1Fa or Cry1Ac + Cry2Ab, but not Cry1Ac + Cry1Fa + Vip3Aa. Moreover, analysis of data paired by field site and year shows higher survival in bioassays was generally associated with lower efficacy of Bt cotton. CONCLUSIONS The results confirm and extend previous evidence showing widespread practical resistance of H. zea in the United States to the Cry toxins produced by Bt cotton and corn, but not to Vip3Aa. Despite deployment in combination with Cry toxins in Bt crops, Vip3Aa effectively acts as a single toxin against H. zea larvae that are highly resistant to Cry toxins. Furthermore, Vip3Aa adoption is increasing and previous work provided an early warning of field-evolved resistance. Thus, rigorous resistance management measures are needed to preserve the efficacy of Vip3Aa against this highly adaptable pest. © 2022 Society of Chemical Industry.
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Affiliation(s)
- Fei Yang
- Department of Entomology, Texas A&M University, College Station, TX, USA
| | - David L Kerns
- Department of Entomology, Texas A&M University, College Station, TX, USA
| | - Nathan Little
- Southern Insect Management Research Unit, USDA-ARS, Stoneville, MS, USA
| | - Sebe A Brown
- Department of Entomology and Plant Pathology, University of Tennessee, Jackson, TN, USA
| | - Scott D Stewart
- Department of Entomology and Plant Pathology, University of Tennessee, Jackson, TN, USA
| | - Angus L Catchot
- Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology, Mississippi State University, Mississippi State, MS, USA
| | - Donald R Cook
- Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology, Mississippi State University, Mississippi State, MS, USA
| | - Jeffrey Gore
- Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology, Mississippi State University, Mississippi State, MS, USA
| | - Whitney D Crow
- Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology, Mississippi State University, Mississippi State, MS, USA
| | - Gustav M Lorenz
- Department of Entomology and Plant Pathology, University of Arkansas, Lonoke, AR, USA
| | - Tyler Towles
- Department of Entomology, Louisiana State University, Winnsboro, LA, USA
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Santiago-González JC, Kerns DL, Head GP, Yang F. Effective dominance and redundant killing of single- and dual-gene resistant populations of Helicoverpa zea on pyramided Bt corn and cotton. PEST MANAGEMENT SCIENCE 2022; 78:4333-4339. [PMID: 35750998 DOI: 10.1002/ps.7052] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 06/13/2022] [Accepted: 06/24/2022] [Indexed: 06/15/2023]
Abstract
BACKGROUND Pyramided Bacillus thuringiensis (Bt) crops producing multiple Bt proteins with different modes of action are widely planted in the United States. Helicoverpa zea is a major target pest of pyramided Bt crops and has evolved practical resistance to both Cry1 and Cry2 proteins in some regions of U.S. However, little information is available regarding redundant killing and the dominance of resistance for insects possessing multiple resistance on pyramided Bt crops. In this study, we evaluated redundant killing and the dominance of resistance for H. zea strains resistant to Cry1 or Cry1 + Cry2 on pyramided Bt corn and cotton. RESULTS We found that the Cry1-resistant H. zea was incompletely dominant on Cry1Ac + Cry1F cotton. Pyramided crops producing Cry2 and/or Vip3Aa proteins showed a complete redundant killing against the Cry1-resistant H. zea. The Cry1 + Cry2-resistant H. zea displayed incompletely recessive to completely dominant resistance on pyramided Bt crops containing Cry1 and/or Cry2 proteins. The redundant killing was complete for the Cry1 + Cry2-resistant H. zea on pyramided Bt crops producing Vip3Aa protein. CONCLUSION The dominant resistance of Cry1 and Cry2 in H. zea on pyramided Bt crops deviates from the assumption of functionally recessive resistance underlying the high-dose refuge strategy. However, the assumptions of complete redundant killing are achieved for both Cry1- and Cry1 + Cry2-resistant H. zea on pyramided Bt crops. These results suggest that the pyramided strategy could be valuable for increasing the durability of Bt technology for managing H. zea, a pest with inherently low susceptibility against Cry proteins. © 2022 Society of Chemical Industry.
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Affiliation(s)
| | - David L Kerns
- Department of Entomology, Texas A&M University, College Station, TX, USA
| | | | - Fei Yang
- Department of Entomology, Texas A&M University, College Station, TX, USA
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11
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Godbold RE, Crow WD, Catchot AL, Gore J, Cook DR, Dodds DM, Musser FM, Little NS. Feeding Behavior and Fruiting Form Damage by Bollworm (Lepidoptera: Noctuidae) in Bt Cotton. JOURNAL OF ECONOMIC ENTOMOLOGY 2022; 115:160-167. [PMID: 34791314 DOI: 10.1093/jee/toab220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Indexed: 06/13/2023]
Abstract
Bt technologies have played a major role in the control of bollworm, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae), in cotton. Variation in expression levels among varieties and plant parts, along with selection pressure on bollworm populations, has led to the development of resistance to some Bt proteins. Trials were conducted to evaluate how cotton varieties expressing different Bt proteins affect bollworm larval behavior and their damage in flowering cotton. Differences in larval recovery were observed among cotton varieties at 3 d with 3-gene Bt cotton having the lowest recovery and non-Bt cotton having the greatest recovery. Loss of bloom tags and abscission of small bolls at the site of infestation affected bollworm larval recovery among varieties. Day after infestation was the main factor that affected bollworm movement across all varieties. Number of total damaged fruiting forms by an individual bollworm larva was different among all varieties. Overall, flower bud (square) and fruit (boll) damage by an individual larva was lower on 3-gene cotton than 2-gene cotton and non-Bt cotton. An individual larva damaged fewer squares on 2-gene cotton than non-Bt cotton, but boll damage from bollworm was similar among 2-gene cotton and non-Bt cotton. The level of square and boll damage in 2-gene cotton has increased compared to previous research further supporting the occurrence of bollworm resistance to Cry proteins. The 3-gene cotton containing the Vip3A gene experienced low levels of damage and survival. These results will be important for improving management recommendations of bollworm in Bt cotton technologies.
