虫霉目新种和新记录

本文报道了虫霉目的一个新种和3个新记录种。新种叶蝉虫疫霉(Erynia cicadellisLi et Fan sp.nov.)是我国南方稻叶蝉虫霉流行病的病原之一,与近缘种飞虱虫疫霉[E．Deiphaeis (Heri) Humber et Ben-Ze’ev] 的主要区别在于后者孢子较大,且不具有假根。蚜虫疫霉[E. aphidis (Hoffm.) Humber et Ben-Ze'ev]系世界不常见种,国内首次在陕西岚皋及福州的桃蚜上记录;飞虱虫疫霉和佩氏虫疫霉[E．Petchii Ben-Ze'ev et Kenneth)皆系南方褐稻虱虫霉流行病的病原。     

虫疫霉属新种和中国新记录

本文报道了虫疫霉属2个新种及1个中国新记录种。新种北虫疫霉(Eryniaborea Fan et Li sp.nov.)发生于西北及东北地区的丽蝇成虫体上,菜叶蜂虫疫霉(Eryniaathaliae Li et Fan sp.nov)发生于陕西杨陵的黄翅菜叶蜂幼虫;新记录种近藤虫疫霉(Erynia kondoiensis Milner)发生于福州的烟蚜虫体上。本文详细描述了新种的形态。     

侵染双翅目昆虫的新种、新记录、新组合及新修订

记录了最近在中国记载的侵染双翅目昆虫的虫霉目两个新种,毛蚊虫疠霉(Pandora bibionis)发现于浙江庆元的毛蚊(Bibio sp),其初生分生孢子拟卵形,多对称144～20.5×7.2～11.5μm(平均16．5～174×8.4～10.4μm), L／D 1.4～2.3(平均1.7～2.0);假根2倍粗于分生孢子梗,末端膨大为吸盘状固着器;休眠孢子外壁刺毛状,19．1～23.4μm。食蚜蝇干尸霉(Tarichium syrphis)发现于陕西镇坪县的斑翅狭口食蚜蝇上,其休眠孢子外被圆锥形长刺,长2.2～5.0μm,直径21.2～28.1μm。在毛蠓上发现中国新记录胶孢虫疠霉,并根据本文所采用的Humber(1989)系统,将其组合为胶孢虫瘴霉(Furia gloeosora comb. Nov.);此外,还将北虫疫霉(Erynia borea)组合为北虫疠霉(Pandoraborea comb. Nov.),并同时给予修订。     

沫蝉的病原真菌新种——巨孢虫疫霉(英文)

在浙江省百山祖自然保护区虫生真菌调查中发现松树上的菱沫蝉(Agrophora sp.)的新病原真菌一种,因其分生孢子远大于任何已知种虫疫霉,故定为新种巨孢虫疫霉(Eryniagigantea Li,Chert et Xu)。其初生分生孢子长倒拟卵形或拟纺锤形,对称或略弯曲,42.6—76.7×l 2.3—26.0μm(平均57.6×l 8.6μm),长径比2.2—4.9(平均3.1);顶稍圆或尖削;基部乳突略钝,有时有孢领。次生分生孢子倒拟卵形至广倒拟卵形;毛管分生孢子未见。假根成束。假囊状体及休眠孢子未见。     

沫蝉的病原真菌新种——巨孢虫疫霉

在浙江省百山祖自然保护区虫生真菌调查中发现松树上的菱沫蝉(Agrophora sp.)的新病原真菌一种,因其分生孢子远大于任何已知种虫疫霉,故定为新种巨孢虫疫霉(Eryniagigantea Li,Chert et Xu)。其初生分生孢子长倒拟卵形或拟纺锤形,对称或略弯曲,42.6—76.7×l 2.3—26.0μm(平均57.6×l 8.6μm),长径比2.2—4.9(平均3.1);顶稍圆或尖削;基部乳突略钝,有时有孢领。次生分生孢子倒拟卵形至广倒拟卵形;毛管分生孢子未见。假根成束。假囊状体及休眠孢子未见。     

