灰飞虱种群暴发成灾原因剖析

灰飞虱Laodelphaxstriatellus(Fall n)作为多种植物病毒病的传毒介体,近年来发生数量呈逐年锐增态势,给水稻生产造成了严重的损失。研究表明,灰飞虱种群的暴发有其生理生态基础。种群具有的强抗逆能力和多态现象增加了种群在各种环境条件下的存活机会;体内共生菌的感染增大了种群的繁殖力。暖冬及春季偏高气温与偏少降雨使种群的存活率提高、发育加速;免耕及种植方式的多样性,使得灰飞虱种群从麦田等地转移到稻田的桥梁质量提高、数量增多;种群抗药性的产生与抗性水平的提高,造成主要药剂对灰飞虱防效的下降,致使种群始终处于高数量水平;同时,承灾体水稻抗虫能力的脆弱,最终触发灰飞虱种群的大暴发与成灾。近年灰飞虱的大发生是种群内外多种因素共同作用的结果。另外,文中还对灰飞虱种群暴发成灾及测报中急需解决的问题进行了讨论。     

用模糊聚类方法分析灰鼠种群数量年间变化与松籽产量的关系并预报灰鼠种群数量

小哺乳动物年间种群数量波动规律及其食物的影响,是人们早已关注的问题(May,1976;Finerty,1980;Xia Wuping等,1982)。研究这些问题一般使用的数学方法是确定性的非线性常微分方程(nonlinear ordinary differential equation),统计学的自相关分析(autocorrelation analysis)或谱分析(spectral analysis)和快速傅里哀变换(FFT)。     

新疆野核桃自然保护区不同坡向野核桃种群生命表与波动周期

为了掌握新疆野核桃种群的波动周期、预测未来种群结构变化,在新疆野核桃自然保护区的阳坡和阴坡分别设置样地大样本调查,以径级结构代表年龄结构编制野核桃种群静态生命表,绘制其期望寿命图、年龄结构图、存活曲线和死亡率曲线,同时应用谱分析方法比较分析不同坡向生境野核桃种群的波动周期。结果表明:(1)野核桃种群不同坡向同一龄级和同一坡向不同龄级的期望寿命均存在波动,期望寿命在10龄级前为阳坡高于阴坡,10龄级后为阳坡低于阴坡。(2)阳坡和阴坡野核桃种群均为增长型年龄结构。(3)不同坡向生境野核桃种群的存活曲线均趋于Deevey-Ⅱ型,但阳坡种群各龄级的存活率均高于阴坡。(4)1龄级植株以高死亡率为代价发育为幼树;阳坡种群在其生活史中经历2个死亡高峰,最高峰在16龄级,阴坡种群经历4个死亡高峰,最高峰在9龄级。(5)谱分析表明,新疆野核桃种群的数量动态除受基波影响外,并表现明显的小周期波动,具有大周期内有小周期的多谐波迭加特征,且在11龄级的小周期波动与野核桃高生长特性有关,在17龄级的小周期波动可能与野核桃的生理特性有关。     

小家鼠种群中长期预测—灰色系统模型及随机序列分析

小家鼠种群中长期波动受很多因素影响,采用灰色系统模型及随机序列分析的方法可以较好地从宏观上预测其波动趋势。本文以灰色系统GM(1,1)模型为基础,利用历年小家鼠种群数量的调查值,对其变动趋势进行预测;然后,对预测剩余误差进行随机序列分析,建立线性预测式预测随机项;趋势预测值与随机项预测值的和,做为小家鼠种群中长期波动的预测。对新疆天山北麓农区1969年至1979年小家鼠自然种群数量的模拟结果表明,本文中的方法是较为简便有效的。     

