eCry1Gb.1Ig-03 synthetic protein acts as a crystal delta-endotoxin produced by Bacillus thuringiensis. Similarly to other three-domain Cry proteins, it binds proteins in the epithelial gut lining of feeding insect larvae and oligomerizes to form pores, which then allows for an influx of water, cell swelling and eventual lysis. This leads to the destruction of the larval midgut epithelium and death of susceptible larvae. The protein is active on lepidopteran insect species such as Spodoptera frugiperda. eCry1Gb.1Ig differs from other Cry proteins, allowing it to kill FAW strains that are already resistant to Cry1Fa, Vip3Aa and Cry1A.105/Cry2Ab, and Vip3Aa, showing that it operates through a distinct mode of action by binding to a different midgut receptor.