灿小峰生物学特性的初步研究

乌盟后山地区榆树小蠹虫为害十分严重,被害植株2年左右即可死亡。灿小蜂是榆小蠹虫寄生性天敌之一,对控制榆小蠹虫的危害起着重要作用,在我旗乌兰花、大青河和江岸地区调查寄生率分别为27％、17.9％和43％。灿小蜂(Chiropachys Colon L.)属膜翅目,小蜂总科,金小蜂科灿小蜂亚科。是榆小蠹幼虫体外寄生蜂,被其寄生的榆小蠹幼虫停止发育而死。在我旗一年6代,以幼虫越冬,春季气温达11℃时开始活动,秋季9月末进入越冬。室内饲养每头成虫可寄生25头寄主。除了产卵寄生外,还可刺死部分寄主幼虫,江岸地区总致死率达52％。成虫完成一世代历期为17—22天。有效积温为247日度,温度23 1.5℃,湿度60—70％时有利于成虫交尾产卵活动。而且对寄主幼虫体长有一定选择性,一般产卵于2.5～4.2mm的幼虫上。对不同种榆小蠹虫的寄生率没有明显差异。     

榆跳象生活习性及其防治技术

榆跳象(Phynchaenus alni L.)又名榆潜叶象甲,为害榆树叶片。近年来在我区乌盟后山地区发生比较严重。据四子王旗江岸苗圃调查,虫口密度达45头/枝(枝长25厘米)。使全株树叶发黄,枝梢部于枯,影响生长,消弱树势,可导致榆树小蠹虫等蛀干害虫的发生。在江岸苗圃和红旗林场的榆树林中,每年大约有80％的叶片全部变枯,小蠹虫、吉丁等蛀干害虫的发生面积逐年扩大。现将几年来对此虫生活习性及防治方法的观察试验结果整理如下。     

抗性榆树的选育

本世纪初,荷兰榆病和板栗萎凋病传到美国,造成了无数美国榆和美国板栗的死亡。数十年来,树木学家、病理学家、遗传学家通过多种途径,已经探索到致命的病原。不过对美国板栗来说,问题的解决还是可望而不可及,板栗萎凋病的防治仍在探索中(见本刊1982年第1期《美国板栗萎凋病之谜》)。关于榆树的情况就好得多了。新培育的抗性榆树,完全有希望象过去那样,可以生存几百年。     

榆树干枯病初探

:榆树是华北地区的主要造林树种 ,榆树干枯病能引起榆树枝干干枯死亡 ,是榆树的重要病害 ,为了探明该病的病原菌 ,于 1 997～ 2 0 0 0年对榆树干枯病的病原进行了反复的分离培养与接种试验 ,找到了该病的致病菌     

溴甲烷熏蒸榆树原木防治欧洲榆小蠹

欧洲榆小蠹[Scolytus multistriatus(Marsham)]是国际检疫对象——榆荷兰病的主要传病介体,其本身也对榆树造成危害。在美国,防治榆荷兰病的方法多为卫生伐,即及早将病株砍下用土掩埋。为     

乌海市榆树蛀干害虫的发生与防治

乌海市位于乌兰布和沙漠的东南缘,生态条件较差。长期以来,这里受大陆性气候的影响,终年干旱,多风沙,年降水量只有160毫米;天然植被稀少,以灌木和小乔木为主。榆树是该地区的乡土树种,具有耐旱、耐风沙、耐土壤瘠薄等特点,深受欢迎,广泛栽植。但是近几年榆树受蛀干害虫危害日趋严重,使其生存受到很大的威胁,对于脆弱的乌海生态产生了很大的影响。现就榆树蛀干害虫的发生与防治问题谈几点意见。一、乌海市榆树蛀干害虫的种类、分布与发生情况乌海市榆树现阶段蛀干害虫主要有四种:光肩星天牛、黄斑星天牛、蒙古木蠹蛾、榆小蠹虫。     

