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为了提高Bt的杀虫活性,运用扫描电镜、SDS-PAGE电泳和生物测定技术,研究了荧光增白剂FB28对棉铃虫Cry1Ac抗性和敏感品系围食膜的影响及对Cry1Ac杀虫蛋白的增效作用。结果表明,正常棉铃虫围食膜表面光滑致密,没有空洞和缝隙。用含1%FB28的人工饲料饲喂刚蜕皮的5龄棉铃虫幼虫2 h后,抗感棉铃虫围食膜表面均出现许多空洞,且敏感棉铃虫的空洞明显大于抗性棉铃虫;随着处理时间的延长,围食膜上的空洞逐渐变小,13 h后恢复正常。用1%FB28离体或活体处理抗、感品系棉铃虫,均可造成围食膜蛋白被降解。用1%FB28与Cry1Ac杀虫蛋白混合饲喂抗、感棉铃虫初孵幼虫,可明显提高棉铃虫的死亡率,且对抗性品系的增效作用明显大于敏感品系,对敏感和抗性品系棉铃虫的增效比分别为2.23和9.34;1%FB28还可以明显增加对抗、感品系3龄棉铃虫幼虫的生长抑制作用。
In order to improve the insecticidal activity of Bt, the effects of FB26 on the peritrophic membrane of the resistant and susceptible strains of the cotton bollworm (Helicoverpa armigera) and the increase of Cry1Ac insecticidal protein were studied by scanning electron microscopy, SDS-PAGE and bioassay techniques Effective effect. The results showed that the normal bollworm surface smooth and dense periocular membrane, no holes and gaps. After 2-hour feeding of the newly hatched larvae of 5th instar larvae of Molluscum chongqing with 1% FB28 artificial diet, many hollows were found on the surface of the resistant bollworm, and the cavity of the sensitive bollworm was obviously larger than that of the resistant bollworm. Processing time extended, the peritoneal cavity gradually diminished, returned to normal after 13 h. In vitro or in vivo treatment of the resistant and susceptible strains of cotton bollworm with 1% FB28 all caused the peritrophic membrane protein to be degraded. The mixed feeding of 1% FB28 with Cry1Ac insecticidal protein against newly hatched larvae of H. armigera could significantly increase the mortality of H. armigera, and the synergistic effects of the antagonistic strains were significantly greater than that of the susceptible strains. The synergistic ratio of insects was 2.23 and 9.34, respectively; 1% FB28 could also significantly increase the growth inhibition of 3-day-old H. armigera larvae.