弯孢虫疫霉的分离和鉴定

1984—1987年,在福建的南平、福州、南安等地持续发生了由弯孢虫疫霉(Eryniacurvlspora)感染而引起库蚊(culex sp.)成虫死亡的流行病,病原菌分生孢子梗掌状分枝;分生孢子浅绿色,窄而长,略弯曲,单核,双囊壁,含有多个小脂肪粒,大小29.7—39.6×13.2—19.8(平均32.5×16.1)μm,长宽比1.5—3.0(平均2.0);次生分生孢子梨形,基部为钝的乳突,中间有一大的脂肪粒,孢子大小16.6—19.9×11.6—14.9(平均18.7×13.7)μm;休眠孢子球形,棕褐色,直径23.2—33.2(平均29.5)μm;有假根及囊状体。     

广东省侵染摇蚊的库蚊虫霉研究

在中国首次报道了侵染摇蚊的库蚊虫霉(Entomophtora culichs)的形态特征、侵染症状以及发生动态等。库蚊虫霉初生分生孢子,钟罩形,顶部有一明显小尖突,(14.6±1.5)μm×(10.8±1.2)μm。次生分生孢子形似初生分生孢子,但略小,(11.0±1.1)μm×(8.0±0.5)μm。休眠孢子,球形至亚球形,直径(29.3±1.9)μm。被侵染摇蚊尸体以假根附着于基物上,通体覆盖着绿色的真菌子实层。库蚊虫霉侵染率在不同植物上明显不同。库蚊虫霉侵染率随季节不同波动很大,春季最高达90.2%,其次为秋季和冬季,夏季最低为0。2006—2009年库蚊虫霉侵染率为93.5%～95.7%,年际之间变动不大。     

环境因子对努利虫疠霉产孢和孢子萌发的影响

探讨努利虫疠霉Pandoranouryi(Remaudi埁re&Hennebert)H櫣mber在田间蚜虫种群中发生与流行的规律,研究外界环境因子对感菌虫尸产孢和孢子萌发的影响。结果表明,处于水琼脂培养平板上感染努利虫疠霉的桃蚜虫尸在8~25℃的温度范围内均能产生大量的初生分生孢子,在30℃下,仅弹射极少量孢子。8℃下,孢子弹射可以持续120h,当温度高于15℃,大部分的孢子会在48h内完成弹射。相对湿度小于95%,虫尸停止产孢。20℃下,光照条件不会影响虫尸弹射孢子的总量。在8℃和30℃时,24h后处于水琼脂培养平板上的孢子萌发率分别为45.23%和61.74%,显著低于15~25℃温度范围内的孢子萌发率(95%以上)。处于叶片上的真菌孢子,当相对湿度大于74%时出现萌发,但在盖玻片的表面,当湿度低于100%时未发现孢子萌发。     

温湿度和光照对宁夏灌区春小麦白粉病菌分生孢子萌发的影响

在宁夏灌区,春小麦白粉病菌(Erysiphe graminis f.sp.tritici)的分生孢子在-3-29℃温度范围都可萌发。温度达33℃时不能萌发,最适温度为10—15℃。分生孢子虽然在0—100%的湿度下都可以萌发。但以饱和湿度最适。紫外光对分生孢子有强烈的杀伤作用。直射阳光对分生孢子的萌发有抑制作用;在散射光和黑暗条件下,孢子的萌发率没有显着差异。     

飞虱虫疠霉分生孢子在桃蚜体壁上的附着与入侵

用飞虱虫疠霉（Pandora delphacis)初级分生孢子接种桃蚜（Myzus persicae),24h内定时取样,在扫描电镜下观察孢子的萌发及其对寄主体壁的入侵。结果表明,附着到蚜体表面的孢子在4h内有30－40％已萌发产生芽管,少数是呈叉状分枝的营养生长型芽管。且侵染性芽管的孢子部分孢入体壁蜡质层中,显示孢子有分泌物产生并作用于寄主体壁。接种10h内,侵染性芽管通过顶端膨大的附着胞或直接穿透入寄主体壁。到24h时,产生侵染性芽管的孢子全部侵入寄主体内,寄主体表仅留下少数未萌发的孢子或营养生长型芽管。初级分生孢子在蚜体表面很少产生次级分生孢子,说明桃蚜是适合该菌侵染的寄主。陷入寄主体壁的孢子不因若蚜蜕皮而被去掉,表明该菌对成蚜和若蚜都具有侵染力。     

鸡腿菇特有病害鸡爪菌分生孢子萌发特性研究

研究了鸡腿菇特有病害鸡爪菌分生孢子萌发特性。结果表明,鸡爪菌分生孢子以单极萌发为主．在子座上一般不萌发。萌发需要较高的温湿环境和营养条件,pH值中性偏酸,光照对萌发影响不大。致死温度为43℃-45℃。     

