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Jurat-Fuentes Lab Home > Our Research > Mechanisms of resistance to Cry toxins

Mechanisms of resistance to Cry and Vip proteins  

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Parts of this research are supported by Biotechnology Risk Assessment Grant Program competitive grant No. 2014-33522-22215 from the USDA National Institute of Food and Agriculture


Are Bt-resistant moths migrating into southeastern US?

Since their commercialization in 1996, transgenic crops producing insecticidal proteins from the bacterium Bacillus thuringiensis (Bt) have revolutionized agricultural pest control. Benefits of this technology include high efficacy and lack of toxicity to non-target organisms. The most important threat to the susbtainability of Bt crops is the evolution of resistance by target pests. After >20 years since their commercialization, there are reports of resistance to Bt crops developing in lepidopteran and coleopteran pests. Our efforts are focused on resistance to Bt corn producing the Cry1Fa protein in populations of the the fall armyworm (Spodoptera frugiperda). This insect is particularly interesting because it has the most cases of field-evolved resistance to Bt crops at different locations (Puerto Rico, Florida, North Carolina, Brazil).

Our work takes advantage of fall armyworm strains with fiedl-evolved resistance to Cry1Fa corn that originated in Puerto Rico. We have identified the resistance mechanism and allele responsible, and developed a DNA-based tool to detect the resistant allele in field collections. Using this assay we have determined that the resistance allele from Puerto Rico has not left the island.

Our current goals are to identify the resistance gene and allele/s from Florida, North Carolina, and Brazil, and to determine the ferquency of these allleles in the US, South America, and AFrica, were the fall armyworm is not a hugely devastating pest.


Resistant Spodoptera frugiperda larva feeding on Bt corn
Are Bt crops altering migratory behaviour of fall armyworms?  
Our current collaborative project with Dr. Fangneg Huang (Louisiana State University), and Drs. Robert Meagher and Rodney Nagoshi (USDA-ARS CMAVE, Florida) funded by the USDA-NIFA Biotechnology Risk Assesment Grant Program (BRAG) is aimed at assessing the risk of transgenic crops altering the migratory behaviour of fall armyworms. Adults (moths) of this insect migrate north each year from populations in south Texas and Florida to colonzie corn-growing areas of the USA. Considering that there is evidence for lepidopteran pests modifying their migratory behaviour in response to feeding cues during the larval stage, we hypothesize that transgenic Bt corn may be influencing the migratory behaviour of S. frugiperda, especially in the case of Bt-resitant populations. Our goal is to determine the effect of Bt corn and Bt cotton on S. frugiperda flight propensity. Information from this project, together with the use of Bt-resistance gene and available haplotype markers for genotyping moths would allow the development of mathematical predictive models for abundance and movement of Bt-resistant armyworms.
Publications from this area of research
Banerjee, R., J. Hasler, R. Meagher, R. Nagoshi, L. Hietala, F. Huang, K. Narva, and J. L. Jurat-Fuentes (2017) "Mechanism and DNA-based detection of field-evolved resistance to transgenic Bt corn in fall armyworm (Spodoptera frugiperda)" Sci. Reports 7(1): 10877. PDF
Nagoshi, R. N., D. Koffi, K. Agboka, K. A. Tounou, R. Banerjee, J. L. Jurat-Fuentes, and R. L. Meagher (2017) "Comparative molecular analyses of invasive fall armyworm in Togo reveal strong similarities to populations from the eastern United States and the Greater Antilles"  PloS ONE, 12(7): e0181982. PDF
Velez, A., N. Vellichirammal, J. L. Jurat-Fuentes, and B. Siegfried (2016)  "Cry1F resistance among lepidopteran pests: a model for improved resistance management?"  Curr. Opin. Insect Sci. 15(1): 116-124. PDF
Jakka, S. R. K., Gong, L., Hasler, J., Banerjee, R., Sheets, J. J., Narva, K., Blanco, C. A., and J. L. Jurat-Fuentes (2015) "Field-evolved Mode 1 fall armyworm resistance to Bt corn associated with reduced Cry1Fa toxin binding and midgut alkaline phosphatase expression" Appl. Environ. Microbiol. 82(4): 1023-1034. PDF
Gong, L., Wang, H., Qi, J., Han, L., Hu, M., and J. L. Jurat-Fuentes (2015) "Homologs of Cry toxin receptor genes in a de novo transcriptome and their altered expression in resistant Spodoptera litura larvae" J. Invertebr. Pathol. 129: 1-6. PDF
Guo, Z., Kang, S., Chen, D., Wu, Q., Wang, S., Xie, W., Zhu, X., Baxter, S. W., Zhou, X., Jurat-Fuentes, J. L., and Y. Zhang (2015) "MAPK signaling pathway alters expression of midgut ALP and ABCC genes and causes resistance to Bacillus thuringiensis Cry1Ac toxin in diamondback moth” PLoS Genetics 11(4): e1005124. PDF
Adang, M., Crickmore, N., and J. L. Jurat-Fuentes (2014) "Diversity of Bacillus thuringiensis crystal toxins and mechanism of action”, in Advances in Insect Physiology, Vol. 47: Insect Midgut and Insecticidal Proteins, pp. 39-87, Academic Press, San Diego, CA PDF
Jakka, S. R. K., Knight, V. R., and J. L. Jurat-Fuentes (2014) "Spodoptera frugiperda (J.E. Smith) with field-evolved resistance to Bt maize are susceptible to Bt pesticides” J. Inverbr. Pathol. 122: 52-54. PDF
Jakka, S. R. K., Knight, V. R., and J. L. Jurat-Fuentes (2014) "Fitness costs associated with field-evolved resistance to Bt maize in Spodoptera frugiperda (Lepidoptera: Noctuidae)” J. Econ. Entomol. 107(1): 342-351. PDF
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. PDF
Blanco, C., Portilla, M., Jurat-Fuentes, J. L., Sanchez, J. F., Viteri, D., Vega-Aquino,P., Teran-Vargas, A. P., Azuara-Dominguez, A., Lopez, J. D., Arias, R., Zhu, Y.-C., Lugo –Barrera, D., and R. Jackson (2010) “Susceptibility of isofamilies of Spodoptera frugiperda (Lepidoptera: Noctuidae) to Cry1Ac and Cry1Fa proteins of Bacillus thuringiensis” Southwest. Entomol. 35: 409-415. PDF
Parts of this research are supported by Biotechnology Risk Assessment Grant Program competitive grant No. 2014-33522-22215 from the USDA National Institute of Food and Agriculture.
Dr. Juan Luis Jurat-Fuentes
Department of Entomology and Plant Pathology
The University of Tennessee
2431 Joe Johnson Drive
205 Ellington Plant Sciences Building
Knoxville, TN, 37996
Tel: (865) 974-5931