Study On Biodiversity Of Entomogenous Fungi In Different Forest Ecosystems

In the present dissertation,community diversity and distribution of entomogenous fungi,niche measurement and niche indices were investigated and systematically analyzed,and genetic diversity of Beauveria bassiana were studied by ISSR marker,in 3 different forest ecosystems:National Langyashan Forest Park in Chuzhou City,eastern Anhui,National Yaoluoping Nature Reserve in Dabie Mountains in Yuexi County, Western Anhui,and Magushan Forest Farm in Xuanzhou,Southeastern Anhui.The investigation revealed 672 specimens of entomogenous fungi belonging to 20 species of 9 genera in 4 families from Langyashan.Among them,B.bassiana was the most dominant with relative abundance of 92.7%.Cordyceps heteropoda var. langyashaneasis was a new variety,and its anamorph was a new species,Hirsutella heteropoda.The diversity index(H) and evenness(E) of entomogenous fungi were both high in cool and less humid season,and low in the hot and humid season.Evenness in June to August was significantly lower than in others months.Diversity Index was generally low with the maximum only at 1.9505.In the study on niche of 3 dominating entomogenous fungi,the results showed that B.bassiana had the widest nutritional and time niches breadth,and Isaria farinosus had widest space niche breadth.The nutritional niche overlap was largest between Isaria cateniannulata and I.farinosa,and time niche overlap was largest among B.bassiana and I.cateniannulata up to 0.8957,while there was small space niche overlap among B.bassiana and I.cateniannulata.In Yaoluoping,abundant community diversity was recorded with 687 isolates belonging to 27 species of 11 genera in 4 families.Among them,Cordyceps nutans was the most dominant.Abundance and richness of entomogenous fungi reached peak level in summer.Community index of the community was the highest at altitude of 1100～1150m.Cordyceps,the dominant genus in this area,distributed intently within 1050～1200m,particularly C.nutans.Comparably,Isaria distributed widely at various altitudes.In the study on niche here:B.bassiana had the biggest nutritional,space and time niche widths.The nutritional niche overlap was smallest between C.nutans and the other 3 entomogenous fungi.C.nutans had the largest time niche overlap to I.farinosa, while I.farinosa and I.tenuipes had the biggest space niche overlap.Two-dimensional niche overlap of time and space among these 4 fungi were all small,and only that between C.nutans and I.farinosa was comparably big.In Magushan,the artificial forest ecosystem of pure Masson's pines,simple community diversity was revealed by a collection of 355 specimens belonging to 14 species of 5 genera in 3 families with I.cateniannulata as the most abundant.Biggest species number appeared in June.In general,the diversity index was low here.Study on niche width of 3 dominant species showed that B.bassiana had largest time and nutritional niche width.Nutritional niche overlap was largest between I.cateniannulata and I.farinosa,while time niche overlap was biggest between I.cateniannulata and B. bassiana.As for two-dimensional niche width of The 3 fungi,B.bassiana had the biggest,the followed by I.farinosa,and I.cateniannulata had the smallest.All suggested that B.bassiana had strongest viability while I.cateniannulata had the poorest.The genetic diversity of 497 isolates of B.bassiana from Langyashan was investigated using ISSR markers.The result showed that 90 bands were amplified by 8 informative and reliable primers,of which 86(95.56%) were polymorphic.A relatively high level of genetic diversity was revealed with H=0.2687,I=04181 at origins level and with indices at valley as the highest;H=0.2696,I=04193 at time level with that of June as the highest;Nei's genetic diversity H=0.2652,Shannon's information index I=04128 at the host level and with that of Lepidoptera as the highest.A higher level of genetic differentiation was detected in the population with Nei's analysis.The result of the analysis on molecular variance showed genetic differentiation factor Gst=0.0198,gene flow Nm=24.7810 at origins level;Gst=0.2634,Nm=1.3980 at time level;and Gst=0.0800,Nm=5.7473 at host level.The genetic distance of different origin groups was small with that between stream and hillside as the smallest.The genetic distance between groups from Coleoptera and Lepidoptera was also small.The genetic distance of different time groups was relatively large between those of September and November were smallest.It suggested that B.bassiana in Langyashan had high rate of polymorphic loci, i.e.,it had strong adaptability to the environment.The genetic diversity of 35 isolates of B.bassiana from Yaoluoping was estimated using inter-simple sequence repeat(ISSR) marker.With 8 rimers scored,total 69 fragments were amplified,in which 64(92.75%) were polymorphic with H=0.2896 and I=0.4416.Gst of among populations was 0.3181 with gene flow at 1.0718.Genetic distance between groups of July and October was smallest.The polymorphic loci percentage of different altitudes was also 92.75%with H=0.2781 and I=0.4850.Gst among populations was 0.2180 with Nm=1.7935;The genetic distance between isolates in latitudes of 900m and 1000～1050m was smallest.It suggested that B.bassiana from Yaoluoping had high genetic diversity,with slightly large interpopulation genetic variation and high level intrapopulation genetic differentiation.The analysis by ISSR on genetic diversity of 111 isolates of B.bassiana from Magushanrevealed that 7 ISSR primers chosen amplified a total of 58 fragments,54 of which(93.10%) were polymorphic.For groups of isolates based on time,H=0.2552, I=0.3825,Gst=0.2269,and Nm=1.7037.Genetic distance between May and July was shortest.For groups of isolates based on host,H=0.2623,I=0.3884.Gst=0.1965,and Nm=2.0441.The genetic distance between isolates from Coleoptera and Hymenotera was shortest.According to gene flow,it was known that intrapopulation genetic variation of B. bassiana was relatively small,while interpopulation genetic variation was pretty big.All above results showed that:the genetic diversity indices of B.bassiana were substantially influenced by forest ecological condition.Community of entomogenous fungi and genetic diversity of B.bassiana are abundant in virgin forest ecosystem where exist complex terrain,flourish broad-leaf and deciduous forest,and adequate rainfall.On the contrary,those are simple in pure pine plantation ecosystem where ecological environment was monotone and exists frequent artificial disturbance.While those in less interfered natural forest are intermediate.B.bassiana has large niche width in all different forest ecosystems,and its niche overlap to other entomogenous fungi is small. All evidences suggest that B.bassiana has strong adaptability to the environment.It can widely exist for long term in different forest ecosystems.