Median lethal concentrations (LC50) and 95% confidence limits (CL) based on larval mortality of Cry1F-susceptible (SS-TX) and -resistant (FL-39) strains of Spodoptera frugiperda to five individual Cry proteins.

SS-TX was developed from insects collected from Hidalgo Co., TX in 2013 and documented to be susceptible to Cry1F maize and Cry1F protein. FL-39 was a resistant family isolated from an FL population collected in 2011 using an F2 screen. n = total number of neonates assayed. Limited by the amount of Cry proteins available, the highest concentrations used in some bioassays didn’t cause a 50% or greater larval mortality. LC50 value of an insect strain was considered to be greater than the highest Cry concentration assayed if its larval mortality was 50 value by the smaller one. A negative sign was given if the LC50 of FL-39 was smaller than that of SS-TX. Analysis of variance for growth inhibition: F4,29 = 22.19, P1,29 = 12.18, P = 0.0016 for insect strain; and F4,29 = 4.79, P = 0.0043 for the interaction. Mean values followed by a common letter in a column were not significantly different at α = 0.05 (Tukey’s HSD test).Median lethal concentrations (LC50) and 95% confidence limits (CL) based on larval mortality of Cry1F-susceptible (SS-TX) and -resistant (FL-39) strains of Spodoptera frugiperda to five individual Cry proteins.