飞虱虫疠霉分生孢子在不同温湿度组合条件下的存活率

用荧光染色法研究了不同温度（10－30℃）和湿度（51－100％RH）组合条件下飞虱虫疠霉Pandora delphacis分生孢子的存活率。在无放回抽样观察中,孢子弹射后第24h的存活率在51％、74％、85％、90％、95％和100％RH与不同温度的组合中分别为42－81％、69－89％、70－95％、67－100％、76－100％和56－100％。存放4个月后,不同温度下的孢子存活率在51％、74％、85％和90％RH下分别为55－74％、52％－87％、38－73％和1－65％。而在≥95％RH下孢子存活率24h后锐减,至第7d几乎全部失活。以上结果表明,弹射后的飞虱虫疠霉孢子在头24h的存活易受低湿影响,但存活下来的孢子能继续在低湿下存活较久;饱和或接近饱和的高湿度最不利孢子长久存活。     

土壤丝状真菌中能引起稻瘟霉分生孢子形态畸变的活性菌种筛选的 …

本实验对安徽,湖南,江苏等十三个省的６０份土样进行了分离纯化,获得７９１株真菌。采用目前属国内领先的以稻瘟霉分生孢子生态变化为指标的筛选体系,初筛得到能使稻瘟霉孢子畸变和抑制孢子萌发的菌株１４０株,进而经过复筛得么能够使稻温霉孢子畸变的１９株,抑制稻瘟霉孢子萌发的１６株,其中７６－２,７６－６,１００－３,１００－７,１００－１０,５株菌的孢子畸变活性最好且遗传稳定。     

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)     

Morning dew and Tripospermum (Hyphomycetes)

Morning dew appears to be an important factor in the habitat of Tripospermum species. It affects both conidial development and liberation.     

Development,Ultrastructure, and Mode of Transmission of Amblyospora sp. (Microspora) in the Mosquito*

SYNOPSIS. Amblyospora sp. in Culex salinarius (Coquillett) is transovarially transmitted and has 2 developmental sequences, one in each host sex. In females, the entire life cycle is restricted to oenocytes which become greatly hypertrophied due to the multiplication of diplokaryotic cells during merogony and come to lie next to ovaries. Sporulation occurs only after a blood meal is taken and is shortly followed by infection of the oocytes and subsequent transmission to the next host generation. In the male host, infections spread from oenocytes to adipose tissue where diplokaryotic cells undergo a 2nd merogony. During this merognic cylce, the number of diplokaryotic cells greatly increases and the infection is spread throughout the body of the larval host. Sporulation is initiated with the physical separation of the 2 members of the diplokaryon and the simulatneous secretion of a pansporoblastic membrane. Subsequent meiotic division and morphogenesis result in the formation of 8 haploid spores enclosed with a pansporoblastic membrane. Buildup of spores and subsequent destruction of host adipose tissue prove fatal to the male host during the 4th larval stage.     

Influence of growth environment on tolerance to UV-B radiation, germination speed, and morphology of Metarhizium anisopliae var. acridum conidia

We previously reported wide variability in UV-B tolerance among different Metarhizium anisopliae isolates [Braga, G.U.L., Flint, S.D., Miller, C.D., Anderson, A.J., Roberts, D.W., 2001a. Variability in response to UV-B among species and strains of Metarhizium isolated from sites at latitudes from 61 degrees N to 54 degrees S. J. Invertebr. Pathol. 78, 98-108] as well as wide phenotypic variability in some of these isolates in response to alterations in their growth environments [Rangel, D.E.N., Braga, G.U.L., Flint, S.D., Anderson, A.J., Roberts, D.W., 2004. Variations in UV-B tolerance and germination speed of M. anisopliae conidia produced on artificial and natural substrates. J. Invertebr. Pathol. 87, 77-83]. Studies on other biological systems have demonstrated that strong selective pressure for tolerance to a stress factor may reduce the phenotypic variability of this trait. In the present study, conidia of the isolate most tolerant to radiation and heat, ARSEF 324, presented very little phenotypic variability in UV-B tolerance in response to production on either artificial culture medium or infected insects. The phenotypic plasticities in two other traits (conidial morphology and germination speed), however, were considerably higher.     

影响库蚊幼虫摄食鱼腥藻的因素

在实验室条件下,致乏库蚊幼虫可大量摄食鱼腥藻,并能消化利用,完成生活史。鱼腥藻在蚊幼虫肠道中滞留时间约6h,酵母约5h,鱼腥藻比酵母稍难消化。对比幼虫孵化至化蛹周期,饲喂鱼腥藻为194h,而饲喂酵母则为142h,饲喂鱼腥藻比饲喂酵母延缓了蚊幼虫期52h。致乏库蚊幼虫摄食鱼腥藻的适宜条件为:pH7-8,温度25-30℃,藻液浓度愈高,摄食越多。随着蚊幼虫的生长,摄食量递增。     

Isolation and Characterization of a Spore Germination Inhibitor from Streptomyces sp. CB-1-1, a Phytopathogen Causing Root Tumor of Melon

The germination rate and activation conditions of spores were examined for four strains of Streptomyces sp., a phytopathogen causing root tumor of melon. An inhibitor was isolated from the agar-cultured material of strain CB-1-1 and then characterized. The inhibitor selectively acted on spore germination and did not affect hyphal growth, and inhibition was abolished by washing the spores in water. The inhibitor was produced by an agar culture, and most of the inhibitor existed in the spores. The IC₅₀ value for the inhibitor was approximately 0.25 μg/ml.