The Florida population contains individuals with resistance to the Cry1F trait. The Texas population does not have this modified gene. Why only Florida? This is likely because the Florida population interbreeds with populations in the Caribbean which are the probable source of the resistance. South Florida and the Caribbean have year-round FAW populations and lots of use and testing of single trait corn products. It appears that the Texas population does not mix with the Florida population very much so it has not acquired the resistance gene.
“This is a huge wake-up call for farmers north of Louisiana and Florida – this is definitely something to keep an eye on,” Reisig says. “Resistance happens, and it’s a stark reminder that we need to take steps – such as planting non-Bt ‘refuge’ crops near the Bt crops – to limit the development of resistant insect strains.”
The real fear is that these Bt-resistant armyworms will move from corn to cotton.
“That would be problematic, since cotton usually begins producing fruit (the marketable cotton bolls) in July or early August – when fall armyworm populations have grown,” Reisig says. “Corn is less threatened, since it is at its most vulnerable in the spring, when fall armyworm populations are still low.
Source:uga.edu