直翅目虫草（肉座菌目）：物种多样性及其与寄主的关系

迄今为止,以直翅目昆虫为寄主的虫草共报道25种,本研究详细介绍了它们的种类、寄主与分布,并给出了相关的分类学注释。ITS和tef1-α基因联合数据的分子系统发育显示,直翅目虫草分别隶属于白僵菌属Beauveria、绿僵菌属Metarhizium和线虫草属Ophiocordyceps 3个属。基于直翅目昆虫六大类群的生态习性特点,分析并讨论了直翅目虫草物种多样性与寄主的关系。以两种白僵菌Beauveria及戴氏虫草Metacordyceps taii（贵州绿僵菌Metarhizium guizhouense的异名）为例,介绍了虫草的根状菌索,一种介于子实体和孢梗束形体之间的根须状结构。种类修订：蟋螽白僵菌新组合Beauveria grylli comb. nov. ≡ 蟋蟀虫草Cordyceps grylli = Beauveria loeiensis,Beauveria kirkii comb. nov. ≡ Cordyceps kirkii。寄主更正：蟋螽白僵菌的寄主由原来的蟋蟀成虫（蟋蟀科Gryllidae）更正为螽斯（蟋螽）若虫（蟋螽科Gryllacrididae）,蟋蟀线虫草Ophiocordyceps tettigonia 寄主由原来的螽斯成虫（螽斯科Tettigoniidae：螽斯属Tettigonia）更正为蟋蟀成虫（蟋蟀科）。     

Review on safety of the entomopathogenic fungus Metarhizium anisopliae

The entomopathogenic fungus Metarhizium anisopliae (Metschn.) Sorokin is widely used for biocontrol of pest insects, and many commercial products are on the market or under development. The aim of this review is to summarise all relevant safety data of this fungus, which are necessary for the commercialisation and registration process. The review contains the following sections: (1) identity, (2) biological properties (history, natural occurrence and geographical distribution, host range, mode of action, production of metabolites/toxins, effect of environmental factors), (3) methods to determine and quantify residues, (4) fate and behaviour in the environment (mobility and persistence in air, water and soil), (5) effects on non-target organisms (microorganisms, plants, soil organisms, aquatic organisms, predators, parasitoids, honey bees, earth worms, etc.), (6) effects on vertebrates (fish, amphibia, reptiles, and birds), and (7) effects on mammals and human health (allergy, pathogenicity/toxicity). On the basis of the presented knowledge, M. anisopliae is considered to be safe with minimal risks to vertebrates, humans and the environment.     

Laboratory and glasshouse evaluation of entomopathogenic fungi against the two-spotted spider mite, Tetranychus urticae (Acari: Tetranychidae), on tomato, Lycopersicon esculentum

Forty isolates of entomopathogenic fungi from six genera were assessed against the two-spotted spider mite, Tetranychus urticae, in a single dose, direct application laboratory bioassay on tomato leaflets. Only three isolates caused greater mortality than the control: these were Metarhizium anisopliae 442.99, Hirsutella spp. 457.99, and Verticillium lecanii 450.99. These isolates were assessed in a multiple dose bioassay, together with three isolates cultured from commercial biopesticides as follows: Beauveria bassiana 432.99 (cultured from 'Naturalis-L', Troy Biosciences, Phoenix, TX, USA); Hirsutella thompsonii 463.99 (cultured from 'Mycar', Abbott Laboratories USA); and V. lecanii 19.79 (used in 'Mycotal' Koppert BV, The Netherlands). Beauveria bassiana 432.99, H. thompsonii 463.99, M. anisopliae 442.99, and V. lecanii 450.99 were all pathogenic to T. urticae in this bioassay. In addition, it was found that the mortality caused by B. bassiana 432.99 and Naturalis-L was increased when the mites were exposed to tomato leaflets sprayed previously with conidia suspensions, compared to spraying the mites directly. In a glasshouse experiment, sprays of B. bassiana 432.99, H. thompsonii 463.99, M. anisopliae 442.99, V. lecanii 450.99 and Naturalis-L reduced T. urticae populations in a tomato crop grown according to commercial practice. Naturalis-L reduced T. urticae numbers by up to 97%. In a second glasshouse experiment, single sprays of Naturalis-L and the acaricide fenbutatin oxide (Torq) were compared as supplementary treatments to release of the predatory mite, Phytoseiulus persimilis. Supplementary sprays of fenbutatin oxide reduced the numbers of T. urticae nymphs (80% reduction), while Naturalis-L reduced numbers of T. urticae adults, nymphs and eggs (98% reduction in all three cases). It is concluded that Naturalis-L has the potential to be used against T. urticae on glasshouse tomato crops.     

