Insect Resistance And High-Expression Of Transgenic Cotton And It's Influence On Development Of Helicoverpa Armigera(H(?)bner)

Using leaf or square feeding bioassay. the insect resistance of transgenic Bt cotton (Bollgard?Xinmian33B) leaves and squares to neonates of susceptible Helicoverpa armigera (Hubner) were determined in 2000. 2001 and 2003, respectively. The results showed that the insect resistance of the 33B to susceptible neonates decreased with increase of the leaf order on the main stem . The insect resistance of the 6th - 10th leaf on the main stem was very high (the mean mortality was 91.4 - 100 %, the same as follow), then it decreased significantly (p<0.05) since the 11th leaf (82.0 - 80.0% and 83.3% -70.6 % ). The insect resistance order of the major organs of Bt cotton on the late July was: tender squares (85.0 - 89.0 % ) > terminal leaf on the main stem (66.7 - 74.0 % ) > tender leaf on the branch (29.4 - 44.0 % ). There was no obvious difference between the same organ in the three different years.Using leaf or square feeding bioassay. the insect resistance of the leaves and squares of the single (Bt) and dual (Bt and CpTI) -toxin transgenic cotton to neonates of susceptible H. armigera were determined on June to August in 2001. The results showed that the insect resistance of the single and dual-toxin transgenic cotton to susceptible neonates decreased significantly with increase of the leaf order during 5th -15th leaf on the main stem, but the insect resistance of dual-toxin transgenic cotton decreased significantly slower than that of single toxin (Bt) cotton. The insect resistance order of the major organs on the transgenic cottons in the mid-late season was: tender squares > terminal leaf on the main stem >tender leaf on the branch, and the insect resistance of the dual-toxin transgenic cotton was obviously (p<0.05) or slightly higher than that of the single toxin (Bt) transgenic cotton.Using leaf or square feeding bioassay, the insect resistance of the tender leaves and tender squares of single (Bt) and dual (Bt and CpTI) -toxin transgenic cotton to neonates of resistant H. armigera strain(YSR2) was determined on June to August in 2001. The results showed that the insect resistance of the single and dual-toxin transgenic cotton to resistant neonates decreased significantly with increase of the leaf order during 7th -15th leaf on the main stem, and the insect resistance of dual-toxin transgenic cotton decreased slightlyslower than that of single toxin (Bt) cotton. But the insect resistance to resistant neonates (YSR2) decreased obviously slower than that to susceptible neonates (HZS|), the mean mortality of the transgenic cottons were ZM41(100~85.6 % (HZS1) and 85.7-40.0 % (YSR2). the same as follows)), SGK321(100~67.7 % and 68.0-25.0%), 99B (100-74.8 % and 68.0-21.7 % ) and ZM29 (96.0-66.7 % and 70.0-15.6 % ), respectively, and the insect resistance of the single and dual-toxin transgenic cotton decreased significantly with increase of the resistance level of H. armigera. The insect resistance order of the major organs on the transgenic cottons in the mid-late season was: tender squares > terminal leaf on the main stem > tender leaf on the branch, but there were no significant difference between the single and dual-toxin transgenic cotton.In the field of Funing county , the insect resistance of the transgenic cotton to the 2nd generation H.armigera population was very high , but it decreased when the 3rd and 4th generation H.armigera appeared.Using leaf or square feeding bioassay, the insect resistance and the percent of survival larvae reaching mid-2nd instar of 33B to the susceptible (HZS1 and HZS2) and hybrid progeny neonates were determined in 2000 2001 and 2003,respectively. The results showed that the 6th and 10th leaf could express a dose of Bt toxin high enough (high-expression) to kill almost all of the neonates of susceptible strain and reciprocal crosses F1 generation (Mean mortality to the neonates of susceptible strain and reciprocal crosses F1 generation was 99.2-93.5% and 81.2-92.0%, percent of survival larvae reaching mid-2nd instar was 0% and 0-4.1%,the same as follows.) during the three years. The...