Genetic population structure of sugarcane aphid, Melanaphis sacchari, in sorghum, sugarcane, and Johnsongrass in the continental USA

Authors: MEDINA, RAUL - Texas A&M University; Armstrong, John; HARRISON, KYLE - Texas A&M University

Submitted to: Entomologia Experimentalis et Applicata
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/31/2017
Publication Date: 3/9/2017
Citation: Medina, R.F., Armstrong, J.S., Harrison, K. 2017. Genetic population structure of sugarcane aphid, Melanaphis sacchari, in sorghum, sugarcane, and Johnsongrass in the continental USA. Entomologia Experimentalis et Applicata. 162(3):358-365.

Interpretive Summary: We studied the population genetics of a new invasive aphid called the sugarcane aphid. The study aphids were collected from all available host plants, including grain sorghum, forage sorghum, sugarcane, and Johnson grass from 13 different states within the Continental U.S. From our analysis, there existed no evidence of variation in the geographic or host-plant population structure. The sugarcane aphid thus far seems to occur as a genetic clone within the continental U.S.

Technical Abstract: In 2013, an outbreak of Melanaphis sacchari, the sugarcane aphid, was reported in sorghum in Texas. Although this aphid has been reported in the continental U.S. since the 1920s, its occurrence was limited to Florida and Louisiana sugarcane. In just two years M. sacchari has been reported in almost all sorghum growing regions from south central to southeastern states. Sorghum fields in affected areas have sustained considerable losses. This aphid has also been reported on Johnson grass and other feral grasses. The speed, at which this aphid has spread, raises serious concerns about future infestations. Many aphid species present genetically distinct populations when feeding on different host-plants. Thus, it is likely that the recent outbreak in sorghum could be explained by a recent introduction of a sorghum-adapted genotype. In this study we genetically characterized M. sacchari in three of its most common host-plants: sorghum, sugarcane, and Johnson grass, across its geographic distribution in the continental U.S. We did not find evidence of geographic or host-plant population structure. M. sacchari seems to occur as a superclone in the continental U.S. Our characterization of the genetic structure of this pest species provide baseline data aimed to explain its recent outbreak in sorghum as well as provide information that may aid in the design of sustainable control strategies.