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Affiliation(s)
- R E Godbold
- Mississippi State University, Delta Research and Extension Center, P.O. Box 197, Stoneville, MS 38776, USA
| | - W D Crow
- Mississippi State University, Delta Research and Extension Center, P.O. Box 197, Stoneville, MS 38776, USA
| | - A L Catchot
- Mississippi State University, Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology, Mississippi State, MS 39762, USA
| | - J Gore
- Mississippi State University, Delta Research and Extension Center, P.O. Box 197, Stoneville, MS 38776, USA
| | - D R Cook
- Mississippi State University, Delta Research and Extension Center, P.O. Box 197, Stoneville, MS 38776, USA
| | - D M Dodds
- Mississippi State University, Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology, Mississippi State, MS 39762, USA
| | - F M Musser
- Mississippi State University, Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology, Mississippi State, MS 39762, USA
| | - N S Little
- USDA-ARS, Southern Insect Management Research Unit, Stoneville, MS 38776, USA
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12
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Ravanfar SA, Achor DS, Killiny N, Shilts T, Chen Y, El-Mohtar C, Stelinski LL, Bonning BC, Orbović V. Genetic Modification of Bergera koenigii for Expression of the Bacterial Pesticidal Protein Cry1Ba1. FRONTIERS IN PLANT SCIENCE 2022; 13:899624. [PMID: 35685021 PMCID: PMC9171844 DOI: 10.3389/fpls.2022.899624] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Accepted: 04/20/2022] [Indexed: 05/09/2023]
Abstract
The curry leaf tree, Bergera koenigii, is highly attractive to the Asian citrus psyllid, Diaphorina citri, which vectors the bacterial causative agent of citrus greening or huanglongbing disease. This disease has decimated citrus production in Florida and in other citrus-producing countries. As D. citri exhibits high affinity for feeding on young leaves of B. koenigii, transgenic B. koenigii expressing bacteria-derived pesticidal proteins such as Cry1Ba1 have potential for D. citri management when planted in or adjacent to citrus groves. Importantly, the plant pathogenic bacterium that causes citrus greening does not replicate in B. koenigii. Transgenic plants of B. koenigii were produced by insertion of the gene encoding the active core of the pesticidal protein Cry1Ba1 derived from Bacillus thuringiensis. The transformation success rate was low relative to that of other citrus, at 0.89%. T-DNA integration into the genome and cry1ba1 transcription in transgenic plants were confirmed. Transgenic plants expressing Cry1Ba1 differed from wild-type plants, differed in photosynthesis parameters and hormone levels in some instances, and a marked delay in wilting of detached leaves. The gut epithelium of D. citri fed on transgenic plants was severely damaged, consistent with Cry1Ba1-mediated pore formation, confirming expression of the pesticidal protein by transgenic B. koenigii. These results demonstrate that transgenic B. koenigii expressing bacteria-derived pesticidal proteins can be produced for potential use as trap plants for suppression of D. citri populations toward protection of citrus groves from citrus greening.
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Affiliation(s)
- Seyed Ali Ravanfar
- Citrus Research and Education Center, University of Florida, IFAS, Lake Alfred, FL, United States
| | - Diann S. Achor
- Citrus Research and Education Center, University of Florida, IFAS, Lake Alfred, FL, United States
| | - Nabil Killiny
- Citrus Research and Education Center, University of Florida, IFAS, Lake Alfred, FL, United States
| | - Turksen Shilts
- Citrus Research and Education Center, University of Florida, IFAS, Lake Alfred, FL, United States
| | - Yuting Chen
- Department of Entomology, Iowa State University, Ames, IA, United States
| | - Choaa El-Mohtar
- Citrus Research and Education Center, University of Florida, IFAS, Lake Alfred, FL, United States
| | - Lukasz L. Stelinski
- Citrus Research and Education Center, University of Florida, IFAS, Lake Alfred, FL, United States
| | - Bryony C. Bonning
- Entomology and Nematology Department, University of Florida, Gainesville, FL, United States
- *Correspondence: Bryony C. Bonning,
| | - Vladimir Orbović
- Citrus Research and Education Center, University of Florida, IFAS, Lake Alfred, FL, United States
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Lawrie RD, Mitchell RD, Deguenon JM, Ponnusamy L, Reisig D, Pozo-Valdivia AD, Kurtz RW, Roe RM. Characterization of Long Non-Coding RNAs in the Bollworm, Helicoverpa zea, and Their Possible Role in Cry1Ac-Resistance. INSECTS 2021; 13:12. [PMID: 35055855 PMCID: PMC8779162 DOI: 10.3390/insects13010012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 12/19/2021] [Accepted: 12/20/2021] [Indexed: 12/13/2022]
Abstract
Multiple insect pest species have developed field resistance to Bt-transgenic crops. There has been a significant amount of research on protein-coding genes that contribute to resistance, such as the up-regulation of protease activity or altered receptors. However, our understanding of the role of non-protein-coding mechanisms in Bt-resistance is minimal, as is also the case for resistance to chemical pesticides. To address this problem relative to Bt, RNA-seq was used to examine statistically significant, differential gene expression between a Cry1Ac-resistant (~100-fold resistant) and Cry1Ac-susceptible strain of Helicoverpa zea, a prevalent caterpillar pest in the USA. Significant differential expression of putative long non-coding RNAs (lncRNAs) was found in the Cry1Ac-resistant strain (58 up- and 24 down-regulated gene transcripts with an additional 10 found only in resistant and four only in susceptible caterpillars). These lncRNAs were examined as potential pseudogenes and for their genomic proximity to coding genes, both of which can be indicative of regulatory relationships between a lncRNA and coding gene expression. A possible pseudogenic lncRNA was found with similarities to a cadherin. In addition, putative lncRNAs were found significantly proximal to a serine protease, ABC transporter, and CYP coding genes, potentially involved in the mechanism of Bt and/or chemical insecticide resistance. Characterization of non-coding genetic mechanisms in Helicoverpa zea will improve the understanding of the genomic evolution of insect resistance, improve the identification of specific regulators of coding genes in general (some of which could be important in resistance), and is the first step for potentially targeting these regulators for pest control and resistance management (using molecular approaches, such as RNAi and others).
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Affiliation(s)
- Roger D. Lawrie
- Department of Entomology and Plant Pathology, North Carolina State University, Campus Box 7647, 3230 Ligon Street, Raleigh, NC 27695, USA; (R.D.L.); (R.D.M.III); (J.M.D.); (L.P.)
- Environmental and Molecular Toxicology Program, Department of Biology, College of Sciences, North Carolina State University, 2601 Stinson Drive, Raleigh, NC 27606, USA
| | - Robert D. Mitchell
- Department of Entomology and Plant Pathology, North Carolina State University, Campus Box 7647, 3230 Ligon Street, Raleigh, NC 27695, USA; (R.D.L.); (R.D.M.III); (J.M.D.); (L.P.)
