球孢白僵菌种群在松林中的寄主转移及遗传多样性对松毛虫持续控制的影响

通过林间接种式放菌及其后一周年的野外调查,从林间采集到30种寄主昆虫及从土壤、落叶和气流中分离到119株球孢白僵菌.酯酶同工酶分析表明,它们属于32个不同酯酶型,呈现出丰富的遗传多样性.释放菌株所属的酯酶型02包括从11种昆虫上分离出的18个菌株,表明林间释放的菌株已成功地在不同寄主昆虫种群中宿存下来,并以常发的地方病状态存在于松毛虫及松灰象甲等12种昆虫种群之中;当林间目标寄主缺乏时,其它寄主可将食物链维系下去.其它酯酶型分别包括1～23个菌株.一周年内的寄主转移动态结果表明,球孢白僵菌在松林生态系统中不同寄主间可转移寄生.每个酯酶型中的菌株对松毛虫的毒力相差很大.表明球孢白僵菌在松林中的延续和扩散流行不是1条路线,每个酯酶型至少代表食物网上的1条支链.有些环节的寄主连接了不同的酯酶型,使松林中食物网变得十分复杂.另外,从土壤、枯枝落叶层、林冠层和空气中分离到的球孢白僵菌分属于不同的酯酶型,表明松林中还存在着复杂的腐生食物链,有利于松毛虫及其它害虫的持续控制.     

白僵菌生物防治林中虫生真菌群落结构分析

对白僵菌生物防治林中虫生真菌群落的结构研究表明,长期接种式释放白僵菌的马尾松林中虫生真菌共有属7种.球孢白僵菌的数量占绝对优势,为总数的63.22%;拟青霉次之,占25.86%;绿僵菌占9.20%;轮枝孢仅占1.72%.从寄主昆虫的多样性来看,球孢白僵菌和环链拟青霉的Brillouin多样性指数分别为3.56和2.315,均匀度分别为0.81和0.865;粉拟青霉和蜡蚧轮枝孢的多样性指数分别为1.71和0.862,均匀度为0.963和1.000而黄绿绿僵菌、金龟子绿僵菌和玫烟色拟青霉多样性和均匀度指标均较低.不同季节中被白僵菌侵染的寄主昆虫多样性指数呈现出春秋高、夏季低的趋势,反映了白僵菌种群的季节性变化.     

球孢白僵菌释放后在森林系统中定殖及持续控虫作用的证据

在皖南马尾松林中使用球孢白僵菌无纺布菌条接种式放菌防治松褐天牛。在放菌前进行球孢白僵菌本底调查,在放菌后半年内采集该菌感染的各种僵虫,得到87株分离物。利用28SrDNA-PCRⅠ型内含子标记技术,测定放菌后释放菌株的回收率。结果表明,在87株球孢白僵菌中有66株与释放菌株的核型相同,占75.86%。半年中平均回收率为81.7%(75%-90.9%之间),这表明释放菌株已在该生态系中定殖,对松褐天牛种群发挥持续控制作用。在放菌前后球孢白僵菌种群结构有所变化,释放菌株有取代土著菌株优势地位的趋向。     

球孢白僵菌释放后在森林系统中定殖及持续控虫作用的证据

在皖南马尾松林中使用球孢白僵菌无纺布菌条接种式放菌防治松褐天牛。在放菌前进行球孢白僵菌本底调查,在放菌后半年内采集该菌感染的各种僵虫,得到87株分离物。利用28SrDNA-PCRⅠ型内含子标记技术,测定放菌后释放菌株的回收率。结果表明,在87株球孢白僵菌中有66株与释放菌株的核型相同,占75.86%。半年中平均回收率为81.7%(75%-90.9%之间),这表明释放菌株已在该生态系中定殖,对松褐天牛种群发挥持续控制作用。在放菌前后球孢白僵菌种群结构有所变化,释放菌株有取代土著菌株优势地位的趋向。     

