Abstract: The Asian gypsy moth (Lymantria dispar) is a key forest defoliator throughout the world. Study on regulation of G protein for GST genes mediated by G protein coupled receptor contributes to exploring molecular targets for developing novel pesticides to control gypsy moth. In the present study, transformant Drosophila vector was constructed and transformant Drosophila lines expressing LdOA1 were successfully obtained, GSTs gene expression levels in transformant Drosophila and its response to deltamethrin stress were analyzed. These results provided basic information for elucidating insect OA1 gene functions. The recombinant vector pUAST-attB-LdOA1 was constructed by traditional enzyme digestion and ligation technology. The transformant Drosophila lines were obtained by transgenic technology and validated using PCR technology. The expression levels of GSTs Delta family genes and the effects of deltamethrin on GSTs gene expressions in transformant Drosophila were analyzed by real-time RT-PCR technology. The RT-PCR results showed that the 453bp band of LdOA1 gene was detected in transformant Drosophila lines expressing LdOA1 gene. Compared with untransformant Drosophila, the expression levels of GSTs Delta family genes, except for GSTd4 and GSTd7 genes, in transformant Drosophila lines were up-regulated with 1.01- to 3.27-fold of untransformant Drosophila using qRT-PCR analysis. Under low concentration of deltamethrin stress for 6h, the GSTd6 and GSTd10 were obviously induced while other GSTs genes were significantly inhibited in untransformant Drosophila, and the inhibition ratios were 6.48%-95.84%. Under deltamethrin stress for 12-72h, the expressions of GST genes, except for GSTd1 and GSTd10, were significantly inhibited in untransformant Drosophila. Compared with untransformant Drosophila, the expressions of GSTs genes in transformant Drosophila varied in similarity under low concentration of deltamethrin stress. However, the GST gene expressions in transformant Drosophila were significantly higher than those in untransformant Drosophila except for GSTd1 and GSTd10 for 12-48h, and the GST gene expressions in transformant Drosophila were highest under low concentration of deltamethrin stress for 6h. These results indicated LdOA1 may mediate G protein signal transduction to regulate GSTs Delta subfamily genes in response to deltamethrin stress.