0.05%氟虫腈杀蚁饵剂对红火蚁的传毒活性测定

应用联杯法等室内测定了0.05%氟虫腈杀蚁饵剂对红火蚁的引诱力、毒杀速度及其传导毒杀活性.结果表明,供试饵剂对红火蚁的引诱性、毒杀速度显著优于正舒(对照药剂).红火蚁觅食到供试饵剂的初始时间为2.00 min,与正舒的2.33 min达显著差异;供试饵剂处理后24 h的工蚁死亡率为80.65%,显著高于对照饵剂的50.15%;72 h的工蚁死亡率即达到100%.联杯法测定结果表明,0.05%氟虫腈杀蚁饵剂能通过工蚁的取食和交哺行为进行传导.供试饵剂受药杯中工蚁、幼蚁和蚁后3 d后死亡率均达到100%,显著高于对照饵剂.0.05%氟虫腈杀蚁饵剂引诱性强、对红火蚁具有高胃毒、高传导毒杀活性,可适用于防控入侵红火蚁.     

西双版纳地区两种榕树上黄猄蚁生活习性调查

黄猄蚁Oecophylla smaragdina,织叶蚁属,是热带亚洲地区很常见的一种捕食性蚂蚁。在西双版纳地区黄猄蚁常见在多种榕树上筑巢繁衍和生活。研究榕树上生活黄猄蚁的生活习性对于了解黄猄蚁与榕蜂互惠系统间的相互影响具有重要意义。本文选取西双版纳最常见的垂叶榕和高榕两种榕树和树上筑巢的黄猄蚁作为研究材料。观察研究黄猄蚁在一年内三个季节的活动情况;黄猄蚁在榕树上的筑巢位置;黄猄蚁对食物和光的选择;黄猄蚁对榕小蜂的捕食。结果发现:(1)黄猄蚁的活动在三个季节间有明显差异,其活动强度、活动时间依次为雨季干热季雾凉季;(2)黄猄蚁在不同的榕树会选择不同的位置筑巢,在垂叶榕上,它们主要在树顶部筑巢,而在高山榕上则在杈下垂的小枝条上筑巢;(3)黄猄蚁食性的研究中我们进一步证实了黄猄蚁为肉食性蚂蚁。在黄猄蚁的光反应实验中我们发现黄猄蚁偏好光亮处,而且在光亮处的黄猄蚁活动强度明显大于黑暗处;(4)榕小蜂是榕树上黄猄蚁重要的食物来源,而且黄猄蚁捕食榕小蜂的种类是与榕树的发育时期密切相关,在花前期和间花期黄猄蚁以捕食非传粉榕小蜂为主,而在雌花期和雄花期会捕食传粉榕小蜂,所以榕树上栖息的黄猄蚁在花前期和间花期对榕树-榕小蜂互利共生有利,而雌花期和雄花期由于取食传粉榕小蜂,则对榕蜂互利共生产生负面影响。     

不同营养源对伞裙追寄蝇的寿命及生活力的影响

本文研究了取食不同浓度的蜂蜜、果糖、葡萄糖、蔗糖和清水对照对伞裙追寄蝇寿命、日均存活率、产卵量、产卵期、逐日产卵量,以及子代发育历期、寿命、寄生率、羽化量、雌蝇率等指标的影响。结果表明,10%的蜂蜜水处理的伞裙追寄蝇,雌蝇平均寿命为33.13 d,雄蝇平均寿命为21.71 d,与清水对照存在显著性差异。喂食10%蜂蜜水的雌蝇存活天数最长为51 d。补充10%蜂蜜水的伞裙追寄蝇产卵量和日均产卵量与其他处理差异显著（P<0.05）,分别为70.20和13.77粒/d。10%蜂蜜水喂食的成虫其子代羽化出的雌蝇平均寿命最长,为35.41 d。不同营养源对伞裙追寄蝇子代蛹重、寄生率、雌蝇率的影响差异不显著。     