基于SSR标记的琅琊山球孢白僵菌寄主专化性

球孢白僵菌Beauveria bassiana是一类常见的昆虫病原真菌,其自然侵染的寄主昆虫众多,达15目149科750种。为了解球孢白僵菌自然种群的遗传多样性,探讨种群异质性和寄主来源之间的关系,分析其寄主专化性的强弱,本研究利用SSR分子标记技术,比较了安徽琅琊山国家森林公园的85株球孢白僵菌（寄主种类涉及7目24种）群体遗传多样性差异,通过构建聚类树分析菌株基因型和寄主关联性。结果表明琅琊山球孢白僵菌群体Nei’s基因多样性指数h=0.2906,Shannon信息指数I_s=0.4510,多态位点百分率P为100%。不同寄主目球孢白僵菌遗传多样性水平由高至低为鞘翅目>膜翅目>同翅目>双翅目>鳞翅目>直翅目>半翅目,其中菌株数量较多的鞘翅目、膜翅目和同翅目3个亚种群的遗传多样性较高且水平接近。聚类分析发现8对SSR引物将85株球孢白僵菌分成29个基因型,并在遗传相似系数0.70处分别聚为3个分支。分析寄主类型发现相同基因型的株系可侵染不同目的寄主,而同一类型寄主也可被不同基因型的菌株侵染。球孢白僵菌种群的总体遗传多样性较高,遗传谱系与寄主来源无明显相关性,菌株的寄主专化性弱。     

皖南与皖西南蚕区球孢白僵菌种群遗传结构的ISSR分析

由球孢白僵菌引起的家蚕白僵病是影响蚕业生产的重要因素之一.本研究在皖南泾县和皖西南潜山县蚕区的病蚕、蚕室环境、蚕室周边桑园、松林及农田调查取样,共分离出124株球孢白僵菌;通过ISSR分子标记对它们及用于防治松毛虫的菌株进行种群遗传结构分析,追踪家蚕白僵病的来源及传播途径.结果表明： 两个地区的球孢白僵菌种群均为异质性明显的种群.潜山的蚕病亚种群是多源的,而泾县的蚕病亚种群是单源的;泾县蚕病亚种群和潜山的蚕病优势亚种群具有典型的地方性,只在蚕室内循环侵染家蚕,引起低频常在性的地方性白僵病;而潜山的非优势亚种群可以在蚕室外的少数转主寄主中传播.在两地松林的松毛虫种群中流行的类群、真菌杀虫剂生产菌株以及在潜山蚕室附近引起螳螂种群流行病的类群均与蚕病类群无关,表明其对蚕业是安全的.     

马尾松林中球孢白僵菌寄主转移和专化性的SSR标记分析

球孢白僵菌是一种最常见的虫生真菌,已被广泛应用于害虫生物防治。利用SSR简单序列重复(simple sequence repeat,SSR)分子标记对来自安徽省麻姑山马尾松林的102株球孢白僵菌进行基因分型、寄主转移和寄主专化性研究。9对微卫星引物将102株白僵菌分成31个微卫星基因型。在这31个微卫星基因型中,有5种基因型株系为相对优势菌株,这5种基因型株系通过侵染不同寄主昆虫即寄主转移延续自身在马尾松林生态系统中的传播和流行,从而证实寄主转移是白僵菌群体中的普遍现象。同时,这些相对优势基因型并不是在各个月份均匀分布,在大部分月份中,存在1–2种优势度高的基因型。相同基因型株系可侵染不同寄主的结果揭示出白僵菌不仅在种的水平,而且在菌株水平上寄主专化性也较弱。正是白僵菌较弱的寄主专化性特征促使部分基因型株系通过寄主转移,在马尾松林生态系统中得以宿存和延续。     

粗放经营茶园土壤昆虫病原真菌种群多样性及时间生态位

本文系统调查了粗放经营状态下黄山毛峰茶园根际土壤昆虫病原真菌的种群多样性及其时间生态位水平.于2012年8月至2013年6月,在安徽省黄山市汤口镇选择粗放经营茶园采集土壤样品140份,经稀释平板法分离共获得昆虫病原真菌1041株.结果表明： 昆虫病原真菌种群多样性较为丰富,经鉴定分为6属13种.其中,淡紫紫孢菌、球孢白僵菌和金龟子绿僵菌为优势种群,其菌株数分别为309、255和101株,占总数的29.7%、24.5%和9.7%.茶园土壤中淡紫紫孢菌的时间生态位宽度最大,球孢白僵菌最小.昆虫病原真菌之间以球孢白僵菌和布氏白僵菌的时间生态位重叠值最大,为1.965;而爪哇棒束孢和球孢白僵菌的时间生态位重叠值最小,仅为0.374.     

