| For 2020 and newer grants, please go to https://grants.ipmcenters.org/ |
|---|
|
|
| Home Current RFAs PD User Guide Projects Login |
|
Funded Project |
|
Funding Program:
Regional IPM Grants (S-RIPM) |
|
Project Title:
Enhancing Sustainable Use of Transgenic Bt-corn Through Resistance Management for the Mid-Southern Region of the United States |
Project Directors (PDs):
|
|
Lead State: LA Lead Organization: Louisiana State University Agricultural Center |
|
Cooperating State(s):
Mississippi, Texas |
| Research Funding: $133,900 |
|
Start Date: May-02-2008 End Date: May-01-2011 |
|
Pests Involved: sugarcane borer |
|
Site/Commodity: Bt-corn |
|
Area of Emphasis: resistance management |
|
Summary:
This is a research project for validation and improvement of a strategy for managing resistance to Bt-corn in the sugarcane borer (SCB), a research priority recently identified by a USDA multi-state research group (NC-205). The rapid adoption of Bt-corn in the midsouthern region necessitates implementation of an effective insect resistance management (IRM) plan to ensure the long-term success of Bt-corn. In recent years, SCB has become a dominant corn borer species in several areas across the mid-southern region. The first major resistance gene to Bt-corn in any corn borer species has been recorded in two Louisiana SCB populations.
The currently adopted high dose/refuge IRM strategy for Bt-corn was developed to manage the European corn borer /southwestern corn borer resistance. Information that can support such a strategy to manage Bt resistance in SCB is lacking. This proposal is designed to validate three key prerequisites of the high dose/refuge strategy for managing SCB resistance to Bt-corn. In this project, selected Bt-corn hybrids will be evaluated to determine if commercial Bt-corn hybrids planted in the mid-southern region qualify as high dose against SCB. Mating studies will provide insight into the genetic basis of Bt resistance to determine if Bt resistance in SCB is recessive. Bt resistance frequency in SCB populations will be estimated with novel screening procedures to validate if the frequency is sufficiently low to meet the requirements for the current IRM strategy. This study will provide information necessary to support and improve the Bt-corn IRM and ensure its long-term success as an effective corn borer management tool for the mid-southern region. Objectives: 1. Determine larval survival of Bt-susceptible and -resistant SCB on diet containing Bt plant tissues and on intact Bt-corn plants to verify if commercial Bt-corn cultivars in the mid-southern region qualify as high dose as defined by the FIFRA Scientific Advisory Panel; 2. Assess the genetic basis of resistance in SCB to determine if Bt resistance in this insect pest is controlled by a recessive gene as required for the high dose/refuge IRM strategy; 3. Estimate the allele frequencies for Bt resistance in SCB populations to verify if the frequencies are low enough to ensure success of the current high does/refuge strategy for the mid-southern region. |
|
Final Report: |
|
Outcomes 1. Two Ph.D. students who were partially supported by this project successfully graduated, one in Dec. 2009, and another in May 2011. 2. Two book chapters have been published. 3. Seven referred scientific papers have been published and two other referred papers are in press. 4. Five conference proceedings were published. 5. >20 oral and poster displays were presented at local, regional, national, and international meetings. 6. Eight new Bt resistant strains of sugarcane borer were developed, which have been used for novel research materials for several on-coming research projects. |
|
Impacts During the three years, >10000 corn borers were identified across the major corn production areas in Louisiana, Texas, and Mississippi. The survey showed that a complex of sugarcane borer (SCB) and southwestern corn borer occurs in the mid-southern region. SCB is the dominant species. A total of > 4000 SCB were collected from the three states and examined for Bt resistance. Bt resistance allele frequency was low for the populations from Texas, Mississippi, and those collected during 2004-2008 in Louisiana, but increased for the Louisiana populations sampled during 2009. Eight new Bt resistant strains of SCB were established from the collections during 2009. These strains have been used as novel research materials for several on-coming projects. In addition, a total of 382 F2 families collected from Louisiana and Mississippi were screened against three new Bt corn technologies. None of these families survived on the Bt corn leaf tissue for >12 days. The Bt resistance allele frequency in these populations was estimated to be very low (<0.0063). During the three years, genetic basis of Bt resistance in SCB was analyzed using various genetic crosses. The results showed that Bt resistance in SCB was likely inherited as a single or a few linked autosomal genes. The resistance was incompletely recessive. In addition, fitness of Bt resistance in SCB were compared on non-toxic diet and on non-Bt corn plants for five genotypes. Bt resistance in SCB was not associated with any fitness cost. The lack-of-fitness cost of Bt resistance in SCB implies a greater challenge in managing resistance for this corn borer species. Furthermore, cross-resistance of the Cry1Ab-resistant strain of SCB was evaluated against 16 other Bt toxins. Several novel Bt toxins that are able to overcome the Cry1Ab resistance have been identified. During the three years, multiple trials were conducted to evaluate the performance of SCB on 15 commercial hybrids and 6 experimental corn lines. The results showed that most Bt corn hybrids currently planted do not express a sufficiently high Bt dose against SCB. There appears to be a high risk for development of Bt resistance in SCB if Cry1Ab corn continues to be widely used in the U.S. mid-south region. This study also demonstrated that the Cry1Ab-resistance in SCB can been completely overcome by a Bt corn containing two different Bt genes. Information generated from this project has provided valuable knowledge for developing better resistance management strategies to ensure the sustainable use of Bt corn in the mid-south region. Several collaborative research projects have been established to develop better Bt corn technologies for managing corn borers. Data generated from this research has become an integral part of an advanced graduate course, which has been offered at LSU. Results from this project have been presented at many local, regional, national, and international meetings. Seven manuscripts and two book chapters have been published. Two Ph.D. students who were partially supported by this project successfully graduated, one in Dec. 2009, and another in May, 2011. Both students received several awards from ESA, Louisiana Crop Protection Association, and the Oversea Chinese Entomologists Association. In addition, in recognition of Dr. Huangs excellent research work which was partially supported by this project, he was selected for the 2011 G & H Seed Company Research Excellence Award. This Award is given to the scientist who during the past five years has made the most significant contributions to the research programs of the Louisiana Agricultural Experiment Station. |
|
Results During the three years, >10000 corn borers were identified across the major corn production areas in Louisiana, Texas, and Mississippi. The survey showed that a complex of sugarcane borer (SCB) and southwestern corn borer occurs in the mid-southern region. SCB is the dominant species. A total of > 4000 SCB were collected from the three states and examined for Bt resistance. Bt resistance allele frequency was low for the populations from Texas, Mississippi, and those collected during 2004-2008 in Louisiana, but increased for the Louisiana populations sampled during 2009. Eight new Bt resistant strains of SCB were established from the collections during 2009. These strains have been used as novel research materials for several on-coming projects. In addition, a total of 382 F2 families collected from Louisiana and Mississippi were screened against three new Bt corn technologies. None of these families survived on the Bt corn leaf tissue for >12 days. The Bt resistance allele frequency in these populations was estimated to be very low (<0.0063). |
| Report Appendices |
| Close Window |
|
Southern IPM Center North Carolina State University 1730 Varsity Drive, Suite 110 Raleigh, NC 27606 p. 919.513.1432 f. 919.513.1114 |
 |
Developed by the Center for IPM © Copyright CIPM 2004-2025 |
|