烟草粉斑螟的观察

烟草粉斑螟是烟叶及卷烟贮存期的重要害虫。本工作研究了烟草粉斑螟的生活史、习性及影响消长的主要因子。在湖北省该虫一年发生2～3代,在26～30℃,相对湿度70～90％对,卵历期5～7天,幼虫期29～50天,幼虫5～6龄,蛹期6～18天。幼虫蚕食烟叶成孔洞,老熟幼虫在烟叶表面或麻袋及仓库隐蔽处吐丝结茧化蛹。烟叶从收购入库至贮存各环节均可遭受为害,以卷烟厂贮存过程受害最甚。通常高、中档烟叶受害重于低挡烟叶,其烟草粉斑螟种群密度随着贮存期的延长呈线性增加。烟叶含水量达13％时,幼虫发育迅速,为害重;含水量低于10％时,幼虫发育受到明显影响。     

厦门地区朱红毛斑蛾的发生情况

朱红毛斑蛾(Phauda flammans)是榕属(Ficus)植物重要的食叶害虫。调查发现,朱红毛斑蛾在厦门市辖区内已广泛分布,主要为害小叶榕(Ficus microcarpa)和垂榕(F. benjamina),对高山榕(F. altissima)和黄金榕(F. microcarpa ‘Golden Leaves’)也有少量为害。朱红毛斑蛾在厦门一年发生3代,1、2、3代低龄幼虫施药防治适期分别是5月上旬、7月中旬和10月中旬。     

杨白潜叶蛾的研究

杨白潜叶蛾是为害杨树幼苗、幼树的一种较严重的害虫。幼虫在表皮下潜食叶肉,形成黑色虫斑。在河北易县为害多种杨树,其中毛白杨、唐柳虫斑面积占全株叶片面积达20%以上,严重影响光合作用的进行,树势衰弱,往往提早落叶。 此虫在易县一年发生四代,9月中旬至10月上旬相继以蛹作“工”字形茧在树干树皮缝内、落叶上越冬。同时有一小部分蛹羽化,成虫交配后产卵并孵化,但小幼虫在10月下旬全部冻死在潜叶上。成虫在4月中旬开始出现。有趋光性。产卵在叶片正面贴近主脉或侧脉,通常5—7粒卵排列成行。每头雌虫平均产卵量为49粒。幼虫孵化后从卵壳底面(与叶正面表皮接触处),咬破卵壳潜入叶组织内取食叶肉。 防治方法:秋冬季节在苗圃、幼林内大量扫集落叶,可消灭一定数量的越冬茧;根据室内和苗圃大面积防治幼虫试验,用40%的乐果乳剂1:1,000倍液喷洒叶面,毒杀潜叶内的幼虫效果很好。     

甘蓝薄翅螟的生物学特性

甘蓝薄翅螟Crocidolomia pavonana(Fabricius)是广西南宁新发现的一种蔬菜害虫。该虫在当地年发生13个世代,卵期2.5~6.5d,幼虫期8.0~13.0d,世代历期18~39.5d。整年均可发生为害,为害峰期在4~6月。主要寄主是甘蓝、白菜、芥菜、萝卜、油菜等。幼虫共4龄,以幼虫咬食寄主的叶片、嫩茎和花,老熟幼虫在土表下化蛹。     

大叶黄杨长毛斑蛾的生物学研究

大叶黄杨长毛斑蛾于1990年在山东威海地区首次发现,是为害大叶黄杨的重要害虫,一年发生1代,以卵在枝条上越冬,翌年4月初出现幼虫,5月中旬初开始结茧化蛹,10月底始见成虫,作于1990-1993年对该虫的形态特征,生活史及为害习性进行了观察研究,并提出综合防治措施。     

云斑天牛在白蜡树上的发生与防治研究

云斑天牛Batocera horsfieldi(Hope)是白蜡树上近年来新出现的一种蛀干害虫。在东营市的市区绿化中危害日趋严重,目前其受害率达到10％强,成为白蜡树上继“窄吉丁虫”为害后的又一主要蛀干害虫。该虫2—3年完成1代,以第1年幼虫和第2年成虫,在主干或主干分叉处的蛀道内越冬。主要危害胸径8cm以上生长的白蜡树,在树干根基部30cm以下,或在主干分叉处蛀食为害,并常引起“风折木”。在9月下旬进行注药和4月上旬进行埋药防治,控制效果可达90％以上。     

