Currently, objective 1, investigating the specificity and efficacy of immune priming response in ACP, is underway. The objective of this experiment is to identify if ACP will survive a lethal dose of pathogenic bacteria, Serratia marcescens, if they have had prior immune challenge by a sublethal dose of the same or other species of bacteria. We are currently investigating the effect of: a) pathogen and b) non-pathogen to determine whether immune priming regulates the response of ACP to subsequent infections. Fifty experimental 3 day old ACP adults were collected and starved for 3 h. Half of the insects were orally primed by feeing on an artificial diet solution containing a sublethal dose priming treatment, corresponding to a lethal dose response of 1% (LD1) of the insect pathogen S. marcescens, while they other half were fed a control artificial diet solution containing bacterial media only (Tidbury et al. 2011) (Table I, Objective 1a; Fig 2A). The diet solution consist edof 15% (w:v) sucrose and 1/10 (v:v) green food coloring (McCormick & Co.) sandwiched between two parafilm layers, as described in Hall et al. (2010). After 24 hours, each treatment group was enclosed on separate branches of a potted citrus plant (var. ‘Swingle’). Seven days after priming, insects were removed from plants, starved for 3 h, and either injected (experiment 1) or orally inoculated (experiment 2) on a diet solution containing a lethal dose pathogen challenge or control treatment. After feeding or injection, the ACP were returned to the ‘Swingle’ plants for 14 days or 100% mortality. Mortality throughout the experiment was recorded every 24 hours. After 14 d, ACP were examined for the presence of S. marcescens by plating crushed insects on Petri dishes containing LB nutrient agar. Samples of colonies formed after 3 d were collected for DNA extraction and confirmation of bacterial identity using conventional PCR. Each experiment was replicated six times. We are currently analyzing the results of these experiments. Subsequent experiments to address the effects of non-pathogen immune priming to pathogenic bacteria (objective 1b) are still underway. Additionally, we have initiated the second project objective, to determine the specificity of RNAi immune priming in D. citri. We have begun construct dsRNA using a GFP sequence. GFP is not naturally present in ACP; therefore, introduction of the dsRNA for this target should activate the RNAi response without inducting psyllid mortality. Additional targets will be constructed during the current project quarter.