【摘要】 防治斜纹夜蛾主要依赖化学防治.为了寻求防治该虫新的有效措施,从自然罹病虫体上分离得到爪哇拟青霉Paecilomyces javanicus(Friedrichs & Bally)Brown&Smith,经室内毒力测定后,筛选出1株对斜纹夜蛾具有较强致病力菌株Px04.时间-剂量-死亡率模型拟合结果表明,26℃下幼虫接菌后第10天的LC50为1.722×106个孢子/mL.当剂量为107个孢子/mL时,致死中时间为3.6 d.在不同温度下,菌丝生长与产孢量均在25℃时达到最大.不同培养基对Px04菌株的生长和产孢量具有明显的影响.在26℃下采用PD(马铃薯葡萄糖)+0.5%蛋白胨液体发酵培养3 d,每50 mL培养基的菌丝产量为461.5 mg,高于PD,Czapek-Dox和Cz-P(Czapek-Dox加0.5%蛋白胨)3种培养基;采用大米+0.2%蛋白胨和碎玉米+0.2%蛋白胨作为菌株的固相产孢培养料培养28 d,产孢量分别为8.75×1012和8.38×1012/kg,高于未加0.2%蛋白胨母体培养料的产孢量.更多还原

【Abstract】 Spodopotera litura(Fabricius) is an important polyphyagous insect pest to many crops worldwide.In order todevelop an alternative technique to control this pest other than heavily using chemical,an isolate of Px04 Paecilomycesjavanicus,which is highly virulent to S.litura was screened from cadavers collected from field.Bioassay was conductedby immersing second instar larvae into conidial suspension for 5 seconds and then reared on cabbage leaf at 26 ℃ and12∶12(L∶ D).The results showed a time-dose-mortality model was fit well to variation of mortality affected by bothtime and dosage of the isolate Px04.After ten days inoculation,the estimates LC50 was 1.722×106 conidia/mL,while ata concentration of 107 conidia/mL,the estimates LT50 was 3.6 days.The highest production for both hyphae and sporesoccurred at 25 ℃ when compared to other temperature regimes.461.5 mg hyphae was harvested when grown in a 50 mLaqueous medium of PD(Potato Dextrose)with 0.5% peptone at 26 ℃ for three days,which was significant higher thanthat grown on PD,Czapek-Dox and Czapek-Dox with 0.5% peptone.At 26℃ after 28 days Spores produced on solidmedium of both rice and corn mixed with 0.2% peptone were 8.75×1012 and 8.38×1012 conidia/kg respectively,whichwere significantly higher than on rice and corn with no peptone added.更多还原