The spiders of a citrus grove in israel and their role as biocontrol agents ofCeroplastes floridensis [Homoptera: Coccidae]

A 12 month survey was carried out of the spider population in a commercial citrus grove at Kibbutz Afeq in Northern Israel. The spiders collected from grapefruit foliage and ground cover were identified; young stages were reared to maturity and then identified.Chiracanthium mildei L. Koch represented 52% of all spiders captured during the year andTheridion sp. accounted for 34%. In the undercover,Gnaphosidae spiders represented 43% of the total spiders captured in pitfall traps andLycosidae 35%. A field experiment was carried out to evaluate the effectivness of spiders in biological control of the scaleCeroplastes floridensis Mask. in the citrus ecosystem. Wherever spiders were undisturbed on tree branches, populations ofC. floridensis were not able to develop to a level sufficient to cause economic damage. The increase in the number of scales was minimal: from 47 initially to 56. There was no damage to leaves nor was honeydew or sooty mold observed. During the same time period, on the 3 branches from which spiders had been eliminated, the number of scales increased seven-fold from 44 to 309. Leaves were heavily infested with sooty mold fungi that developed on the honeydew produced by the scales. Contribution from the Agricultural Research Organization, Neve Ya'ar, Regional Experiment Station. P.O. Haifa 31999, Israel. No. 1314-E 1984, series.     

Comparative study of methods for the quantification of fungal spores at the leaf surfaces ofPopulus xeuramericana

Summary The removal of fungal spores, urediniospores ofMelampsora medusae and conidia ofPestalozzia sp., from the leaf surfaces ofPopulus xeuramericana (Dode) Guinier cv. I-488 was assessed using three cultural techniques conventionally employed in phylloplane studies. The method of removal and the original density of spore deposition, but not the interaction of these factors, were significant determinants of variability in spore removal. Irrespective of the original density of deposition, the leaf print method was the most, and the leaf washing technique the least, efficient means of spore removal from the leaf surface. Factors which could contribute to this difference in efficiency are discussed.     

A versatile bacterial enzyme: l-methionine γ-lyase

The properties and application of l-methionine γ-lyase [methioninase, l-methionine methanethiol-lyase (deaminating), EC 4.4.1.11], a pyridoxal 5′-phosphate enzyme, purified from Pseudomonas putida and Aeromonas sp. are presented. The enzyme has multicatalytic functions: it catalyses α,γ-elimination and γ-replacement reactions of l-methionine and its analogues (e.g. ethionine, homocysteine, O-acetylhomoserine and selenomethionine), α,β-elimination and β-replacement reactions of l-cysteine and its analogues (e.g. S-methylcysteine, O-acetylserine and Se-methylselenocysteine), deamination and γ-addition of vinylglycine, and deuterium labelling at the α and β positions of l-methionine and other straight-chain l-amino acids. These reactions are applicable to the synthesis of various optically active sulphur and selenium amino acids, preparation of deuterium or tritium labelled l-amino acids, and determination of sulphur amino acids. In addition, the enzyme shows potent anti-neoplastic activity.     

Revision ofVerbesina sect.Pseudomontanoa (Asteraceae)

Verbesina sect.Pseudomontanoa is revised. The last treatment of the group byRobinson & Greenman (1899) recognized 5 species; the present treatment recognizes 12 species, 3 of which (V. breedlovei, V. cronquistii andV. olsenii) are described as new. A key to species, phyletic diagram and distribution maps are provided.     

球针壳属一新种和一新组合

本文报道了球针壳属(Phyllactinia)的一个新种和一个新组合,即寄生于杜鹃花科(Ericaceae)吊钟花属(ENkianthus)灯笼花(E.chinensis Franch)上的灯笼花球针壳(Phyllactiniaenkianthi z.y. zhao sp. nov.)和寄生于茶藨子科(Grossulariaceae)茶藨子(Ribes sp.)上的茶藨子球针壳(Phyllactinia ribesii(Jacz.)z. y. zhao comb. nov.)。上述新分类单位均有汉文和拉丁文描述,新分类单位与近似种有汉文讨论。     

霜霉属一新种

本文报道寄生在卷茎蓼Polygonum convolvulus L.植物上的一种霉霜,命名为中国霜霉Peronospora sinensis Tang,并作了描述和比较。     

