The Study On Rice Stem Borer's Plant Selectivity To Transginec Bt Rice And Risistance To Stem Borers Of The Transgenic Bt Rice

The resistance to striped stem borer(SSB), yellow stem borer(YSB) and purplish stem borer(PSB) were studied by using Bt transgenic rice Shanyou63/Bt, Shanyou63 as the control varieties. The feeding and oviposition choice tests were carried to the two kinds of different rice.The feeding choice test discovered that SSB, YSB and PSB lavae of different instars had a little difference in the selectivity between the rice variety and the control, the penetrative rates were very close.The oviposition choice test in the laboratory showed that both SSB and PSB had little difference in oviposition selectivity to the two kinds of rice.Using the methods of "detached stem bioassay", it showed that Bt transgenic rice Shanyou63/Bt was highly resistant to YSB and SSB. The Bt transgenic rice had good risistance to the 1^st and 2^nd instar PSB, but many 3^rd and 4^th instar lavaes could survive it, the resistance of Bt transgenic rice to PSB is much lower than the resistance to SSB and YSB.The feeding test on YSB's 1st instar lavae with young Bt transgenic rice shoot had a good rapid identification performance, there was a remarkable difference of lavae mortality between Bt transgenic rice and the control. 1^st YSB's mortality was 36.74% after 24 hours, and 48 hours later, the mortality reached to 62.80%. Test indicated that the difference of the young rice shoot's length had no effect to 1^st YSB's mortality. Feeding the 1^st PSB with young Bt transgenic rice shoot, it showed little difference of mortality between Shanyou63/Bt rice and Shanyou63 rice, so 1^st PSB is not proper for rapid identification of Bt transginec rice.The whitehead ratio was investigated from 2002 to 2004, it showed good resistance of Bt transgenic rice to stem borers. By investigating the number of borer in the Shanyou63/Bt rice and Shanyou63 rice, we found that the whitehead of the Bt transginec rice was mostly caused by PSB while the whitehead of the Shanyou63 rice was mostly caused by SSB. The number difference of SSB, YSB and PSB in the two kinds rice told us that the PSB's resistance to Shanyou63/Bt was higher than SSB and YSB's.