皖南与皖西南蚕区球抱白僵菌种群遗传结构的ISSR分析

由球袍白僵菌引起的家蚕白僵病是影响蚕业生产的重要因素之一本研究在皖南泾县和皖西南潜山县蚕区的病蚕、蚕室环境、蚕室周边桑园、松林及农田调查取样,共分离出124株球袍白僵菌;通过ISSR分子标记对它们及用于防治松毛虫的菌株进行种群遗传结构分析,追踪家蚕白僵病的来源及传播途径.结果表明:两个地区的球袍白僵菌种群均为异质性明显的种群.潜山的蚕病亚种群是多源的,而泾县的蚕病亚种群是单源的;泾县蚕病亚种群和潜山的蚕病优势亚种群具有典型的地方性,只在蚕室内循环侵染家蚕,引起低频常在性的地方性白僵病;而潜山的非优势亚种群可以在蚕室外的少数转主寄主中传播.在两地松林的松毛虫种群中流行的类群、真菌杀虫剂生产菌株以及在潜山蚕室附近引起螳螂种群流行病的类群均与蚕病类群无关,表明其对蚕业是安全的.     

中国北方球孢白僵菌的遗传多样性和种群遗传结构

将在中国北方13省采集分离的622株球孢白僵菌按省份划分成13个亚种群,其中寄主可以鉴定到目的8目昆虫和蜘蛛目的568株按目划分成9个亚种群,用ISSR(简单重复序列区间)分子标记技术进行遗传多样性和种群遗传结构分析.结果表明:各多样性指数皆显示我国北方地区球孢白僵菌的遗传多样性水平较高,种群的异质性较强.其中内蒙古亚种群的遗传多样性和种群异质性最高,河南亚种群最低;鳞翅目亚种群的遗传多样性和种群异质性最高,蜘蛛目亚种群最低.河南与辽宁亚种群间以及蜘蛛目与螳螂目亚种群间的遗传分化系数以及遗传距离最大,宁夏与陕西亚种群间以及鞘翅目与膜翅目亚种群间最小.按寄主目划分的亚种群间的平均遗传分化系数和平均遗传距离均低于按省份划分的亚种群.这些结果以及基于遗传距离的亚种群聚类分析都证明我国北方球孢白僵菌的遗传谱系与寄主来源和地理来源均无关系.我国北方球孢白僵菌的变异主要是由各不同寄主目内科间及属间的变异造成的,也是由各省不同采集地以及采集地内部不同微生境间的差异造成的.     

三种森林生态系统昆虫病原真菌优势种生态位比较

研究了天然阔叶林、天然阔叶次生林和马尾松人工纯林3种不同森林生态系统中昆虫病原真菌优势种的数量组成及生态位宽度和生态位重叠值.结果表明:球孢白僵菌在这3种森林生态系统中分别为第三、第一和第二优势种.该菌在3种森林生态系统中的营养生态位宽度和时间生态位宽度均最大,远大干环链棒束孢、粉棒束孢和细脚棒束孢等优势种;该菌与其他优势种的时间生态位重叠值较大,而营养生态位重叠值较小.球孢白僵菌在3种森林生态系统中都是发生时间最长、寄主昆虫最丰富、适应环境能力最强的昆虫病原真菌.     