α -三联噻吩对红火蚁Solenopsis invicta觅食行为和触角功能的影响

通过研究光活化杀虫活性成分 α -三联噻吩( α -T)对红火蚁 Solenopsis invicta Buren工蚁觅食行为和触角识别功能的影响,探讨了光活化成分用于控制红火蚁的可行性。用Potter喷雾法将100 μg/mL的 α -T丙酮水溶液喷施于红火蚁中型工蚁体表,再经紫外(UVA)光照射30 min,在处理后5、10、15、20和30 min时,试蚁对火腿肠的识别率分别为20.00%、25.00%、38.33%、40.00% 和41.67%,对杀虫剂饵料的识别率分别为3.33%、0、0、3.33%和0,聚集率分别为17.50%、38.33%、 32.50%、45.00%和48.33%;经100 μg/mL的 α -T涂抹试蚁触角再经紫外光照处理30 min后,触角对丙酮反应的电位值为-0.177 mV,可正常行走的工蚁比率为75.00%;以100 μg/mL的 α -T涂抹试蚁触角并经紫外光照射30 min后10 h,红火蚁的死亡率为27.50%;上述结果均与 α -T黑暗处理、对照(CK)光照处理和CK黑暗处理结果差异显著。 α -T对红火蚁工蚁食物识别和探路行走能力均具有良好的光活化抑制作用,以其防治红火蚁具有良好可行性。     

黄翅大白蚁地面裸露采食习性的观察

本文报道了黄翅大白蚁地面裸露采食的习性,采食对象依巢群所在环境条件而不同,在板栗园环境中,主要采食板栗的枯落叶、枯枝、带刺总苞、枯草茎、鲜活苔藓及地面上的昆虫茧壳。采食时明确分工,强壮的大工蚁负责啃咬工作,部分大工蚁及小工蚁负责运送食物;小兵蚁在采食点及运送食物的蚁路上负责保卫,大兵蚁则偶尔出现。工蚁啃咬食物一次所需时间因食物的种类、厚度、腐烂程度的不同有长有短。来食枯叶平均在11．08～23．18s／次,枯枝枯草茎平均为29．28～30．285／次,带刺总苞则需325．6s／次。     

三种杀虫剂亚致死剂量对黄胸散白蚁工蚁体内纤维素酶活性的影响

采用工蚁与浸药滤纸接触或取食含药松木粉的方法,测定了啶虫脒、氰戊菊酯和硼酸,在亚致死剂量下对黄胸散白蚁Reticulitermes flaviceps工蚁体内内切-β-1,4-葡聚糖酶(EG)和β-葡糖苷酶(BG)活性的影响。结果表明,用0.5、1.0和2.0 mg/L的啶虫脒处理黄胸散白蚁工蚁6~48 h,对其体内的EG和BG酶活性(处理48 h的除外)无显著影响;用0.5、1.0和2.0 mg/L的氰戊菊酯处理,可显著降低黄胸散白蚁工蚁体内的EG和BG酶活性;硼酸对黄胸散白蚁工蚁体内EG和BG酶活性的影响与处理浓度和处理时间有关。     

补充营养对二点委夜蛾成虫生殖与寿命的影响

为明确补充营养对二点委夜蛾Athetis lepigone(Mschler)的影响,通过室内试验研究了5%蜂蜜水、5%葡萄糖水及蒸馏水3种补充营养处理对其成虫生殖与寿命的影响。结果表明,补充营养对二点委夜蛾成虫生殖和寿命均有显著影响。经5%蜂蜜水处理的雌蛾产卵历期最长,为7.17d,平均单雌产卵量最高,为248.23粒;经5%葡萄糖水处理的雌蛾产卵历期、平均单雌产卵量与5%蜂蜜水处理均无显著差异;经蒸馏水处理的雌蛾产卵历期最短,为5.53 d,平均单雌产卵量最低,为162.13粒,显著低于5%蜂蜜水;3种补充营养处理间雌蛾产卵前期、交配率、交配次数和卵孵化率均无显著差异;经蒸馏水处理的雄蛾寿命显著低于其它处理。研究表明,补充营养主要对二点委夜蛾成虫的产卵历期、产卵量和雄蛾寿命有影响,是影响其种群动态的重要因素。     

外源营养补充对圆柏大痣小蜂成虫寿命的影响

为探究外源营养对圆柏大痣小蜂Megastigmus sabinae Xu et He成虫寿命的影响,本研究通过给当日羽化的同批次圆柏大痣小蜂成虫饲喂清水、蔗糖水及蜂蜜水,研究不同外源营养饲喂对雌、雄成虫寿命的影响。研究表明：3种喂养条件下雄蜂寿命均短于雌蜂,其中清水饲喂雌、雄蜂寿命差异显著;取食蔗糖水和蜂蜜水的圆柏大痣小蜂雌蜂寿命分别为18 d和14 d,两者均与饲喂清水对照之间存在显著差异;雌、雄蜂单独饲喂与雌、雄蜂混合饲喂存活数变化趋势基本一致。本研究为圆柏大痣小蜂生物防治研究提供虫源保障,同时也为研究圆柏大痣小蜂的生物学特点和行为提供支持。     

