芦笋木蠹蛾的生物学特性

芦笋木蠹蛾Isoceras sibirica(Alpheraky)是危害芦笋的重要害虫。该虫在山西省运城市1年发生1代,以老熟幼虫在土中结薄茧越冬。翌年3~4月老熟幼虫由深土层上移至地表土壤结茧化蛹。4月中下旬为化蛹高峰。5月上中旬为蛹羽化高峰期。6月上旬为卵孵化高峰期。幼虫为害期为5月下旬至10月下旬。对该虫的形态、生活习性和发生规律作了描述和报道。     

芦笋茎基部施药对芦笋木蠹蛾幼虫的防治试验

芦笋木蠹蛾Isoceras sibirica(Alpheraky)为芦笋(Asparagus officinalis(L.))上的一种蛀茎性害虫。试验结果表明,采用50%辛硫磷乳油300倍液在芦笋茎基部给药(5月中旬至6月中旬)为该虫的最佳化学防治方法,相对防治效果为92.5%,在所有处理中其加权Borda值最高(2.9)。调整芦笋播期,可使定植当年最易受害的笋苗免于虫害。     

沙棘木蠹蛾蛹的空间分布

沙棘木蠹蛾（Holcocerus hippophaecolus Hua, Chou , Fang et Chen）是近几年在内蒙古、辽宁、山西、宁夏和陕西等地大面积爆发的一种钻蛀性害虫,该虫约4a完成1代,主要以幼虫危害沙棘（Hippophae rhamnoidea）的根部和干部,老熟幼虫在土壤中化蛹.为了解种群的空间结构,从而有效控制其危害,应用生物学统计方法和地质统计学（Geostatistics）方法对沙棘木蠹蛾蛹的空间分布特性进行了分析研究.结果表明：约90%的蛹在6月初到7月末之间羽化,而7月份羽化的数量占总数的一半之多.在调查样地中,雌雄蛹的比例基本为1：1.每株沙棘树周围,蛹的数量为0～4个,有蛹株率仅为24.3%.蛹在距离根基部周围1.3m的范围内均有分布,不同分布区间内蛹的数量变化没有一定的规律性,但90%的蛹分布在距根基部1m的范围内.沙棘木蠹蛾蛹的种群呈现较明显的空间聚集状态,空间依赖范围大小为11.1m,局部空间连续性强度为90.7%,呈现较明显的斑块状分布,在整个区域内有很多聚集点.对不同样方大小的变异曲线图进行比较得知：样方边长分别为5、6、7m时,变程、空间局部连续性强度和基台值的变化幅度均很小,几乎相等,而样方边长为5m时的决定系数较大,此样方为最适样方大小.     

木蠹蛾性信息素研究的进展

综述了木蠹蛾性信息素研究及在综合防治措施中应用的最新进展,重点评述了木蠹蛾性信息素的结构鉴定与化学结构。至今有4种木蠹蛾的性信息素被鉴定,另外还筛选出2种木蠹蛾的性诱剂。在我国,对木蠹蛾的防治,应采取化学防治、生物防治及使用人工合成性信息素或性诱剂诱捕法和迷向法综合防治措施。     

沙棘木蠹蛾生殖系统形态学和组织学观察

沙棘木蠹蛾Holcocerus hippophaecolus Hua,Chou,Fang et Chen属鳞翅目(Lepidoptera)木蠹蛾科(Cossidae),是我国的特有种.2001年以来,沙棘木蠹蛾在我国大面积爆发,是屹今为止我国沙棘林最大的蛀干害虫,给我国的沙棘产业造成了巨大的损失.本论文从形态学和组织学2个方面确定了沙棘木蠹蛾雌、雄生殖系统的特征,同时,对比了雄性交尾前后生殖系统各部位的差异.未交尾雄蛾的生殖系统贮精囊、附腺管和射精管呈白色,其内包含大量的精子束待交尾,已交尾雄蛾的生殖系统呈透明或半透明状.除雄性附腺外,在交尾后的精巢、贮精囊和射精管中都能观察到真核精子束.通过上述对雄性生殖系统的形态学和组织学观察,尤其是对贮精囊和射精管中精子束观察,可判断精子束的填充状态,从而判断雄蛾交尾与否,能够检验性信息素引诱剂对沙棘木蠹蛾的防治效果,确立判断雄蛾交尾与否的标准对指导沙棘木蠹蛾防治具有重要意义.     

