褐飞虱高毒力绿僵菌菌株的筛选

从田间褐飞虱Nilaparvata lugens(Stl)罹病虫体上新分离鉴定一株黄绿绿僵菌Mf82,将其与实验室保存的8株绿僵菌Metarhizium spp.一起,分别测定其对褐飞虱成虫毒力和几丁质酶活力,并用扫描电镜观察侵入昆虫表皮的过程和体表的形态变化,进而分析侵入能力与几丁质酶的相关性。结果表明:菌株Mf82累计校正死亡率和几丁质酶活力均最高,为82.1%和9.78U/mg,与其他菌株差异显著。同时,扫描电镜照片显示Mf82分生孢子既可以由褐飞虱体壁节间膜和凹陷处侵入,还可以从含几丁质较多的胸部背板侵入。比较9株绿僵菌菌株菌落生长速度、产孢初始时间、产孢量和萌发率显示,Mf82菌株具有生长速度快、产孢初始时间短、萌发率高和产孢量大等优点,可见筛选的Mf82菌株致病力强,在褐飞虱的微生物防治方面将有良好的应用前景。

Screening of high virulent strain of Metarhizium spp. against the brown planthopper, Nilaparvata lugens

Nine strains of different species of Metarhizium,including strain of M.flavoviride(Mf82) newly isolated from Nilaparvata lugens(Stl),and eight M.anisopliae strains from lab collection,were tested against the adults of N.lugens.The chitinase activities of these strains were also assayed.The results showed that both the cumulative mortality(82.1%) and the chitinase activity(9.78U/mg) of strain Mf82 were the highest among all tested strains.Scanning electron microscope(SEM) observations showed the germinating conidia of the strain Mf82 penetrated the cuticle not only via the intersegmental membranes and folded regions,but also through the pronotum which contained a large quantity of chitin.The biological characteristics of these strains,including growth rate,sporulation,germination rate and timing of sporulation,were further investigated.The results showed Mf82 was the best strain having strong pathogenicity and exhibited a great potential for sustainable control of N.lugens.