我国榆树害虫发生及研究现状

我国榆树害虫种类繁多,已报道并经确认的有35科200种以上,未经鉴定还有数十种。危害榆树的害虫有3大类:钻蛀类害虫有小蠹、天牛和木蠹蛾等;食叶类害虫有榆绿叶甲、榆黄足毒蛾和榆长翅卷蛾等;刺吸类害虫有红足壮异蝽、榆四脉绵蚜等。部分害虫危害较重,可使抗逆能力很强的榆树致死,某些榆树害虫不仅本身对榆树有较大危害,还与榆树病害发生有着密切关系,成为榆树病害传播媒介。     

五种榆树在榆阳区的生长适应性研究

为了丰富榆阳区榆树种类,给当地植树造林、改善生态环境以及城乡绿化提供更多优良榆树种类,从新疆和河南引进了裂叶榆、圆冠榆、大叶垂榆和金叶榆,与榆阳区乡土树种白榆对照进行生长适应研究,结果表明:4种引进榆树均可以成活生长,除白榆之外,裂叶榆和金叶榆能够完成生长、开花、结果及果实成熟等整个生命周期。生长量由大到小依次为裂叶榆、圆冠榆、大叶垂榆和金叶榆。新引进的4种榆树分别作为风沙治理、改善生态环境以及市内观赏景观树种可在榆阳区引种推广应用。     

小蠹虫的防治技术

<正>小蠹虫属鞘翅目小蠹科,成虫体长3毫米~4.5毫米,身体黑色,鞘翅暗黑色,有光泽。是一种在榆树及其嫁接品种上普遍发生的蛀干害虫。一、小蠹虫的发生及危害情况小蠹虫每年4月底至5月初开始暴发,因其生存繁殖能力强,危害隐蔽,遇到气温突降、干旱等气候条件极易暴发。林中衰弱木或濒死木以及风倒木、冰雪损害木及断落枝条等,均会招来小蠹虫进行繁殖,尤其是受到小蠹虫侵害的林木,更容易聚集大量同种小蠹虫前     

榆荷兰病症状、病原菌和侵染周期

一、症状榆荷兰病的症状随榆种、病原菌株、发病期的早晚、当年天气、侵染方式及寄主生长势等而不同,主要有下述两种类型: 1.树冠上层个别枝条叶片变黄并逐渐脱落,进而向周围更多的枝叶扩展,远看树冠有一明显的由稀疏的黄叶和秃枝构成的“病灶”,细看病枝条分叉处常有小蠹虫的蛀食槽。     

Dutch elm disease has currently a low incidence on wych elm in Norway

A rapid increase in the frequency of Dutch elm disease (DED), a wilting disease of elm trees caused by bark‐beetle vectored fungi, was observed in the early 1990s on several wych elm stands around Oslofjord, southern Norway. To examine the current status of the disease and its impacts on elm population, disease frequency and size distribution of elms were recorded at four locations. Northern parts of Lier, a municipality most affected by DED in Norway 15 years ago, showed in the survey season 4% disease frequency, whereas 13.8% of trees were dead, the dead trees having accumulated over several years in the unmanaged stands. In southern parts of the municipality the mean disease and death percentages were 1.9 and 2.4%. Compatible with their low disease incidence in early 1990s, the other two areas now examined, municipality of Larvik and district of Grenland, showed comparably low frequency of DED. Northern part of Lier showed significantly higher overall density of elm trees per hectare than the other examined areas, and also the small elms below 5 cm in d.b.h. were most frequent in this region. In contrast, the density of large trees was lower in northern Lier than in the other examined areas. These data suggest that regeneration of the tree is not prohibited owing to the disease but that the large trees have been locally reduced in frequency as a result of DED. The superior general density of elm trees in northern Lier, owing to the exceptionally rich soil in the warm southern slopes of the region,> may have contributed to the rapid increase of DED in the area 15 years ago and to the subsequent settlement of the disease outbreak as a chronic stage.     

