绿僵菌对草坪灰翅贪夜蛾和粘虫的毒力及田间防治效果

测定了从草坪灰翅贪夜蛾上分离的绿僵菌(Metarhizium anisopliae)对灰翅贪夜蛾和粘虫的毒力,采用时间-剂量-死亡率模型分析了绿僵菌对灰翅贪夜蛾和粘虫的毒力。结果表明绿僵菌对灰翅贪夜蛾和粘虫的剂量效应常数分别为0.69和0.66;在孢子含量1×10^6～7个／mL高剂量下接种,灰翅贪夜蛾和粘虫幼虫在接种第7天和第8天累积死亡率达100％;在孢子含量1×10^3～4个／mL低剂量下,接种后第10天达到死亡高峰。在孢子含量1×10²个／mL下的累积死亡率分别为6％和4％。绿僵菌对灰翅贪夜蛾和粘虫致死剂量是时间的函数,对灰翅贪夜蛾第5天和第7天的LC₅₀为孢子含量2.1×10⁶和3.5×10⁴个／mL,在孢子含量10⁷～10⁵个／mL下的LT₅₀分别为4.15、5.1、6.18、7.7 d;对粘虫第5天和第7天的LC₅₀为孢子含量1.55×10⁷、2.39×10⁵个／mL,在孢子含量10⁷～10⁵个／mL下的LT₅₀分别为4.4、5.4、6.4、7.8 d。在草坪禾草上喷洒绿僵菌孢子含量1×10⁶个／mL,5、7、10 d后对粘虫的防治效果分别为46.4％、65.8％、71.4％,对灰翅贪夜蛾的防效分别为47.6％、66.0％和79.6％。绿僵菌制剂孢子含量为1×10⁵个／mL对两种害虫的防治效果相近。

Virulence of Metarhizium anisopliae to Spodoptera mauritia (Boisduval) and Leucania separata Walker and its field control effects

Virulence of isolate Ma020815 of Metarhizium anisopliae to the larvae of Spodoptera mauritia (Boisduval) and Leucania separata Walker was assessed in the laboratory. A time - dose - mortality model was applied to analysis of the variation of mortality rates. The model showed that the isolate Ma020815 was a bit more virulent to S. mauritia than to L. separata . The accumulative mortality went up to 100 % at 7 and 8 day after inoculation with a dose of 1 × 10⁷ and 1 × 10⁶ conidia/mL for S. mauritia and L. separata , respectively, and the accumulative mortality was 6% and 4% for S. mauritia, L. separata respectively, under the dose of 1 × 10² conidia/mL. The LT₅₀ranged from 4.15to 7.7 days for S. mauritia but 4.4 to 7.8 days for L. separata under the dose of 1 × 10⁷ and 1 × 10⁵ conidia/ mL. Its field control effect on L . separata at 5th, 7th and 10th day was 46.4 % ,65.8% and 71.4% , respectively. Its control effect on S. mauritia was 47.6% , 66.60% ,and 79.6% at 5th, 7th and 10th day accordingly. The control effect with the dose of 1 × 10⁵ conidia/mL on L. separata and S. mauritia was nearly the same as that with the dose of 1 × 10⁶ conidia/mL.