柄锈属二新种

本文描述了柄锈属的二个新种,一种是寄生在金线草(Antenoron filiforme(Thunb.)Roberty et Vautier](蓼科)上的金线草柄锈(Puccinia antenori J.Y.Zhuang et Wang sp.nov.),模式标本采自福建省浦城;另一种是寄生在花锚(Halenia sp.)(龙胆科)上的波壁柄锈(Puccinia undulitunicata J.Y.Zhuang et Wang sp.nov.),模式标本采自四川省炉霍与甘孜之间的锣锅梁子。金线草柄锈的夏孢子堆均匀密布于叶背面,褐色粉末状;夏孢子亚球形、倒卵形或椭圆形,18—35×17—23μm,壁厚1—2μm,淡黄褐色,有刺,芽孔2个,生在腰部附近。冬孢子堆颜色较深;冬孢子棍棒形或椭圆形,隔膜处不缢缩或稍缢缩,25—45×13—23μm, 顶壁厚3.5—5μm,肉桂褐色,光滑;上部细胞芽孔顶生,下部细胞芽孔生于隔膜附近。本种近似韦氏蓼柄锈(Puccinia polygoni-weyrichii T.Miyake),但其夏孢子壁厚度均匀,冬孢子顶壁增厚,而后者夏孢子顶壁增厚(5—7μm),冬孢子壁厚度均匀(2—2.5μm)。波壁柄锈的冬孢子堆在叶两面散生,黑褐色或黑色粉末状。夏孢子在冬孢子堆中混杂,近球形或宽椭圆形,22—25×18—23μm,壁厚2—2.5μm,密生小刺,暗褐色,有3—5个散生的芽孔。冬孢子椭圆形或倒卵形,隔膜处不缢缩,25—40×20—25μm,壁波状起伏,厚度不均匀(1.5—2.5μm),栗褐色;上部细胞芽孔顶生,下部细胞芽孔近基生或基生。本种由于冬孢子壁呈波状起伏而不同于龙胆科植物上的其他已知的柄锈。     

双孢蘑菇上的丝枝霉新种

1980—1981年先后自北京、昆明、福州等地双孢蘑菇[Agaricus bisporus (Lange)Sing.]上分离到一种真菌,在PDA上的培养性状与蘑菇轮枝菌(Vertieillium psalliotae Tresch．)和蛛网丝枝霉中国变种[Aphanocladium aranearum(Petch) Gams var sincase J．D．Chen]近 似。镜检可见其兼具上述两种菌的形态。经反复多次纯化,并挑取单孢子培养,肯定了这种真菌是纯菌。在培养基上已保存4年,形态稳定。它具典型蘑菇轮枝菌形态,而其丝枝霉型瓶梗的形成和瘪缩时间、长度、原瓶梗数量、末端瓶梗数及排列密度等,都与蛛网丝枝霉中国变种有一定差异,与丝枝霉属其它种亦不同,故定为两型丝枝霉新种(Aphanocladium dimorphum sp-nov.)。本文详细描述了该新种的形态,井对文甲所提的五种真菌及其与Engyodontium属间的关系进行了讨论。     

The effect of bacterial strain and temperature changes on the nitrogenase activity of Lotus pedunculatus root nodules

After 40 days of growth at 25°C, Lotus pedunculatus cav., cv. Maku plants infected with Rhizobium loti strain NZP2037 displayed similar relative growth rates but had twice the nodule mass and only one third the whole plant dry weight of plants infected with Bradyrhizobium sp. (Lotus) strain CC814s. In the NZP2037 symbiosis, the rate of CO₂ evolution (per g dry weight of nodulated root) was 1.6 times as high as that in the CC814s symbiosis while the rate of C₂H₂ reduction (per g dry weight of nodule) was only 48% of that in the CC814s symbiosis. Studies of the effect of short term temperature changes on the gas exchange characteristics (CO₂ and H₂ evolution, C₂H₂ reduction) of these symbioses revealed wide differences in the optima for C₂H₂ reduction. Nodules infected with NZP2037 displayed maximal C₂H₂ reduction rates [157 μmol (g dry weight nodule)^?1 h^?1] at 12°C, whereas nodules infected with CC814s were optimal at 30°C [208 μmol (g dry weight nodule)^?1 h^?1]. These short term studies suggested that differences in temperature optima for N₂ may have partially accounted for the poorer effectivity, at 25°C, of strain NZP2037 when compared with strain CC-814s. The relative efficiency [RE = 1 – (H₂ evolution/C₂H₂ reduction)] of N₂ fixation varied widely with temperature in the two symbioses, but there was a general trend toward higher RE with lower temperatures. The ratio of CO₂ evolution: C₂H₂ reduction (mol/mol) in nodulated roots infected with CC814s was constant (ca 10 CO₂/C₂H₂) between 5°C and 30°C, whereas in plants infected with NZP2037 it reached a minimal value of 3.3 CO₂/C₂H₂ at 10°C and was 19 CO₂/C₂H₂ at the growing temperature (25°C).