黄埔口岸从非洲原木上截获两种白蚁

20 0 2年 9月 ,黄埔局从一批来自莫桑比克的原木上截获到大量的白蚁 ,由于只截获到补充型生殖蚁和伪工蚁 ,无兵蚁 ,经广东昆虫研究所平正明研究员协助鉴定为 :白蚁科(Termitidae)锯白蚁属 (Microcerotermes)和木白蚁科 (Kalotermitidae)新白蚁属 (Neoter mes)。鉴于此两种白蚁危害性和检疫重要性 ,现将鉴定的有关资料整理如下 ,以供参考。锯白蚁 ,前胸背板马鞍状为白蚁科 ,解剖工蚁上颚缘齿为锯白蚁型。锯白蚁属 3只工蚁标本量度 (mm)如下。表 1　锯白蚁属工蚁标本测量值工蚁 1工蚁 2工蚁 3头宽 0 82 0 930 82前胸背板宽 0 4 6 0 5 1…     

短稳杆菌对斑痣悬茧蜂成虫羽化、生殖和寿命的影响

室内测定了短稳杆菌对斑痣悬茧蜂蛹和成虫的直接毒性,以评价其对寄生蜂的直接影响。分别用短稳杆菌低浓度(1.25×107 cfu/mL)和高浓度(5.00×107 cfu/mL)菌液浸渍1和3日龄蜂茧(用清水处理作为对照),结果表明,菌液浓度和茧龄对成蜂羽化率、羽化蜂生殖力、成蜂寿命均无显著互作影响;蜂茧日龄对成虫生殖力和寿命无显著影响,但短稳杆菌浓度显著影响羽化后成蜂的生殖力和寿命,高浓度菌液处理下产卵量和寿命显著小于清水对照和低浓度菌液处理,但在清水与低浓度菌液处理之间无显著差异。为揭示短稳杆菌在寄生蜂补充营养过程中对其造成的直接影响,先将短稳杆菌用糖水配成不同浓度糖液饲喂成蜂,发现含有推荐施用浓度及其以上的短稳杆菌糖液对寄生蜂存活有较强的不良影响,受药后48 h出现死亡,96 h后死亡率超过50%;随后测定了含有较低浓度短稳杆菌(1.25×107和3.13×106 cfu/mL)的糖液及其吸食频次(4水平)对成虫寿命的影响,结果表明,短稳杆菌浓度和寄生蜂吸食频率互作显著影响成虫的寿命,在高浓度菌液处理下,取食频率对成虫寿命没有显著影响;但在低浓度菌液和对照处理下,成虫寿命随取食频率增加而延长。研究结果说明,短稳杆菌对斑痣悬茧蜂成蜂具有一定的毒性,但以略低于大田推荐浓度进行施用时,对斑痣悬茧蜂的不良影响较小。     

Dermestid beetles in ‘evolution Canyon’, lower Nahal Oren, Mt. Carmel, including new records for Israel

Fifteen species of dermestid beetles were recorded at ‘Evolution Canyon’ (EC), Lower Nahal Oren, Mt. Carmel, Israel. They represent ~35% of known Israeli dermestid species. The following three species were recorded for the first time in Israel:Trogoderma svriaca Dalla Torre, 1911;Ctesias svriaca Ganglbauer, 1904; andAnthrenus (s.str.) jordaniens Pic, 1934. Adults of 13 species were collected on the more solar radiated, warmer and climatically more fluctuating south-facing slope (SFS); ten species were collected on the opposite, north-facing slope (NFS), which was cooler and climatically more stable. The abundance of adult dermestid beetles was 1.9 times higher on the SFS than on the NFS (86 and 47, respectively). Species richness and abundance distribution at EC (three collecting stations on each slope and one at the valley bottom) were significantly negatively correlated with the plant cover that consisted of trees and bushes (Spearmanr _s ,P=0.007 and 0.039, respectively) and perennials (Spearmanr _s ,P=0.039 and 0.077, respectively), indicating that non-woody plants were preferred by adult dermestid beetles.     