- Office of Pesticide Programs, Invertebrate and Vertebrate Branch 1, Registration Division, U.S. Environmental Protection Agency, 1200 Pennsylvania Avenue, Washington, DC 20460, USA
| | - Jean Marcel Deguenon
- Department of Entomology and Plant Pathology, North Carolina State University, Campus Box 7647, 3230 Ligon Street, Raleigh, NC 27695, USA; (R.D.L.); (R.D.M.III); (J.M.D.); (L.P.)
| | - Loganathan Ponnusamy
- Department of Entomology and Plant Pathology, North Carolina State University, Campus Box 7647, 3230 Ligon Street, Raleigh, NC 27695, USA; (R.D.L.); (R.D.M.III); (J.M.D.); (L.P.)
| | - Dominic Reisig
- Vernon G. James Research & Extension Center, Department of Entomology and Plant Pathology, 207 Research Station Road, Plymouth, NC 27962, USA; (D.R.); (A.D.P.-V.)
| | - Alejandro Del Pozo-Valdivia
- Vernon G. James Research & Extension Center, Department of Entomology and Plant Pathology, 207 Research Station Road, Plymouth, NC 27962, USA; (D.R.); (A.D.P.-V.)
| | - Ryan W. Kurtz
- Cotton Incorporated, 6399 Weston Parkway, Cary, NC 27513, USA;
| | - Richard Michael Roe
- Department of Entomology and Plant Pathology, North Carolina State University, Campus Box 7647, 3230 Ligon Street, Raleigh, NC 27695, USA; (R.D.L.); (R.D.M.III); (J.M.D.); (L.P.)
- Environmental and Molecular Toxicology Program, Department of Biology, College of Sciences, North Carolina State University, 2601 Stinson Drive, Raleigh, NC 27606, USA
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Calvin W, Yang F, Brown SA, Catchot AL, Crow WD, Cook DR, Gore J, Kurtz R, Lorenz GM, Seiter NJ, Stewart SD, Towles T, Kerns DL. Development of Economic Thresholds Toward Bollworm (Lepidoptera: Noctuidae), Management in Bt Cotton, and Assessment of the Benefits From Treating Bt Cotton With Insecticide. JOURNAL OF ECONOMIC ENTOMOLOGY 2021; 114:2493-2504. [PMID: 34625803 DOI: 10.1093/jee/toab173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Indexed: 06/13/2023]
Abstract
Widespread field-evolved resistance of bollworm [Helicoverpa zea (Boddie)] to Cry1 and Cry2 Bt proteins has threatened the utility of Bt cotton for managing bollworm. Consequently, foliar insecticide applications have been widely adopted to provide necessary additional control. Field experiments were conducted across the Mid-South and in Texas to devise economic thresholds for foliar insecticide applications targeting bollworm in cotton. Bt cotton technologies including TwinLink (TL; Cry1Ab+Cry2Ae), TwinLink Plus (TLP; Cry1Ab+Cry2Ae+Vip3Aa), Bollgard II (BG2; Cry1Ac+Cry2Ab), Bollgard 3 (BG3; Cry1Ac+Cry2Ab+Vip3Aa), WideStrike (WS; Cry1Ac+Cry1F), WideStrike 3 (WS3; Cry1Ac+Cry1F+Vip3Aa), and a non-Bt (NBT) variety were evaluated. Gain threshold, economic injury level, and economic thresholds were determined. A 6% fruiting form injury threshold was selected and compared with preventive treatments utilizing chlorantraniliprole. Additionally, the differences in yield from spraying bollworms was compared among Bt cotton technologies. The 6% fruiting form injury threshold resulted in a 25 and 75% reduction in insecticide applications relative to preventive sprays for WS and BG2, respectively. All Bt technologies tested in the current study exhibited a positive increase in yield from insecticide application. The frequency of yield increase from spraying WS was comparable to that of NBT. Significant yield increases due to insecticide application occurred less frequently in triple-gene Bt cotton. However, their frequencies were close to the dual-gene Bt cotton, except for WS. The results of our study suggest that 6% fruiting form injury is a viable threshold, and incorporating a vetted economic threshold into an Integrated Pest Management program targeting bollworm should improve the sustainability of cotton production.
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Affiliation(s)
- Wilfrid Calvin
- Department of Entomology, Texas A&M University, 2475 TAMU, College Station, TX 77843, USA
| | - Fei Yang
- Department of Entomology, Texas A&M University, 2475 TAMU, College Station, TX 77843, USA
| | - Sebe A Brown
- Dean Lee Research Station, Louisisana State University, 8105 Tom Bowman Drive, Alexandria, LA 71302, USA
| | - Angus L Catchot
- Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology, Mississippi State University, P.O. Box 9775, Mississippi State, MS 39762, USA
| | - Whitney D Crow
- Delta REC, Mississippi State University, P.O. Box 197, Stoneville, MS 38776, USA
| | - Donald R Cook
- Delta REC, Mississippi State University, P.O. Box 197, Stoneville, MS 38776, USA
| | - Jeffrey Gore
- Delta REC, Mississippi State University, P.O. Box 197, Stoneville, MS 38776, USA
| | - Ryan Kurtz
- Cotton Incorporated, 6399 Weston Pkwy, Cary, NC 27513, USA
| | - Gustav M Lorenz
- Department of Entomology and Plant Pathology, University of Arkansas, 2001 Highway 70 E., Lonoke, AR 72086, USA
| | - Nicholas J Seiter
- Crop Sciences, 380 National Soybean Research Center, University of Illinois, 1101 W. Peabody Drive, Urbana, IL 61801, USA
| | - Scott D Stewart
- West Tennessee REC, University of Tennessee, 605 Airways Boulevard, Jackson, TN 38301, USA
| | - Tyler Towles
- Macon Ridge Research Station, Louisisana State University, 212A Macon Ridge Road, Winnsboro, LA 71295, USA
| | - David L Kerns
- Department of Entomology, Texas A&M University, 2475 TAMU, College Station, TX 77843, USA
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15
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Dorman SJ, Hopperstad KA, Reich BJ, Majumder S, Kennedy G, Reisig DD, Greene JK, Reay-Jones FP, Collins G, Bacheler JS, Huseth AS. Landscape-level variation in Bt crops predict Helicoverpa zea (Lepidoptera: Noctuidae) resistance in cotton agroecosystems. PEST MANAGEMENT SCIENCE 2021; 77:5454-5462. [PMID: 34333843 DOI: 10.1002/ps.6585] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2021] [Revised: 07/25/2021] [Accepted: 08/01/2021] [Indexed: 06/13/2023]
Abstract
BACKGROUND Helicoverpa zea (Boddie) damage to Bt cotton and maize has increased as a result of widespread Bt resistance across the USA Cotton Belt. Our objective was to link Bt crop production patterns to cotton damage through a series of spatial and temporal surveys of commercial fields to understand how Bt crop production relates to greater than expected H. zea damage to Bt cotton. To do this, we assembled longitudinal cotton damage data that spanned the Bt adoption period, collected cotton damage data since Bt resistance has been detected, and estimated local population susceptibility using replicated on-farm studies that included all Bt pyramids marketed in cotton. RESULTS Significant year effects of H. zea damage frequency in commercial cotton were observed throughout the Bt adoption period, with a recent damage increase after 2012. Landscape-level Bt crop production intensity over time was positively associated with the risk of H. zea damage in two- and three-toxin pyramided Bt cotton. Helicoverpa zea damage also varied across Bt toxin types in spatially replicated on-farm studies. CONCLUSIONS Landscape-level predictors of H. zea damage in Bt cotton can be used to identify heightened Bt resistance risk areas and serves as a model to understand factors that drive pest resistance evolution to Bt toxins in the southeastern United States. These results provide a framework for more effective insect resistance management strategies to be used in combination with conventional pest management practices that improve Bt trait durability while minimizing the environmental footprint of row crop agriculture. © 2021 Society of Chemical Industry. This article has been contributed to by US Government employees and their work is in the public domain in the USA.