Dutch elm disease pathogen transmission by the banded elm bark beetle Scolytus schevyrewi

Dutch Elm Disease (DED) is a vascular wilt disease of Ulmus species (elms) incited in North America primarily by the exotic fungus Ophiostoma novo‐ulmi. The pathogen is transmitted via root grafts and elm bark beetle vectors, including the native North American elm bark beetle, Hylurgopinus rufipes and the exotic smaller European elm bark beetle, Scolytus multistriatus. The banded elm bark beetle, Scolytus schevyrewi, is an exotic Asian bark beetle that is now apparently the dominant elm bark beetle in the Rocky Mountain region of the USA. It is not known if S. schevyrewi will have an equivalent vector competence or if management recommendations need to be updated. Thus the study objectives were to: (i) determine the type and size of wounds made by adult S. schevyrewi on branches of Ulmus americana and (ii) determine if adult S. schevyrewi can transfer the pathogen to American elms during maturation feeding. To determine the DED vectoring capability of S. schevyrewi, newly emerged adults were infested with spores of Ophiostoma novo‐ulmi and then placed with either in‐vivo or in‐vitro branches of American elm trees. The inoculation of trees via feeding wounds was successful 30% of the time for in‐vivo trials and 33% for in‐vitro trials. Although the infection rate of DED has declined in Colorado over the past 10 years, the disease is still present in urban elms. While it appears that S. schevyrewi is another vector of the DED pathogens, it appears that S. schevyrewi is no more efficient than S. multistriatus. Thus, management programs that remove elm bark beetle breeding sites, rapidly remove DED‐infected elms and include the planting of DED‐resistant elms should continue to be effective management tactics.     

Fatty acids triggering coremia formation by Ceratocystis ulmi their occurrence and distribution in elm wood

This paper reports the identification of fatty acids in elm wood and its active extractives triggering coremia formation, their distribution between bark, sapwood and heartwood of elms, and their occurrence in the mycelium of the pathogen.     

绿化榆树树种常见的病虫害

榆树是北方常见的绿化树种,由于在品种的选择、栽培及气候的异常变化,使榆树近几年病虫害不断发生,特别是2010年春大量的绿化榆树死亡,不仅造成严重的经济损失,同时,也影响街区的美化绿化。文章阐述了扎兰屯地区绿化榆树的常见病虫害并提出防治建议。     

混交林中黄斑星天牛选择寄主的行为与寄主抗虫性关系的研究

通过观察混交林中黄斑星天牛选择寄主的行为,认为对不同抗生寄主,它选择寄主的行为不同。它能通过复杂的感觉行为和一定的时间找到混交林中的感性树种并造成严重危害和它们种群密度在感性树种上的上升。这种天牛选择寄主在远距离一般以植物气味定向,近距离则以性信息素 增加种群密度。除视觉外,它的主要感觉行为是触角摆和胫节磨擦,选择到达合适寄主是通过逐步的感觉阶段完成的。树皮粗糙程度,叶片特征,枝条特征及混交林密度     

Effects of forest restoration treatments on the abundance of bark beetles in Norway spruce forests of southern Finland

