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利用 3株转 Bt cry1A(c)基因的抗虫工程菌 ,对亚洲玉米螟 Ostrinia furnacalis进行离体生物测定。结果表明 :在相同浓度下 ,工程菌对玉米螟的杀虫活性均高于 Bt野生菌株 ;幼虫死亡率与浓度呈正相关 ,体重、体长与浓度呈负相关 ;工程菌 RPT4 0、RPT5 0、RPT5 5和野生型 Bt菌株 HD- 73对玉米螟的 L C50 值分别为71.2 6 ,36 .33,84 .71和 172 .36μg.g-1。在以 RPT5 0注射接种的活体生测中 ,处理株对玉米螟具有明显的抗性 ,虫体重减轻 2 4 .5 %～ 5 2 .3% ,体长降低 2 2 .6 %～ 6 4.6 %。工程菌 RPT5 0接种玉米 10 d后 ,玉米体内菌量逐步增多 ,2 0 d后菌量迅速增加 ,30 d左右达到最高峰 ,根、茎、叶中的菌量分别达 3.7× 10 6,3.0× 10 6,1.3×10 6cfu.g-1;此后开始回落 ,5 0 d后趋于稳定 ;6 0 d后根、茎、叶中的菌量约保持在 4 .0× 10 5,3.5× 10 5,7.0× 10 4cfu.g-1的水平。该菌在玉米根、茎中的分布量明显高于叶片
Three in vitro bioassays of Ostrinia furnacalis were carried out using three insect-resistant strains of Bt cry1A (c) gene. The results showed that at the same concentration, the insecticidal activity of the engineered bacteria to the corn borer was higher than that of the wild Bt. The larval mortality was positively correlated with the concentration and the body weight and body length were negatively correlated with the concentration. The engineered bacteria RPT4 0, RPT5 0, The L C50 values of RPT5 5 and wild-type Bt strain HD-73 against Ostrinia furnacalis were 71.26, 36.33, 84.71 and 172.36 μg.g -1 respectively. In the live test inoculated with RPT50 injection, the treated plants showed obvious resistance to the corn borer, the body weight was reduced from 24.5% to 52.3% and the body length was reduced from 22.6% to 46.6% . After inoculated with engineering strain RPT5 0 for 10 days, the amount of bacteria in the corn increased gradually. After 20 days, the amount of bacteria increased rapidly and reached its peak around 30 days. The amount of bacteria in roots, stems and leaves reached 3.7 × 10 6, 3.0 × 10 6,1.3 × 10 6cfu.g-1, then began to drop, and tended to be stable after 50 days. After 60 days, the amount of bacteria in the roots, stems and leaves remained about 4.0 × 10 5 and 3.5 × 10 5, 7.0 × 10 4 cfu.g -1 levels. The distribution of the bacteria in the corn root, stem was significantly higher than the leaves