粘虫高龄幼虫对转Bt基因玉米的消化和利用

在室内用重量法研究了粘虫Mythimna separata (Walker)高龄幼虫对转Bt基因玉米MON810和Bt11叶片的消化和利用，以明确Bt玉米对暴食期幼虫取食的影响。结果表明，在连续测定的5天中，取食MON810和Bt11两种Bt玉米叶片时，幼虫存活率和取食量均显著低于各自的对照组幼虫，取食Bt玉米叶片的幼虫体重呈下降趋势，第3 天时分别比第2 天减少12.2 mg 和7.4 mg，而取食对照玉米叶片时的幼虫日增重显著的高于处理组的幼虫，第3 天的日增重分别为100.4 mg 和119.9 mg。取食Bt玉米叶片的幼虫对食物的转化率(ECI和ECD)均为负值，在最初4 天的ECI和ECD都显著低于对照组幼虫，但取食两种非Bt玉米叶片的幼虫的近似消化率(AD) 随取食时间的延长而逐渐下降，取食第5 天分别为20.6 %和15.1 %；而取食MON810和Bt11叶片时幼虫的AD均显著地高于对照组幼虫。

Food consumption and utilization of the fifth instar larvae of Mythimna separata (Walker) feeding on the leaves of transgenic Bacillus thuringiensis corn expressing CryIAb protein

Consumption and utilization of the 5th instar larvae of Mythimna separata (Walker) feeding on the leaves of transgenic Bacillus thuringiensis corn were assayed in the laboratory. Two Bt corn hybrids with events MON810 and Bt11 expressing CryIAb protein and their non-Bt controls were employed in the bioassays. Results showed that the survival rate of the 5th instar larvae of M. separata was significantly lower when fed on MON810 and Bt11 leaves. The food ingestion was 88.1 mg and 115.4 mg, respectively, when larvae fed on MON810 and Bt11, whereas 653.6 mg and 715.4 mg when fed on non-Bt corn DK647 and NX4906 separately, at 4th day. The larvae exhibited an average weight loss of 12.2 mg and 7.4 mg when fed on MON810 and Bt11 leaves, and showed an average weight gain of 100.4 mg and 119.9 mg when fed on two non-Bt controls at 3rd day. The efficiency of conversion of ingested food (ECI) and efficiency of conversion of digested food (ECD) by the larvae feeding on the two Bt corn leaves were significantly lower than by the larvae feeding on non-Bt corn hybrids. This indicated that the Bt corn significantly restrained the feeding, food consumption and utilization of the 5th instar larvae of M. separata. However, the approximate digestibility (AD) by the larvae was much higher when fed on Bt corn leaves than on non-Bt corn controls, and a possible explanation is that the digestion function of the larvae fed the Bt corn leaves was restrained as a result of the toxication by Bt toxin.