Abstract: 【Aim】 Ecological risk assessment of transgenic crops is a necessary step before large-scale planting. There are hundreds of species of flower visiting insects in ricem(Oryza sativa), including the housefly (Musca domestica). This study aims to assess the potential risk of rice gene flow mediated by flowervisiting M. domestica. 【Methods】 We conducted field experiments with the genetically modified (GM) rice lines B1, B6 and G8-7 as the pollen donors, the parental non-GM rice lines Jiazao 935 and Wuyunjing 7 as the pollen recipients, and M. domestica as the pollinator in Huajiachi and Changxing testing base of Zhejiang University in 2010. All harvested rice offspring seeds were planted in the laboratory and the plants were used for the detection of transgenic hybrids by the hygromycin B and glyphosate treatments, and then the surviving plants were further detected for hygromycin- and glyphosate-resistant genes by PCR to test the gene flow of GM rice mediated by M. domestica. 【Results】 The results based on the examination of over 216 500 geminated seeds from the three GM rice lines in the two testing bases in Zhejiang showed that there were few hybrids, indicating low frequencies (0-0.64%) of transgene flow from GM to non-GM rice at close spacing both in plots with and without M. domestica. 【Conclusion】 It is concluded that the frequency of transgene flow from GM to non-GM rice mediated by M. domestica is low and M. domestica does not increase the risk of gene flow of rice.

Key words:  Oryza sativa, Musca domestica, gene flow, genetically modified crop, hygromycin-resistant gene, glyphosate