What Ever Happened to Old World Bollworm Invasion of the US?

Following its initial discovery in Brazil in the early 2010s, many speculated that the highly mobile and polyphagous Old World bollworm (Helicoverpa armigera) would likely arrive in the US in the near future. Proposed invasion routes were by land to active in the southwestern US via Central America and Mexico or by island hopping in the Caribbean to ultimately arrive in the southeastern US. Hybridization between the Old World bollworm and its sister species in the New World (Helicoverpa zea) has since been confirmed in Brazil, opening the possibility of invasion of the US by parts of the genome of H. armigera through hybridization as opposed to direct colonization by pure breeding H. armigera individuals. We tested for genomic evidence of H. armigera invasion of the US using whole genome sequencing of over 200 Helicoverpa adults collected in populations across the southern US in 2019. Our results indicated that all collected individuals were H. zea with little to no genomic evidence of introgression between H. zea and H. armigera in moths from the sampled populations in the US.