山楂童锤角叶蜂的生物学及防治

山楂童锤角叶峰是近年来在安徽大别山区发现的一种新害虫。该虫严重为害山植和梨树、1年发生1代,以预蛹在茧内越夏越冬。幼虫食叶为害,每年5月上中旬为猖极为害期。此虫发生与海拔高度及温湿度关系密切。     

冀南棉鼎点金钢钻的初步研究

鼎点金钢钻(Earias cupreoviridis Walker)是棉花蕾铃期的重要害虫之一,以往在我国北部棉区为害不甚显著。近来它的发生有所增加,从邯郸的调查来看,1959年百株幼虫数最高达到114头。尤其后期虫口密度超过棉铃虫的数量,虫株率一般为10—40％,对秋桃为害很大,因此按其为害程度已渐为我地高产棉田的重要害虫。它除严重为害棉花外,尚在蜀葵、锦葵、苘麻及野生苍耳上找到过幼虫,但为数极少。     

白蜡吉丁虫肿腿蜂对三种蛀干害虫的寄生效能研究

利用白杨透翅蛾Paranthrene tabaniformis、杨十斑吉丁虫Melanophila picta和纳曼干脊虎天牛Xylotrechus namanganensis幼虫作为替代寄主对天敌昆虫白蜡吉丁虫肿腿蜂Sclerodermus pupariae进行人工饲养，成功繁殖出了成蜂。人工繁蜂的条件为：温度26℃，相对湿度70%，接蜂的蜂虫比3:1，三种替代寄主白杨透翅蛾、杨十斑吉丁虫和纳曼干脊虎天牛幼虫的被寄生率分别为43.77%、87.12%和82.41%；平均繁蜂时间分别为42 d、33.17 d和34.58 d；白杨透翅蛾、杨十斑吉丁虫和纳曼干脊虎天牛单个幼虫平均繁殖白蜡吉丁肿腿蜂分别为4083头、9033头和5092头；子代蜂的雌性率分别为9553%、9670%和94.57%。在7℃，相对湿度70%的条件下储藏，白蜡吉丁肿腿蜂子代成蜂的平均寿命150 d；寿命超过一个月的雌蜂占95%，雄蜂寿命5-7 d。     

杨潜叶蜂生活史及防治的初步研究

<正> 杨潜叶蜂Messa hcrticulana Kl,属膜翅目叶蜂科(Tenthredinidae)。由于幼虫为害杨树,且潜叶为害,故名杨潜叶蜂;又因为被害叶片潜痕部分充满空气,呈泡状,为与近缘种区别,所以亦称杨泡叶蜂。幼虫潜伏于杨树叶片上下表皮之间蛀食叶肉,随着幼虫的生长发育,潜痕也日益扩大,一般可占整个叶片面积的3/5—4/5,致使叶片失去正常营造养分的功能;更为严重的是常常造成叶片早期脱落,严重影响树木的生长。此虫为害的另一个特点是为害时间早,也就是在杨树生长发育的关键时期,使杨树     

Is precipitation a trigger for the onset of xylogenesis in Juniperus przewalskii on the north-eastern Tibetan Plateau?

Background and Aims A series of studies have shown that temperature triggers the onset of xylogenesis of trees after winter dormancy. However, little is known about whether and how moisture availability influences xylogenesis in spring in drought-prone areas.Methods Xylogenesis was monitored in five mature Qilian junipers (Juniperus przewalskii) by microcore sampling from 2009 to 2011 in a semi-arid area of the north-eastern Tibetan Plateau. A simple physical model of xylem cell production was developed and its sensitivity was analysed. The relationship between climate and growth was then evaluated, using weekly wood production data and climatic data from the study site.Key Results Delayed onset of xylogenesis in 2010 corresponded to a negative standardized precipitation evapotranspiration index (SPEI) value and a continuous period without rainfall in early May. The main period of wood formation was in June and July, and drier conditions from May to July led to a smaller number of xylem cells. Dry conditions in July could cause early cessation of xylem differentiation. The final number of xylem cells was mainly determined by the average production rate rather than the duration of new cell production. Xylem growth showed a positive and significant response to precipitation, but not to temperature.Conclusions Precipitation in late spring and summer can play a critical role in the onset of xylogenesis and xylem cell production. The delay in the initiation of xylogenesis under extremely dry conditions seems to be a stress-avoidance strategy against hydraulic failure. These findings could thus demonstrate an evolutionary adaptation of Qilian juniper to the extremely dry conditions of the north-eastern Tibetan Plateau.     

