Melanaphis sorghi (Hemiptera: Aphididae) Clonal Diversity in the United States and Brazil

SIMPLE SUMMARY: Melanaphis sorghi has been a perennial economically important pest to U.S. sorghum since 2013. Previous research has shown its recent infestation on sorghum has been spreading as a super-clone, a highly abundant clone that is distributed over a large geographic area and persists over time, in the U.S. To continuously monitor the genotypes present in the U.S. and to determine the genotype present in Brazil on sorghum, Melanaphis spp. were collected in 2019 and 2020. Genotyping of aphid samples with microsatellite markers revealed that the super-clone predominated in the U.S. in 2019 and 2020 and Brazil in 2020. Thus, the M. sorghi super-clone remains in the U.S. on sorghum, Johnsongrass, and giant miscanthus and is present in Brazil on sorghum. ABSTRACT: Melanaphis sorghi (Hemiptera: Aphididae), are an economically important pest to sorghum in the Americas. Previous studies have found that a super-clone that belongs to multilocus lineage (MLL)-F predominated in the U.S. from 2013 to 2018 and uses multiple hosts besides sorghum. In contrast, previous studies found that aphids in South America belong to MLL-C, but these studies only examined aphids collected from sugarcane. In this study we sought to determine if the superclone persisted in the U.S. in 2019–2020 and to determine the MLL of aphids found on sorghum in the largest country in South America, Brazil. Melanaphis spp. samples (121) were collected from the U.S. in 2019–2020 and Brazil in 2020 and were genotyped with 8–9 Melanaphis spp. microsatellite markers. Genotyping results showed that all samples from the U.S. in 2019 and Brazil in 2020 had alleles identical to the predominant superclone. Of the 52 samples collected in the U.S. in 2020, 50 samples were identical to the predominant super-clone (multilocus lineage-F; M. sorghi), while two samples from Texas differed from the super-clone by a single allele. The results demonstrated that the super-clone remains in the U.S. on sorghum, Johnsongrass, and giant miscanthus and is also present on sorghum within Brazil.