思茅松毛虫2龄幼虫肠道好氧细菌的筛选及毒力测定

目的]筛选思茅松毛虫（Dendrolimu.kikuchii Matsumura）2龄幼虫肠道好氧细菌并测定其毒力。方法]将思茅松毛虫2龄幼虫中肠样品倍比稀释后涂布平板分离菌株,共分离得到5株好氧细菌。以细菌基因组DNA为模板,用细菌16S rDNA通用引物（27f和1492r）对模板扩增,并用4种限制性内切酶Hae Ⅲ和Hind Ⅲ、HinfⅠ和TaqⅠ对PCR扩增产物进行ARDRA多态性分析。结果]聚类图谱分析发现,5株好氧细菌在95%的相似水平上聚成2个不同分类操作单元（OTU）,表明思茅松毛虫2龄幼虫肠道内好氧细菌的遗传多样性水平偏低。室内毒力试验表明,肠道细菌杀虫死亡高峰期在4～10d,菌株4杀虫效果最佳,12d时校正死亡率达到53.57%。结论]为防治思茅松毛虫提供了参考。

Screening and Toxicity Determination of Intestinal Aerobic Bacteria from 2nd instar Larva of Dendrolimu.kikuchii

Objective] The paper was to screen intestinal aerobic bacteria from 2nd instar larva of Dendrolimu.kikuchii and determine its toxicity.Method] The intestinal samples of 2nd instar larva of D.kikuchii was diluted in 2-fold and coated on plates to isolate strains,and a total of 5 strains of aerobic bacteria were isolated.With bacterial genomic DNA as template,the universal primers of bacterial 16S rDNA(27f and 1492r) was used to amplify the template,4 restriction enzymes Hae Ⅲ and Hind Ⅲ,HinfⅠand TaqⅠwere used to carry out ARDRA polymorphism analysis on PCR products.Result] Cluster map analysis showed that 5 strains of aerobic bacteria clustered into two different taxonomic operating units(OTU) on 95% similarity level,this indicated that the genetic diversity level of intestinal aerobic bacteria from 2nd instar larva of D.kikuchii was relatively low.The indoor toxicity test showed that the death peaks of insects killed by intestinal bacteria were during 4-10 d,the insecticide effect of strain 4 was the best with corrected mortality of 53.57% at 12 d.Conclusion] The paper provided reference for control of D.kikuchii.