WHEN INVASIVE INSECTS ARRIVE TO A NEW LOCATION, THEY BRING WITH THEM A SUITE OF MICROBIAL SYMBIONTS, INTERACTING ORGANISMS THAT CAN HAVE BENEFICIAL, HARMFUL OR NEUTRAL INTERACTIONS. FOR EXAMPLE APHIDS HAVE THE OBLIGATE SYMBIONT BUCHNERA APHIDICOLA, A BACTERIA THAT PROVISIONS ESSENTIAL NUTRIENTS THAT THE APHID CANNOT MAKE. ALTHOUGH SUGARCANE APHIDS HAVE BEEN IN THE CONTINENTAL US SINCE THE 1970S ON SUGARCANE (DESIGNATED MULTILOCUS LINEAGE D), THIS APHID BECAME A SERIOUS PEST AFTER A NEW INTRODUCTION OF A SORGHUM ADAPTED STRAIN (DESIGNATED MULTILOCUS LINEAGE F) IN 2013. MY PREVIOUS RESEARCH SHOWS THAT THERE ARE GENETIC AND MICROBIAL COMPOSITION DIFFERENCES BETWEEN SUGARCANE APHIDS ON SORGHUM AND SUGARCANE. HOWEVER, IT IS STILL UNKNOWN WHETHER VARIATION AMONG BUCHNERA APHIDICOLA STRAINS IN SUGARCANE APHIDS POSITIVELY INFLUENCE THIS INSECT'S PESTIFEROUS NATURE, CALLED ECOLOGICAL FACILITATION.THIS RESEARCH PROJECT PROPOSES TO CHARACTERIZE THE GENETIC COMPOSITION OF BOTH THE INVASIVE SUGARCANE APHID AND ITS OBLIGATE SYMBIONT BUCHNERA APHIDICOLA, TO ASSESS WHETHER A SYMBIONT CAN ECOLOGICALLY FACILITATE PEST DAMAGE. MOLECULAR SEQUENCING WILL ALLOW ME ANALYZE WHETHER GENETIC VARIATION IN BUCHNERA APHIDICOLA IS ASSOCIATED WITH GENETICALLY DISTINCT SUGARCANE APHIDS (FROM MULTILOCUS LINEAGE F AND D). I WILL ALSO COMPARE GENE COMPOSITION AMONG BUCHNERA APHIDICIOLA FROM SORGHUM AND SUGARCANE ADAPTED APHIDS. ANALYZING GENE COMPOSITION AND COMPARING GENE REGIONS ASSOCIATED WITH METABOLIC ACTIVITIES WILL ALLOW ME TO DETERMINE WHETHER SYMBIONT GENETIC VARIATION IS RESPONSIBLE FOR DAMAGE POTENTIAL DIFFERENCES IN SUGARCANE APHIDS. I HYPOTHESIZE THAT GENETIC VARIATION AMONG SCA'S OBLIGATE SYMBIONT BUCHNERA APHIDICOLA MAY PARTIALLY EXPLAIN SCA DAMAGE AND SUCCESS IN SORGHUM. ASSESSING POTENTIAL ECOLOGICAL FACILITATION FOR SUGARCANE APHIDS IN SORGHUM MAY PROVIDE THE FOUNDATION TO DEVELOP NEW TOOLS TO AID SORGHUM GROWERS.