Periodicity of Cambial Activity and Changes of Starch Content in Broussonetia papyrifera

Methods of sampling and sections preparaction were the same as reported previously. Except that sampling was made at monthly intervals between May 20 and July 30, then at 7–14 day-intervals between July 30 and October 14, and then at monthly intervals between October 14 and March 25 in the next year. The stored starch in various tissues was stained with PAS reaction. During active period of cambium in Broussonetia papyrifera after July 30, the cell layers of immature xylem and phloem decreased progressively, and the formation of mature xylem and phloem increased rapidly. The formation of late wood started early in August, formation of xylem ceased after September 5, followed by ceasation of phloem formation about 1.5 months later. Increasing and decreasing of stored starch were closely related to the periodicity of cambial activity during the year. Starch grains decreased progressively after cambial activity was resumed in early spring until they disappeared in all the stem tissues. Then, starch accumulated progressively again after cambial activity slowed down, particularly after the ceasation of xylem formation. However, after the formation of phloem had ceased, the stored starch once again disappeared progressively until the end of December, and accumulated again. Such changes might be related to the transition of cambium activity involving two periods of dormancy.     

Changes of Peroxidase and Estease Isozymes During Periodicity of Cambial Activity in Broussonetia papyrifera (L.) Vent.

Methods of sampling and sections preparaction were the same as reported previously. Except that sampling was made at monthly intervals between May 20 and July 30, then at 7–14 day-intervals between July 30 and October 14, and then at monthly intervals between October 14 and March 25 in the next year. The stored starch in various tissues was stained with PAS reaction. During active period of cambium in Broussonetia papyrifera after July 30, the cell layers of immature xylem and phloem decreased progressively, and the formation of mature xylem and phloem increased rapidly. The formation of late wood started early in August, formation of xylem ceased after September 5, followed by ceasation of phloem formation about 1.5 months later. Increasing and decreasing of stored starch were closely related to the periodicity of cambial activity during the year. Starch grains decreased progressively after cambial activity was resumed in early spring until they disappeared in all the stem tissues. Then, starch accumulated progressively again after cambial activity slowed down, particularly after the ceasation of xylem formation. However, after the formation of phloem had ceased, the stored starch once again disappeared progressively until the end of December, and accumulated again. Such changes might be related to the transition of cambium activity involving two periods of dormancy.     

Wood diameter indicates diurnal and long-term patterns of xylem water potential in Norway spruce

The stem diameter of adult Norway spruce trees was measured to see whether changes in xylem water potential lead to detectable radial deformation of the wood. The dendrometers used in these experiments measured only the dimensional changes of the woody cylinder (sap- and heartwood). Wood diameter was measured close to the ground and just below the living crown. After correction for thermal expansion of dendrometers and wood, diurnal variation of wood diameter ranged between 50 and 180 µm. Psychrometric measurements showed that xylem water potential varied in parallel to wood diameter. Diameter changes were always more pronounced at the higher stem position and exhibited a clear diurnal pattern. During the day, wood diameter decreased with increasing vapor pressure deficit and transpiration rate and with decreasing twig water potential. At night, the wood re-expanded but did not always reach the dimension of the previous day. Pre-dawn wood diameter decreased during periods of soil drought, a process which rapidly stopped and reversed after rain events. On several days, oscillation in wood diameter was observed during the mid-day hours. The oscillation had a period of approximately 50 min and showed a phase shift between different stem heights. All observed patterns of wood shrinkage and expansion were consistent with the hypothesis that xylem water tension leads to an elastic contraction of xylem conduits. The results demonstrate that xylem diameter is more suitable than whole-stem diameter for monitoring changes in xylem water potential.     

Seasonal development of phloem in Siberian larch stems

The seasonal development of phloem in the stems of Siberian larch (Larix sibirica Ldb.) was studied over two seasons on 50–60-year-old trees growing in a natural stand in the Siberian forest-steppe zone. Trees at the age of 20–25 years were used to study metabolites in differentiating and mature phloem elements, cambial zone, and radially growing xylem cells in the periods of early and late wood formation. The development of the current-year phloem in the stems of 50–60-year-old trees started, depending on climatic conditions, in the second-third decades of May, 10–20 days before the xylem formation, and ended together with the shoot growth cessation in late July. Monitoring of the seasonal activity of cambium producing phloem sieve cells and the duration of their differentiation compared to the xylem derivatives in the cambium demonstrated that the top production of phloem and xylem cells could coincide or not coincide during the season, while their differentiation activity was always in antiphase. Sieve cells in the early phloem are separated from those in the late phloem by a layer of tannin-containing cells, which are formed in the period when late xylem formation starts. The starch content in the structural elements of phloem depends on the state of annual xylem layer development. The content of low molecular weight carbohydrates, amino acids, organic acids, and phenols in phloem cells, cambial zone, and xylem derivatives of the cambium depends on the cell type and developmental stage as well as on the type of forming wood (early or late) differing by the cell wall parameters and, hence, by the requirement for assimilates. Significant differences in the dynamics of substances per dry weight and cell were observed during cell development.     

