Progress 10/01/06 to 09/30/12
Outputs
OUTPUTS: Between October 2006 and the present there have been many significant outputs from our program on "Development of evolutionarily stable crop protection tactics and strategies". In the arena of insecticidal transgenic crops our theoretical models and empirical results have been used by the USDA and the EPA in regulating the use of transgenic crops at the commercial level. The criteria for the high-dose/refuge strategy that we were instrumental in developing is now being seen globally as a solid approach for sustainable use of pesticidal transgenic crops. With the advent of pyramided Bt crops, our models for dual-toxins have informed policy. Our novel approaches to measuring resistance allele frequencies have been adopted by other labs and our technique for using stable isotopes to examine the size of refuges has been used in the US ad other countries. The focus of our lab has shifted from transgenic crops to transgenic pests. This novel approach to pest management is highly reliant on a solid understanding of population genetics and population structure. As with our earlier work on resistance management models, we have developed a set of models that range from heuristic to operational. Both of these types of models have produced outputs that have been used by a $23 million consortium of researchers supported by the Gates Foundation in their strategic planning and in design of experiments. Our published papers in this area have been used by government groups and GOs. PARTICIPANTS: Fred Gould, Alun Lloyd, Krisztian Magori, Kenichi Okamoto, Yunxin Huang, all worked on the project. We collaborated with the USDA in Stoneville Mississippi and with the Chinese Academy of Agricultural Sciences TARGET AUDIENCES: US-EPA, USDA. All country governments where Bt crops are ground. All countries considering release of transgenic insects. Companies inovled in development and commercialization of Bt crops or transgenic insects. Farmers affected by the use of transgenic crops or transgenic insects. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
The results of our models and our empirical experiments in the realm of managing resistance to insecticidal crops has changed the way researchers and regulators view the sustainability of these crops. Some of our collaborative work has resulted in a better understanding of the mechanisms by which insects adapt to Bt toxins and has also led to long-term sets of data that allow the tracking of changes in the level of resistance in specific pest populations. Our work on genetic pest management has led to the development of two novel approaches for driving refractory genes into insect populations that vector diseases.
Publications
- Abney, M. R., C. E. Sorenson, F. Gould, J. R. Bradley. 2008. Limitations of stable carbon isotope analysis for determining natal host origins of tobacco budworm, Heliothis virescens. F. Entomol. Exp. Appl. 126:46-52.
- Gould, F., Huang, Y., Legros, M., Lloyd, A. L. 2008. A killer rescue system for self limiting gene drive of anti-pathogen constructs. Proc. Royal. Soc. Lond. B. 275:2823-2829.
- Huang, Y., A. Lloyd, M. Legros and F. Gould. (2009) Gene-drive in age-structured insect populations. Evolutionary Applications 2:143-159.
- Magori, K., and F. Gould. 2006. Genetically engineered underdominance for manipulation of pest populations: A determinisitic model. Genetics 172 (4): 2613-2620
- Sinkins, S. P., and F. Gould. 2006. Gene drive systems for insect disease vectors. Nature Reviews Genetics. 7:427-435.
- Gould, F., K. Magori, Y. X. Huang. 2006. Genetic strategies for controlling mosquito-borne diseases. American Scientist. 94: 238-246.
- Gould, F., Cohen M. B., J. S. Bentur, G. G. Kennedy, J. W. Van Duyn. 2006. Impact of small fitness costs on pest adaptation to crop varieties with multiple toxins: A heuristic model. J. Econ. Entomol. 99:2091-2099. Jackson, R.E., F. Gould , J. R. Bradley, J. W. Van Duyn. 2006.Genetic variation for resistance to Bacillus thuringiensis toxins in Helicoverpa zea (Lepidoptera : Noctuidae) in eastern North Carolina. J. Econ. Entomol. 99:1790-1797.
- Jackson, R. E., M. A. Marcus, F. Gould, J. R. Bradley, J. W. Van Duyn. 2007. Cross-resistance responses of Cry1Ac-selected Heliothis virescens (Lepidoptera : Noctuidae) to the Bacillus thuringiensis protein Vip3A. J. Econ. Entomol. 100:180-186.
- Gahan, L. J., F. Gould, J. D. Lopez, S. Micinski, D. G. Heckel . 2007. A polymerase chain reaction screen of field populations of Heliothis virescens for a retrotransposon insertion conferring resistance to Bacillus thuringiensis toxin. J. Econ. Entomol. 100:187-194.