Effect of combination treatment with entomopathogenic fungi Beauveria bassiana and Nomuraea rileyi (Hypocreales) on Spodoptera litura (Lepidoptera: Noctuidaeae)

In biocontrol of insect pests, efficacy of treatment with multiple pathogens has not been frequently investigated but may have potential for effective management. The possible advantage of a combination treatment with two entomopathogenic fungi - Beauveria bassiana and Nomuraea rileyi - was assessed in laboratory bioassays on second instar Spodoptera litura. From among the fungal isolates of an epizootic population, two isolates of each fungus differing in virulence to S. litura were chosen, one highly virulent and the other with low virulence. The bioassays were carried out at either a continuous temperature of 25±1°C or at a temperature cycle of 32±2°C 8 h/21±2°C 16 h to mimic the field temperatures during the epizootic. Treatments with the two fungi were done both simultaneously and sequentially. In combination treatments at 25±1°C, in all isolate combinations, a majority of the larvae showed N. rileyi induced mycosis; the percentage mortality and speed of kill of insects in these treatments was similar to the N. rileyi isolate used in the combination treatments. At the temperature cycle of 32±2°C 8 h/21±2°C 16 h, in all combination treatments, all the dead insects exhibited B. bassiana mycosis; the mortality pattern was similar to the B. bassiana isolate used in the combination treatments. The adverse effect of high temperature on virulence of N. rileyi was however, not evident in in vitro growth assays. Combination treatment with both fungi did not have a synergistic effect on insect mortality.     

Laboratory investigations on the potential of entomopathogenic fungi for biocontrol of Helicoverpa armigera (Lepidoptera: Noctuidae) larvae and pupae

The susceptibility of third instar Helicoverpa armigera to seven strains of three entomopathogenic fungal species, i.e. Metarhizium anisopliae, Beauveria bassiana and Paecilomyces fumosoroseus, was tested under laboratory conditions using the larval immersion method. High efficacies ranging from 68 to 100% corrected mortality were recorded with more profound effects in treatments with B. bassiana and P. fumosoroseus strains. The median lethal concentration (LC₅₀) for L3 was 6.0×10⁵ in M. anisopliae 79, 1.5×10⁵ in B. bassiana 124 and 4.2×10⁴ in P. fumosoroseus 14. These three strains were further used to characterize the age-dependent mortality of different larval stages (L2-L5) and the effect against pupae of H. armigera. Larval stages did not differ in their mortality but differed i in median lethal time, with shorter values recorded in the second instar. Tested fungi also caused a high reduction between 74.4 and 100% in the emergence of pupae using the soil inoculation method and the pupal immersion technique. All three fungal species, especially P. fumosoroseus, have a high potential for biocontrol of H. armigera larvae and also as a soil treatment targeting the pupae.     

