The objective of this project is first to identify a Bacillus thuringiensis (Bt) crystal toxin with basal toxicity against Asian citrus psyllid (ACP). The toxicity of the selected toxin will then be enhanced by addition of a peptide that binds to the gut of ACP. This peptide addition to the toxin is expected to enhance both binding and toxicity against ACP. To identify a Bacillus thuringiensis strain with basal toxicity against ACP, bioassays were conducted with solubilized and activated toxins derived from 46 different Bt isolates. Six isolates showed promise with statistically significant ACP mortality at 500ug/ml relative to control treatments. One strain was selected for further identification of individual toxins by MS/MS analysis and the three primary toxins expressed by this strain identified. Additional bioassays are underway to select the toxin with the greatest toxicity against ACP for modification with ACP gut binding peptides. Four ACP gut binding peptides were isolated and the peptide sequences cloned for production of mCherry fusion proteins as described in previous reports. Binding of these fusion peptides to gut proteins was confirmed by pull down analysis with ACP brush border membrane vesicles (BBMV). Two negative control proteins, mCherry alone and a random peptide-mCherry fusion were included as negative controls for binding to ACP BBMV. Replication of 2D gel electrophoresis of BBMV proteins coupled with ligand blot analysis (1 to 3 replicates per peptide-fusion protein) showed that the four peptide-mCherry fusion proteins bind 50kDa, 37kDa and 25kDa proteins all at pI ~9. As negative control, mCherry showed non specific binding to an abundant 50kDa protein, pI ~5. In vivo binding of the fusion peptides and mCherry negative control using fluorescence analysis indicated that fusion proteins with peptides 15 and 18 bind the ACP gut. These two peptides represent promising candidates for use in Bt toxin modification.