Restoration of protected areas in boreal forests frequently includes creating substantial volumes of dead wood. While this benefits a wide range of dead wood dependent invertebrate species, some of these are regarded as forest pests. Therefore, the risk of elevated levels of tree mortality in surrounding commercial forests must be considered. In a large-scale field experiment in southern Finland, we studied the effects of restoration treatments on the abundance of bark beetles within and in the vicinity of restored areas, in particular focusing on Ips typographus and Pityogenes chalcographus. The treatments applied to managed Norway spruce forests were controlled burning and partial harvesting combined with retaining 5, 30 or 60 m³/ha of cut down wood. We found that the abundance of bark beetles increased by both burning and harvesting with down wood retention, being highest where burning and harvesting had been combined. The actual volume of down wood retention had no significant effect. The effect of burning on the number of bark beetles along host tree boles was negative which suggests that burnt spruces provided a less suitable resource for bark beetles than unburnt dead spruces. The abundance of bark beetles along host trees also decreased with increasing volume of down wood retention. The abundance of P. chalographus was slightly elevated up to 50 m outside restored areas but the abundance was very low compared to that within the areas. The abundance of I. typographus was extremely low outside restored areas. We conclude that restoration treatments increase the abundance of bark beetles via increased availability of resources, but that the effect of burning is likely to be counteracted by decreased resource quality. Thus, burning might be the “safest” way to produce large quantities of dead wood. Furthermore, the fact that only few beetles were collected in adjacent areas suggests that restored areas pose little threat of serving as refugia in which bark beetle populations increase in sufficient numbers to attack live trees in adjacent forests. However, restoration actions repeated at consecutive years within a small area might enable the populations to grow to outbreak levels.     

Dutch elm disease on the island of Gotland: monitoring disease vector and combat measures

The island of Gotland (Sweden) possesses the largest (more than one million trees) wild population of elms in northern Europe, which until recently was not affected by Dutch elm disease (DED). In 2005, DED was observed for the first time in the northeastern part of Gotland, and in the following years, it rapidly spread in all directions, generally following the major distribution of elms. Implementation of intensive control measures including ground surveys and geographic information system mapping of DED-diseased trees, their felling and destruction, and stump treatment with the herbicide glyphosate allowed reduction of the source of infection and probably suppression of an otherwise very rapid spread of the disease. Monitoring the flying periods of Scolytus multistriatus vector beetles between the years 2007 and 2011 showed that the abundance of trapped beetles in most cases differed significantly among individual years. Over the entire monitoring period, 55.2% of the beetles were trapped in June, 31.2% in July and 13.5% in August (difference among individual months significant at p?S. multistriatus, suggesting that the removal of trees attacked in the previous vegetation period as a combat measure should be completed before the beginning of the flying season of S. multistriatus, and that the application of the integrated DED management has the potential to arrest the development of the disease in a geographically isolated area such as Gotland.     

浑善达克沙地桑根达来古榆树调查研究

榆树疏林草原是浑善达克沙地上的一种原始自然景观,被认为是最稳定的植被类型.我们把胸径＞50 cm的榆树定义为古榆树.2009年5～8月在浑善达克沙地正蓝旗桑根达来镇境内用样方法对宝绍代苏木安夏日嘎查、额木格德苏木白音胡舒嘎查等8个区域胸径＞ 50 cm的古榆树进行实地调查,结果表明:(1)该区共有古榆树308株,分布最...     

秦岭华山松小蠹生态位研究

通过对秦岭林区海拔１６００～２２００ｍ的中山地带华山松小蠹虫种类和生态位的研究,结果表明：在秦岭林区入侵危害寄主华山松的小蠹虫有１９种,其中能构成竞争和共存的小蠹虫主要有１１种。虽然,这１１种小蠹虫具有各自不同的生态位宽度,且存在不同程度的生态位重叠,但各小蠹虫可依据其对寄主树木营养和空间需求的不同、种群密度的相互制约,以及入侵寄主树木时序的差异达到竞争的平衡和共存。秦岭华山松小蠹生态系统的建立,首先是由华山松大小蠹入侵健康华山松,并通过携带蓝变真菌入侵寄主树木,迅速克服寄主树木抗性系统,使寄主树木树势衰弱;其次松六齿小蠹、暗额星坑小蠹和松十二齿小蠹,作为秦岭华山松的主要次期性小蠹,迅速入侵衰弱的寄主华山松;最后其它次期性小蠹虫入侵寄主树木,利用寄主华山松剩余营养和空间。从而实现秦岭华山松立木小蠹生态系统的动态稳定。