Source: UNIVERSITY OF NEBRASKA submitted to
ECOLOGY AND MANAGEMENT OF EUROPEAN CORN BORER AND OTHER LEPIDOPTERAN PESTS OF CORN
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
TERMINATED
Funding Source
HATCH
Reporting Frequency
Annual
Accession No.
0216011
Grant No.
(N/A)
Project No.
NEB-28-100
Proposal No.
(N/A)
Multistate No.
NC-205
Program Code
(N/A)
Project Start Date
Jul 1, 2008
Project End Date
Sep 30, 2010
Grant Year
(N/A)
Project Director
Siegfried, B. D.
Recipient Organization
UNIVERSITY OF NEBRASKA
(N/A)
LINCOLN,NE 68583
Performing Department
ENTOMOLOGY
Non Technical Summary
Since the 1996 commercial release of transgenic corn hybrids containing a gene from the bacterium Bacillus thuringiensis subsp. kurstaki (Bt), a revolution in field and sweet corn insect pest management has been underway. This revolution is rapidly moving field corn pest management away from synthetic pesticides to plant-based toxin delivery systems coupled with low dosage commercial seed treatments. The goal of this movement is to eliminate the need to store and handle toxic chemicals, eliminate the need for special insecticide application equipment, increase the ease of planting, and increase pest control effectiveness. Major seed technology companies continue to develop new transgenic crops for pest protection. These revolutionary changes in corn-hybrid technology are causing major adjustments in the agricultural community, pointing out major knowledge gaps and increasing the need to reevaluate past knowledge about European corn borer and other pests of corn. For instance, an insect resistance management (IRM) program was never a legal requirement for any pest management technology until the introduction of Bt-corn hybrids for protection against European corn borer. Publicity and attention to scientific advisors lead the U.S. Environmental Protection Agency (EPA) to require IRM programs on farms where Bt-corn hybrids are used. During 2004, 32% of all field corn hybrids planted in the Unites States contained a Bt gene. Stacked gene field corn hybrids that have multiple modes of action to prevent injury from both European corn borer and corn rootworm were commercially released in 2004. As the level of adoption increases, particularly in the western Corn Belt, the potential for resistance evolution increases. Research conducted by this committee has been used to develop models predicting the rates of resistance evolution and to investigate the role of refuge structure in preventing or minimizing resistance evolution. These models suggest that a minimum refuge size of 20% is required to slow resistance development in this species. Although these models were constructed using the best information available on the pest's biology and known population genetic relationships, a number of assumptions had to be made about pest biology for the simulations to be completed. These assumptions need to be tested and research conducted to move them from assumptions to quantified variables with known uncertainty. In addition to addressing information gaps needed to improve these models, information is needed on the economics of this new technology, and the non-target impacts of Bt-corn toxins. Eliminating these information gaps forms the basis for several objectives of the project.
Animal Health Component
(N/A)
Research Effort Categories
Basic
50%
Applied
50%
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
2111510113025%
2113110113050%
2115220113025%
Knowledge Area
211 - Insects, Mites, and Other Arthropods Affecting Plants;

Subject Of Investigation
5220 - Pesticides; 1510 - Corn; 3110 - Insects;

Field Of Science
1130 - Entomology and acarology;
Goals / Objectives
Investigate ecological, evolutionary, genetic and behavioral factors that impact pest populations, including resistance management.
Project Methods
A. Corn Borer Resistance Mechanisms. Researchers in Nebraska, Kansas, Iowa and Minnesota will establish and maintain colonies of resistant European corn borers. The resistant colonies will be developed by selection on diets containing various Cry proteins. Purified insecticidal crystal proteins (Cry1Ab, Cry1Ac, Cry1F, and other Cry proteins) and transgenic Bt plants, based on transformation events encoding for the same Cry toxins, will be used in these experiments. These states will investigate mechanisms of resistance and cross-resistance. Studies will include comparisons of the level and profile of midgut proteinases and the affinity and density of Bt binding receptors(s) in midgut brush border membranes between Bt-susceptible and resistant strains of European corn borer. Nebraska will develop the methods to establish and maintain resistant colonies of European corn borer. B. Corn Insect Genetics. Another goal of proposed research in Iowa and Nebraska is to use molecular markers and linkage maps to mark regions of the ECB genome associated with Bt-resistance traits. The marker-trait associations will be used to extend characterizations of the genetic architecture of Cry1Ab resistance found in classical genetic studies of three colonies of ECB. The final product of the research will be isolating and examining what expressed resistance genes are actually linked to our markers ("gene characterization"). Three colonies of resistant ECB with moderate levels of Bt resistance are available. Knowledge obtained from these studies can be applied to cross resistance issues as well as improving the efficiencies of resistance monitoring methods. Because we do not currently have a physical map for ECB, crosses are designed to allow comparisons to be made among the three resistant lines, and also to maximize linkage disequilibrium between markers and regions of the genome associated with resistance. Our work will use three types of marker loci: (1) amplified fragment length polymorphisms (AFLPs), (2) microsatellites, and (3) cadherin loci. The AFLP markers will be the primary means of saturating our linkage map.

