Resistance Of Spodoptera Frugiperda To Bacillus Thuringiensis Proteins In The Western Hemisphere

Resistance to Bacillus thuringiensis (Bt) Cry1 insecticidal proteins expressed in genetically modified plants (Bt maize and other Bt crops) has been documented in the fall armyworm (FAW; Spodoptera frugiperda [J.E. Smith]) in South America. The factors that led to the onset of resistance include less-than-optimal product characteristics (dose) and poor compliance with the requirement for structured refuges of non-Bt maize. In this article, we review the documented cases of resistance in FAW and explore the path forward to the implementation of effective insect resistance management (IRM) programs to support the sustainable deployment of this technology, particularly in tropical regions. Effective IRM plans require effective product design and management of Bt maize technology. Due to the challenges presented in tropical regions, the development of effective Bt maize pyramids combining highly effective and novel modes of action is fundamental to a successful IRM strategy. The integration of IRM and business imperatives through the development of a multilayer, multi -stakeholder strategy to ensure the proper use of the technology, and particularly to adequate compliance with refuge requirements, is another critical element of an IRM strategy for Bt crops.