A novel dodine-free selective medium based on the use of cetyl trimethyl ammonium bromide (CTAB) to isolate Beauveria bassiana, Metarhizium anisopliae sensu lato and Paecilomyces lilacinus from soil

This study evaluated the quaternary ammonium compound cetyl trimethyl ammonium bromide (CTAB) as an alternative to the chemically related dodecylguanidine (dodine) for the selective isolation of entomopathogenic fungi. Oatmeal agar (OA) with chloramphenicol was used as basal medium, and three concentrations of CTAB (0.5, 0.6, 0.7 g/L) were evaluated and compared against OA + 0.46 g/L dodine. Selective isolation and growth studies were performed with the entomopathogens Beauveria bassiana, Metarhizium anisopliae s.l. and Paecilomyces lilacinus and five common non-entomopathogenic non-target species. The three entomopathogenic fungi sporulated earlier on OA + 0.6 g/L CTAB than on OA + 0.46 g/L dodine, while none of the non-target fungi sporulated on OA + 0.6 g/L CTAB. All entomopathogenic fungal isolates grew on OA + 0.6 g/L CTAB, despite some intra-species variation, whereas non-target fungi showed no growth or sporulation. OA + 0.6 g/L CTAB resulted in an efficient medium to isolate B. bassiana, M. anisopliae s. l. and P. lilacinus from soil samples. Results of our study suggest that OA + 0.6 g/L CTAB is a suitable, simple and inexpensive to prepare medium to replace OA + 0.46 g/L dodine for the selective isolation of these fungi.     

Efficacy of Beauveria bassiana (Hyphomycetes) for control of Russian wheat aphid (Homoptera: Aphididae) on resistant wheat under field conditions

The Russian wheat aphid, Diuraphis noxia (Kurdjumov) (Homoptera: Aphididae) is considered the most important pest of wheat produced under dryland field conditions in South Africa. As part of an integrated pest management strategy, the entomopathogenic hyphomycete Beauveria bassiana (Balsamo) Vuillemin was evaluated in combination with antibiotic host plant resistance under dryland field conditions during 1998 and 1999. A commercial formulation, Mycotrol® ES, was applied at a rate of 2.4 L (5×10¹³ conidia) per hectare +0.1% organosilicone surfactant. During both years, two applications were administered, i.e., on growth stages 31 (first node detectable) and 39 (early flag leaf). An additional treatment, application at growth stage 39 only, was included during 1999. Over the duration of the 1998 trial, ca. 65% fewer aphids were observed on treated plots compared with controls. A similar level of population reduction was observed during the 1999 trial; however, treatment effects were only briefly evident due to a rapid field-wide decline in aphid populations caused by adverse (cool, wet) weather conditions. The early application (GS 31) resulted in some level of control only during 1998. It was hypothesized that this phenomenon was the result of greater exposure to the spray applications and/or greater secondary pick-up of fungal inoculum by the aphids due to the higher level of aphid activity observed on the cultivar employed during that year. In this regard, migration of D. noxia onto the flag leaves should be further investigated as a behavioural trait for possible exploitation when considering the use of a mycoinsecticide.     

Coating Beauveria bassiana with lignin for protection from solar radiation and effects on pathogenicity to Lygus lineolaris (Heteroptera: Miridae)

The entomopathogenic fungus, Beauveria bassiana, is highly susceptible to the damaging effects of solar radiation. This study demonstrates protection from simulated solar radiation by coating B. bassiana (GHA) spores with lignin and effects on pathogenicity to Lygus lineolaris (Palisot de Beauvois) adults in direct spray and contact uptake bioassays. Spores were coated with either lignin or cross-linked lignin by spray drying to produce spore coatings of high and low water solubility, respectively. Non-coated spores and the two spore coating treatments were suspended in either water (0.04% Silwet L77) or oil (Orchex 692) to produce six formulations. Rates of loss in spore viability under simulated solar radiation were approximately ten times lower for the three formulations in which spores remained coated in suspension (cross-linked lignin in water, cross-linked lignin in oil, and lignin in oil). However, these three formulations were the least pathogenic. Estimates of LC₅₀ and LC₇₅ values for the most pathogenic formulation (non-coated in oil) were 5 and 12 times lower, respectively, than the least pathogenic formulation (cross-linked lignin in oil), but these differences were not significant. The three lignin-coated formulations that provided the greatest UV protection were also the least pathogenic based on LT values, which were significant. Overall, L. lineolaris mortality was approximately 80 times less when exposed to treated broccoli rather than sprayed directly, based on LC₅₀ values. If the contribution of spore uptake from plant surfaces to L. lineolaris mortality is similarly low under field conditions, then improving persistence may be less important for improving efficacy. However, under control conditions where solar radiation significantly impacts mycoinsecticide efficacy, the improved persistence of lignin coating formulations may outweigh negative effects on pathogenicity.     

