Establishment of an embryonic cell line of Grapholita molesta (Lepidoptera: Tortricidae) and in vitro replication of Cydia pomonella granulovirus in it.

The oriental fruit moth, Grapholita molesta (Busck) (Lepidoptera: Tortricidae), is a major pest of fruit trees worldwide. In this study, an embryonic cell line QAU-Gm-E-L of the oriental fruit moth was successfully established. The cells grew adherently, round cells and spindle cells accounted for 43.0% and 42.2% of the total population, respectively, and rod-shaped cells accounted for 14.8%. The amplified mitochondrial cytochrome oxidase I subunit (CoI) gene fragment was 651 bp in length, and its similarity with the CoI gene of the oriental fruit moth was 100%. The chromosomes of QAU-Gm-E-L cells were granular or short rod-shaped. Its number varied from 66 to 444, indicating that aneuploidy occurred. The observations were consistent with the chromosome characteristics of lepidopteran insect cell lines. The population doubling time of QAU-Gm-E-L cells was 27.64 h. Real-time fluorescence quantitative polymerase chain reaction (qPCR) confirmed that the number of copies of Cydia pomonella granulovirus (CpGV) gradually increased in QAU-Gm-E-L cells with inoculation time. The electron microscopy observations results showed that occlusion bodies (OBs) of CpGV could be formed in the cells at 4 d post-infection; a large number of OBs were seen in the cells at 8 d post-infection. Hence, the QAU-Gm-E-L cells can support the in vitro replication and proliferation of CpGV, and it will provide an ideal material for the molecular biology research of oriental fruit moth and CpGV.