Genetic Variability of Dalbulus maidis Populations from Brazil and Their Infectivity with Pathogens of Corn Stunt Complex.

Abstract

The corn leafhopper, Dalbulus maidis (DeLong & Wolcott) (Hemiptera: Cicadellidae), is a key pest of maize crops in the tropical and subtropical regions of the Americas. In addition to direct damage, its major impact is related to its action as insect vector of pathogens related to corn stunting complex (CSC). CSC diseases are currently the most important and cause severe crop losses in Argentina, Mexico, Brazil, and the southern United States, and outbreaks have been more oftenly reported. Little information is available on the population characteristics of the corn leafhopper and its bioecology. In this sense, we analyzed the genetic diversity of 120 representative specimens of D. maidis from four regions of Brazil (Northeast, Southeast, South, and Central-West) using a region of the mitochondrial gene coding for the cytochrome oxidase subunit I (mtCOI) as molecular marker. In addition, the infectivity of the collected insects with CSC pathogens was assessed to verify the prevalence of each CSC pathogen in specimens collected from different regions of Brazil. The Brazilian D. maidis population studied was divided into 18 mitochondrial haplotypes, focusing on haplotypes A, B, and C, which are predominant in this country. In addition, the mtCOI gene of D. maidis was found to have low variability in Brazil (π = 0.00171). Our data suggest that there are no spatial or temporal barriers between the different populations of D. maidis studied, which could be due to a short evolutionary time and its outstanding dispersion capacity. In addition, this study revealed a prevalence of infected leafhoppers with any of the CSC pathogens in Brazil, with more than half of the samples analyzed carrying at least one of the phytopathogens studied. Our study provides insights on population pest management of D. maidis in order to prevent CSC incidence in maize crops and pest resistance development in these vector populations to agricultural pesticides.