Effect of Plant Type on the Persistence of Beauveria bassiana

Field evaluation of isolate MK 2001 of the entomopathogenic fungus Beauveria bassiana (Balsamo) Vuillemin, revealed conidia persistence and infectivity up to 26 days on foliage of lettuce and celery, two crops with substantial plant differences. Plants were treated at a rate of 100 ml/cage at a concentration of 1×10⁸ conidia/ml. The number of colony-forming units (CFU) recovered immediately after treatments from discs sampled on lettuce and celery leaves were not significantly different, due to similar foliar coverage of conidia by application. Significant differences were observed between both host plants during the 26 days of the field trial. The number of CFUs recovered on lettuce was significantly higher than that on celery leaves. However, for each host plant, there were no significant differences either between lettuce external leaves and internal leaves or between celery canopy and bottom leaves. An in vitro pathogenicity test carried out on Lygus lineolaris adults fed with leaf discs harvested from treated cages resulted in a high pathogenicity of B. bassiana isolate MK 2001. The mortality immediately after treatment did not differ from the death counts taken every other day for 26 days. However, efficacy was significantly different between both plants. Mortality was 91% on lettuce and 78% on celery, 7 days post-treatment. This study highlighted that plant type must be taken into account in foliar application of B. bassiana.     

Use of chitin to improve a Beauveria bassiana alginate-pellet formulation

A study was undertaken to evaluate optimum concentrations of chitin in sodium alginate pellet formulations to enhance conidia production. Chitin concentrations tested were 0, 0.5, 1, 2, 3 and 4% (w/v), with (2%, w/v) or without wheat bran. The different chitin-wheat bran pellet combinations were prepared with Beauveria bassiana isolate Qu-B306 at 10⁸ conidia mL^-1. After 21 days of incubation in a humid chamber at 28°C, conidia production was assessed. Improvements up to three times the initial conidia number were achieved using 2% chitin and 2% wheat bran. Higher levels of chitin decreased the number of conidia per pellet. For all chitin concentrations, conidia number increased with the addition of wheat bran (P≤0.05). Contamination by saprophytic fungi was reduced by the incorporation of chitin in the pellet formulation.     

Variability in tolerance to UV-B radiation among Beauveria spp. isolates

Solar radiation, particularly the UV-B component, negatively affects survival of entomopathogenic fungi in the field. In an effort to identify Beauveria spp. isolates with promise for use in biological control settings with high insolation, we examined 53 Beauveria bassiana isolates, 7 isolates of 4 other Beauveria spp. and Engyodontium albus (=Beauveria alba). The origins of these fungi varied widely as to host/substrate and country, but approximately 30% of these isolates were B. bassiana from ticks in Brazil. A preliminary trial with three B. bassiana isolates (Bb 19, CG 310 and CG 481) at several UV-B dosages indicated that 2h of weighted UV-B irradiance at 978mWm(-2) (providing a total dose of 7.04kJm(-2)) allowed separation of isolates into low, medium or high UV-B tolerance. This dose, therefore, was selected as a single dose to compare UV-B tolerances of all 60 Beauveria spp. isolates. There was high variability in tolerance to UV-B radiation among the B. bassiana isolates, ranging from virtually zero tolerance (e.g., Bb 03) to almost 80% tolerance (e.g., CG 228). In addition, surviving B. bassiana conidia demonstrated delayed germination; and this is likely to reduce virulence. Conidia of the other species were markedly more sensitive to UV-B, with E. albus (UFPE 3138) being the least UV-B tolerant. Among B. bassiana isolates originating from 0 degrees to 22 degrees latitudes, those from lower latitudes demonstrated statistically significant greater UV-B tolerances than those isolates from higher latitudes. Isolates from above 22 degrees , however, were unaffected by latitude of origin. A similar analysis based on host type did not indicate a correlation between original host and UV-B tolerance. The identification in this study of several B. bassiana isolates with relatively high UV-B tolerance will guide the selection of isolates for future arthropod microbial control experiments.     