Progress 07/01/08 to 09/30/10

Outputs
OUTPUTS: Monitoring techniques developed at the University of Nebraska for detecting Bt resistance in the European corn borer are currently used in support of an annual resistance monitoring program. This effort provides a means for early detection of Bt resistance and is an essential component of Bt resistance management programs. Additional testing of new Bt toxins was initiated in 2009 and continued in 2010. Efforts to characterize Bt resistance have continued and have resulted in research results that will be important to future resistance management efforts. We continue to develop techniques for identification of Bt receptors in the gut of pest insects and potential modifications that may result from resistance development. We have completed experiments to characterize fitness costs and have published two recent papers from this work. We continue to collaborate with researchers from other countries. Formal collaborations with researchers in Philippines and Malaysia to compare susceptibility of European and Asian corn borer to a variety of Bt toxins have been completed and a Ph.D. student graduated with her dissertation from this work. A combined study of Bt susceptibility of N. American and European populations of corn borers was completed and submitted for publication. We have also initiated research to characterize field evolved resistance to Bt toxins in Puerto Rican populations of the fall army worm which represents one the first instances of control failures with Bt transgenic corn. PARTICIPANTS: Much of this work represent a collaboration with other researchers associated with the regional project. Additionally two Ph.D. students participated in research associated with this project. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
Planting of Bt corn has increased dramatically since its introduction in 1996. Widespread adoption of the technology has caused increased selection pressures and place increased priority on development of sound resistance management practices. The identification of resistant strains and characterization of resistance among field populations will provide critical information to federal agencies that regulate the use of this technology and help ensure that the technology is used a sustainable manner. Bt resistance monitoring information provided by our lab is currently utilized by most of the major seed and biotechnology companies to support registrations of transgenic corn for both European corn borer.

Publications

  • Pereira, E.J.G., H.A.A. Siqueira, M. Zhuang, N.P. Storer, and B.D. Siegfried. 2010. Studies on the mechanism of Cry1F resistance in laboratory-selected European corn borer (Lepidoptera: Crambidae). J. Invert. Pathol. 103: 1-7.
  • Crespo., A.L.B., T. Spencer, S.Y. Tan, and B.D. Siegfried. 2010. Fitness Costs of Cry1Ab resistance in a field-derived Strain of Ostrinia nubilalis (Lepidoptera: Crambidae). J. Econ. Entomol. 103: 1386-1393.


Progress 10/01/08 to 09/30/09

Outputs
OUTPUTS: Monitoring techniques developed at the University of Nebraska for detecting Bt resistance in the European corn borer are currently used in support of an annual resistance monitoring program. This effort provides a means for early detection of Bt resistance and is an essential component of Bt resistance management programs. Additional testing of new Bt toxins was initiated in 2008 and continued in 2009 with an additional project to establish baseline susceptibility for two new Bt toxins. Efforts to develop Bt resistant strains of European corn borer and to characterize their resistance have continued and have resulted in research results that will be important to future resistance management efforts. We continue to develop techniques for identification of Bt receptors in the gut of pest insects and potential modifications that may result from resistance development. One paper resulting from this work is currently in press. One strain of European corn borer has been identified that is the first to be shown to complete development on transgenic plants. We have completed an initial set of experiments to characterize fitness costs and we continue to evaluate other factors related to the potential for resistance to affect reproductive fitness. We continue to collaborate with researchers from other countries. Formal collaborations have resulted in a USAID funded project in the Philippines and Malaysia to compare susceptibility of European and Asian corn borer to a variety of Bt toxins. We have also obtained samples for further biochemical and molecular analysis of toxin binding and have initiated a population genetic study to compare ACB populations from throughout Southeast Asia. We have also established a formal collaboration with researchers at the National University in Medellin, Colombia to develop bioassay methods for fall armyworm and a Ph.D. student has been recruited from Colombia to begin this work. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
Planting of Bt corn has increased dramatically since its introduction in 1996. Widespread adoption of the technology will likely increase selection pressures and place increased priority on development of sound resistance management practices. The identification of resistant strains and characterization of resistance among field populations will provide critical information to federal agencies that regulate the use of this technology and help ensure that the technology is used a sustainable manner. Bt resistance monitoring information provided by our lab is currently utilized by most of the major seed and biotechnology companies to support registrations of transgenic corn for both European corn borer.

Publications

  • Bel, Y., H.A.A. Siqueira, B.D. Siegfried, J. Ferre, and B. Escriche. 2009. Variability in the cadherin gene in Ostrinia nubilalis selected for Cry1Ab resistance. Insect Molec. Biol.39: 218-223.
  • Crespo, A.L.B., T. Spencer, A.P. Alves, R.L. Hellmich, E.E. Blankenship, L.C. Magalhaes, and B.D. Siegfried. 2009. On-plant survival and inheritance of resistance to Cry1Ab toxin from Bacillus thuringiensis in a field-derived strain of European corn borer, Ostrinia nubilalis. Pest Manag. Sci. 10: 1071-1081.
  • Khajuria, C., Y.C. Zhu, M. Chen, L.L. Buschman, R.A. Higgins, J. Yao, A.L.B. Crespo, B.D. Siegfried, S. Muthukrishnan, and K.Y. Zhu. 2009. Expressed sequence tags from larval gut of the European corn borer (Ostrinia nubilalis): Exploring candidate genes potentially involved in Bacillus thuringiensis toxicity and resistance. BCM Genomics doi:10.1186/1471-2164-10-286.
  • Pereira, E.J.G. , H.A.A. Siqueira, M. Zhuang, N.P. Storer, and B.D. Siegfried. 2009. Measurements of Cry1F binding and activity of luminal gut proteases in susceptible and Cry1F resistant Ostrinia nubilalis larvae (Lepidoptera: Crambidae). J. Invert. Pathol. doi:10.1016/j.jip.2009.08.014.