- Huang, Y., K. Magori, A. L. Lloyd, F. Gould. 2007. Introducing desirable transgenes into insect populations using Y-linked meiotic drive a theoretical assessment. Evolution 61:717-726.
- Li, G. P., K. M. Wu, F. Gould, J. K. Wang, J. Miaoi, X. W. Gao, Y. Y.Guo. 2007. Increasing tolerance to Cry1Ac cotton from cotton bollworm, Helicoverpa armigera, was confirmed in Bt cotton farming area of China. Ecological Entomology 32:366-375.
- Heckel, D. G., L. J. Gahan, S.W. Baxter, J. Z. Zhou, A. M. Shelton, F. Gould, B. E. Tabashnik. 2007. The diversity of Bt resistance genes in species of Lepidoptera. J. Invert. Pathol. 95:192-197 Sp. Iss.
- Huang,, Y., K. Magori, A. L. Lloyd, F. Gould. 2007. Introducing transgenes into insect populations using combined gene-drive strategies: Modeling and analysis. Insect biochem. Mol. Biol. 37:1054-63.
- Blanco, C. A., O. P. Perera, F. Gould, D. V. Sumerford, G. Hernandez, C. A. Abel, D. A. Andow. 2008. An empirical test of the F-2 screen for detection of Bacillus thuringiensis-resistance alleles in tobacco budworm (Lepidoptera : Noctuidae). J. Econ. Entomol. 101:1406-1414.
- Legros, M., Lloyd, A. L., Y. Huang, F, Gould. 2009. Density-Dependent Intraspecific Competition in the Larval Stage of Aedes aegypti (Diptera: Culicidae): Revisiting the Current Paradigm. J. Med. Entomol. 46:409-419.
- Blanco CA, Gould F, Vega-Aquino P, Jurat-Fuentes JL, Perera OP, Abel CA. 2009. Response of Heliothis virescens (Lepidoptera: Noctuidae) Strains to Bacillus thuringiensis Cry1Ac Incorporated Into Different Insect Artificial Diets J. Econ Entomol. 102:1599-1606
- Gao YL, Wu KM, Gould F, Shen ZC 2009. Cry2Ab Tolerance Response of Helicoverpa armigera (Lepidoptera: Noctuidae) Populations From Cry1Ac Cotton Planting Region. J. Econ. Entomol.102:1217-1223
- Gao YL, Wu KM, Gould F. 2009. Frequency of Bt Resistance Alleles in H-armigera During 2006-2008 in Northern China Environ. Entomol. 38:1336-1342
- Magori*K., M. Legros*, M. Puente, D. A. Focks, T. W. Scott, A. Lloyd, F, Gould. 2009. Skeeter Buster: a stochastic, spatially-explicit modeling tool for studying Aedes aegypti population replacement and population suppression strategies. PLoS Negl Trop Dis 3(9): e508. doi:10.1371/journal.pntd.0000508
- Feng, H. Q., F. Gould, Y. X. Huang, Y. Y. Jiang, K. M. Wu. 2010. Modeling the population dynamics of cotton bollworm Helicoverpa armigera (Hubner) (Lepidoptera: Ecol. Modelling 221:1819-1830.
- Xu, C., Legros, M., Gould, F, Lloyd, A. L. 2010.Understanding Uncertainties in Model-Based Predictions of Aedes aegypti Population Dynamics. PLoS Negl. Trop. Dis. 4(9): e830. doi:10.1371/journal.pntd.0000830
- An, J. J., Y. L. Gao, K. M. Wu, F. Gould, J. H. Gao, Z. C. Shen, C. L. Lei. 2010. Vip3Aa Tolerance Response of Helicoverpa armigera Populations From a Cry1Ac Cotton Planting Region. J. Econ. Entomol.103:2169-2173.
- Jurat-Fuentes, J. L., Karumbaiah, L., Jakka, S.R.K., Ning, C., Liu, C., Wu, K., Jackson, J., Gould, F., Blanco, C., Portilla, M., Perera, O. P., and M. J. Adang. 2011. Reduced levels of membrane-bound alkaline phosphatase are common to lepidopteran strains resistant to Cry toxins from Bacillus thuringiensis. PLoS ONE 6(3): e17606. doi:10.1371/journal.pone.0017606
- Gao, Y., J. An, F. Gould, C. A. Blanco, K. M. Wu, 2011. Susceptibility of Helicoverpa armigera from different host plants in northern China to Bacillus thuringiensis toxin Cry1Ac. Crop. Prot. 30:1421-1424.
