Fruit fly is one of the most important pests for vegetables and crops worldwide. Since 1895, four species of fruit flies has invaded into Hawaii. In 2000, a group of scientists from Hawaii has initiated and implemented an area wide pest management program to suppress fruit fly population in Hawaii. Six techniques developed within the program has been transferred to many countries that have the fruit fly problem. Four techniques (monitoring, sanitation, bait spray, and male annihilation) are readily done by farmers. The other two techniques (sterile insect release and augmentative parasitoid release) involve mass fruit fly stock. Sterile insect technique (SIT) used in sterile insect release requires continuous mass rearing. Current mass rearing system has been satisfactory for rearing need. However, there are problems such as pesticide contamination of supporting material, spent diet management, labor intensive, and space issue. USDA-Agricultural Research Service looked for alternatives. In 2004, a novel fruit fly liquid diet has been developed. The core of this diet is using an inert substance (sponge cloth) to replace biological supporting material for mill feed (wheat product). During this diet development process, we have observed that fruit fly performance changes associate with the change of diet components. One of the most significant components is wheat germ oil. Larval diet supplemented with wheat germ oil (WGO) causes physiological reactions, such as increased fecundity and fertility, in some insects. Although the impact of WGO on insect physiology is important, the mechanisms of these actions are poorly understood. In this presentation, we will confirm our hypothesis that the addition of WGO to medium developed for larval oriental fruit flies modulates gene expression in the corresponding adults and further to identify when and how these gene expressed during different life cycle stages. We separately reared larvae of Bactrocera dorsalis on diets lacking or supplemented with WGO, and analyzed for expressed proteins in the resulting adult males and females by 2D-electrophoresis. Analysis of the gels revealed significant changes in expression levels of >70 proteins, 64 of which were identified by mass spectrometric analysis on MALDI-TOF/TOF. Apparent changes in expression levels for 6 of these proteins were confirmed by quantitative real-time PCR, showing that the changes in mRNA expression were reflected in changes in protein expression. These findings support the hypothesis that one mechanism of WGO actions in insect nutrition is the modulation of gene expression. Our goal is to identify molecular markers that serve as early indicators of the quality of insect culture media. Markers of deficient culture media will increase the efficiency of developing optimal systems for mass rearing beneficial insects and some pest species because decisions on culture media quality can be made without waiting through one or several life cycles.