In vitro compatibility of Beauveria bassiana strain ATCC 74040 with copper fungicides

Copper fungicides and mycoinsecticides based on entomopathogenic fungi Beauveria spp. are the most common pesticides used in organic crop production systems. The in vitro effects of the copper fungicides copper oxide, copper hydroxide, copper oxychloride, copper sulphate, dicopper chloride trihydroxide and tribasic copper sulphate were investigated for mycelial growth, sporulation and conidial germination of the ATCC 74040 commercial strain of Beauveria bassiana. Mycelial growth was evaluated on potato dextrose agar plates with 100%, 75%, 50%, 25%, 12.5%, 6.25% and 0% of the recommended application rates of each fungicide at 15 and 25°C. Sporulation and conidial germination were determined at the recommended field doses of each fungicide at 25°C. All copper fungicides had fungistatic or fungicidal effects on B. bassiana that varied according to the dose. Only in two cases, copper oxide at 15°C and copper hydroxide at 25°C, at the lowest concentration of 6.5%, was mycelial growth not statistically significantly inhibited. Inhibition of mycelial growth depended both on the fungicide and its concentration, and partly on temperature. Both sporulation and conidial germination of B. bassiana were significantly inhibited by all fungicides. All fungicides inhibited the sporulation in a similar way (99.8%–100%). With the exception of copper oxychloride (inhibition, 13.6%), the other fungicides showed high detrimental effects on conidial germination (inhibition, 91.7%–100%). The fungus was strongly affected by some fungicides even at the lowest doses. The biological index used for the B. bassiana with copper fungicides ranged from 0.6 (copper sulphate) to 18.1 (copper oxychloride). Therefore, the tested fungicides were classified into the upper half of the highly toxic (T) category and are considered incompatible with the entomopathogenic fungus B. bassiana strain ATCC 74040 under in vivo experimental conditions. These results need to be further verified in vitro under both greenhouse and open-field conditions.     

Evaluation of Beauveria bassiana and Metarhizium anisopliae for Controlling Chilo partellus (Lepidoptera: Crambidae) in Maize

Maize (variety Katumani) was planted in a greenhouse and plants were infested with 20 Chilo partellus second instar larvae 3 and 4 weeks after plant emergence. One isolate of Beauveria bassiana (BB-01) and four isolates of Metarhizium anisopliae (PPRC-4, PPRC-19, PPRC-61 and EE-01) were sprayed onto the leaf whorl at 2×10⁸ conidia/mL 24 h after infestation. Leaf damage by the larvae was greatly reduced by the treatments. The mean daily temperature and relative humidity in the greenhouse ranged from 10 to 35°C and 30 to 90%, respectively. The growth of infested unsprayed plants was less than that of fungi treated plants. Stem tunneling (1-5%), deadheart (0-33%), number of attacked nodes (0.3-2.5) and holes (0.2-3.3) were also reduced in plants sprayed with conidial suspensions. Isolates PPRC-4, PPRC-19 and PPRC-61 seemed to be the best candidates for further development.     

Autodissemination of Beauveria bassiana by Sap Beetles (Coleoptera: Nitidulidae) to Overwintering Sites