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Affiliation(s)
- Seth J Dorman
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC, USA
- USDA-ARS Forage Seed and Cereal Research Unit, Corvallis, OR, USA
| | - Kristen A Hopperstad
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC, USA
| | - Brian J Reich
- Department of Statistics, North Carolina State University, Raleigh, NC, USA
| | - Suman Majumder
- Department of Statistics, North Carolina State University, Raleigh, NC, USA
| | - George Kennedy
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC, USA
| | - Dominic D Reisig
- Department of Entomology and Plant Pathology, North Carolina State University, Vernon James Research and Extension Center, Plymouth, NC, USA
| | - Jeremy K Greene
- Department of Plant and Environmental Sciences, Clemson University, Edisto Research and Education Center, Blackville, SC, USA
| | - Francis Pf Reay-Jones
- Department of Plant and Environmental Sciences, Clemson University, Pee Dee Research and Education Center, Florence, SC, USA
| | - Guy Collins
- Department of Crop and Soil Science, North Carolina State University, Raleigh, NC, USA
| | - Jack S Bacheler
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC, USA
| | - Anders S Huseth
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC, USA
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16
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Effectiveness of the natural resistance management refuge for Bt-cotton is dominated by local abundance of soybean and maize. Sci Rep 2021; 11:17601. [PMID: 34475501 PMCID: PMC8413434 DOI: 10.1038/s41598-021-97123-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Accepted: 08/18/2021] [Indexed: 11/18/2022] Open
Abstract
Genetically engineered crops expressing Bacillus thuringiensis (Bt) Cry toxins have transformed insect management in maize and cotton, reducing insecticide use and associated off-target effects. To mitigate the risk that pests evolve resistance to Bt crops, the US Environmental Protection Agency requires resistance management measures. The approved resistance management plan for Bt maize in cotton production regions requires a structured refuge of non-Bt maize equal to 20% of the maize planted; that for Bt cotton relies on the presence of an unstructured natural refuge comprising both non-Bt crop and non-crop hosts. We examined how abundance of Bt crops (cotton and maize) and an important non-Bt crop (soybean) component of the natural refuge affect resistance to Bt Cry1Ac toxin in local populations of Helicoverpa zea, an important lepidopteran pest impacted by Bt cotton and maize. We show refuge effectiveness is responsive to local abundances of maize and cotton and non-Bt soybean, and maize, in its role as a source of H. zea infesting cotton and non-Bt hosts, influences refuge effectiveness. These findings have important implications for commercial and regulatory decisions regarding deployment of Bt toxins targeting H. zea in maize, cotton, and other crops and for assumptions regarding efficacy of natural refuges.
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17
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Karthik K, Negi J, Rathinam M, Saini N, Sreevathsa R. Exploitation of Novel Bt ICPs for the Management of Helicoverpa armigera (Hübner) in Cotton ( Gossypium hirsutum L.): A Transgenic Approach. Front Microbiol 2021; 12:661212. [PMID: 33995323 PMCID: PMC8116509 DOI: 10.3389/fmicb.2021.661212] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Accepted: 03/18/2021] [Indexed: 12/02/2022] Open
Abstract
Cotton is a commercial crop of global importance. The major threat challenging the productivity in cotton has been the lepidopteron insect pest Helicoverpa armigera or cotton bollworm which voraciously feeds on various plant parts. Biotechnological interventions to manage this herbivore have been a universally inevitable option. The advent of plant genetic engineering and exploitation of Bacillus thuringiensis (Bt) insecticidal crystal proteins (ICPs) marked the beginning of plant protection in cotton through transgenic technology. Despite phenomenal success and widespread acceptance, the fear of resistance development in insects has been a perennial concern. To address this issue, alternate strategies like introgression of a combination of cry protein genes and protein-engineered chimeric toxin genes came into practice. The utility of chimeric toxins produced by domain swapping, rearrangement of domains, and other strategies aid in toxins emerging with broad spectrum efficacy that facilitate the avoidance of resistance in insects toward cry toxins. The present study demonstrates the utility of two Bt ICPs, cry1AcF (produced by domain swapping) and cry2Aa (produced by codon modification) in transgenic cotton for the mitigation of H. armigera. Transgenics were developed in cotton cv. Pusa 8–6 by the exploitation of an apical meristem-targeted in planta transformation protocol. Stringent trait efficacy-based selective screening of T1 and T2 generation transgenic plants enabled the identification of plants resistant to H. armigera upon deliberate challenging. Evaluation of shortlisted events in T3 generation identified a total of nine superior transgenic events with both the genes (six with cry1AcF and three with cry2Aa). The transgenic plants depicted 80–100% larval mortality of H. armigera and 10–30% leaf damage. Molecular characterization of the shortlisted transgenics demonstrated stable integration, inheritance and expression of transgenes. The study is the first of its kind to utilise a non-tissue culture-based transformation strategy for the development of stable transgenics in cotton harbouring two novel genes, cry1AcF and cry2Aa for insect resistance. The identified transgenic events can be potential options toward the exploitation of unique cry genes for the management of the polyphagous insect pest H. armigera.
