Bidochka M J, Kamp A M, Lavender T M, Dekoning J, De Croos J N
Department of Biology, Trent University, Peterborough, Ontario, Canada K9J 7B8.
Appl Environ Microbiol. 2001 Mar;67(3):1335-42. doi: 10.1128/AEM.67.3.1335-1342.2001.
Strains of insect-pathogenic fungi with high virulence toward certain pest insects have great potential for commercial biological control applications. Identifying such strains has been a central theme in using fungi for biological control. This theme is supported by a persistent paradigm in insect pathology which suggests that the host insect is the predominant influence on the population genetics of insect-pathogenic fungi. In this study, a population genetics analysis of the insect-pathogenic fungus Metarhizium anisopliae from forested and agricultural habitats in Ontario, Canada, showed a nonrandom association of alleles between two distinct, reproductively isolated groups (index of multilocus association = 1.2). Analyses of the mitochondrial DNA showed no differences between the groups. The two groups were associated with different habitat types, and associations with insect hosts were not found. The group from forested areas showed an ability for cold-active growth (i.e., 8 degrees C), while the group from the agricultural area showed an ability for growth at high temperatures (i.e., 37 degrees C) and resilience to UV exposure. These results represent a significant paradigm shift; habitat selection, not host insect selection, drives the population structure of these insect-pathogenic deuteromycetous fungi. With each group we observed recombining population structures as well as clonally reproducing lineages. We discuss whether these groups may represent cryptic species. Worldwide, M. anisopliae may be an assembly of cryptic species, each adapted to certain environmental conditions. The association of fungal genotypes with habitat but not with host insects has implications on the criteria for utility of this, and perhaps other, fungal biocontrol agents.
对某些害虫具有高毒力的昆虫病原真菌菌株在商业生物防治应用中具有巨大潜力。鉴定此类菌株一直是利用真菌进行生物防治的核心主题。昆虫病理学中一个持续的范式支持了这一主题，该范式表明宿主昆虫是昆虫病原真菌群体遗传学的主要影响因素。在本研究中，对来自加拿大安大略省森林和农业栖息地的昆虫病原真菌绿僵菌进行的群体遗传学分析表明，两个不同的、生殖隔离的群体之间存在等位基因的非随机关联（多位点关联指数 = 1.2）。线粒体DNA分析显示两组之间没有差异。这两个群体与不同的栖息地类型相关，且未发现与昆虫宿主的关联。来自森林地区的群体表现出低温生长能力（即8摄氏度），而来自农业地区的群体表现出高温生长能力（即37摄氏度）以及对紫外线照射的耐受性。这些结果代表了一个重大的范式转变；栖息地选择而非宿主昆虫选择驱动了这些昆虫病原半知菌类真菌的群体结构。对于每个群体，我们都观察到了重组的群体结构以及克隆繁殖的谱系。我们讨论了这些群体是否可能代表隐性物种。在全球范围内，绿僵菌可能是一个隐性物种的集合，每个物种都适应特定的环境条件。真菌基因型与栖息地而非宿主昆虫的关联对这种以及其他真菌生物防治剂的效用标准具有影响。
