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以小菜蛾Plutella xylostella为试虫,采用生物测定方法测定了粘虫颗粒体病毒(Pseudaletia unipuncta granulosis virus,PuGV-Ps)对苏云金杆菌(Bacillus thuringiensis,Bt)的增效作用。结果表明:不同配伍PuGV-Ps和Bt间的共毒系数在105.3至195.0之间,PuGV-Ps对Bt毒力具有增强作用,其中以Bt∶PuGV-Ps为4∶1增效作用最明显,72hLC50为0.039mg/mL。不同温度和pH值都影响PuGV-Ps对Bt的增效作用,16℃~20℃增效程度明显高于24℃~32℃,而碱性条件下(pH8~9)增效作用更显著。PuGV-Ps对Bt的增效作用因小菜蛾龄期不同而变化,2、3龄幼虫死亡率较单独使用Bt分别提高了50%和30.31%,而作用于低龄(1龄)和高龄(4龄)幼虫时对Bt的增效作用不显著。PuGV-Ps饲喂2h后再接毒Bt,小菜蛾死亡率明显提高,48h死亡率达66.67%,较直接饲喂Bt+PuGV-Ps处理死亡率提高了53.87%,差异极显著。SDS-PAGE表明PuGV-Ps具有碱性蛋白酶的活性,离体条件下能促进δ-内毒素酶解为47kD,60kD和61kD的毒性肽。
The synergistic effect of Pseudaletia unipuncta granulosis virus (PuGV-Ps) against Bacillus thuringiensis (Bt) was determined by bioassay using Plutella xylostella as test insect. The results showed that the co-toxicity coefficient between PuGV-Ps and Bt was between 105.3 and 195.0, and PuGV-Ps had an enhancement effect on the Bt virulence. The synergistic effect of Bt: PuGV-Ps was the most obvious at 4: The 72hLC50 was 0.039 mg / mL. The effect of PuGV-Ps on Bt was affected by different temperature and pH. The synergism of PuGV-Ps at 16 ℃ ~ 20 ℃ was significantly higher than that at 24 ℃ ~ 32 ℃, while the synergism of PuGV-Ps at pH8 ~ 9 was more significant. The synergism of PuGV-Ps to Bt varied with the age of Plutella xylostella, the mortality of 2nd and 3rd larvae increased by 50% and 30.31% respectively compared with that of Bt alone, Age) larvae on the Bt synergistic effect was not significant. The mortality of PuGV-Ps was higher than that of Bt + PuGV-Ps after 2 hours of feeding, and the mortality of the diamondback moth was significantly increased. The mortality rate of PuGV-Ps was 66.67% at 48h, which was 53.87% higher than that of Bt + PuGV-Ps. SDS-PAGE showed that PuGV-Ps had the activity of alkaline protease and could promote the enzymatic degradation of δ-endotoxin to 47kD, 60kD and 61kD in vitro.