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Affiliation(s)
- Kesiraju Karthik
- ICAR-National Institute for Plant Biotechnology, New Delhi, India
| | - Jyotsana Negi
- ICAR-National Institute for Plant Biotechnology, New Delhi, India
| | - Maniraj Rathinam
- ICAR-National Institute for Plant Biotechnology, New Delhi, India
| | - Navinder Saini
- Division of Genetics, ICAR-Indian Agricultural Research Institute, New Delhi, India
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18
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Del Pozo-Valdivia AI, Reisig DD, Braswell L, Greene JK, Roberts P, Taylor SV. Economic Injury Levels for Bt-resistant Helicoverpa zea (Lepidoptera: Noctuidae) in Cotton. JOURNAL OF ECONOMIC ENTOMOLOGY 2021; 114:747-756. [PMID: 33615386 DOI: 10.1093/jee/toab012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Indexed: 06/12/2023]
Abstract
Thresholds for Helicoverpa zea (Boddie) in cotton Gossypium hirsutum L. have been understudied since the widespread adoption of Bt cotton in the United States. Our study was possible due to the widespread presence of H. zea populations with Cry-toxin resistance. We initiated progressive spray timing experiments using three Bt cotton brands (Deltapine, Stoneville, and Phytogen) widely planted across the U.S. Cotton Belt expressing pyramided toxins in the Cry1A, Cry2, and Vip3Aa19 families. We timed foliar insecticide treatments based on week of bloom to manipulate H. zea populations in tandem with crop development during 2017 and 2018. We hypothesized that non-Bt cotton, cotton expressing Cry toxins alone, and cotton expressing Cry and Vip3Aa19 toxins would respond differently to H. zea feeding. We calculated economic injury levels to support the development of economic thresholds from significant responses. Pressure from H. zea was high during both years. Squares and bolls damaged by H. zea had the strongest negative yield associations, followed by larval number on squares. There were fewer yield associations with larval number on bolls and with number of H. zea eggs on the plant. Larval population levels were very low on varieties expressing Vip3Aa19. Yield response varied across experiments and varieties, suggesting that it is difficult to pinpoint precise economic injury levels. Nonetheless, our results generally suggest that current economic thresholds for H. zea in cotton are too high. Economic injury levels from comparisons between non-Bt varieties and those expressing only Cry toxins could inform future thresholds once H. zea evolves resistance to Vip3Aa19.
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Affiliation(s)
- Alejandro I Del Pozo-Valdivia
- Department of Entomology, Hampton Roads Agricultural Research and Extension Center, Virginia Polytechnic Institute and State University, Virginia Beach, VA, USA
| | - Dominic D Reisig
- Department of Entomology and Plant Pathology, North Carolina State University, Vernon G. James Research and Extension Center, Plymouth, NC, USA
| | - Lewis Braswell
- Product Biology Division, Syngenta Crop Protection Inc., Greensboro, NC, USA
| | - Jeremy K Greene
- Department of Plant and Environmental Sciences, Edisto Research and Education Center, Clemson University, Blackville, SC, USA
| | - Phillip Roberts
- Department of Entomology, University of Georgia, Tifton Campus, Tifton, GA, USA
| | - Sally V Taylor
- Department of Entomology, Tidewater Agricultural Research and Extension Center, Virginia Polytechnic Institute and State University, Suffolk, VA, USA
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Carrière Y, Degain BA, Tabashnik BE. Effects of gene flow between Bt and non-Bt plants in a seed mixture of Cry1A.105 + Cry2Ab corn on performance of corn earworm in Arizona. PEST MANAGEMENT SCIENCE 2021; 77:2106-2113. [PMID: 33350567 DOI: 10.1002/ps.6239] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Revised: 12/08/2020] [Accepted: 12/17/2020] [Indexed: 06/12/2023]
Abstract
BACKGROUND Using natural populations of Helicoverpa zea from Arizona, we tested the hypotheses that gene flow between Bacillus thuringiensis (Bt) plants and non-Bt plants in a seed mixture of 10% non-Bt corn and 90% Bt corn producing Cry1A.105 and Cry2Ab reduces larval performance on ears from non-Bt plants, or increases performance on ears from Bt plants. RESULTS Gene flow was not detected in blocks of non-Bt or Bt corn but was extensive in seed mixtures. Analyses of larval weight and abundance over a period of 3 to 4 weeks did not indicate consistent effects of gene flow on development rate and survival. However for non-Bt plants, the ear area damaged and percentage of ears with exit holes were significantly lower in the seed mixtures than blocks. By contrast, the percentage of ears with exit holes and ear damage did not differ significantly between the seed mixtures and blocks for Bt plants. Nearly 100% of the ears were damaged and the damaged area was substantial, showing that H. zea is a major ear-feeding pest in Arizona. Relative to non-Bt corn, the pyramided Bt corn did not significantly reduce the percentage of damaged ears and only reduced the ear area damaged by 21 to 39%, indicating that H. zea may have evolved resistance to Cry1A.105, Cry2Ab, or both. CONCLUSIONS Our results indicate that gene flow between Bt and non-Bt plants in seed mixtures reduced effective refuge size, and that block refuges may be needed to manage the evolution of H. zea resistance to Bt corn in Arizona. © 2020 Society of Chemical Industry.
