平沙绿僵菌SG-A两种培养基比较及其对瓜绢螟的致病活力

Comparison of two culture medium of Metarhizium pingshaense SG-A and its pathogenic activity against Diaphania indica(Saunders)

为比较平沙绿僵菌SG-A在两种培养基上的生物学特性及对瓜绢螟不同虫态的致病力,室内测定了平沙绿僵菌SG-A在马铃薯葡萄糖琼脂培养基(PDA)和萨氏培养基(SDAY)上培养14 d后的菌落大小、产孢量及孢子萌发率等指标,并采用浸虫法测定了对瓜绢螟不同虫态的致病力。结果表明,平沙绿僵菌SG-A在PDA培养基中培养14 d后的产孢量显著高于SDAY培养基,菌落大小和孢子萌发率差异不显著。平沙绿僵菌SG-A对瓜绢螟2龄、4龄幼虫和蛹均存在较高的致病力,孢子浓度越大,致病力越高,其中对蛹的致病力最高,LC_(50)为1.93×10^(5)个·mL^(-1),当孢子浓度为1×10^(8)个·mL^(-1)时,处理8 d蛹的累积死亡率为90%,2龄和4龄幼虫的累积死亡率也分别达到86.67%和83.33%,但4龄幼虫出现死亡的时间要早于蛹和2龄若虫,LT_(50)为2.60 d。综上所述,平沙绿僵菌SG-A对瓜绢螟各虫态均具有较高的致病力,可进一步挖掘其生防潜力。

In order to compare the biological characteristics and pathogenicity of Metarhizium pingshaense SG-A on two media,the size of colony,sporulation yield and spore germination rate of M.pingshaense SG-A on potato glucose AGAR medium(PDA)and sabouraud dextrose agar with yeast extract(SDAY)were measured after 14 days.The pathogenicity of M.pingshaense SG-A against different insect states of Diaphania indica(Saunders)was determined by dip method.The biological characteristics on different media and pathogenicity to D.indica of M.pingshaense SG-A were measured.The results showed that the spore production of M.pingshaense SG-A after 14 days of PDA culture was significantly higher than that of SDAY culture medium,and there was no significant difference in colony size and spore germination rate.M.pingshaense SG-A showed high pathogenicity against the 2nd and 4th instar larvae and pupae,and the pupae had the highest pathogenicity.The LC_(50) was 1.93×10^(5) conidia·mL^(-1),and the cumulative mortality of pupae was 90%when the spore concentration was 1×10^(8) conidia·mL^(-1).The cumulative mortality of 2nd instar and 4th instar larvae also reached 86.67%and 83.33%,respectively,but the death time of 4th instar larvae was earlier than that of pupa and 2nd instar nymphs,and the LT_(50) was 2.60 days.In conclusion,M.pingshaense SG-A has high pathogenicity against each species of D.indica,which can further explore its biocontrol potential.