中国橡胶树疫霉种的研究*

疫病是我国植胶区的主要病害。近年来,作者从云南西双版纳和广东海南岛的橡胶树和胶园土共分离出57株疫霉菌种。通过分类研究,共鉴定出4个种:恶疫霉 Phytophthoracactorum(Leb.＆ Cohn)Schroeter,辣椒疫霉 P.capsici Leoman,柑桔褐腐疫霉 P.citrophthora(Sm.＆ Sm.)Leonian,和棕榈疫霉 P.palmivora(Butl.)Butler。其中辣椒疫霉是首次在橡胶树上发现。我国橡胶树疫霉的种群结构与东南亚和南亚的有所不同,除棕榈疫霉外,其余3种在东南亚和南亚均未发现。而东南亚常见种:簇囊疫霉(P.botryosa)、橡胶疫霉(P.heveae)和蜜色疫霉(P.meadii),在我国却迄今尚未发现或有待证实。以前报道分离自胶园土壤中的芋疫霉(P.colocasiae),可能系柑桔褐腐疫霉之误。绝大多数分离物经配对培养均可产生性器官:辣椒疫霉的A~1交配型和A~2交配型大致相等;柑桔褐腐疫霉和棕榈疫霉的A~2交配型则明显多于A~1交配型。     

中国橡胶树疫霉种的研究

疫病是我国植胶区的主要病害。近年来,作者从云南西双版纳和广东海南岛的橡胶树和胶园土共分离出57株疫霉菌种。通过分类研究,共鉴定出4个种:恶疫霉 Phytophthoracactorum(Leb.＆ Cohn)Schroeter,辣椒疫霉 P.capsici Leoman,柑桔褐腐疫霉 P.citrophthora(Sm.＆ Sm.)Leonian,和棕榈疫霉 P.palmivora(Butl.)Butler。其中辣椒疫霉是首次在橡胶树上发现。我国橡胶树疫霉的种群结构与东南亚和南亚的有所不同,除棕榈疫霉外,其余3种在东南亚和南亚均未发现。而东南亚常见种:簇囊疫霉(P.botryosa)、橡胶疫霉(P.heveae)和蜜色疫霉(P.meadii),在我国却迄今尚未发现或有待证实。以前报道分离自胶园土壤中的芋疫霉(P.colocasiae),可能系柑桔褐腐疫霉之误。绝大多数分离物经配对培养均可产生性器官:辣椒疫霉的A~1交配型和A~2交配型大致相等;柑桔褐腐疫霉和棕榈疫霉的A~2交配型则明显多于A~1交配型。     

飞虱虫疫霉的产孢生物学研究

飞虱虫疫霉Erynia delphacis (Hori) 是水稻害虫稻褐飞虱的天敌,在田间常造成流行病,使大量褐飞虱死亡。在研究利用真菌防治害虫方面,一个很重要的问题就是如何在人工培养基上培养病原菌,并获得大量可以保存的孢子然后用于田间。本试验的重点在于用液体培养的方法获得这种菌的分生孢子,并测定了液体和固体培养的产孢量和产孢时间。     

粉蝶虫疫霉的鉴定及流行

感染重阳木斑蛾的粉蝶虫疫霉分生孢子卵圆型或倒卵型,单核,双囊壁,21.7—26.7×12.5—16.7μm,平均24.6士1.4×14.2土0.9μm,长径比(L/D)1.73士0.1。分生孢子梗单枝,二叉分枝或掌状分枝。囊状体和假根众多。假根多数单枝,少数末端二叉分枝或多叉分枝。可感染鳞翅目、半翅目和双翅目等多种害虫。     