- Legros M., K. Magori, A. C. Morrison Amy C., C. G. Xu, T. W. Scott, A. L. Lloyd, F. Gould. 2011. Evaluation of Location-Specific Predictions by a Detailed Simulation Model of Aedes aegypti Populations PLoS ONE 6 Issue: 7 Article Number:10.1371/journal.pone.0022701.
- Huang, Y., Lloyd, A.L., Legros, M., Gould, F. 2011. Gene-drive into insect populations with age and spatial structure: a theoretical assessment. Evol. Appl. 4:415-428 DOI: 10.1111/j.1752-4571.2010.00153.x
- Blanco, C. A., F. Gould, A. T. Groot, C. A. Abel, G. Hernandez, O. P. Perera, A. P. Teran-Vargas. 2010. Offspring from sequential matings between Bacillus thuringiensis-resistant and Bacillus thuringiensis-susceptible Heliothis virescens moths (Lepidoptera: Noctuidae). J. Econ. Entom. 103:861-868.
- Jongsma, M. A., F. Gould, M. Legros, Y. M. Yang, J. J. A. van Loon, M. Dicke. 2010. Insect oviposition behavior affects the evolution of adaptation to Bt crops: consequences for refuge policies. Evol. Ecol. 24:1017-1030.
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Progress 10/01/09 to 09/30/10
Outputs
OUTPUTS: We have continued our collaborations with the USDA and with the Chinese Academy of Agricultural Sciences to improve our capacity to predict the evolution of pest resistance to Bt crops. We have a number of publications from this work. We also continued a collaboration with a group from the Netherlands exploring the potential for behavioral resistance to Bt crops. One manuscript from this work was recently published. Regarding transgenic pests, we have continued our collaboration with the Aedes project out of UC Irvine. We have also begun interactions with an Australian group working on Wolbachia. As proof of principle, we have developed a Drosophila strain with the Killer-Rescue constructs described in our theoretical paper.We have been running a population genetics experiment to determine how well these constructs work. PARTICIPANTS: Alun Lloyd Biomath NCSU Faculty Mathieu Legros NCSU postdoc Yunxin Huang NCSU postdoc, Chonggang Xu Postdoc, Rachael Katz NCSU graduate student Sandra Paa NCSU graduate student. We also collaborated with a visiting scientist from China, Hongqiang Feng. Work with the group in the Netherlands will also educate researchers in a new area. TARGET AUDIENCES: : USDA EPA NIH General public PROJECT MODIFICATIONS: : Nothing significant to report during this reporting period. PARTICIPANTS: Alun Lloyd Biomath NCSU Faculty Mathieu Legros NCSU postdoc Yunxin Huang NCSU postdoc, Chonggang Xu Postdoc, Rachael Katz NCSU graduate student Sandra Paa NCSU graduate student. We also collaborated with a visiting scientist from China, Hongqiang Feng. Work with the group in the Netherlands will also educate researchers in a new area. TARGET AUDIENCES: USDA EPA NIH General public PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
We hope that our Bt resistance management work with the USDA and the Chinese governent will lead to more science-based resistance management policies. Both our modeling and empirical work on gene drive systems has had an impact on groups trying to develop population suppression and population replacement strategies This has been especially important for the ongoing projects with Aedes being conducted by the Bill and Melinda Gates Foundation.
