Are cases of resistance to Cry1Fa corn in diverse populations of Spodoptera frugiperda due to the same mechanism?

The bacterium Bacillus thuringiensis (Bt) produces Cry toxins, which are broadly used in insecticidal mixtures and expressed in transgenic crops for environmentally safe and efficient control of insect pests.  The major drawback of the intensive use of Cry toxins is the increased pressure for selection of resistance in targeted pests.  In Puerto Rico, populations of the fall armyworm (Spodoptera frugiperda) have developed high levels of resistance to transgenic corn producing the Cry1Fa toxin from Bt.  More recently, Cry1Fa-resistant S. frugiperda have been detected in Florida counties.  While the mode of action of Cry toxins involves several steps, we previously reported reduced expression of a putative Cry toxin receptor membrane bound alkaline phosphatase as mechanism of resistance to Cry1Fa corn in S. frugiperda from Puerto Rico.  In this study, we focus on testing whether a similar mechanism is responsible for resistance to Cry1Fa in S. frugiperda from Florida.  Data resulting from our research increases our understanding of the mode of action and resistance mechanisms to Cry toxins and identifies targets for development of improved toxins for crop protection.