我国草地螟发生间歇期的区域格局变化

2010—2016年我国草地螟一直维持总体轻发态势。为从长时间序列上分析连续轻发年份的历史地位,以1979年以来第2、3个暴发周期及其之间的间歇期为对照,分析了2010—2016年草地螟连续轻发的特点,即全国种群规模维持在历史低位,西北地区发生面积和比率加大,发生区域向西部缩减,提示我国草地螟种群发生已进入间歇期。分析了1979—2016年时间序列上华北、东北、西北3个地区的发生情况对全国的影响,结果表明:(1)华北地区、东北地区的发生面积自然对数值与全国发生面积自然对数值呈极显著的线性正相关,即华北、东北地区与全国发生趋势的年际波动完全一致;(2)西北地区发生面积自然对数值与全国的线性相关性达显著水平,但在不同的历史阶段西北地区与全国的波动趋势有明显差别;(3)自第3个暴发周期的2005年以后,西北地区的波动曲线逐渐与全国趋同,推测这一变化与新疆种群的建立和发展有关。     

我国粘虫发生概况:60年回顾

本文总结了我国1950—2013年粘虫Mythimna separata(Walker)发生、防治和损失概况,揭示了60余年中我国粘虫种群数量动态的演化规律。(1)南方地区越冬代种群发生年代间有波动,江淮1代发生区为害减轻,东北、华北、黄淮、西北和西南等2、3代发生区发生加重。(2)2代粘虫为发生最为广泛的1代,1995年以来粘虫主要危害作物已由小麦变为玉米。(3)寄主作物种植面积对种群数量总体变动起重要作用,气候条件影响年度间和区域间的种群波动和变化,农田生境影响小区域的发生危害程度。     

生态学简介(三)

三、种群数量变动的型式“J”和“S”型种群增长,只能代表种群增长期数量上升的状况。种群数量上升以后,将是怎样呢?理论上说,有几种可能(图10),即种群的平衡、下降、灭亡、不规则波动和周期性波动。     

小家鼠(Mus musculus)种群动态预测及机制的探讨

我国学者夏武平(1966)用9月铗日捕获率预测东北棕背(鼠平)(Clethrionomys rufocanus)数量以来,严志堂等(1983)应用种群年龄结构的回归方程预测新疆天山北麓农区塔西河地区的小家鼠(Mus musculus)种群密度获初步成功,并根据该文提供的一个改进公式M₁₀=5.60x+5.80(x表示种群年龄的成亚比,M₁₀表示小家鼠10月数量,即年内最高数量),提前11个月预测该地的小家鼠种群最高数量。     

干旱环境中褐家鼠的种群数量动态研究

动物种群数量动态研究是种群生态学研究的主要对象之一．借用Leslei矩阵建立数学模型对分布在新疆北部干旱环境中的褐家鼠种群数量动态进行了预测．同时经计算得新疆北部干旱环境中褐家鼠种群的特征根(λ),及其对应的特征向量(ns)．结果表明,12年后雌体总数达到29 801．686 28,同时根据褐家鼠种群增长曲线,发现该种群的增长属于稳定型的指数增长类型．     

马尾松毛虫种群消长与寄主受害程度的关系

研究不同受害程度松林与马尾松毛虫Dedrolimuspunctatus(Walker)种群发育阶段的关系。结果表明,松毛虫大面积发生时松林的受害程度可以很好地标示着松毛虫种群的发生阶段。松林点片受害显示松毛虫种群进入上升开始阶段;松林受害程度中等时,松毛虫仍处于上升种群阶段;当松林的针叶被吃光,表明松毛虫已处暴发阶段。松毛虫暴发种群在自然情况下,将出现典型的蛹期和下一代卵期的寄生率大幅度升高、雌性比、蛹重和产卵量等种群参数大幅度下降等特征;其后代会自然转入下降种群或进入低虫口期。但这些暴发种群的卵转入在保证充足饲料的可控条件下饲养时,其后代的生长发育、存活率、性比、蛹重等主要种群参数没有明显差异。即没显示出上升种群和暴发种群的特征差异,说明暴发种群的终止主要是受外界环境的限制而不是松毛虫本身的内因所致。     

Crystal structures of two hemoglobin components from the midge larva Propsilocerus akamusi (Orthocladiinae, Diptera)

The polymorphic components of hemoglobin (Hb) of the midge larva Propsilocerus akamusi were classified into two distinct types dependent on their spectroscopic properties, normal absorption (N) and low absorption (L). Analyses of the amino acid sequences of component VII (N-type Hb) and component V (L-type Hb) from P. akamusi indicated that one remarkable difference is the replacement of the distal histidine (His) with isoleucine (Ile) in component V. To clarify the structural differences between the two Hb components, we determined the crystal structures of components V and VII at resolutions of 1.64 A and 1.50 A, respectively. These crystal structures indicated a short additional helix comprising three amino acid residues at the C-terminal region in component V, and a typical globin fold including eight helices in component VII. Comparison of the heme regions of the Hb components suggests that the structural changes of the heme region in component V on ligation differ from that of usual Hb.     