An autoinoculative device was used to test the ability of sap beetles (Coleoptera: Nitidulidae) to carry a specific strain of Beauveria bassiana (Balsamo) Vuillemin to overwintering sites in a multiyear field study. The device was baited with the pheromone and coattractants for the dusky sap beetle (Carpophilus lugubris Murray) and placed in the field in the fall of each year. The introduced strain occurred at high frequency among the B. bassiana isolated in the fall of all four years tested (100% of all isolates from 21 of 22 collection dates). The introduced strain of B. bassiana was isolated at high frequency from all the B. bassiana-contaminated sap beetles recovered from the overwintering traps (100% of all isolates from 13 of 23 trap/beetle species combinations) and was highest after the longest fall exposure. The introduced strain was primarily isolated from C. lugubris and C. antiquus, but species distribution was also dependent on the overwintering trap design used. Few non-sap beetles species of insects were recovered from the artificial overwintering sites. Although B. bassiana was isolated from free flying sap beetles caught in traps in the spring of each year, none were infected with the introduced strain. The autoinoculating device provides selective contamination of sap beetles in overwintering sites when used in the fall. It may be useful in providing some control of sap beetles or other insects where limited numbers of mass overwintering sites (such as tree holes) occur.     

锌离子响应转录激活因子ZafA对球孢白僵菌锌离子利用及生防潜能的影响

球孢白僵菌作为丝孢类昆虫病原真菌,已广泛应用于农林害虫的生物防治,但是田间多变的环境影响了真菌制剂的效能。此外,真菌侵染宿主后,宿主体内的环境也影响真菌的增殖和侵染速度。为研究球孢白僵菌对环境中酸碱度及微量元素的平衡能力,本研究初步探讨了锌离子响应转录激活因子ZafA与真菌生长繁殖、抗逆能力、毒力以及锌离子利用的关系。结果表明,敲除zafA削弱了真菌生长繁殖和孢子萌发的能力,增加了菌株对氧化、高渗、孢壁干扰剂以及紫外胁迫的敏感性,杀虫毒力显著下降,并抑制了相关性状基因的表达水平。基因敲除菌株无法在锌离子缺失的条件下生长,且zafA基因和锌离子转运蛋白编码基因zrf1–8的表达水平会受到酸碱度以及锌离子浓度的影响。由此可见,ZafA不仅直接影响球孢白僵菌利用锌离子的能力,还与球孢白僵菌抗逆能力和毒力密切相关,本研究为提高生防真菌环境适应性和发挥毒力提供新的依据。     

Beauveria bassiana for the control of Sunn Pest (Eurygaster integriceps) (Hemiptera: Scutelleridae) and aspects of the insect's daily activity relevant to a mycoinsecticide

A series of investigations was carried out at ICARDA during April-June 2004 and May-June 2005 to investigate the use of the entomopathogenic fungus Beauveria bassiana to control Eurygaster integriceps and to determine aspects of the insect's biology that could be relevant to control with the fungus. Application in 2004 of an oil-based formulation of B. bassiana showed distribution of the spray decreasing from the top of the wheat to the bottom, although the proportion of tillers with coverage at the base was still 80%. Seventy percent of Sunn Pest had received direct hits, with the highest amount on the dorsal surface, followed by the ventral surface, then the legs and antennae. Mortality of field-treated, then laboratory-maintained insects, ranged from 47.6% for insects exposed only to the B. bassiana spray, 74.2% for unsprayed insects exposed to treated wheat and 86.4% for insects receiving direct spray and being exposed to treated wheat. Some field results demonstrated mortality. Mortality assessments following the 2005 treatments were conducted solely in the field, there was no apparent effect upon Sunn Pest numbers. The majority of studies on Sunn Pest biology were carried out on untreated insects outside the trial plots. Different assessment methods resulted in varying estimates of adults and juveniles in the field. The numbers of Sunn Pest found and the proportion of these at the top of the wheat crop, declined after early morning and increased again in the early evening, suggesting sheltering deeper in the crop or in the soil during the middle part of the day. Mobility and location of marked insects was followed in micro-plots and by mark and recapture studies, demonstrating a range of activities, from movement around the crop for a number of metres, including contact with numerous tillers to almost total immobility; Sunn Pest generally avoided movement on the soil. The potential for Sunn Pest control with a mycoinsecticide and how Sunn Pest behaviour is relevant to a mycoinsecticide application are discussed.     

