The objective of this project was to identify a Bacillus thuringiensis (Bt) crystal toxin with basal toxicity against Asian citrus psyllid (ACP) and to enhance the toxicity of the selected toxin by addition of a peptide that binds to the gut of ACP. The added peptide is expected to enhance both binding and toxicity of the toxin against ACP. Having identified two Bt toxins with toxicity to ACP, the most toxic of these ACP-active toxins was modified with gut binding peptide 18. The sequence encoding ACP gut binding peptide 18 was introduced into the toxin at four different sites. However, some of the modified toxins did not express well in E. coli. To identify the optimal system for toxin expression, ACP-active and wild type toxins are being expressed in Bt acrystalliferous strains 4Q7 and 78/11 using E. coli – Bt shuttle vectors. Once toxin expression has been optimized, toxins will be purified for use in ACP bioassays to test for enhancement of toxicity.