To determine the optimal concentration of dsRNA priming, ACP were exposed to a series of dsRNA concentrations (10, 100, 1000 ng. �l-1) in artificial diet for 24 hrs, and 5 days. ACP were subsequently transferred to artificial diet containing S. marcescens for 4 days, then transferred to C. macrophylla for 14 days. Survival of ACP was recorded every 24 hrs for 14 days. ACP survival in response to S. marcescens was lowest after feeding on 100 ng. �l-1 of dsRNA T7_pGEMT for 24hrs, as compared with control (no dsRNA priming) treatments. The survival rates of ACP exposed to S. marcescens or sucrose following control (no dsRNA priming) were not significantly different. Eighty percent of ACP survived after feeing on 100 ng.�l-1 dsRNA ATPase for 5 d prior to being transferred to sucrose, and was significantly higher than among ACP that fed only on sucrose prior to S. marcescens exposure. This suggests that initial (24 h) exposure to dsRNA may increase susceptibility of ACP to pathogens. Among the insects that did not survive pathogen challenge, S. marcescens was detected in 79% of ACP following priming with 100 ng. �l-1 dsRNA T7_pGEMT100 fior 24 h, as compared with 9-15% of ACP not primed with dsRNA. Insects primed for 5 days on dsRNA followed by exposure to S. marcescens, 75% of insects fed with 100 ng. �l-1 dsRNA ATPase were infected with the pathogen. No bacterial infection was observed in insects fed on 1000 and 10 ng. �l-1 of T7_pGEMTdsRNA , or control (no dsRNA priming) treated insects. The high percentage of bacterial infection in the dsRNA-treated insects indicates that dsRNA may contribute to bacterial loads in ACP, although this effect appears to be dose-dependent. Target gene expression decreased among ACP that were primed with 1000 ng. �l-1 T7_pGEMT or 100, 1000 ng. �l-1 of dsRNA ATPase prior to S. marcescens exposure but this reduction was not statistically different from untreated (no dsRNA priming) ACP. It is expected that the time between feeding dsRNA and quantifying mRNA at the end of the feeding bioassay is too long long to detected dsRNA-associated changes in expression; therefore, experiments are underway to evaluated changes in expression following 24 h and 5 d exposure to dsRNA. In addition, subsequent analyses will be conducted to determine whether priming facilitates Liberibacter acquisition.