Résumé
The sugarcane aphid (Melanaphis sacchari (Zehnter) (Hemiptera: Aphididae)) has become a serious pest of sorghum (Sorghum bicolor (L.) Moench) in the United States since it was detected in 2013. The sugarcane aphid was considered only a pest of sugarcane in Florida and Louisiana for over three decades before the 2013 outbreak. Recent studies suggest that the 2013 outbreak in sorghum was due to the introduction of a new genotype. Our scope for this study was to quantify phenotypic behaviors (host suitability as measured through life table statistics) and genetic diversity among sugarcane aphid clones collected from different hosts. We collected sugarcane aphid clones from sorghum (SoSCA), sugarcane (SuSCA), and Columbus grass (CoSCA) and determined biodemographic data and host suitability when offered five different hosts plants including, sugarcane, Columbus grass, Johnsongrass, and a resistant and susceptible grain sorghum. Sugarcane aphid clones collected from different hosts varied in performance among hosts plants. The survivorship and reproduction of the sugarcane-collected aphid clone (SuSCA) was significantly higher when offered sugarcane (>85%) as compared to other hosts and in contrast, there was negligible survival and reproduction when SoSCA and CoSCA were offered sugarcane as host. Genotyping of the aphid clones collected from various hosts with microsatellite markers indicated that SuSCA was a different genotype and belonged to the multilocus lineage MLL-D as compared to SoSCA and CoSCA which belonged to MLL-F. Our results suggest there exists two different host-specific biotypes of the sugarcane aphid within the United States.