斜纹拟木蠹蛾在广州发生的生物学特征

本文报道了斜纹拟木蠹蛾Indarbela obliquifasciata在广州的发生和为害特征,对其形态和生物学特征做了阐述,表明该虫在广州一年发生一代,其取食寄主达18种,但主要寄主植物为羊蹄甲,其幼虫共6龄并以幼虫越冬。并对该虫的防治提出了建议。     

三唑磷防治咖啡木蠹蛾的初步研究

咖啡木蠢蛾在福建省1年发生2代,幼虫的孵化高峰期分别发生在6月与10月,掌握其幼虫孵化高峰期适时喷施20％三唑磷乳油1500倍稀释液,结果表明,对药前10d内孵化已蛀枝干的幼虫杀虫率为90oA～100％,对药后10d内已蛀枝干的幼虫杀虫率为85％～100％,2次施药就能有效防治咖啡木蠢蛾为害。由于此法简便,经济,易行,故建议在生产上可以推广应用。     

沙棘木蠹蛾的人工饲养

采用A、B和C 3种饲料饲养沙棘木蠹蛾Holcocerushippophaecolus,A饲料成分为水、玉米粉、豆粉、蔗糖、琼脂、酵母粉、山梨酸钾、对羟基苯甲酸甲酯 ;B饲料成分为水、玉米粉、豆粉、琼脂、酵母粉、抗坏血酸、苯甲酸钠 ;C饲料成分为大豆粉、沙棘木粉、蔗糖、琼脂、维生素混合液、酵母浸粉、抗坏血酸、防腐剂混合液、无机盐。其中 ,B饲料防腐能力较差 ,饲养 1 2周后放弃。A和C 2种饲料能使沙棘木蠹蛾幼虫体重持续增长 ,饲养前期A饲料平均体重增量是C饲料的 1 6倍 ,A和C 2种饲料化蛹率分别为83. 3 %和 66. 7% ,羽化率分别为 3 0 % ,1. 6 7%。选择在沙土中结茧化蛹 ,能显著提高饲养成功率。     

沙棘木蠹蛾的幼虫空间分布与抽样技术

利用常用的聚集度指标 ,对沙棘木蠹蛾HolcocerushippophaecolusHua ,Chou ,FangetChen幼虫的分布进行了分析。结果显示 ,该幼虫的空间分布格局为聚集型分布。通过Iwao的m - x回归检验方程 ,确定了其最适抽样数和最佳样方大小。采用对角线、之字型、五点式、棋盘式和平行线等 5种抽样方法对沙棘木蠹蛾幼虫的抽样技术分别进行了研究 ,结果表明 :最佳的抽样方法为棋盘式。     

Growth regulator effects on storage root development in carrot

The major carbohydrates stored in carrots are sucrose, glucose and fructose. The ratio of sucrose to reducing sugars varies between cultivars, with early forcing types generally having a higher level of reducing sugars while storage types have a greater proportion of sucrose.In an early forcing cultivar, Super Sprite, high acid invertase activity was correlated with low levels of stored sucrose. As acid invertase activity decreased, the levels of reducing and non-reducing sugars appeared to be related to a balance between alkaline invertase and sucrose synthetase activities.Foliar applications of gibberellic acid at 35 and 42 days after sowing reduced the root/shoot ratio while similar applications of chlormequat chloride marginally increased the ratio. Both growth regulators temporarily increased sucrose stograge, but only gibberellic acid consistently reduced hexose accumulation.Gibberellic acid reduced acid invertase activity following both applications while only reducing the activities of sucrose synthetase after the first application and alkaline invertase after the second application, respectively. Chloremequat chloride increased acid invertase activity after the first application but otherwise has no effect on the activities of the enzymes studied. The significance of changes in assimilate partitioning are discussed in relation to published schemes on carbohydrate storage in root vegetables.     

Long-term effects of asparagus virus 2 infection on growth and productivity in asparagus

An asparagus field trial was established with clonal plants to determine the long-term effects of asparagus virus 2 (AV2) infection on spear production. Yield data, analysed by ANOVA, showed that AV2 infection caused significant (P < 0.05) decreases in spear yield which became more pronounced as the trial progressed. Mean marketable spear yields were reduced by 14%, 28%, 20%, 48% and 57% and reject spear yields were increased by 93%, 105%, 207%, 352% and 167%, during harvest years 1–5 respectively. Marketable spear yields from AV2–free plants increased annually to yr 5, but for AV2–infected plants, yields increased to yr 3 and decreased annually thereafter. Spears from AV2–infected plants were thinner than those from AV2–free plants, resulting in more reject thin spears by 109%, 88%, 220%, 499% and 216% during harvest yr 1–5, respectively. Further, data collected in yr 4 and 5 showed that AV2 infection had caused a 31 % reduction in mean spear diameter and reductions of 27% and 22% respectively, in diameter and height of fern stalks. Clearly, plants with smaller fern stalks were less able to accumulate carbohydrate reserves and therefore produced fewer, smaller spears and fern stalks the following spring. This may result in annual cycles of diminishing productivity in which the size and number of spears and fern stalks decrease with each successive year. The type and timespan of symptoms caused by AV2 infection in this trial are similar to those reported for asparagus decline syndrome and therefore it is likely that AV2 infection is a factor contributing to asparagus decline.     