Epidemiology of Toxigenic Fungi and their Associated Mycotoxins for Some Mediterranean Crops

Recent data on the epidemiology of the common mycotoxigenic species of Fusarium, Alternaria, Aspergillus and Penicillium in infected or colonized plants, and in stored or processed plant products from the Mediterranean area are reviewed. Emphasis is placed on the toxigenicity of the causal fungal species and the natural occurrence of well known mycotoxins (aflatoxins, ochratoxins, fumonisins, trichothecenes, zearalenone, patulin, Alternaria-toxins and moniliformin), as well as some more recently described compounds (fusaproliferin, beauvericin) whose toxigenic potential is not yet well understood. Several Fusarium species reported from throughout the Mediterranean area are responsible of the formation of mycotoxins in infected plants and in plant products, including: Fusarium graminearum, F. culmorum, F. cerealis, F. avenaceum, F. sporotrichioides and F. poae, which produce deoxynivalenol, nivalenol, fusarenone, zearalenone, moniliformin, and T-2 toxin derivatives in wheat and other small grains affected by head blight or scab, and in maize affected by red ear rot. Moreover, strains of F. verticillioides, F. proliferatum, and F. subglutinans, that form fumonisins, beauvericin, fusaproliferin, and moniliformin, are commonly associated with maize affected by ear rot. Fumonisins, were also associated with Fusarium crown and root rot of asparagus and Fusarium endosepsis of figs, caused primarily by F. proliferatum. Toxigenic A. alternata strains and associated tenuazonic acid and alternariols were commonly found in black mould of tomato, black rot of olive and citrus, black point of small cereals, and black mould of several vegetables. Toxigenic strains of A. carbonarius and ochratoxin A were often found associated with black rot of grapes, whereas toxigenic strains of A. flavus and/or P. verrucosum, forming aflatoxins and ochratoxin A, respectively, were found in moulded plant products from small cereals, peanuts, figs, pea, oilseed rape, sunflower seeds, sesame seeds, pistachios, and almonds. Finally, toxigenic strains of P. expansum and patulin were frequently found in apple, pear and other fresh fruits affected by blue mould rot, as well as in derived juices and jams.     

A survey of the genera of<Emphasis Type="Italic">Microgaster</Emphasis> latreille and<Emphasis Type="Italic">Hygroplitis</Emphasis> thomson (Hymenoptera: Braconidae: Microgastrinae) from China

The genera ofMicrogaster Latreille 1804 andHygroplitis Thomson 1895 from China are presented systematically in this paper. Thirty-two species ofMicrogaster and three species ofHygroplitis are known in China. Diagnosis, character variation, distribution and host of each species among the two genera are presented, including its host and distribution. Keys to the species ofMicrogaster andHygroplitis are given. http://www.phytoparasitica.org posting Dec. 19, 2006.     

Plant Viruses Transmitted by Whiteflies

One-hundred and fourteen virus species are transmitted by whiteflies (family Aleyrodidae). Bemisia tabaci transmits 111 of these species while Trialeurodes vaporariorum and T. abutilonia transmit three species each. B. tabaci and T. vaporariorum are present in the European–Mediterranean region, though the former is restricted in its distribution. Of the whitefly-transmitted virus species, 90% belong to the Begomovirus genus, 6% to the Crinivirus genus and the remaining 4% are in the Closterovirus, Ipomovirus or Carlavirus genera. Other named, whitefly-transmitted viruses that have not yet been ranked as species are also documented. The names, abbreviations and synonyms of the whitefly-transmitted viruses are presented in tabulated form together with details of their whitefly vectors, natural hosts and distribution. Entries are also annotated with references. Whitefly-transmitted viruses affecting plants in the European–Mediterranean region have been highlighted in the text.     

Broad bean mottle virus in Morocco; curculionid vectors,and natural occurrence in food legumes other than faba bean (Vicia faba)

Broad bean mottle virus (BBMV) was transmitted from infected to healthy faba-bean plants by the curculionid weevilsApion radiolus Kirby,Hypera variabilis Herbst,Pachytychius strumarius Gyll,Smicronyx cyaneus Gyll, andSitona lineatus L. The latter appeared to be an efficient vector: acquisition and inoculation occurred at the first bite, the rate of transmission was c. 41%, and virus retention lasted for at least seven days.S. lineatus transmitted the virus from faba bean to lentil and pea, but not to the three genotypes of chickpea tested. This is the first report on the generaHypera, Pachytychius, andSmicronyx as virus vectors, and onA. radiolus, H. variabilis, P. strumarius, andS. cyaneus as vectors of BBMV.Out of 351 samples of food legumes with symptoms suggestive of virus infection, 16, 11, 19, and 17% of the samples of chickpea, lentil, pea, and common bean, respectively, were found infected when tested for BBMV in DAS-ELISA. This is the first report on the natural occurrence of BBMV in chickpea, lentil, pea, and common bean. The virus should be regarded as a food-legume virus rather than a faba-bean virus solely, and is considered an actual threat to food legume improvement programmes.     

