黄绿绿僵菌Mf82菌株对不同虫态褐飞虱的毒力

对水稻重要害虫褐飞虱Nilaparvata lugens目前市场上尚无一种理想的微生物杀虫剂。昆虫病原真菌具有从体壁侵入的能力因而对刺吸性害虫的防治具有优势。为此， 本研究选用不同原寄主和来源地的3种昆虫病原真菌（金龟子绿僵菌Metarhizium anisopliae、 黄绿绿僵菌Metarhizium flavoviride和球孢白僵菌Beauveria bassiana）的12个不同菌株， 以1 100孢子/mm²孢子悬浮液进行室内毒力测定。结果表明： 在参试的不同菌种12个菌株中， 黄绿绿僵菌Mf82菌株对褐飞虱成虫致病力最高， 10 d累计校正死亡率为83.5%， 致死中时（LT₅₀）为4.6 d。其不同浓度孢子液对褐飞虱3个发育阶段有不同程度的致病力， 毒力大小顺序为成虫>高龄若虫>低龄若虫。黄绿绿僵菌孢子液对各处理稻株褐飞虱产卵痕部位、 卵粒均有侵染作用， 10 d侵染率分别为66.7%和51.2%， 卵龄越低， 侵染效果越好， 卵龄为0.5 d时侵染率最高。本研究表明黄绿绿僵菌Mf82菌株对褐飞虱成虫、 若虫和卵均有较强的致病性， 是一株极具应用潜力的生防真菌。

Virulence of Metarhizium flavoviride 82 to different developmental stages of the brown planthopper,Nilaparvata lugens(Hemiptera:Delphacidae)

At present there still lacks ideal commercial microbial insecticides to control the brown planthopper(BPH),Nilaparvata lugens(Stl),an important pest of rice in Asia.Entomopathogenic fungi can penetrate the cuticle of insect hosts and thus have the advantage of controlling sucking pests.In this study,laboratory bioassays were carried out on 12 isolates of three entomopathogenic fungal species,Metarhizium anisopliae,Metarhizium flavoviride and Beauveria bassiana,which were originally obtained from various hosts and geographic origins,for their virulence against BPH adults.The results showed that at the concentration of 1 100 conidia/mm2,the strain Mf82 had the highest virulence to adults with the corrected mortality reaching 83.5% within 10 d after treatment and the LT50 value 4.65 d.The pathogenicity of Mf82 to adults,nymphs at different instars and eggs of BPH were further assessed at a series of conidial concentrations.This strain was most virulent to adults,moderately virulent to old nymphs,and least virulent to young nymphs.It was also found that Mf82 could infect both oviposition marks and eggs in rice seedlings,with the infection rates of 66.7% and 51.2%,respectively,at 10 d after treatment.The younger the eggs,the higher the infection rate,with the 0.5 d-old eggs to be the most easily vulnerable.The results suggest that Mf82 is a promising biocontrol agent for BPH.