Changes in the gamma chain heterogeneity of hemoglobin F of the baboon (Papio cynocephalus) postnatally and after partial switching to hemoglobin F production by various stimuli

The postnatal switch from hemoglobin (Hb) F to Hb A in the baboon (Papio cynocephalus) occurs somewhat more rapidly than in humans. Minor components which are related to Hb F and Hb A are also present and show reciprocal rise and fall. The baboon produces two types of gamma chain presumably from nonallelic genes. These have either an isoleucyl (I gamma) or a valyl (V gamma) residue in position 75. As in the human case with G gamma and A gamma chains, the ratio I gamma to V gamma chains changes during the postnatal switch. Production of Hb F in the baboon may be stimulated by phenylhydrazine or more effectively by 5-azacytidine. With phenylhydrazine, the ratio of I gamma to V gamma chains in the Hb F is the same as in the traces of Hb F in the juvenile or adult baboon. However, with 5-azacytidine, at least some of the Hb F that is produced probably has been synthesized with an I gamma to V gamma ratio that is present prenatally and in the newborn baboon.     

Neuronal types and their percent distribution within the magnocellular nuclei of the human basal forebrain

Three neuronal types constituting the magnocellular nuclei of the human basal forebrain have been differentiated with the aid of preparations stained for both Nissl material and pigment deposits: type I = large multipolar neurons contain loosely packed and faintly stained lipofuscin granules occupying a large portion of the cell body; type II = large spindle-shaped neurons reveal a densely packed accumulation of coarse and intensely stained lipofuscin granules, and type III = small nerve cells, scattered among these large neuronal components, with only a small number of faintly stained lipofuscin granules. The determination of the projection areas of the somata of the three neuronal types has led to a distribution pattern with three peaks. The ratio of the nerve cell types has been evaluated: 73.6% type I; 8.6% type II, and 17.8% type III neurons.     

武汉东湖南部湖汊的鼓藻类

从1963年9月到1964年12月,作者在武汉东湖南部的湖汊定点采得48号藻类标本,其鼓藻类十分丰富,经鉴定共有20个属,164个种,75个变种和13个变型。其中有2个新种、7个新变种和2个新变型,12个种、25个变种和5个变型是中国的新记录;在四季中出现频率较高的优势种类有11个种和1个变种。在不同季节共6次所采得的鼓藻种类的统计结果得出,在夏季(6月、8月)的种类最多,秋季和冬季(9月、10月、12月)次之,春季(4月)最少。在东湖252个鼓藻类的分类单位中,热带、亚热带类群共有45个,其中的19个是南亚和东南亚地区特有或普遍分布的类群,13个是以广西为模式产地的类群,从而反映武汉地区鼓藻类区系具有亚热带类型的特点,并与南亚和东南亚的鼓藻类区系关系密切。     

Immunohistochemical studies on hemoglobin-haptoglobin and hemoglobin catabolism sites

In order to clarify the catabolism sites of Hb-Hp and free Hb, the organ distributions of [125I]-Hb-Hp and [125I]-Hb were studied, and the cell types in each organ incorporating them were determined by immunohistochemical methods. After administration of [125I]-Hb-Hp in very small amounts to rats, 84.5% was incorporated into the liver, but the renal uptake was only 0.6%. [125I]-Hb was incorporated into the kidneys rather than into the liver when a fivefold greater amount of [125I]-Hb than the binding capacity of plasma Hp was administered. Parenchymal cells, but not Kupffer cells, in the liver were stained with anti-Hb or anti-Hp IgG after administration of Hb in an amount corresponding to the Hb binding capacity of Hp. The proximal tubule cells, but not the distal tubule cells, in the kidney were stained with anti-Hb IgG after administration of a fivefold greater amount of Hb than the binding capacity of Hp. On the basis of these results, we suggest that Hb-Hp was incorporated mainly into liver parenchymal cells and did not traverse glomeruli in the kidney. In contrast to Hb-Hp, free Hb could pass through the glomeruli easily and was incorporated into the proximal tubule cells.     

