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为了寻找更有效的利用虫生真菌爪哇棒孢霉Isaria javanicus防治小菜蛾Plutella xylostella的新方法,测定了绿僵菌素(destruxin)对SP053菌株生长发育与产孢量与萌发率的影响,利用协同毒力指数法和毒力回归分析法评价了两者混用对小菜蛾2龄幼虫的联合毒力。结果表明:绿僵菌素对SP053菌株菌丝生长、孢子萌发率和孢子产量均无显著影响(P>0.05)。而一定浓度的绿僵菌素与SP053菌株分生孢子混用具有增效作用,S50-CD100(指爪哇棒孢霉SP053菌株的分生孢子浓度为50×105个/mL和绿僵菌素粗毒素的浓度为100mg/L的组合;依此类推)、S25-CD100、S25-CD50及S12.5-CD100等混配组合都有显著的增效效果,尤其以S25-CD100组合增效效果最好,其48h和72h的协同毒力指数(c.f.)分别达到52.31和31.07。毒力回归分析结果也显示,添加绿僵菌素粗毒素25～100mg/L的混剂的LC50值明显降低,比如添加100mg/L绿僵菌素粗毒素的混剂(SP053-CD100),其48和72h的LC50分别为17.45和10.55(×105个孢子/mL),而SP053菌株分生孢子单剂的LC50相应值为>50和35.85(×105个孢子/mL)。本研究证明绿僵菌素与爪哇棒孢霉SP053菌株混用有增效作用,对改进小菜蛾的生物防治方法有一定指导意义。
In order to find out a new method to control Plutella xylostella, an effective insecticidal strain of Isaria javanicus, the effect of destruxin on the growth and sporulation and the spore germination rate of SP053 was studied. The virulence index method and virulence regression analysis were used to evaluate the combined virulence of the two compounds against 2nd instar larvae of Plutella xylostella. The results showed that there was no significant effect of Metarhizium on mycelium growth, spore germination rate and spore yield of SP053 strain (P> 0.05). However, the synergism of sporranosperbene and SP053 strain conidia was observed at a certain concentration. The conidia concentration of S50-CD100 (means the conidia of Cercospora clavatum SP053 strain was 50 × 105 / mL and the strain of Metarhizium mutans crude toxin The combination of S25-CD100, S25-CD50 and S12.5-CD100 has a significant synergistic effect, especially the S25-CD100 synergy effect is the best , 48h and 72h synergistic virulence index (cf) reached 52.31 and 31.07 respectively. The results of virulence regression analysis also showed that the LC50 value of the mixture of 25 ~ 100 mg / L of Metarhizium anisopliae crude toxin was obviously decreased, such as the mixture of SP053-CD100 with 100 mg / L of Metarhizium anisopliae crude toxin The LC50 values at 48 and 72 h were 17.45 and 10.55 (x 105 spores / mL), respectively, while the LC50 values for single splenic SP053 strains were> 50 and 35.85 (x 105 spores / mL), respectively. This study shows that the synergistic effect of the combination of Metarhizium and Cladosporium clavatum SP053 strain has some guiding significance for improving the biological control of diamondback moth.