桑螟绒茧蜂的生物学特性

采用不定期随机取样的方式 ,连续 3年就桑螟绒茧蜂ApantelesheterusiaeWilkinson对桑螟DiaphaniapyloalisWalker的自然寄生率进行了调查。结果表明 ,桑螟绒茧蜂在苏州一带的发生十分普遍 ,其自然寄生率为 2 2. 95 %～ 5 5. 41 % ,平均 3 3 . 99% ,全年各代都处于相对较高的水平 ,其中 9月份第 5代的自然寄生率最高 ,达 5 5 . 41 % ,是当地的优势天敌种群 ,对于桑螟的发生与危害具有明显的控制作用。该文报道了桑螟绒茧蜂的自然寄生情况及其成虫的生物学习性 ,为进一步开展桑螟的生物防治奠定了基础。     

幼虫密度对桑螟生长发育和繁殖的影响

【目的】本研究旨在了解桑螟Diaphania pyloalis幼虫不同饲养密度对其生长发育和繁殖的影响。【方法】本研究测定了室内同一条件下5个幼虫密度(130, 650, 1 300, 1 950和2 600头/m²)下桑螟生长发育和繁殖指标,包括发育历期、幼虫存活率、化蛹率、成虫羽化率、蛹重、产卵期、单雌产卵量等。【结果】幼虫密度对桑螟的生长发育和繁殖均产生不同程度影响,幼虫密度偏低或偏高都不利于桑螟生长发育和繁殖。其中以1 300和1 950头/m² 2种幼虫密度下的桑螟幼虫生长发育和成虫繁殖状态均最佳且两密度下各项指标无明显差异,1 300头/m²密度下,桑螟的幼虫历期、蛹历期和成虫历期分别为11.32, 6.33和5.31 d; 1 950头/m²密度下,桑螟的幼虫历期、蛹历期和成虫历期分别为11.50, 6.00和5.47 d。1 300头/m²幼虫密度下,桑螟化蛹率、成虫羽化率和幼虫存活率分别为86.67%, 100%和86.67%, 1 950头/m^2<...     

桑螟发生规律及防治策略

通过室内饲养和大田调查 ,证实湖州地区桑螟DiaphaniapyloalisWalker年发生以 5代为主 ,少数年份有 4代 ;桑螟成灾主要集中在第 4,5代。大田桑螟消长同气候、养蚕形式、天敌、防治水平有密切关系 ,不同年份之间发生时间、数量差异很大。桑螟防治方法 :以调整养蚕布局为主 ,辅以化学防治。在大批桑螟 3龄前用药是药剂防治的关键。药剂有 :40 %桑宝乳油 1 1 4mg kg,养蚕安全间隔期 6～ 8d。     

桑螟的羽化和生殖行为节律

【目的】本研究旨在探明桑螟Diaphania pyloalis的羽化和生殖行为节律,为该虫性信息素提取鉴定、种群动态监测、两性通讯机制及行为调控技术研究提供依据。【方法】在光照强度5 200 lx、温度(25±1)℃、相对湿度85%±5%和光周期14L∶10D条件下,通过桑螟雌成虫单头和雌雄成虫单对设置,采用定时持续观察法记录并分析桑螟的羽化、求偶、交配和产卵行为节律。【结果】在光照强度5 200 lx、温度(25±1)℃、相对湿度85%±5%和光周期14L∶10D条件下,桑螟的羽化率为91.30%,羽化期为6 d左右,雌雄蛹日羽化高峰期均集中出现在暗期(2:00-6:00),雌雄蛹比为1.12∶1,且雄成虫先于雌成虫羽化,大约提前0.5 d;桑螟雌成虫求偶行为集中在羽化后的3 d内发生,求偶行为高峰期为暗期7-8 h, 2日龄雌成虫求偶率出现最高值,为47.78%;桑螟雌雄成虫在进入暗期1 h后开始出现交配行为,至暗期7-8 h达到高峰,桑螟交配行为受到成虫日龄影响,2日龄成虫交配率最高,为53.33%;桑螟雌成虫交配后1-3 d内的产卵量占总产卵量的80%以上。【结论】桑螟成虫的羽化和生殖行为存在较明显的昼夜节律,可为桑螟防控提供关键时间参考,也为桑螟绿色防控技术研究与应用奠定基础。     