Facilitation of tiger moths by outbreaking tussock moths that share the same host plants

1.?Ecologists have argued about the commonness and strength of interspecific competition between insect herbivores, but facilitation between herbivores has received much less consideration. We previously found that when two species of folivorous caterpillars co-occurred on a shared host plant, feeding by early season tiger moth caterpillars reduced the growth and reproduction of later season tussock caterpillars. However, densities of tussock caterpillars in summer were positively correlated with densities of tiger moth caterpillars the following spring. 2.?In this study, we experimentally manipulated numbers of feeding tussock caterpillars and found that they facilitated tiger moth caterpillars. 3.?The depth of the litter layer beneath host lupine bushes was positively correlated with the number of tussock caterpillars feeding on each bush. Experimental additions of litter beneath lupine canopies during summer resulted in increased numbers of tiger moth caterpillars in the following spring, indicating a causal role of litter. Litter potentially provides food, habitat and protection from desiccation and predation. We failed to find evidence that tussock caterpillars facilitated tiger moth caterpillars by mechanisms independent of litter. 4.?Our study demonstrates that facilitation may operate between insect herbivores, across life-stages through indirect interactions that are non-trophic. Facilitation operated by a novel mechanism, the accumulation of litter which was a by-product of feeding by one species was valuable to a second species. Facilitation persisted in time and space far beyond the creation of litter by tussock caterpillars which should be considered important ecosystem engineers from the point of view of tiger moths. Facilitations that involve habitat modification may generally connect species that do not interact directly or trophically, and have not previously been considered to affect one another.     

马尾松林生态系统中球孢白僵菌种群动态研究

应用选择性培养基标准平板技术 ,对接种式施放球孢白僵菌的试验区球孢白僵菌种群数量动态进行了调查研究 .监测 1年的结果表明 ,各放菌区在放菌初期的带菌量与初始放菌量密切相关 ,1个月后关系不明显 .放菌初期各宿存部位带菌量的大小依次为落叶层 >林冠层 >土壤层 .4个月后 ,不同放菌频度和放菌量区的带菌量基本一致 ,稳定在一定范围内波动 .在 12个放菌方案中 ,1年 2次放菌、每次放菌37.5g·hm-2 (10 0 0× 10 8孢子·g-1)为最佳放菌方案 .     

Direct and indirect chemical defence of pine against folivorous insects

The chemical defence of pine against herbivorous insects has been intensively studied with respect to its effects on the performance and behaviour of the herbivores as well as on the natural enemies of pine herbivores. The huge variety of terpenoid pine components play a major role in mediating numerous specific food web interactions. The constitutive terpenoid pattern can be adjusted to herbivore attack by changes induced by insect feeding or oviposition activity. Recent studies on folivorous pine sawflies have highlighted the role of induced pine responses in herbivore attack and have demonstrated the importance of analysing the variability of pine defence and its finely tuned specificity with respect to the herbivore attacker in a multitrophic context.     

Molecular monitoring and evaluation of the application of the insect-pathogenic fungus Beauveria bassiana in southeast China

AIMS: To monitor the fate of inundatively applied strains of Beauveria bassiana against Masson's pine caterpillar, Dendrolimus punctatus, in Magushan Forest, southeast China, and evaluate the potential environmental risks of biocontrol introduction. METHODS AND RESULTS: Filed samplings of mycosed cadavers were carried out continuously for more than one year after the inundative applications of two exotic B. bassiana strains. By employing four complementary molecular markers, the purified cultures from collections were characterized and the two released strains Bb17 and Bb13 were recovered with respective frequencies of 9.1 and 5.2%. The released strains were isolated from nontarget hosts. The genetic diversity of the population of B. bassiana in the trial plot changed dynamically over time and no single genotype strain dominated throughout the sampling period or at different seasons. The indigenous strains were observed to be predominant in the local environment. Co-infection and/or genetic recombination might occur between strains under natural conditions. CONCLUSION: Field applications of the biocontrol agent B. bassiana appear to pose no major risk to the environment. There was no evidence of displacement of indigenous strains of B. bassiana. SIGNIFICANCE AND IMPACT OF THE STUDY: The results indicate that the introduction of exotic B. bassiana strains can persist in local environment and infect nontarget insect hosts, highlighting the importance of safety assessment of the large-scale application of fungal biocontrol agents.