Variation in virulence of Beauveria bassiana isolates and its relatedness to some morphological characteristics

Ten Beauveria bassiana isolates were characterized using the following parameters: virulence, morphological measurements, germination in solid and liquid media, in vitro growth and physiological changes in liquid media. There were significant differences in mortality of second-instar larvae of the diamondback moth (DBM), Plutella xylostella (Lepidoptera: Plutellidae) and the Colorado potato beetle (CPB), Leptinotarsa decemlineata (Coleoptera, Chrysomelidae) according to isolate used (DBM; 14.51-53.37%, CPB; 25.05-74.07%). The most virulent isolates to DBM and CPB were KCF107 (soil origin) and KCF106 (Chilo suppressalis origin), respectively. Several morphological and physiological characteristics of isolates were evaluated for a possible link to virulence against both insect species. Special mean diameter (2.45-3.58 µm) and area of conidia (5.72-10.25 µm²) were significantly different among isolates. Time for 50% of conidia to germinate (GT₅₀) varied from 11 to 21 h depending on isolate. There was no correlation to virulence of size of conidia, GT_50, red pigment production and mycelial growth. Acidity of 7-day-old broth cultures of isolates was positively correlated with virulence. Iranian isolates KCF106 and KCF107 were the most promising and virulent isolates but field testing is needed to further evaluate their potential for use in DBM and CPB management.     

Horizontal Transmission of the Entomopathogenic Fungus Beauveria bassiana among the Spruce Bark Beetle, Ips typographus (Col., Scolytidae) in the Laboratory and under Field Conditions

In laboratory and field cage experiments, the horizontal transmission of the entomopathogenic fungus Beauveria bassiana (Boverol®) between adults of the spruce bark beetle Ips typographus was examined. In a laboratory experiment, conidia transfer between treated and untreated beetles at different ratios resulted in 96% mortality (MST 4.3 days) at a ratio of 1:1 and 90% mortality (MST 4.5 days) at a ratio of 1:2. At ratios of 1:5, 1:10 and 1:20, the mortalities at 7 days were 83, 77 and 75%, respectively. In a second laboratory experiment, the efficacy of B. bassiana was investigated after transmission from contaminated to healthy beetles over a period of 5 days. Two weeks later, the mortality of treated and untreated beetles was 99% (control mortality was 44%), while the rate of mycosis was 79% in the treatment compared to 10% in the control beetles. A single contact between one treated male (2.0×10⁵ conidia/beetle) and an untreated female was found to be sufficient to transmit a lethal dose of B. bassiana of about 1.2×10⁴ conidia. Two experiments in field cages in a spruce stand demonstrated horizontal transmission of B. bassiana (Boverol®) between beetles. In the first experiment the transmission was investigated following the introduction of B. bassiana-inoculated beetles into a population of untreated beetles. Significant reductions were observed in the length of maternal galleries, and the number of larvae and pupae. In the second field cage experiment, natural populations of beetles were lured into a flight cage using a pheromone trap, and treated with B. bassiana or left untreated on alternate days. In this experiment, significant reductions were observed in the number of bore holes and the length of maternal galleries, while no larvae, pupae or juveniles were found under the bark of spruce trunks in the Boverol® transmission treatment. It is concluded that B. bassiana has potential for control of I. typographus, and further field experiments are warranted to investigate its efficacy under more practical conditions.     

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。     

Enantioselective benzylic microbial hydroxylation of indan and tetralin

A screening with 15 strains of bacteria and fungi targeted at the production of specific hydroxylated benzylic derivatives of indan 1 and tetralin 2 was carried out. Mortierella isabellina, Mortierella ramanniana and Beauveria bassiana were shown to mediate the respective conversions to 1-indanol (3) and 1-tetralol (4), the most satisfactory results being obtained with M. isabellina, which gave 78% conversion of 1 to (1R)-3 (64% yield, 86% ee) after a 2-day-incubation, and 52% conversion of 2 to (1R)-4 (38% yield, 92% ee) in a 4-day-incubation. Over-oxidation of alcohols 3 and 4 during the reactions resulted on the formation of 1-indanone and 2-tetralone, respectively.