向日葵螟幼虫的空间分布型及抽样技术

欧洲向日葵螟Homoeosoma nebulellum Denis et Schiffermüller是向日葵上的主要害虫,本文利用6种聚集指标对向日葵螟幼虫的空间分布型进行了测定,结果表明其呈现聚集分布。样本平均数(m)与方差(S2)的对数值的关系式为:lgS2=lg0.2130+0.5639lgm,显示向日葵螟幼虫的空间分布随密度的升高而趋向均匀分布。Iwao的m*-m回归方程为:m*=8.1177+0.1447m,显示该虫在田间分布的基本成分是个体群,个体间相互吸引,个体群的空间分布型为均匀分布。对聚集原因进行分析,得出λ<2,表明向日葵螟幼虫的聚集是由于环境作用所引起的。用Iwao的理论抽样数模型计算出向日葵螟幼虫的理论抽样数模型为:D=0.1时,n=911.77/m-85.53,D=0.2时,n=227.94/m-21.38。采用m*-m关系的序贯抽样模型制定出食葵田间的序贯抽样模型为:T1(n),T0(n)=7.40n±4.54n,油葵田间的序贯抽样模型为:T1(n),T0(n)=10.05n±2.29n。     

豆荚螟幼虫空间分布型及其抽样技术的研究

<正> 我们于1989～1990年,在山东省微山县对豆荚螟Etiella zinckenella(Treitschke)的空间分布型及其抽样技术进行了研究,现将结果整理如下。 研究方法 在大豆鼓粒期,选择4块有代表性豆田,进行连片调查,调查样方为1m~2,在1m~2内随机取大豆5株,分别调查5345、2290、789和1680株。以调查大豆被害荚代替豆荚螟幼虫。取样60m~2,以不同的抽样方式进行抽样,分别记载各样本内的被害荚数。以每块田为1组,用波松、     

Uptake and distribution of trace elements in maturing soybean

The uptake and translocation of trace elements in maturing soybean plants cultivated on soil were studied over 360 h under diurnal conditions after the administration of a multitracer. The contents (%/g) of Co, Se, Rb, Sr, Ru, Rh, and Cs in all the leaves and stems collected from each node increased up to around 200 h after the administration of the multitracer and then decreased with time. The contents of Zn, Tc, and Re in the leaves and Zn in the stems continuously increased up to 360 h, but Tc and Re in the stems showed maximum content. This observation suggests the translocation of these elements from old leaves to growing leaves via stems. The relationship between the content (%/g) of an element in the seeds and pods, and the cultivation time varied depending on the kind of element and on the growth steps. Mathematical analyses were applied to the behavior of the elements in the soybean. The time dependence of the uptake rate (%/g/h) and distribution of elements in each part of the plant were characteristic of the element.     

Effects of adrenalectomy and of adrenal hormones on the tissue distribution of 14 elements in the rat

The effects of adrenalectomy (ADY) and of replacement therapy using a mineralocorticoid, deoxycorticosterone (DOC) and a glucocorticoid, dexamethasone (DEX) on the tissue distribution of elements in the rat, were studied under semichronic conditions. The elements, Na, K, Ca, Mg, Fe, S, P, Rb, Sr, Mn, Cu, and Zn were determined in whole blood, plasma, brain liver, kidney, heart, skeletal muscle, spleen, thymus, and bone. Additionally Mo was determined in kidney and liver and Ba in bone. ADY modified concentrations of all elements tested. Small changes were observed for K, Mg, Ca, S, and P, whereas much larger changes were noted for Na, Rb, and Sr. Cu, Zn, and Fe were mainly modified in liver and kidney, organs involved in storage and/or elimination. The consequences of ADY were corrected fairly well by DEX for Mg, Mn, Ca, Cu, and Mo; by DOC for Na and K, and by the two corticoids for Zn, Fe, Sr, and Rb. This study revealed that corticoids, mainly glucocorticoids, play an important role in the plasma and tissue balance of elements. It is suggested that these results may have a pathological and clinical significance.     