Publications
- Blanco, C. A., F. Gould, A. T. Groot, C. A. Abel, G. Hernandez, O. P. Perera, A. P. Teran-Vargas. 2010. Offspring from sequential matings between Bacillus thuringiensis-resistant and Bacillus thuringiensis-susceptible Heliothis virescens moths (Lepidoptera: Noctuidae). J. Econ. Entom. 103:861-868. Jongsma, M. A., F. Gould, M. Legros, Y. M. Yang, J. J. A. van Loon, M. Dicke. 2010. Insect oviposition behavior affects the evolution of adaptation to Bt crops: consequences for refuge policies. Evol. Ecol. 24:1017-1030. Feng, H. Q., F. Gould, Y. X. Huang, Y. Y. Jiang, K. M. Wu. 2010. Modeling the population dynamics of cotton bollworm Helicoverpa armigera (Hubner) (Lepidoptera: Ecol. Modelling 221:1819-1830. Xu, C., Legros, M., Gould, F, Lloyd, A. L. 2010.Understanding Uncertainties in Model-Based Predictions of Aedes aegypti Population Dynamics. PLoS Negl. Trop. Dis. 4(9): e830. doi:10.1371/journal.pntd.0000830 Huang, Y., Lloyd, A.L., Legros, M., Gould, F. 2010. Gene-drive into insect populations with age and spatial structure: a theoretical assessment. Evol. Appl. ISSN 1752-4571
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Progress 10/01/08 to 09/30/09
Outputs
OUTPUTS: We have continued to work on both insect resistance management for transgenic crops and the use of transgenic insects for disease prevention and crop protection. We have continued our collaborations with the USDA and with the Chinese Academy of Agricultural Sciences to improve our capacity to predict the evolution of pest resistance to Bt crops. We have a number of publications from this work. We also started a collaboration with a group from the Netherlands exploring the potential for behavioral resistance to Bt crops. One manuscript from this work has been written.Regarding transgenic pest, we have continued our collaboration with the Aedes project out of UC Irvine. We have also begun interactions with an Australian group working on Wolbachia.As proof of principle, we have developed a Drosophila strain with the Killer-Rescue constructs described in our theoretical paper. PARTICIPANTS: Alun Lloyd Biomath NCSU Faculty Mathieu Legros NCSU postdoc Yunxin Huang NCSU postdoc, Chonggang Xu Postdoc, Rachael Katz NCSU graduate student Sandra Paa NCSU graduate student. We also collaborated with a visiting scientist from China, Hongqiang Feng. Work with the group in the Netherlands will also educate researchers in a new area. TARGET AUDIENCES: : USDA EPA NIH General public PROJECT MODIFICATIONS: : Nothing significant to report during this reporting period.
Impacts
We hope that our Bt resistance management work with the USDA and the Chinese governent will lead to more science-based resistance management policies. Both our modeling and empirical work on gene drive systems has had an impact on groups trying to develop population suppression and population replacement strategies.
Publications
- Huang, Y., A. Lloyd, M. Legros and F. Gould. (2009) Gene-drive in age-structured insect populations. Evolutionary Applications 2:143-159.
- Legros, M., Lloyd, A. L., Y. Huang, F, Gould. 2009. Density-Dependent Intraspecific Competition in the Larval Stage of Aedes aegypti (Diptera: Culicidae): Revisiting the Current Paradigm. J. Med. Entomol. 46:409-419.
- Blanco CA, Gould F, Vega-Aquino P, Jurat-Fuentes JL, Perera OP, Abel CA. 2009. Response of Heliothis virescens (Lepidoptera: Noctuidae) Strains to Bacillus thuringiensis Cry1Ac Incorporated Into Different Insect Artificial Diets J. Econ Entomol. 102:1599-1606
- Gao YL, Wu KM, Gould F, Shen ZC 2009. Cry2Ab Tolerance Response of Helicoverpa armigera (Lepidoptera: Noctuidae) Populations From Cry1Ac Cotton Planting Region. J. Econ. Entomol.102:1217-1223
- Gao YL, Wu KM, Gould F. 2009. Frequency of Bt Resistance Alleles in H-armigera During 2006-2008 in Northern China Environ. Entomol. 38:1336-1342
- Magori*K., M. Legros*, M. Puente, D. A. Focks, T. W. Scott, A. Lloyd, F, Gould. 2009. Skeeter Buster: a stochastic, spatially-explicit modeling tool for studying Aedes aegypti population replacement and population suppression strategies. PLoS Negl Trop Dis 3(9): e508. doi:10.1371/journal.pntd.0000508
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Progress 10/01/07 to 09/30/08
Outputs
OUTPUTS: We have been continuing our efforts to assess the potential and problems with Genetic Pest Management by use of a mixture of theoretical and empirical approaches. A main concern of our work has been with the characteristics of various gene drive mechanisms. Perhaps our most important output this year was the theoretical development of a new approach to gene drive that could be used in risk abatement. We have recently begun development of Drosopila strains with this gene drive mechanism. PARTICIPANTS: Alun Lloyd Biomath NCSU Faculty Mathieu Legros NCSU postdoc Yunxin Huang NCSU postdoc Rachael Katz NCSU graduate student Sandra Paa NCSU graduate student TARGET AUDIENCES: USDA EPA NIH General public PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Our work has resulted in publication of a number of research and review papers that have received international attention. We are in the process of building a program in Genetic Pest Management at NCSU that is interdisciplinary in nature. We now have a web site available to all interested parties from which a person can run our simple and complex simulation models.