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Affiliation(s)
- Yves Carrière
- Department of Entomology, University of Arizona, Tucson, AZ, USA
| | - Ben A Degain
- Department of Entomology, University of Arizona, Tucson, AZ, USA
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20
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Rabelo MM, Paula-Moraes SV, Pereira EJG, Siegfried BD. Contrasting susceptibility of lepidopteran pests to diamide and pyrethroid insecticides in a region of overwintering and migratory intersection. PEST MANAGEMENT SCIENCE 2020; 76:4240-4247. [PMID: 32614113 DOI: 10.1002/ps.5984] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2019] [Revised: 04/25/2020] [Accepted: 07/02/2020] [Indexed: 06/11/2023]
Abstract
BACKGROUND Pesticide resistance is a growing issue worldwide, and susceptibility of pest populations should be monitored in migratory intersection regions for successful resistance management. We determined the susceptibility of eight noctuid species from the Florida Panhandle to bifenthrin (pyrethroid) and chlorantraniliprole (diamide). Larvae from field and laboratory populations were exposed to commercial insecticide formulations using the leaf-dip method in concentration-mortality bioassays. RESULTS The field populations of Helicoverpa zea (Boddie), Spodoptera frugiperda (Smith), S. eridania (Stoll), S. exigua (Hubner) and Chloridea virescens (Fabricius) had reduced susceptibility to bifenthrin compared with the laboratory populations. Resistance ratios to bifenthrin were as high as 10 071-fold in S. exigua and 436-fold in S. frugiperda, while there was no reduced susceptibility in Agrotis ipsilon (Hufnagel). The susceptibility to chlorantraniliprole was similar between the field and laboratory populations studied, except for S. exigua that exhibited 630-fold resistance to the diamide. The probit regression equations indicated that the larval mortality of S. exigua and S. frugiperda populations was <80% with bifenthrin at the concentration equivalent to the label rate. Likewise, the estimated mortality of S. exigua larvae with chlorantraniliprole at the label rate concentration was <80%. CONCLUSIONS The lepidopteran pest populations tested were variable in susceptibility to bifenthrin by contrast to more consistent susceptibility to chlorantraniliprole. These results help in the choice of effective insecticides for integrated pest management and resistance management in cropping systems colonized by migratory lepidopteran pests from the U.S. Gulf Coast region. © 2020 Society of Chemical Industry.
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Affiliation(s)
- Marcelo M Rabelo
- Department of Entomology, Universidade Federal de Viçosa, Viçosa, Brazil
- Department of Entomology and Nematology, West Florida Research and Education Center, University of Florida, Jay, FL, USA
| | - Silvana V Paula-Moraes
- Department of Entomology and Nematology, West Florida Research and Education Center, University of Florida, Jay, FL, USA
| | - Eliseu José G Pereira
- Department of Entomology, Universidade Federal de Viçosa, Viçosa, Brazil
- National Institute of Science and Technology in Plant-Pest Interactions, Universidade Federal de Viçosa, Viçosa, Brazil
| | - Blair D Siegfried
- Department of Entomology and Nematology, University of Florida, Gainesville, FL, USA
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21
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Carrière Y, Degain BA, Harpold VS, Unnithan GC, Tabashnik BE. Gene Flow Between Bt and Non-Bt Plants in a Seed Mixture Increases Dominance of Resistance to Pyramided Bt Corn in Helicoverpa zea (Lepidoptera: Noctuidae). JOURNAL OF ECONOMIC ENTOMOLOGY 2020; 113:2041-2051. [PMID: 32582955 DOI: 10.1093/jee/toaa138] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Indexed: 06/11/2023]
Abstract
For delaying evolution of pest resistance to transgenic corn producing Bacillus thuringiensis (Bt) toxins, limited data are available to compare the effectiveness of refuges of non-Bt corn planted in seed mixtures versus blocks. Here we addressed this issue in the ear-feeding pest Helicoverpa zea Boddie by measuring its survival and development in the laboratory on ears from field plots with 90% Cry1A.105 + Cry2Ab corn and 10% non-Bt corn planted in a seed mixture or blocks. We compared a strain of H. zea selected for resistance to Cry1Ac in the laboratory, its parent strain not selected in the laboratory, and their F1 progeny. The relative survival of the F1 progeny and dominance of resistance were higher on ears from Bt plants in the seed mixture than the block. Half of the kernels in ears from non-Bt plants in the seed mixture produced both Cry1A.105 and Cry2Ab. However, survival on ears from non-Bt plants did not differ between the block and seed mixture. In simulations based on the observed survival, resistance to Cry1A.105 + Cry2Ab corn evolved faster with the seed mixture than the blocks, because of the higher dominance of resistance in the seed mixture. Increasing the refuge percentage improved durability of Cry1A.105 + Cry2Ab corn more for the blocks than the seed mixture. These findings imply that, for a given percentage of non-Bt corn, resistance of H. zea and other ear-feeding pests to multi-toxin Bt corn is likely to evolve faster for seed mixtures than blocks.
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Affiliation(s)
- Yves Carrière
- Department of Entomology, University of Arizona, Tucson, AZ
| | - Ben A Degain
- Department of Entomology, University of Arizona, Tucson, AZ
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Lawrie RD, Mitchell III RD, Deguenon JM, Ponnusamy L, Reisig D, Pozo-Valdivia AD, Kurtz RW, Roe RM. Multiple Known Mechanisms and a Possible Role of an Enhanced Immune System in Bt-Resistance in a Field Population of the Bollworm, Helicoverpa zea: Differences in Gene Expression with RNAseq. Int J Mol Sci 2020; 21:E6528. [PMID: 32906662 PMCID: PMC7555151 DOI: 10.3390/ijms21186528] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 09/01/2020] [Accepted: 09/01/2020] [Indexed: 12/13/2022] Open
Abstract
Several different agricultural insect pests have developed field resistance to Bt (Bacillus thuringiensis) proteins (ex. Cry1Ac, Cry1F, etc.) expressed in crops, including corn and cotton. In the bollworm, Helicoverpa zea, resistance levels are increasing; recent reports in 2019 show up to 1000-fold levels of resistance to Cry1Ac, a major insecticidal protein in Bt-crops. A common method to analyze global differences in gene expression is RNA-seq. This technique was used to measure differences in global gene expression between a Bt-susceptible and Bt-resistant strain of the bollworm, where the differences in susceptibility to Cry1Ac insecticidal proteins were 100-fold. We found expected gene expression differences based on our current understanding of the Bt mode of action, including increased expression of proteases (trypsins and serine proteases) and reduced expression of Bt-interacting receptors (aminopeptidases and cadherins) in resistant bollworms. We also found additional expression differences for transcripts that were not previously investigated, i.e., transcripts from three immune pathways-Jak/STAT, Toll, and IMD. Immune pathway receptors (ex. PGRPs) and the IMD pathway demonstrated the highest differences in expression. Our analysis suggested that multiple mechanisms are involved in the development of Bt-resistance, including potentially unrecognized pathways.