Characterization of potato potyvirus Y (PVY) isolates from seed potato batches. Situation of the NTN, Wilga and Z isolates

A collection of 38 PVY isolates from seed potato batches, originating from several Western European countries, was characterized by using current biological, serological and molecular tools differentiating PVY strains and groups. The correlation between the three kinds of tests was good but not absolute. No single serological or PCR method was able to discriminate among the five isolate groups found. Twenty-nine isolates belonged to the PVY^N strain and six to the PVY^O strain. No PVY^C was found. Two other isolates reacted serologically like PVY^O, but were unable to elicit a hypersensitive response from the Ny_tbr gene and probably represent the PVY^Z group. At the molecular level, these two isolates showed a combination of both PVY^O and PVY^N and could be recombinants of these strains. Another isolate reacted serologically like PVY^O, but induced vein necrosis in tobacco, like PVY^N-Wilga. Some PVY^N isolates caused tuber ring necrosis in glasshouse conditions. These might belong to the PVY^NTN group. The PVY^NTN, PVY^N-Wilga and PVY^Z groups probably represent pathotypes within strains PVY^N and PVY^O, respectively. The present study also confirms previous reports showing a high genetic variation at the 5 end within the PVYN strain.     

The autumn leafroller: Phenology,damage and parasitoids in a Dutch apple orchard

The phenology of the autumn leafroller,Syndemis musculana, a local pest of apple, was studied in order to forecast larval emergence. From 1983–1986, peak flight as determined with sexpheromone traps was always between 13–18 May. The duration of embryonic development was determined at various constant temperatures and used to estimate the periods of egg hatch in these four years. Each year, most eggs should have hatched in the second decade of June.Differences in attack rates between apple cultivars seem to be explained largely by the variation in picking time. Larvae are only half grown at the beginning of harvest (cv. James Grieve), and have gone into hibernation when the latest variety (cv. Golden Delicious) is picked. Moreover, the varieties Cox's Orange Pippin and Belle de Boskoop, picked about half time, are liable to receive additional damage by caterpillars brought with the picked fruits into storage.Various hymenopterous parasites were reared from caterpillars. As the only leafroller in the orchard which hibernates as mature larva,S. musculana may promote winter survival of some parasitoids, like the eulophidColpyclypeus florus.Samenvatting De fenologie van de herfstbladroller (Syndemis musculana Hübner), een incidentele plaag op appel, werd nader bepaald met het doel het uitkomen van de eieren te kunnen voorspellen. In 1983–1986 viel de piekvlucht, bepaald met behulp van feromoonvallen, steeds tussen 13 en 18 mei.De ontwikkelingsduur van de eieren bij verschillende constante temperaturen werd gebruikt om de periode van uitkomen te schatten. De meeste eieren zullen ieder jaar in de eerste helft van juni uitkomen.Geconstateerde verschillen in schade tussen appelrassen blijken goeddeels terug te voeren op verschillen in pluktijdstip. De rupsen van de herfstbladroller zijn pas half-was als de eerste appels eind augustus geplukt worden, terwijl tegen het einde van de oogst begin oktober de meeste al in winterslaap zijn. Met name tussentijdse rassen, als Cox's Orange Pippin and Schone van Boskoop, lopen extra schade op doordat grotere rupsen met de geplukte vruchten in de kist terecht komen.Uit de rupsen werden negen, al van andere boomgaardbladrollers bekende, sluipwespen gekweekt, Omdat deze bladrollersoort, als enige in de boomgaard, als volgroeide rups overwintert, lijkt zij bij uitstek geschikt als winterwaard.This study was carried out at the Experimental Orchard De Schuilenburg, Schuilenburg 3, 4041 BK Kesteren, the Netherlands, to which address correspondence should be addressed.     

