[目的]通过研究不同农田生态系统土壤虫生真菌的物种多样性,为农田害虫的生态控制提供理论依据.[方法]2018年每月在保山市4种农田生态系统(咖啡田、玉米田、烟田、茶园)中采集土壤样品,用黄粉虫诱导法分离虫生真菌,根据形态特征和多基因系统发育鉴定物种,分析不同类型农田虫生真菌物种和数量的变化特征.[结果]共获得3340株虫生真菌,分属于3科6属20种.4种类型农田中全年均有虫生真菌的分布,夏季(6-8月)菌株检出率较高;虫生真菌的发生主要受作物种类和栽培模式影响,多年生作物(茶和咖啡)农田中虫生真菌的种类和数量高于1年生作物(玉米和烤烟)农田.绿僵菌属、白僵菌属和虫草属在4种农田中都为优势属(共17种、菌株数占比84.10％),其中绿僵菌属为第一优势属(8种,菌株数占比64.76％).优势物种有4种(棕色绿僵菌、保山绿僵菌、淡紫紫孢菌、球孢白僵菌),其中棕色绿僵菌为第一优势物种(菌株数占比34.25％).[结论]保山农田生态系统土壤中蕴藏着较丰富的虫生真菌资源,人为扰动较少的农田中虫生真菌的物种和数量相对较多,优势属种在4种类型农田中均处优势地位.
The Gaoligong Mountains accommodate diverse ecosystems and biological resources. Beauveria species diversity is inventoried in seven vegetation types of the Gaoligong Mountains along an elevation gradient from 600 to 3800m. Strains were isolated from soil by using Tenebrio molitor larvae as baits and from naturally occurring insect cadavers carrying anamorphic or teleomorphic fruiting structures of Beauveria spp. The 231 isolated Beauveria strains were identified based on molecular phylogenetic analyses inferred from Bloc, nrSSU, nrLSU, TEF, RPB1, and RPB2 sequences. Eleven species were identified as Beauveria asiatica, B. bassiana, B. brongniartii, B. caledonica, B. medogensis, B. pseudobassiana, and B. sinensis, previously recorded in other Chinese environments, and B. baoshanensis sp. nov., B. malawiensis, B. rudraprayagi, and B. yunnanensis sp. nov., encountered in China for the first time. Species phylogenies are presented and morphological characters of the new species are described. Most isolates were identified as B. bassiana and B. pseudobassiana (86.1%), while the other nine species were isolated rarely. Beauveria was widely distributed in six vegetation types, but not in the vegetation type of the highest altitude. More than four species were encountered in vegetation types with moderate elevation, and these environments also showed highest diversity of plants and insects.
A new species namely Metarhizium gaoligongense collected from Gaoligong mountains, Yunnan Province, China, was described based on both morphology and multilocus (ITS, nrSSU, nrLSU, EF-1 alpha, RPB1 and RPB2) phylogeny. M. gaoligongense was clustered in M. flavoviride complex which had 6 clearly separated individuals and it developed a well-supported separate clade from other 5 allied species, being more close to M. koreanum and M. minus and closest to M. pemphigi. The microscopic characters of M. gaoligongense were also very similar to M. pemphigi, in accordance with phylogenic affiliation, while the culture characteristics on potato dextrose agar medium could obviously distinguish the two sister species. M. pemphigi colonies often developed radial constriction, showed emerald green, and diffused yellow-green pigmentation into medium. However, M. gaoligongense colonies were flat, green, without pigment diffusion into medium, often guttulated condensation on conidia layer surface. (C) 2018 Friends Science Publishers