构树形成层的活动周期及其淀粉贮量的变化

在构树（Ｂｒｏｕｓｓｏｎｅｔｉａ ｐａｐｙｒｉｆｅｒａ （Ｌ．） Ｖｅｎｔ．）形成层活动周期中,每年７月末以后,未成熟的木质部和韧皮部逐渐减少,成熟的木质部和韧皮部急剧增多。８月初开始分化晚材。进入９月后木质部的形成逐渐停止,而一个半月以后才停止形成韧皮部。淀粉贮量的消长与形成层的活动周期有很强的相关关系。早春形成层恢复活动后,淀粉贮量逐渐减少直至消失。尔后,形成层活动减慢,特别是木质部分化停止后,淀粉又开始积累。当韧皮部分化也停止后,淀粉又消失,直至翌年１月才重新积累,这似乎与两个休眠期的转化有关     

橡胶树(Hevea brasiliensis Muell.Arg.)幼茎木材的超微结构观察

橡胶树是中国重要的热带经济作物,橡胶种植的副产物橡胶木是我国木材供应的重要来源。我们以不同发育阶段的橡胶树幼茎木材为材料,借助扫描电子显微镜技术,对木质部细胞的超微结构进行了观察。结果表明,在橡胶树幼茎木材中,导管和木纤维细胞壁随着木质部发育成熟会发生明显的次生加厚,加厚方式主要为螺纹加厚;木质部各类型细胞均存在大量纹孔,纹孔排列方式主要有散生、网状、梯状和单串状等类型;在木质部发育过程中,木射线和部分薄壁细胞中会逐渐积累大量淀粉粒;木质部细胞内壁及其填充物表面存在不同类型的附着物。研究结果将为橡胶木材材性及其形成机制的研究提供一定理论参考。     

CAMBIUM, a process-based model of daily xylem development in Eucalyptus

In hardwoods such as Eucalyptus spp., xylem (wood) is a heterogeneous tissue consisting of multiple cell types. As such, xylem development involves multiple complex interactions. To describe and understand xylem development, and ultimately predict the resultant wood properties, a process-based approach to modelling wood property variation is potentially very useful. In this paper, a new model (CAMBIUM), which incorporates concepts of these processes, is described. CAMBIUM predicts how wood density and fibre and vessel anatomical properties vary from pith-to-bark at a daily time step as a function of changing environmental conditions and a set of simulated physiological processes. Simulations from an existing process-based model of stand development (CABALA) are used as inputs. A key feature of CAMBIUM is a model of the interaction between different xylem cell types. Some weaknesses were identified in the ability of the model to simulate vessel spatial patterns and frequencies, emphasizing the complexities inherent in this aspect of angiosperm wood formation. The model was, however, able to provide realistic estimates of short-term variation and temporal ranges in eucalypt fibre diameter and secondary wall development and wood density.     

Variation in wood density and anatomy in a widespread mangrove species

Wood density is an important plant trait that influences a range of ecological processes, including resistance to damage and growth rates. Wood density is highly dependent on anatomical characteristics associated with the conductive tissue of trees (xylem and phloem) and the fibre matrix in which they occur. Here, we investigated variation in the wood density of the widespread mangrove species Avicennia marina in the Exmouth Gulf in Western Australia and in the Firth of Thames in New Zealand. We assessed how variation in xylem vessel size, fibre wall thickness and proportion of phloem within the wood contributed to variation in wood density and how these characteristics were linked to growth rates. We found the wood density of A. marina to be higher in Western Australia than in New Zealand and to be higher in taller seaward fringing trees than in scrub trees growing high in the intertidal. At the cellular level, high wood density was associated with large xylem vessels and thick fibre walls. Additionally, wood density increased with decreasing proportions of phloem per growth layer of wood. Tree growth rates were positively correlated with xylem vessel size and wood density. We conclude that A. marina can have large xylem vessel sizes and high growth rates while still maintaining high wood density because of the abundance and thickness of fibres in which vessels are found.