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Affiliation(s)
- Roger D. Lawrie
- Department of Biology/Environmental and Molecular Toxicology Program, 850 Main Campus Dr, North Carolina State University, Raleigh, NC 27695, USA;
- Department of Entomology and Plant Pathology, Campus Box 7647, 3230 Ligon Street, North Carolina State University, Raleigh, NC 27695, USA; (J.M.D.); (L.P.)
| | - Robert D. Mitchell III
- Knipling-Bushland US Livestock Insects Research Laboratory Genomics Center, 2700 Fredericksburg Road, United States Department of Agriculture-Agricultural Research Service, Kerrville, TX 78028, USA;
| | - Jean Marcel Deguenon
- Department of Entomology and Plant Pathology, Campus Box 7647, 3230 Ligon Street, North Carolina State University, Raleigh, NC 27695, USA; (J.M.D.); (L.P.)
| | - Loganathan Ponnusamy
- Department of Entomology and Plant Pathology, Campus Box 7647, 3230 Ligon Street, North Carolina State University, Raleigh, NC 27695, USA; (J.M.D.); (L.P.)
| | - Dominic Reisig
- Department of Entomology and Plant Pathology, Vernon G. James Research & Extension Center, 207 Research Station Road, Plymouth, NC 27962, USA; (D.R.); (A.D.P.-V.)
| | - Alejandro Del Pozo-Valdivia
- Department of Entomology and Plant Pathology, Vernon G. James Research & Extension Center, 207 Research Station Road, Plymouth, NC 27962, USA; (D.R.); (A.D.P.-V.)
| | - Ryan W. Kurtz
- Cotton Incorporated, 6399 Weston Parkway, Cary, NC 27513, USA;
| | - R. Michael Roe
- Department of Biology/Environmental and Molecular Toxicology Program, 850 Main Campus Dr, North Carolina State University, Raleigh, NC 27695, USA;
- Department of Entomology and Plant Pathology, Campus Box 7647, 3230 Ligon Street, North Carolina State University, Raleigh, NC 27695, USA; (J.M.D.); (L.P.)
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23
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Demographic Performance of Helicoverpa zea Populations on Dual and Triple-Gene Bt Cotton. Toxins (Basel) 2020; 12:toxins12090551. [PMID: 32872277 PMCID: PMC7551585 DOI: 10.3390/toxins12090551] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 08/10/2020] [Accepted: 08/26/2020] [Indexed: 01/02/2023] Open
Abstract
Insecticidal toxins from Bacillus thuringiensis (Bt) are valuable tools for pest management worldwide, contributing to the management of human disease insect vectors and phytophagous insect pests of agriculture and forestry. Here, we report the effects of dual and triple Bt toxins expressed in transgenic cotton cultivars on the fitness and demographic performance of Helicoverpa zea (Boddie)—a noctuid pest, known as cotton bollworm and corn earworm. Life-history traits were determined for individuals of three field populations from a region where H. zea overwintering is likely. Triple-gene Bt cotton cultivars that express Cry and Vip3Aa toxins killed 100% of the larvae in all populations tested. In contrast, dual-gene Bt cotton that express Cry1Ac+Cry1F and Cry1Ac+Cry2Ab allowed population growth with the intrinsic rate of population growth (rm) 38% lower than on non-Bt cotton. The insects feeding on Bt cotton plants that express Cry1Ac+Cry2Ab, Cry1Ac+Cry1F, or Cry1Ab+Cry2Ae exhibited reduced larval weight, survival rate, and increased development time. Additionally, fitness parameters varied significantly among the insect populations, even on non-Bt cotton plants, likely because of their different genetic background and/or previous Bt toxin exposure. This is the first report of the comparative fitness of H. zea field populations on dual-gene Bt cotton after the recent reports of field resistance to certain Bt toxins. These results document the population growth rates of H. zea from an agricultural landscape with 100% Bt cotton cultivars. Our results will contribute to the development and validation of resistance management recommendations.
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Caprio MA, Kurtz R, Catchot A, Kerns D, Reisig D, Gore J, Reay-Jones FPF. The Corn-Cotton Agroecosystem in the Mid-Southern United States: What Insecticidal Event Pyramids Should be Used in Each Crop to Extend Vip3A Durability. JOURNAL OF ECONOMIC ENTOMOLOGY 2019; 112:2894-2906. [PMID: 31375824 DOI: 10.1093/jee/toz208] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Indexed: 06/10/2023]
Abstract
Recent studies suggest that resistance in Helicoverpa zea (Boddie) (Lepidoptera, Noctuidae) to Cry1A(b/c) and Cry2Ab2 toxins from the bacterium Bacillus thuringiensis Berliner (Bacillales: Bacillaceae) has increased and field efficacy is impacted in transgenic corn and cotton expressing these toxins. A third toxin, Vip3A, is available in pyramids expressing two or more Bt toxins in corn hybrids and cotton varieties, but uncertainty exists regarding deployment strategies. During a growing season, H. zea infests corn and cotton, and debate arises over use of Vip3A toxin in corn where H. zea is not an economic pest. We used a three-locus, spatially explicit simulation model to evaluate when using Vip3A in corn might hasten evolution of resistance to Vip3A, with implications in cotton where H. zea is a key pest. When using a conventional refuge in corn and initial resistance allele frequencies of Cry1A and Cry2A were 10%, transforming corn with Vip3A slowed resistance to these toxins and delayed resistance evolution to the three-toxin pyramid as a whole. When Cry resistance allele frequencies exceeded 30%, transforming corn with Vip3A hastened the evolution of resistance to the three-toxin pyramid in cotton. When using a seed blend refuge strategy, resistance was delayed longest when Vip3A was not incorporated into corn and used only in cotton. Simulations of conventional refuges were generally more durable than seed blends, even when 75% of the required refuge was not planted. Extended durability of conventional refuges compared to other models of resistance evolution are discussed as well as causes for unusual survivorship in seed blends.
