Studies On The Safety Of Recombinant Helicoverpa Armigera Single Nucleocapsid Nucleoplyedrovirus (HaSNPV) Released Into Environment

To test if the foreign gene of a recombinant baculovirus is possible to be transferred to surrounding organisms, Verticillium dahliae Lleb. was cultivated with a mixture of Occlusion Body Derived Virion (ODV), Buded Virus (BV) and DNA of a recombinant Helicoverpa armigera single nucleocapsid nucleopolyhedrovirus (HaSNPV-AalT) which expresses an insect-selective toxin for up to 90 days. After cultivated without the virus components for 15 days, the genome DNA of Verticillium dahliae Lleb. was isolated and detected for AalT sequence by dot-blot hybridization. Results showed that no positive signal was found. In another experiment, ladybeetles (Propylaea japonica Thunberg) were collected from the plots treated with HaSNPV-AalT and further reared on healthy Apides (Rhopalosiphum psedobrassicae Davis). No homologous sequence of AaIT gene was found from the genome DNA of those lady beetles as well, when detected by dot-blot hybridization. From the results held in this research, there was no evidence that the foreign gene of recombinant HaSNPV was transferred to surrounding organisms.The inactivation rates of wild-type HaSNPV and genetically modified HaSNPVs in which the ecdysteroid UDP-glucosyltransferase (egt) gene was deleted (recombinant HaSNPV-EGTD) or an insect-selective toxin was inserted (recombinant HaSNPV-AalT) were tested and compared in cotton field in three consecutive years. Results showed that there was no significant difference between the inactivation rates of recombinant HaSNPVs and the parent wild-type HaSNPV. Whereas, the inactivation rates of these viruses were significantly different in different years. The average half-lives of these HaSNPVs in 2000, 2001 and 2002 were 0.57,0.90 and 0.39 days, respectively.The ability of persistence and dispersion of wild-type and recombinant HaSNPVs were monitored and compared in cotton ecosystem after they were multiply applied to control cotton bollworm over two cotton growing seasons in 2001 and 2002. The number of the recombinant HaSNPVs persisted in soil was not significantly different from that of the wild-type HaSNPV. Meanwhile, the migration distance of the recombinants from the released locus did not significantly differ from that of the wild-type HaSNPV.