Mechanism and DNA-based detection of field-evolved resistance to transgenic Bt corn in fall armyworm (Spodoptera frugiperda)

Authors: BANERJEE, RAHUL - University Of Tennessee; HASLER, JAMES - Dow Agrosciences; Meagher, Robert - Rob; Nagoshi, Rodney; HIETALA, LUCAS - University Of Tennessee; HUANG, FANGNENG - Louisiana State University; NARVA, KEN - Dow Agrosciences; JURAT-FUENTES, JUAN - University Of Tennessee

Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/31/2017
Publication Date: 7/1/2017
Citation: Banerjee, R., Hasler, J., Meagher Jr, R.L., Nagoshi, R.N., Hietala, L., Huang, F., Narva, K., Jurat-Fuentes, J.L. 2017. Mechanism and DNA-based detection of field-evolved resistance to transgenic Bt corn in fall armyworm (Spodoptera frugiperda). Scientific Reports. 7(1):10877. https://doi.org/10.1038/s41598-017-09866-y.
DOI: https://doi.org/10.1038/s41598-017-09866-y

Interpretive Summary: The fall armyworm is a chewing pest of corn, sweet corn, sorghum, rice, cotton, and many other row and vegetable crops throughout North and South America. It is a migratory species in North America, moving from southern parts of Texas and Florida in the spring to southern Canada in the fall. It has been recently found in many locations in western and southern Africa. Growers in the U.S. plant corn and cotton crops that produce insecticidal proteins from the bacterium Bacillus thuringiensis (Bt). Several years ago, fall armyworm in southern Puerto Rico developed resistance to one of the Bt proteins. Researchers at the University of Tennessee, in collaboration with scientists from the USDA, Agricultural Research Service, Center for Medical, Agricultural and Veterinary Entomology, Gainesville, Florida, and Dow AgroSciences have found that the acquired Bt resistance is due to a single gene mutation that allows caterpillars to survive feeding on transgenic corn. Development of a diagnostic genetic test for the mutation allowed these researchers to reexamine previously collected moth samples which permitted them to chart the movement of the acquired Bt resistance within the Caribbean and U.S. Scientists will also be able to monitor future movement of Bt resistance in populations for this serious agricultural pest that will provide state and federal agencies with information to establish effective, targeted control programs.

Technical Abstract: Evolution of resistance threatens sustainability of transgenic crops producing insecticidal proteins from the bacterium Bacillus thuringiensis (Bt). The fall armyworm is a devastating pest controlled by transgenic Bt corn producing the Cry1Fa insecticidal protein. However, fall armyworm populations in North and South America have developed field-evolved resistance to Bt corn, and this insect has recently become a destructive invasive pest of corn in West Africa. In this study, we show that field-evolved resistance to Cry1Fa Bt corn in Puerto Rico is due to a mutation in an ATP Binding Cassette subfamily C2 (ABCC2) gene that functions as a Cry1Fa receptor in susceptible insects. Furthermore, we report a DNA-based genotyping test and demonstrate its utility to detect increased resistance allele frequency through the past nine years in Puerto Rico but absence in armyworm migratory destinations in the Caribbean and southeastern US. This first example of successful DNA-based field monitoring for a Bt resistance allele exemplifies the utility of this tool to refine migratory models and understand their relevance to the spread of insect resistance.