Characterization of Sclerotinia minor populations in Texas peanut fields

In the summer of 2004 an epidemic of sclerotinia blight of peanut, a disease caused by Sclerotinia minor, occurred in Texas in fields where the disease was never previously detected. The disease was observed on many plants within one of the fields (>3000 disease foci), although most foci were <1 m. It is hypothesized that these observations were inconsistent with the recent introduction of a monocyclic pathogen, even if disease developed under conducive environmental conditions. The pattern of disease is most suggestive of the presence of foliar (ascospore) infections, although air temperature was above the known limits for apothecia development if the pathogen had arrived in the field in 2004 peanut seed. To further examine this epidemic, 232 isolates were collected, across a variety of spatial scales spanning this field and other Texas peanut fields, and evaluated for aggressiveness, fungicide sensitivity and genotypic diversity. There was wide variation among isolates for the phenotypic characteristics measured, but there was no evidence that a genotypically unique, highly aggressive, and fungicide resistant isolate had been introduced or evolved. The predominant genotype, TX1, which contained 154 isolates, was found in every county and field population.     

Eyespot of Cereals Revisited: ITS phylogeny Reveals New Species Relationships

Four species so far classified in Pseudocercosporella or Ramulispora (hyphomycetes) are associated with eyespot disease symptoms of cereals. Two of these have been linked to teleomorphs that were described in Tapesia. Sequence data derived from the Internal Transcribed Spacer region (ITS1, 5.8S and ITS2) of the rDNA operon showed, however, that the eyespot fungi associated with Tapesia are not congeneric with Ramulispora sorghi, the type of Ramulispora. The genus name Tapesia is now rejected in favour of the conserved name Mollisia, which appears to comprise heterogeneous fungi. Tapesia yallundae is not closely related to the type of Mollisia, M. cinerea, but clusters separately, being more closely allied to species with Cadophora anamorphs. A new holomorph genus, Oculimacula, is therefore proposed for teleomorphs of the eyespot fungi, while the anamorphs are accommodated in Helgardia gen. nov.     

Tumours of Begonia and some other ornamentals,induced by Corynebacterium fascians

In 1975 many tumours were observed in plants ofBegonia Schwabenland grown in Aalsmeer. Submersion of the roots ofNicotiana megalosiphon seedlings in a homogenate of tumorous tissue, induced tumours after two weeks. Short periods of submergence yielded results similar to those obtained after longer periods. Tumour homogenates lost their infectivity after ten min at 50°C. Aphids transmitted the infectious agent.Treatment with propylene oxide did not inhibit infectivity completely. Filtration through a 450 nm filter removed the infectious agent.Tobacco tumor virus or a viroid could not be isolated. Cultures ofCorynebacterium fascians, isolated from tumours ofN. megalosiphon were highly infectious and induced tumours in healthyN. megalosiphon andBegonia. Tumorous tissue homogenates ofPelargonium zonale, Dahlia sp.,Gladiolus sp., andLilium sp. also caused tumours inN. megalosiphon, from whichC. fascians was isolated. It was not possible to produce tumours inN. megalosiphon with homogenates from roses with symptoms of bud proliferation.Samenvatting In 1975 werden vele tumoren waargenomen inBegonia Schwabenland op Aalsmeerse bedrijven (Fig. 1). De infectiositeit van tumorweefsel kon goed en snel worden vastgesteld door de wortels van zaailingen vanNicotiana megalosiphon in een homogenaat van tumorweefsel te dompelen. Tumoren ontstonden na twee weken, de eindbeoordeling geschiedde na een maand (Fig. 2). Ook verschillende andereNicotiana spp.,Melilotus officinalis (Fig. 3) enPisum odoratum (Fig. 4) werden aangetast.Bij de infectiositeitstoets gaven zeer korte dompeltijden even goede resultaten als langere (Tabel 1). Infectieus sap verloor zijn infectievermogen na 10 min verhitting bij 50°C. Bladluizen brachten de smetstof over. Propyleenoxide verminderde de infectiositeit wel, doch onderdrukte deze niet totaal. Bij filtratie door een 450 nm filter bleef het infectieuse agens op het filter achter. Het tumor-inducerende agens was ook aanwezig in die delen van planten met tumoren welke gezond leken en het ging voor een gering deel over met zaad (Tabel 2).Uit tumoren konden wij geen tabakstumorvirus of een viroïde isoleren. Culturen vanCorynebacterium fascians, geïsoleerd uit tumoren vanN. megalosiphon bleken zeer infectieus en veroorzaakten tumoren inN. megalosiphon enBegonia. Homogenaten van tumorweefsel vanPelargonium zonale, dahlia (Fig. 5), gladiool (Fig. 6) enLilium Mid Century Hybrid Enchantment (Fig. 7) veroorzaakten ook tumoren opN. megalosiphon, waaruitC. fascians werd geïsoleerd. Met sap van kroeskopzieke rozen konden wijN. megalosiphon niet besmetten.