粉蝶虫疫霉的鉴定及流行

感染重阳木斑蛾的粉蝶虫疫霉分生孢子卵圆型或倒卵型,单核,双囊壁,21.7—26.7×12.5—16.7pm,平均24.6士1.4×14.2士0.9μm,长径比(L/D)1.73士0.1。分生孢子梗单枝,二叉分枝或掌状分枝。囊状体和假根众多。假根多数单枝,少数末端二叉分枝或多叉分枝。可感染鳞翅目、半翅目和双翅目等多种害虫。     

蚜虫的病原真菌新种——安徽虫疫霉

1984年初冬在安徽长江南北大面积蔬菜的桃蚜种群中发生真菌流行病。病原鉴定为虫霉目新种安徽虫疫霉(Erynia anhuiensis Li sp.nov)。分生孢子梗二歧分枝;初生分生孢子单核,双囊壁,长椭圆形、长卵形或倒拟卵形,前二者大小为17.1—33.3×5.9—12.9μm(平均24.7×8.3),长径比2.0—5.4(平均3.0),后者12.6—30.8×8.1—16.5μm(平均22.7×11.6),长径比1.4—2.5(平均2.0);有囊状体及假根,假根有固着器。外休眠孢子球形,光滑,透明,直径22.1—31.9μm(平均26.6)     

A novel computerised image analysis method for the measurement of production of conidia from the aphid pathogenic fungus Erynia neoaphidis

A semi-automated method has been developed for the quantification and measurement of conidia discharged by the aphid pathogen Erynia neoaphidis. This was used to compare conidiation by E. neoaphidis-mycosed pea aphid cadavers, mycelial plugs cut from agar plates, mycelial pellets from shake flasks and by mycelial pellets from different phases of liquid batch fermenter culture. Aphid cadavers discharged significantly more and significantly smaller conidia than plugs or pellets. The volume of conidia discharged was stable over the period of discharge (80 h), but more detailed analysis of the size frequency distribution showed that more very small and very large conidia were discharged after 5 h incubation than after 75 h incubation. Biomass harvested at the end of the exponential growth phase in batch fermenter culture produced significantly more conidia than biomass from any other growth phase. The implications of these findings for the development of production and formulation processes for E. neoaphidis as a biological control agent are discussed.     

Effect of meteorological variates on persistence of primary conidia and capilliconidia of Erynia radicans (Zygomycotin: ntomophthorales) under natural conditions

Persistence of conidia of an isolate of Erynia radicans (Syn. Zoophthora radicans) was investigated in relation to the meteorological conditions which occurred during autumn-winter of 1990–91 in the coastal plain in Israel. Capilljconidia shielded from the sun, placed on the abaxial surface of leaves of Plumeria acuminata, persisted for 24 h to at least 120 h. Exposed capilliconidia, placed on the adaxial surface of the same leaves, died within 24 h. Almost all the primary conidia shielded from the sun (placed on the abaxial surface of the same leaves) died within a single day. Conidial viability was expressed in subsequent germination on an agar medium. Capilliconidial persistence was closely related to the daily air temperatures, expressed as cumulative day-degrees. Differences in relative humidity had no substantial effect on capilliconidial mortality. At daytime temperatures of ≤ 20°C, mortality after 24 h incubation was lowest (≤ 34%) and the persistence duration, longest (at least 120 h). Increases in daytime temperature up to 24°C for a few hours increased mortality (37–57% after 24 h incubation) and shortened the persistence duration (72–120 h). Exposure to 24–29°C during daytime greatly increased mortality (65–58% after 24 h) and further shortened the persistence duration (24–48 h). Daytime temperatures of > 29°C were lethal to all capilliconidia within 24 h. Temperature had a profound effect on capilliconidial persistence also under controlled environmental conditions. The significance of capiliiconidial persistence is discussed in relation to activity of the fungus in its natural environment.     