Publications
- Huang,, Y., K. Magori, A. L. Lloyd, F. Gould. 2007. Introducing transgenes into insect populations using combined gene-drive strategies: Modeling and analysis. Insect biochem. Mol. Biol. 37:1054-63.
- Gould, F. 2008. Broadening the application of evolutionarily based genetic pest management. Evolution 62-2: 500.
- Gould, F., Huang, Y., Legros, M., Lloyd, A. L. 2008. A killer-rescue system for self-limiting gene drive of anti-pathogen constructs. Proc. Royal. Soc. Lond. B. doi:10.1098/rspb.2008.0846
- Magori, K., Huang, Y, Legros, M., Puente, M., Lloyd, A. & Gould, F. 2008. www.nescent.org/wg_selfishdna/Documents
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Progress 10/01/06 to 09/30/07
Outputs
OUTPUTS: Most of our work in this past year has been on the potential use of transgenic insects for Genetic Pest Manangement although we have also been doing some modelling in collaboration with Chinese colleagues on Bt resistance modelling. We have developed general population genetic models for engineered underdominance, meiotic drive, Medea, HEGs. We have also developed an age structured non-spatial model. Our major contribution in this area is a detailed simulation model of the population dynamics and evology of Aedes aegypti. In terms of Bt resistance modelling we have focused on the issue of whether the Chinese government should allow commercialization of Bt corn
PARTICIPANTS: Huang, Y., K. Magori, A. L. Lloyd, F. Gould. NCSU Tony James UCI Tom Scott UC Davis
TARGET AUDIENCES: US govt. Chinese govt. Gates Foundation
Impacts
Results from our Genetic Pest Management models have been used by a Gates Foundation grant in decision making. We recently co-organized a workshop at the annual Gate Grand Challenges meeting on how modelling of mosquito populations can help in setting directions for research on dengue and malaria. Work on Bt resistance management is not yet at a stage where it can be used by the Chinese government.
Publications
- Gould, F., Cohen M. B., J. S. Bentur, G. G. Kennedy, J. W. Van Duyn. 2006. Impact of small fitness costs on pest adaptation to crop varieties with multiple toxins: A heuristic model. J. Econ. Entomol. 99:2091-2099.
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Progress 10/01/05 to 09/30/06
Outputs
We have made good progress in the past year both on the work related to transgenic insects for population replacement and on the work related to insect resistance to transgenic crops. In the area of transgenic insects, we published two review articles and articles related to the population genetics of population replacement. We were especially focused on the engineered underdominance system but we have recently been building models of meiotic drive and Medea drive mechanisms. Regarding resistance to transgenic crops, we published one empirical paper on the genetics of resistance to Bt toxins in field populations of Helicoverpa zea. We also published one theoretical paper on how small fitness costs of resistance genes could affect the rate and possibility of simple genetic resistance to dual toxin Bt crops.
