防治西花蓟马的球孢白僵菌菌株筛选及耐热性测定

采用浸虫法分别测定了191株不同地理来源的球孢白僵菌对西花蓟马初羽成虫的毒力,筛选出61株高毒力的菌株,其LT₅₀均小于4.1 d;对该61株球孢白僵菌用48 ℃热胁迫的方法进行耐热性的测定,将分生孢子丧失50%活力所需的时间,定义为LT₅₀,作为耐热性的指标。结果表明,所测61株球孢白僵菌经受热胁迫后LT₅₀平均值为34.28 min(6.94～53.67 min),其中有10株菌LT₅₀大于45 min,作为耐热性较强的菌株,将该10株菌继代培养5代,继续进行耐热性测定,发现其中6株菌在继代培养过程中耐热性出现了退化,有4株菌耐热性保持稳定,分别为菌株XJWLMQ-49、XJWLMQ-32、JLGZL-14和SCWJ-9,因此,该4株菌具有开发和应用潜力。

Screening of Beauveria bassiana Strains against Frankliniella occidentalis and Their Conidial Thermotolerance

In the test of 191 isolates of Beauveria bassiana for their virulence against adult Frankliniella occidentalis, 61 isolates displayed high virulence and LT₅₀ less than 4.1 d. The conidial suspension of each screened isolate was exposed to the thermal stress of 48 °C in a water bath. LT₅₀, the time for 50% of conidia to lose viability under thermal stress, was defined as a thermotolerance index. The results showed that the median LT₅₀ of the 61 isolates were 34.28 min (6.94-53.67 min), and 10 isolates were determined as high thermotolerance strains, whose LT₅₀ were longer than 45 min. These 10 isolates were further subcultured for five generations separately, and then the conidia were exposed to thermal stress of 48 ℃. As a result, thermotolerance of 6 isolates showed degeneration, while the other 4 isolates, XJWLMQ-49, XJWLMQ-32, JLGZL-14 and SCWJ-9, maintained stable thermotolerance. These 4 isolates could be regarded as biological control strains with potential for development and application.