Production Factors Involved in the Formulation of Erynia neoaphidis as Alginate Granules

Granular formulations of the aphid-pathogenic fungus Erynia neoaphidis were produced by entrapping mycelia in alginate polysaccharide polymers. Four Swiss isolates were compared for the numbers of conidia discharged from the surface of alginate granules in standardized laboratory assays and two were considered to be suitable for further development. Conidiation was achieved from granules produced using nozzle diameters of 2.0. 1.0 and 0.5 mm from glass burettes or a novel vibrating tip apparatus. The mean diameters of dried granules varied from 0.5 to 1.8 mm. The addition of sucrose, potato starch or chitin in alginate solutions significantly improved the numbers of discharged conidia. W ith freshly produced granules, there was a 14.2- fold increase in sporulation from 6.3 to 89.7 conidia mm - 2 using 2% (w/v) sucrose. Increases of 1.6-to 2.3-fold, from 11.0 to 17.7 and 25.2 conidia mm - 2, were observed using 5% (w/v) starch or chitin respectively. The overnight drying of granules in a laminar flow hood and storage for 4 days at 4 C made differences in sporulation more obvious. There was a 15.5-fold difference in conidial numbers of 12.4 and 0.8 conidia mm - 2 from granules with and without sucrose respectively. For starch and chitin, there were 76.0-and 46.5-fold increases from 0.4 to 30.4 and 18.6 conidia mm - 2respectively. Fresh or dried alginate granules containing 2% sucrose and 5% starch gave 8.6-26.6% infection in laboratory bioassays with nymphs of pea aphid, Acyrthosiphon pisum , which were not significantly different when compared with infections of 6.7-22.9% using agar cultures or unsupplemented granules. Further studies on desiccation and storage regimes are required in order to improve the short-term shelf-life of E. neoaphidis alginate granules.     

Effects of 20 fungicides on the infectivity of conidia of the aphid entomopathogenic fungus Erynia neoaphidis

The effect of 20 fungicides on theinfectivity of conidia of the entomopathogenicfungus, Erynia neoaphidis, were assessedin the laboratory. After projection on broadbean leaves, conidia were treated withfungicides applied at their recommended fieldrate. Afterwards, the infectivity of theseinocula was assessed using an aphid bioassay.Four fungicides, carbendazim, kresoxym-methyl, nuarimol and thiophanate-methyl reduced the infectivity of the conidia by less than 25% and can be considered harmless for this aphid pathogen. Propiconazole was a little more toxic, with 37% reduction. Other products reducedinfectivity by between 50% and 100%. These are, from the least to the most toxic:flutriafol, prochloraz, epoxyconazole,iprodione, hexaconazole, triadimenol,azoxystrobine, cyproconazole, cyprodynil,flusilazole and tridemorph. Chlorothalonil,fenpropimorph, spiroxamine and tebuconazoletotally inhibited infectivity of the fungi. Analysis of the results according to chemicalclass showed that the benzimidazoles were theleast toxic for E. neoaphidis and themorpholines the most toxic. Effects oftriazoles and strobilurines were variable, withreduction ranging from 37% to 100% fortriazoles and from 17% to 68% forstrobilurines.     

The effects of photoperiod and light intensity on the sporulation of Brazilian and Norwegian isolates of Neozygites floridana

The objective of this study was to determine the effects of light intensity and duration (photoperiod) on the sporulation (discharge of primary conidia) and conidia germination (from non-infective primary conidia to infective capilliconidia) of Neozygites floridana isolates from Tetranychus urticae originating from Norway and Brazil. Two light intensities (40 and 208 μmol m⁻² s⁻¹), three photoperiods (24 h of continuous light (24 h D), 12 h of darkness followed by 12 h of light (12 h D: 12 h L) and 24 h of continuous darkness (24 h D)) and two temperatures (18 °C and 23 °C) were tested. The fungus produced similar amounts of primary conidia and capilliconidia at 12 h D:12 h and 24 h D, indicating that the fungus discharges almost all of its conidia during the first 12 h of darkness. Light had less of an effect on the production of primary conidia than on capilliconidia formation. At 24 h L, capilliconidia formation was significantly lower for all tested light intensities, temperatures and isolates compared to 12 h D:12 h L and 24 h D. At both light intensities, 24 h L resulted in a significantly lower capilliconidia formation for the Norwegian isolate compared to the Brazilian isolate. Our data suggest that, even though 24 h L reduced sporulation, some capilliconidia formation may occur at the low light intensities found on the underside of strawberry leaves during parts of the day as well as the top of a non-shaded strawberry leaf during the dim evening and morning hours in the tropics and during the dim, long summer days in temperate regions.     

