The Study On Resistance To Pests Of The Transgenic Bt Rice And Effect On Insects Of The Biotic Community In Field

Based on the survey in rice field, the resistance to yellow stem borer Scirpophaga incertulas (Walker) (Lepidotera:Pyralidae) and rice leaf folder Cnaphalocrocis medinalis (Guenee) (Lepidotera:Pyralidae) were studied using the transgenic indica rice CMS restorer line Minghui63 and its derived varieties, Shanyou63/Bt, expressing a Bt fusion protein derived from crylA(b) and crylA(c) sequences, Minghui63 and Shanyou63 as the control varieties.Using the methods of "detached stem bioassay" in laboratory showed that Shanyou63/Bt was highly resistant to 1st and 3rd striped stem borer (SSB) Chilo suppressalis (Walk) 3 instar larvae with the moralities of 67.92% after 72 hours was more resistant to Bt rice than 1 instar larvae. But the larvae of SSB died within ten days of feeding on Bt rice stems, and no stem borers were observed to complete development. The test results were quite coincident with the test of YSB.By means of manual infesting YSB in field, Minghui63/Bt and Shanyou63/Bt showed high resistance to YSB. In natural condition the Bt lines had low levels of stem borer damage at grain-filling stage while damage was high on non-Bt lines. But the damage of stem borer increased from 0 to 0.38% from 2000 to 2003. Shanyou63/Bt line showed high resistance against rice leaf folder. Damage on the Bt line was significantly lower than on the non-Bt check line. But the resistance of Bt rice showed decrease.Systematic studies were carried out on effects of Bt transgenic rice on population dynamic of the main insect pests and some natural enemies in field. The results showed there were resistance of Bt rice to rice skipper butterfly Mycalesis gotama Moore and rice green horned caterpillar Pelopidas mathias Fabricius, while were not resistant to planthopper Sogatella furcifera (Horvtith) and Nilaparvata lugens (Stal) and rice leafhopper. Nephotettix cincticeps Ubler and Nephotettix bipunctatus (Fabricius).Spider populations were also similar on the Bt and non-Bt lines in three years. There was not harmful to rove beetles in Bt rice field, either. There was no negative influence to arthropods in Bt rice field. The arthropod community in Bt rice field was even more stable than it in non-Bt rice field.Compared with normal treatments, mortality of 3r instar Bombyx mori (L.) larvae in either Bt rice pollen or non-transgenic rice pollen treatments were not significantly different, silkworm larvae weight were different before they became pupae. There was no effect on eclosion of silkworms. On the other hand, the results showed there were significant influence to Pieris rapae (L.) and Papilio xuthus L. larvae.