Genetic characterization of invasive Dalbulus maidis (Hemiptera: Cicadellidae) populations in the U.S.

The corn leafhopper is a major agricultural pest native to the Pacific lowlands of Mexico. This pest is a consistent problem in corn growing regions throughout South and Central America, due to its efficient vectoring of various diseases including corn stunt disease. Sporadic invasions of this pest in the U.S. are uncommon and limited to the Southern U.S. In August 2024, corn leafhopper populations in U.S. corn were reported in Texas, Oklahoma, Kansas, Missouri, and Arkansas with later season reports in Minnesota, Illinois, Nebraska, Indiana, and Wisconsin. Unlike previous reports of corn leafhopper in the U.S., this time the dramatic geographic range expansion of this pest was associated with the red-stunt disease complex in corn. This complex consists of corn stunt disease, maize bushy stunt disease, and a disease of unknown etiology with similar symptoms to corn stunt disease. Previous work on corn leafhoppers used a 350bp DNA fragment in the COI gene to characterize this pest. We genetically characterized invasive corn leafhopper populations in the U.S. using the whole mitochondrial genome and conducted a rarefaction analysis to determine the most informative mitochondrial DNA fragment length, which we propose as a standard to characterize corn leafhopper haplotypes. Standardizing haplotype characterization of this pest will ease knowledge transfer and facilitate communication amongst IPM professionals targeting this pest and the diseases it vectors. Genetic characterization of invasive corn leafhopper populations will also provide insights into their origin and increase the precision of IPM against specific corn leafhopper populations.