温湿度对安徽虫瘟霉在桃蚜居群中流行的影响

用安徽虫瘟霉(Zoopphthoraanhuiensis)接种桃蚜(Myzuspersicae)无翅成蚜3头和健蚜3头组成新的蚜群若干,在不同温湿组合条件下任其繁殖、发病和传染,以评价温湿度对该菌在蚜群中流行的影响.持续26d观察,在偏低温与各湿度(90～100%RH)的组合中均成功诱发了蚜病流行,其程度受湿度影响较小.在10℃与各湿度组合中,最终感病死亡率为72.9%～98.2%,15℃下为78.7%～94.4%,流行强度极大.而20℃下仅100%RH诱发了高强度流行病,其余湿度下感病死亡率仅为5.1%～12.8%.在25℃,100%RH下死亡率仅27.2%.与所有湿度组合中的对照蚜群相比,10℃下流行病控蚜效果为89.5%～96.9%,15℃下为96.1%～98.2%,20℃下为45.9%～85.7%,25℃下为56.4%～69.7%.逐步回归分析表明,安徽虫瘟霉引发的蚜病流行与温度及其相对湿度和蚜群带菌后天数的互作项密切相关(r2=0.82,a＜0.01),这些变量在很大程度上决定了安徽虫瘟霉是否在蚜群中流行.     

Effects of long-term storage at -14 degrees C on the survival of Neozygites fresenii (Entomophthorales: Neozygitaceae) in cotton aphids (Homoptera: Aphididae)

Neozygites fresenii-infected Aphis gossypii cadavers, containing dormant hyphal bodies of N. fresenii, were stored in 4 ml glass vials at -14 degrees C in a standard consumer-type refrigerator/freezer for 1, 21, 30, 43, 51, and 68 months to determine the effect of storage on fungal survival. When the cadavers were removed from the freezer and placed in 25+/-1 degrees C, 100% relative humidity, and 12:12 (L:D) conditions, N. fresenii survival, as shown by fungal sporulation from the cadavers, was high at all storage periods. The average percentage of cadavers from which the fungus sporulated were 93, 47, 100, 100, 80, and 60% from 1, 21, 30, 43, 51, and 68 months storage periods, respectively. The number of primary conidia discharged from each sporulating cadaver was estimated using a scale of 1 (low, ca. 1000 primary conidia), 2 (medium, ca. 2000 primary conidia) and 3 (high, ca. 3000 primary conidia). The median scores for the number of primary conidia produced per sporulating cadaver were 3, 2, 3, 3, 2.5, and 1 for 1, 21, 30, 43, 51, and 68 months, respectively. Therefore, except for the longest storage period, most cadavers produced medium to high numbers of primary conidia. Mean germination of primary conidia produced from N. fresenii-infected-aphid cadavers from each time period varied significantly from 66.3 to 86.1% in the 21 and 43 months categories, respectively. Infectivity of capilliconidia, produced from frozen N. fresenii, to live healthy cotton aphids varied significantly from 16.7 to 68.7% from cadavers stored 68 months and 1 month, respectively. Overall N. fresenii survived well in dried frozen cotton aphid cadavers for up to 6 years with little reduction in sporulation, numbers of spores produced, germination of primary conidia, or infectivity.