草鱼产卵类型的研究

本文是对已达性成熟年龄的池养和江河雌性草鱼产卵前后卵巢组织学结构的研究。实验结果证明草鱼是一次产卵类型。经人工催产后的雌性草鱼,由于亲鱼的成熟程度存在个体间的差异,有的全产,有的部分产。在湘江天然产卵场捕得的雌性草鱼,也有全产和部分产的。人工催产全产后的卵巢组织学结构是Ⅰ、Ⅱ时相,部分产后的卵巢组织学结构是Ⅰ、Ⅱ和Ⅳ(Ⅳ+、Ⅳ++)时相,已达满熟阶段但未经人工催产的卵巢组织学结构是Ⅰ、Ⅱ和Ⅳ(Ⅳ+++)时相,以上都未发现有处于Ⅲ时相的卵母细胞。从江河天然产卵场捕得的全产、部分产和尚未产卵的雌性草鱼的卵巢组织学结构,与上述结果一致。证实由Ⅲ时相到Ⅳ时相是同步性的。5月全产后的雌性草鱼,其卵巢组织学结构在6-9月内处于第Ⅱ期,没有新的Ⅳ时相卵母细胞。因此,夏季全产后的雌性草鱼,不可能在当年夏季或秋季完成由Ⅱ-Ⅲ-Ⅳ时相的发育程序。草鱼的卵巢成熟系数在繁殖季节只出现一次高峰。       

Mammalian adenylyl cyclase family members are randomly located on different chromosomes

Molecular cloning studies have elucidated the presence of multiple isoforms of mammalian adenylyl cyclase. So far, six different isoforms (I to VI) have been fully characterized. Comparison of their structural and biochemical characteristics suggests that the mammalian adenylyl cyclase family can be classified into four sub-families: type I, type III, type II/IV, and type V/VI. We have determined the chromosomal localization of these genes. Type I gene was assigned to chromosome 7, type III to chromosome 2, types II and IV to chromosomes 5 and 14, and types V and VI to chromosomes 3 and 12. Our results indicate that the different adenylyl cyclase isoforms, even within the same subfamily, are distributed randomly in the genome, in contrast to the chromosomal organization of other components within the same signaling pathway, such as catecholamine receptors and G proteins.     

桑天牛头部附器感器的扫描电镜观察

利用扫描电镜观测桑天牛Apriona germari(Hope)成虫的触角、下颚须和下唇须上感器的分布及超微结构。结果表明,雌、雄桑天牛触角上共存在6种感器,即毛形感器、锥形感器、刺形感器、芽形感器、鳞形感器和棒形感器,其中锥形感器分5种亚型,刺形感器分2种亚型,且部分感器在雌雄成虫触角上的分布模式及数量存在差异,如棒形感器及角锥形感器丛模式仅在雄虫触角上发现,而雌虫触角上的细锥形感器和耳锥形感器多于雄虫,芽形感器少于雄虫;下颚须和下唇须存在5种感器,即毛形感器、刺形感器、末梢锥形感器、钟形感器和隙缝感器,各种感器在雌、雄天牛下颚须和下唇须上的分布和数量无明显的区别。     

小叶章种群高度的季节动态

探讨了三江平原以小叶章为优势种的典型草旬、沼泽化草甸、沼泽３个植被类型中小叶章种群高度的变化规律。结果表明,在３个类型中,种群高度的季节动态均呈单峰型,极大值均出现在７月末,分别为１１２．６７ｃｍ、１０１．６１ｃｍ、８３．８８ｃｍ。ＨＡＧＲ的季节动态在７月末之前〉０,之后〈０;典型草甸和沼泽化草甸的极大值出现在６月末至７月中旬,沼泽则出现在６月中旬至６月末;极小值典型草甸出现在８月末至９月中旬,而