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Affiliation(s)
- Michael A Caprio
- Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology, Mississippi State University, Mississippi State, MS
| | | | - Angus Catchot
- Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology, Mississippi State University, Mississippi State, MS
| | - David Kerns
- Department of Entomology, Texas A&M University, TAMU, College Station, TX
| | - Dominic Reisig
- Department of Entomology and Plant Pathology, North Carolina State University, Vernon G. James Research and Extension Center, Plymouth, NC
| | - Jeff Gore
- Delta Research & Extension Center, Mississippi State University, Stoneville, MS
| | - Francis P F Reay-Jones
- Department of Plant and Environmental Sciences, Pee Dee Research and Education Center, Clemson University, Florence, SC
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Zhang M, Wei J, Ni X, Zhang J, Jurat-Fuentes JL, Fabrick JA, Carrière Y, Tabashnik BE, Li X. Decreased Cry1Ac activation by midgut proteases associated with Cry1Ac resistance in Helicoverpa zea. PEST MANAGEMENT SCIENCE 2019; 75:1099-1106. [PMID: 30264537 DOI: 10.1002/ps.5224] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Revised: 09/19/2018] [Accepted: 09/22/2018] [Indexed: 06/08/2023]
Abstract
BACKGROUND Field-evolved resistance of Helicoverpa zea to Bacillus thuringiensis (Bt) toxin Cry1Ac was first reported more than a decade ago, yet the underlying mechanisms remain elusive. Towards understanding the mechanisms of resistance to Cry1Ac, we analyzed a susceptible (LAB-S) and two resistant (GA and GA-R) strains of H. zea. The GA strain was derived from Georgia and exposed to Bt toxins only in the field. The GA-R strain was derived from the GA strain and selected for increased resistance to Cry1Ac in the laboratory. RESULTS Resistance to MVPII, a liquid formulation containing a hybrid protoxin similar to Cry1Ac, was 110-fold for GA-R and 7.8-fold for GA relative to LAB-S. In midgut brush border membrane vesicles, activity of alkaline phosphatase and aminopeptidase N did not vary significantly among strains. The activity of total proteases, trypsin-like proteases and chymotrypsin-like proteases was significantly lower for GA-R and GA than LAB-S, but did not differ between GA-R and GA. When H. zea midgut cells were exposed to Cry1Ac protoxin that had been digested with midgut extracts, toxicity was significantly lower for extracts from GA-R and GA relative to extracts from LAB-S, but did not differ between GA-R and GA. Transcriptional analysis showed that none of the five protease genes examined was associated with the decline in Cry1Ac activation in GA-R and GA relative to LAB-S. CONCLUSION The results suggest that decreased Cry1Ac activation is a contributing field-selected mechanism of resistance that helps explain the reduced susceptibility of the GA-R and GA strains. Relative to the LAB-S strain, the two Cry1Ac-resistant strains had lower total protease, trypsin and chymotrypsin activities, a lower Cry1Ac activation rate, and Cry1Ac protoxin incubated with their midgut extracts was less toxic to H. zea midgut cells. © 2018 Society of Chemical Industry.
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Affiliation(s)
- Min Zhang
- School of Life Sciences, Zhengzhou University, Zhengzhou, China
- Department of Entomology, University of Arizona, Tucson, AZ
| | - Jizhen Wei
- Department of Entomology, University of Arizona, Tucson, AZ
- State Key Laboratory for Biology of Plant Disease and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Xinzhi Ni
- USDA-ARS, Crop Genetics and Breeding Research Unit, Tifton, GA, USA
| | - Jie Zhang
- State Key Laboratory for Biology of Plant Disease and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Juan L Jurat-Fuentes
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, TN, USA
| | - Jeffrey A Fabrick
- USDA-ARS, U.S. Arid Land Agricultural Research Center, Maricopa, AZ, USA
| | - Yves Carrière
- Department of Entomology, University of Arizona, Tucson, AZ
- BIO5 Institute, University of Arizona, Tucson, AZ, USA
| | | | - Xianchun Li
- Department of Entomology, University of Arizona, Tucson, AZ
- BIO5 Institute, University of Arizona, Tucson, AZ, USA
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Little NS, Elkins BH, Mullen RM, Perera OP, Parys KA, Allen KC, Boykin DL. Differences between two populations of bollworm, Helicoverpa zea (Lepidoptera: Noctuidae), with variable measurements of laboratory susceptibilities to Bt toxins exposed to non-Bt and Bt cottons in large field cages. PLoS One 2019; 14:e0212567. [PMID: 30865645 PMCID: PMC6415783 DOI: 10.1371/journal.pone.0212567] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Accepted: 02/05/2019] [Indexed: 01/03/2023] Open
Abstract
Interpreting variable laboratory measurements of Helicoverpa zea Boddie susceptibility to toxins from Bacillus thuringiensis Berliner (Bt) has been challenging due to a lack of clear evidence to document declining field control. Research that links laboratory measurements of susceptibility to survival on Bt crops is vital for accurate characterization and any subsequent response to the occurrence of an implied H. zea resistance event. In this study, H. zea survival and the resultant damage to plant fruiting structures of non-Bt, Bollgard II, and Bollgard III cottons from two insect colonies with differing levels of laboratory susceptibility to Bt toxins were evaluated in large field cages. Laboratory bioassays revealed resistance ratios of 2.04 and 622.14 between the two H. zea colonies for Dipel DF and Cry1Ac, respectively. Differences between the two H. zea colonies measured via bioassays with Bollgard II and Bollgard III cotton leaf tissue in the laboratory were not statistically discernable. However, there was 17.6% and 5.3% lower larval mortality in Bollgard II and Bollgard III for the feral relative to the laboratory colony of H. zea, respectively. Although H. zea larval numbers in cages infested with the laboratory susceptible colony did not differ between the two Bt cottons, there were fewer larvae per 25 plants in Bollgard III than in Bollgard II cotton in cages containing tolerant insects. Cages infested with tolerant H. zea moths had higher numbers of total larvae than those containing the laboratory susceptible colony in both Bollgard II and Bollgard III cottons. Bollgard II and Bollgard III cottons received 77.4% and 82.7% more total damage to total plant fruiting structures in cages infested with tolerant insects relative to those containing the laboratory susceptible colony. The damage inflicted to fruiting structures on Bollgard III cotton by a feral H. zea colony with decreased measurements of laboratory susceptibility to Dipel DF and Cry1Ac indicate that the addition of Vip3A to third generation Bt cottons may not provide sufficient control in situations where infestations levels are high.
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Affiliation(s)
- Nathan S. Little
- Southern Insect Management Research Unit, USDA-ARS, Stoneville, Mississippi, United States of America
| | - Blake H. Elkins
- Southern Insect Management Research Unit, USDA-ARS, Stoneville, Mississippi, United States of America
| | - R. Michelle Mullen
- Southern Insect Management Research Unit, USDA-ARS, Stoneville, Mississippi, United States of America
| | - Omaththage P. Perera
- Southern Insect Management Research Unit, USDA-ARS, Stoneville, Mississippi, United States of America
| | - Katherine A. Parys
- Southern Insect Management Research Unit, USDA-ARS, Stoneville, Mississippi, United States of America
| | - K. Clint Allen
- Southern Insect Management Research Unit, USDA-ARS, Stoneville, Mississippi, United States of America
| | - Deborah L. Boykin
- Jamie Whitten Delta States Research Center, USDA-ARS, Stoneville, Mississippi, United States of America
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