以小时为步长的大兴安岭兴安落叶松林地表可燃物含水率预测模型

应用时滞平衡含水率法(包括Nelson和Simard两种)及气象要素回归法,以小时为步长对大兴安岭地区阳坡上部落叶松林下地表细小死可燃物进行动态含水率测定,分析了不同郁闭度林分的预测误差.结果表明:以小时为步长的可燃物含水率预测方法适用于大兴安岭地区的典型落叶松林分,Simard法预测平均绝对误差为1.1%,平均相对误差为8.5%,低于Nelson法和传统的气象要素回归法,接近同类研究的误差范围;同一坡度、坡位上,不同郁闭度下的可燃物含水率变化差异较大,使用以小时为步长的可燃物含水率预测方法,应根据不同地区林分和地点选择合适的平衡含水率模型,或建立基于林分的可燃物含水率模型.     

Residence time distribution in the chromatographic column: Applications in the separation engineering of DNA

Experimental and theoretical works were performed for the separation of large polyelectrolyte, such as DNA, in a column packed with gel particles under the influence of an electric field. Since DNA quickly orient in the field direction through the pores, this paper presents how intraparticle convection affects the residence time distribution of DNAs in the column. The concept is further illustrated with examples from solid-liquid systems, for example, from chromatography showing how the column efficiency is improved by the use of an electric field. Dimensionless transient mass balance equations were derived, taking into consideration both diffusion and electrophoretic convection. The separation criteria are theoretically studied using two different Peclet numbers in the fluid and solid phases. These criteria were experimentally verified using two different DNAs via electrophoretic mobility measurements, which showed how the separation position of the DNAs varies in the column in relation to the Peg/Pef values of an individual DNA. The residence time distribution was solved by an operator theory and the characteristic method to yield the column response.     

Prevalence and distribution of nucleotide sequences typical for pMEA-like accessory genetic elements in the genus Amycolatopsis

The prevalence and distribution of pMEA-like elements in the genus Amycolatopsis was studied. For this purpose, a set of 95 recently isolated Amycolatopsis strains and 16 Amycolatopsis type strains were examined for the presence of two unique pMEA-sequences (repAM and traJ), encoding proteins essential for replication and conjugative transfer. Homologues of repAM and traJ were found in 10 and 26 of 111 investigated strains, respectively, a result which shows that pMEA-like sequences, though not very abundant, can be found in several Amycolatopsis strains. Phylogenetic analysis of the deduced RepAM and TraJ protein sequences revealed clustering with the protein sequences of either pMEA300 or pMEA100. Furthermore, two geographically different populations of pMEA-like elements were distinguished, one originating in Europe and the other in Australia and Asia. Linkage between the distribution of repAM and traJ and the chromosomal identifier, the 16S rRNA gene, indicated that these elements coevolved with their hosts, suggesting that they evolved in an integrated form rather than by horizontal gene transfer of the free replicating form.     

Inter- and intra-specific distribution of Stowaway transposable elements in AA-genome species of wild rice

The presence or absence of miniature inverted-repeat transposable elements (MITEs) that belong to Stowaway family was analyzed at three loci, two of which are newly identified, in five wild rice species having the AA genome. The pattern of the presence or absence of MITEs was found to be highly associated with speciation in this plant group. In Oryza rufipogon, the pattern was also associated with differentiation into annual or perennial ecotypes. These results suggest either that gene flow has been highly restricted between different species, as well as between different ecotypes of O. rufipogon after they were differentiated, or that loci with or without MITEs have been selected in nature together with the linked genes that are responsible for adaptation to environments. In addition, a very low polymorphism with regard to the presence or absence of MITEs within each species or each ecotype suggests that the frequency of transposition of MITEs is very low, assuming that the loci that contain MITEs are free from selection pressure. Received: 30 October 1999 / Accepted: 2 December 1999