Impacts
Our theoretical paper on the impact of small fitness costs on adaptation to dual toxins Bt crops has already been used by the EPA in its decision-making regarding refuge size for Bt cotton. We expect that the results of this work will encourage companies to develop dual toxin crops and will encourage more research in this area. Our work on transgenic insects has received quite a bit of attention including a front page story in the Raleigh News and Observer (December 11, 2006)
Publications
- Gould F, Cohen MB, Bentur JS, Kennedy, GG, VanDuyn, J. 2006 Impact of small fitness costs on pest adaptation to crop varieties with multiple toxins: A heuristic model JOURNAL OF ECONOMIC ENTOMOLOGY 99 (6): 2091-2099 DEC 2006
- Jackson RE, Gould F, Bradley JR, VanDuyn, J. 2006 Genetic variation for resistance to Bacillus thuringiensis toxins in Helicoverpa zea (Lepidoptera : Noctuidae) in eastern North Carolina JOURNAL OF ECONOMIC ENTOMOLOGY 99 (5): 1790-1797 OCT 2006
- Sinkins SP, Gould F. 2006. Gene drive systems for insect disease vectors NATURE REVIEWS GENETICS 7 (6): 427-435
- Magori K, Gould F. 2006. Genetically engineered underdominance for manipulation of pest populations: A deterministic model GENETICS 172 (4): 2613-2620 APR 2006
- Gould F, Magori K, Huang YX. 2006. Genetic strategies for controlling mosquito-borne diseases AMERICAN SCIENTIST 94 (3): 238-246 MAY-JUN 2006
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Progress 10/01/04 to 09/30/05
Outputs
We have had some good success in the past year both with theoretical and empirical work. On the theory side we published two papers. One on the impact of sex ratio alteration as a means to genetically suppress populations of pest insects. The second theoretical paper is on how the recombinational distance between transposon insertion sites can impact the spread through a population of desirable gene-bearing transposons. On the empirical side we finished up a paper on how predation can impact the evolution of resistance to transgenic insecticidal crops. We also published a paper with David Heckel's group on the resistance-related QTL in a Heliothis strain with broad-based resistance to Bt toxins.
Impacts
Our theoretical work on genetic control and strain replacement should be of importance to empirical researchers who are trying to develop transgenic insect strains for control of human diseases and for suppression of populations of crop pests.
Publications
- Schliekelman, P., S. Ellner, and F. Gould. 2005. Pest control by genetic manipulation of sex ratio. J. Econ. Entomol. 98: 18-34
- Mallampalli N, Gould F, and Barbosa P. 2005. Predation of Colorado potato beetle eggs by a polyphagous ladybeetle in the presence of alternate prey: potential impact on resistance evolution Entomol. Exp. Appl. 114:47-54.
- Rasgon, J. L., F. Gould. 2005. Transposable element insertion location bias and the dynamics of gene drive in mosquito populations. Insect. Mol. Biol. 14:493-500.
- Gahan L. J., Y. T. Ma, M. L. M. Coble, F. Gould F, W. J. Moar, D. G. Heckel. 2005. Genetic basis of resistance to Cry1Ac and Cry2Aa in Heliothis virescens (Lepidoptera : Noctuidae) J. Econ. Entomol.98:1357-1368.
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Progress 10/01/03 to 09/30/04
Outputs
We completed publication of papers from the thesis of Nick Storer on a detailed model of Helicoverpa zea evolutionary response to Bt containing crops. This work is being continued in a collaboration with JR Bradley and Ryan Kurtz to include cultivars with multiple toxins and to include non-structured refuges. We collaborated with Bruce Tabashnik's group at U. of Arizona to examine some potentially interesting theoretical results of researchers in France. Paul Schliekelman who is now and assistant proffessor at U. of Georgia collaborated with me in developing a review paper for the Annual Review of Entomology on genetic autocidal control and strain replacement strategies. We also collaborated in finishing up the last paper from his thesis. I received funding from NIH to continue work on autocidal control and strain replacement and have a new postdoc working on this project.
Impacts
With the recent commercialization of cotton with two Bt toxins the EPA must make new decisions about how these transgenic crops should be deployed in the field. A major issue is how large the non-transgenic refuges must be. Simulation models are an essential component in making these decisions and the model being developed in our lab is therefore of utility. There has been a great deal of interest in the possibility of engineering mosquitoes that cannot transmit malaria and dengue fever. We are working on models that could suggest the most efficient approaches for accomplishing this objective.
Publications
- Storer, N. P., S. L. Peck, F. Gould, J. Van Duyn, and G. G. Kennedy. 2003. Spatial processes in the evolution of resistance in Helicoverpa zea (Lepidoptera: Noctuidae) to Bt transgenic corn and cotton in a mixed agroecosystem: a biology-rich stochastic simulation model. J. Econ. Entomol. 96: 156-172.
- Storer, N. P., S. L. Peck, F. Gould, J. Van Duyn, and G. G. Kennedy. 2003. Sensitivity analysis of a spatially-explicit stochastic simulation model of the evolution of resistance in Helicoverpa zea (Lepidoptera: Noctuidae) to Bt transgenic corn and cotton. J. Econ. Entomol. 96: 173-187.
