Professor of Entomology Texas A&M University College Station, Texas
In 2013, a new aphid pest caused yield loss in grain sorghum crops. Recently, my research group and I identified the aphids of this outbreak as sorghum aphids, a cryptic species, that is genetically distinct from the sugarcane aphid (SCA) that feeds predominately on sugarcane. When examining the microbial composition of these aphids, there are differences in microbial abundances among aphids feeding on sorghum and those that feed on sugarcane, with lower overall abundances of the obligate symbiont, Buchnera aphidicola, in aphids that feed on sugarcane. In addition, to microbial differences within the aphid, there are differences in microbial composition in the honeydew secretions of this aphid based upon host plant (i.e., Johnson grass versus grain sorghum), which could influence the attractiveness of ants towards these pest aphids. Greenhouse experiments show that tawny crazy ants readily tend sorghum aphids, both invasive pests that have no evolutionary history together, suggesting that future pest management plans should take into account the presence of ants in facilitating aphid outbreaks. Building upon the knowledge of ant-aphid interactions and microbial community composition, my current USDA NIFA grant research focuses on the potential genetic variation of sorghum aphids and its obligate symbiont Buchnera aphidicola in Texas.