八株蜡蚧轮枝菌的生物学特性及其对烟蚜致病性的影响

为明确田间自然罹病烟蚜僵虫上的真菌种类和筛选出对烟蚜的高毒力菌株，将采集的烟蚜僵虫经过常规分离、纯化，进行了菌落生长、产孢量、形态观察、ITS序列测定、系统发育树构建以及对室内烟蚜毒力测定的研究。结果表明，从烟蚜僵虫体上分离纯化出8株菌株，经生物学特性观察、ITS序列对比和构建系统发育树准确鉴定出这8株菌株均是蜡蚧轮枝菌。综合生物学培养和毒力测定结果，得出菌株V4为优良菌种，具有产孢量高（1.89×10⁹个/皿），生长速率快（15 d菌落直径达到68.78 mm），对烟蚜毒力强（第7天的校正死亡率为84.99%，LT₅₀为4.51 d）的特性，具备田间持续控制烟蚜的潜力。

Biological Characteristics of Eight Verticillium lecanii and Their Effects on the Pathogenicity against Myzus persicae Aphids

The objectives of this study are to identify the species of fungi collected from naturally diseased Myzus persicae(Sulzer) aphids in the field and to screen the highly virulent strains against M. persicae aphids. After conventional isolation and purification of the collected diseased M. persicae aphids, the strains were used for colony growth, sporulation, morphological observation, ITS sequence analysis, phylogenetic tree construction and indoor toxicity determination. The results showed that:8 strains were isolated systematically from diseased M. persicae aphids which were Verticillium lecanii through identification by biological characteristics, ITS sequence comparison and phylogenetic tree construction. Strain V4 was selected based on biological culture and virulence test. Strain 4 showed more sporulation yields (1.89×10⁹/dish), fast growth rate (reached 68.78 mm at 15 days), batter pathogenicity to M. persicae aphids (7 day corrected mortality was 84.99% and the LT₅₀ was 4.51 d) which has the potential to control the M. persicae aphids continuously in the field.