- Tabashnik, B.E., F. Gould, Y. Carriere. 2004. Delaying evolution of insect resistance to transgenic crops by decreasing dominance and heritability. J. Evol. Biol. 17:904-912.
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Progress 10/01/02 to 09/30/03
Outputs
We have been continuing our theoretical work on Bt crop resistance management. Recently, Ryan Kurtz began work to model the evolution of resistance to dual toxin Bt crops by Helicoverpa zea in a corn/cotton system. Nick Storer recently published two papers from his thesis. We have been continuing our work on autocidal control and strain replacement. Paul Schliekelman recently completed the last paper from his thesis on this topic, and will be submitting it for publication. Jason Rasgon started a postdoc in our lab this fall and is developing a model for understanding the spread of transposons used as a genetic drive mechanism. Our Annual Review of Entomology article on autocidal control and strain replacement was just published this month.
Impacts
With the recent commercialization of cotton with two Bt toxins the EPA must make new decisions about how these transgenic crops should be deployed in the field. A major issue is how large the non-transgenic refuges must be. Simulation models are an essential component in making these decisions and the model being developed in our lab is therefore of utility. There has been a great deal of interest in the possibility of engineering mosquitoes that cannot transmit malaria and dengue fever. We are working on models that could suggest the most efficient approaches for accomplishing this objective.
Publications
- Gould F 2003. Bt-resistance management - theory meets data NAT BIOTECHNOL 21 (12): 1450-1451
- Storer NP, Peck SL, Gould F, et al. 2003. Spatial processes in the evolution of resistance in Helicoverpa zea (Lepidoptera : Noctuidae) to Bt transgenic corn and cotton in a mixed agroecosystem: a biology-rich stochastic simulation model J ECON ENTOMOL 96 (1): 156-172
- Storer NP, Peck SL, Gould F, et al. 2003. Sensitivity analysis of a spatially-explicit stochastic simulation model of the evolution of resistance in Helicoverpa zea (Lepidoptera : Noctuidae) to Bt transgenic corn and cotton J ECON ENTOMOL 96 (1): 173-187
- Gould F., and P. Schliekelman. 2004 Population genetics of autocidal control and strain replacement.Annual Review of Entomology 49: 193-217.
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Progress 10/01/01 to 09/30/02
Outputs
Theory: I am in the process of finishing up two papers on insecticide resistance management that deal with pest adaptation to plants that produce multiple toxins, This work demonstrates the importance of even small amounts of fitness cost associated with insecticide resistance genes. Together with George Kennedy and John Van Duyn, I supervised a postdoc who has developed bioeconometric models of resistance management for plants that produce one and two toxins. Empirical: George Kennedy and I published the final paper in a series on the genetics of Colorado potato beetle adaptation to tomato. Three graduate students are working on projects to examine the genetics of host range evolution in Heliothine moths.
Impacts
Our previous theoretical and empirical work on insect adaptation to crops that produce bt toxin(s) has been used by the US EPA in formulating resistance management plans for the target pests of these insecticidal crops. I have served on a number of EPA science advisory committees as well as National Academy of Sciences committees that have addressed issues related to the sustainable use of transgenic crops.
Publications
- Lu, W., G. G. Kennedy, and F. Gould. 2001. Genetic analysis of larval survival and larval growth of two populations of Leptinotarsa decemlineata on tomato. Ent. Exp. Appl. 99: 143-155.
- Bailey, W. D., C. Brownie, J. S. Bacheler, F. Gould, G. G. Kennedy, C. E. Sorenson, and R. M. Roe. 2001. Species diagnosis and Bacillus thuringiensis resistance monitoring of Heliothis virescens and Helicoverpa zea (Lepidoptera: Noctuidae) field strains from the southern United States using feeding disruption bioassays. J. Econ. Entomol. 94: 76-85.
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Progress 10/01/00 to 09/30/01
Outputs
This project was only begun in October of 2001 so we have little progress to report. The progeny of all backcrosses are being held at -80C until we are ready to conduct AFLP analysis. The first step of identifying the most efficient sets of primers for this work has just begun.
Impacts
(N/A)
Publications
- No publications reported this period
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Progress 10/01/99 to 09/30/00
Outputs
n/a
Impacts
(N/A)
Publications
- No publications reported this period
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