Trypsin Modulating Oostatic Factor (TMOF) is a decapeptide that is the physiological signal that terminates trypsin biosynthesis in mosquito's gut epithelial cells. TMOF can pass through adult and larval guts and circulate in the hemolymph. Results from our laboratory demonstrated that feeding TMOF or its analogues (Phase I STTR grant) to mosquito larvae halted trypsin biosynthesis by the gut's epithelial cells causing starvation and up to 100% mortality. Genetically engineered Tobacco Mosaic Virus (TMV) coat protein, Chlorella sp. (phase I STTR), Chlorella desiccata (phase I STTR) and yeast cells (phase I STTR) that produced TMOF or a green fluorescent protein (GFP) TMOF fusion protein with a trypsin cleavage site (IEGR) were as effective as feeding TMOF alone causing death by starvation. We now propose to further develop the TMOF technology in phase II of the STTR grant into a final commercial product for use as a biorational insecticide to control mosquito populations and mosquito carrying diseases. We will accomplish this by further improving our Chlorella and yeast constructs, test the constructs in the laboratory first, and then take it to the field to find the right formulation to apply the TMOF producing Chlorella and yeast cells. The Chlorella, TMOF producing cells are an attractive concept because these cells are ubiquitously present in water where mosquito commonly breed, and thus serve as a native food source for mosquito larvae. Larval death and inhibition of trypsin biosynthesis will be monitored after feeding mosquito larvae live and heat inactivated Chlorella cells that synthesize TMOF. These results will be compared with control cells that do not produce TMOF. By the end of the phase II STTR we will have a commercial available mosquito larvicide that could be used in mosquito control districts in the USA and worldwide. PROPOSED COMMERCIAL APPLICATIONS: We propose to further develop the TMOF technology into a commercial product for use as a biorational insecticide using Chlorella and yeast cells. By the end of the phase II STTR we will have a commercial product that could be used in the USA and worldwide to control mosquito larvae.