Effects of relative humidity on development, fecundity and survival of three storage mites

The developmental rate of immature stages and the reproduction of adults of Tyrophagus putrescentiae (Schrank), T. neiswanderi Johnston and Bruce and Acarus farris (Oudemans) were examined at 70, 80 and 90% r.h. and a constant temperature of 25°C. At 70% r.h., T. putrescentiae and A. farris immature stages failed to reach the protonymph stage as 100% of the larvae died, whereas T. neiswanderi was able to complete development. The developmental time of all immature stages for the three species was significantly increased as relative humidity was reduced. The mobile stages were particularly susceptible, as the time needed to complete their development at lower relative humidities suffered greater increases than the egg stage. At 70% r.h., T. putrescentiae and A. farris were not able to lay eggs and only 24% of T. neiswanderi pairs were fertile. The reproductive parameters of the three species at the relative humidities at which they were able to lay eggs showed significant differences, except for the percentage of fertile mating at 80 and 90% r.h. As relative humidity increased, preoviposition period was reduced and fecundity and daily fecundity was increased, whereas the oviposition period showed different patterns for the three species. The intrinsic rate of increase (r _m ) of T. neiswanderi at 70% r.h. was negative indicating that, at these conditions, mite populations of this species will diminish until they disappear. As relative humidity increased from 80 to 90% r.h. this parameter was almost twofold for both Tyrophagus species. The r _m obtained for A. farris at 90% r.h. was similar to that of T. neiswanderi at the same humidity while at 80% r.h. it was very small so that the population doubling time was more than 84 days. The influence of relative humidity on biology of these mites and its practical application as control measure are discussed.     

The cocoon and humidity in the development of Acrolepiopsis assectella (Lep.) pupae: consequences in adults

Abstract In a saturated atmosphere, the cocpon of the leek moth can absorb up to two-thirds of its weight in water. It is shown that this phenomenon enables the pupae to lose less water in the course of their development, particularly during pupal moulting. Although quantitatively minor, this protection is qualitatively important: it has no effect on mortality or the duration of pupal development, but does affect vitellogenesis and fertility in females. It thus clearly has an adaptive role towards the environment.     

Promotion of asparagus shoot and root growth by growth retardants

Plantlets regenerated from shoot-tip culture of Asparagus officinalis L. possessed weak shoots and roots. Various combinations of auxins and cytokinins did not improve the plantlets. Incorporation of a number of growth retardants, viz. ancymidol, B-995, phosfon, Amo 1618, cycocel and paclobutrazol, promoted growth of stronger shoots and roots. The effectiveness of the growth retardants varied, with ancymidol being most effective and cycocel least effective.The response to ancymidol was prevented by exogenous GA₃ and GA_4/7. GA_1/3 and GA_4/7-like activities were detected in asparagus shoot-tip culture and these activities were reduced by the presence of the growth retardants ancymidol, Amo-1618, and cycocel.     

Sink development and dry matter distribution in storage root crops

Events during early development are examined for their contribution to dry matter distribution in the mature plant. It is concluded that timing of initiation of the storage root is not a major cause of differences between cultivars of carrot. These may airse from differences in the control of partitioning of assimilate at storage organ initiation. Root crop species may be affected differently by environmental factors such as density as a result of different thresholds of response of sink development to source stimuli.     

The growth and development of the storage root of sugar beet

A study was made of the growth of the storage root of sugar beet as a sugar accumulating organ. The storage root grew by simultaneous cell multiplication and expansion from a series of peripheral secondary meristems laid down during the early stages of development. The weight of water and of non-sugar dry matter per cell increased in proportion to the increase in cell volume. The amount of sugar per cell was proportional to cell volume only during the initial stage of cell expansion up to volumes of about 15 times 10^-8 cm³; thereafter it was less proportional. Thus, average cell size is a major determinant of the sugar concentration of the storage root. The implications of this are discussed.     

Redox regulation of root apical meristem organization: Connecting root development to its environment

Post-embryonic root growth relies on the proliferative activity of the root apical meristem (RAM), consisting, in part, of cells with juvenile characteristics (stem cells). It is generally, but erroneously held that the RAM indefinitely produces new cells throughout the lifespan of a plant, resulting in indeterminate root growth. On the contrary, convincing data, mainly from the lab of Thomas L. Rost, show in all species analyzed so far, including Arabidopsis, that RAM organization changes over time in parallel with both a cessation of the production of new cells, and a consequent reduction in root growth, even under optimal conditions. In addition, RAM organization evolved to become highly plastic and dynamic in response to environmental triggers (e.g. water and nutrient availability, pollutants). Under unfavourable conditions, the RAM is rapidly reorganized, and, as a result of the cessation of new cell production at the root tip, root growth is altered, and lateral root production is enhanced, thus providing the plant additional strategies to overcome the stress. It is now becoming increasingly clear that this environment-responsive developmental plasticity is linked to reactive oxygen/nitrogen species, antioxidants, and related enzymes, which form part of a complex signalling module specifically operating in the regulation of RAM functioning, in strict relationship with hormonal control of root development exerted by auxin, gibberellins and cytokinins. In turn, such redox/hormone crosstalk regulates gene expression.