Experienced males have higher mating success than virgin males despite fitness costs to females

It is generally assumed that mating history has potentially important effects on the mating biology of insects, and differences in mating success of males, in relation to their mating history, have been commonly documented in Lepidoptera. Mating success of male European corn borer Ostrinia nubilalis, in relation to their mating history, and consequent fitness parameters for their female mates, were investigated. Mating experience significantly increased mating success for O. nubilalis males. Mating with experienced males significantly reduced lifetime fecundity and longevity of females. Sperm depletion, transfer of less nutritive substances or more toxic substances may explain the female response to mating with experienced males. Male persistence or some other compensatory mechanism may account for female acceptance of experienced males.     

Fate and movement of microorganisms in the environment

Summary This literature review indicates how little is known about the growth of introduced bacteria. The available data base is so sparse that one can only speculate on the environmental conditions and the physiological traits that are needed to permit bacterial growth. Although methods are available to label organisms so that their multiplication can be detected under natural conditions, those methods have not been used sufficiently often to provide a meaningful base of information to allow a definition of conditions that favor multiplication of particular species or the organisms that are likely to proliferate in particular environments. However, because methods exist to monitor microbial growth, and new and better methods can be developed easily, it should not be difficult—provided research funds are made available—to expand greatly the data base and provide adequate information to be used for predicting the behavior of genetically engineered organisms in nature.     

离子色谱法测定环境空气中氯化氢时应注意的问题

用离子色谱法测定大气中低浓度氯化氢,方法灵敏、准确度高,但测定过程极易受污染干扰.本文主要探讨了在前期准备、采样和分析全过程中应注意的一些问题.     

The extent of monoculture and its effects on insect pest populations with particular reference to wheat and cotton

The effects of changes in region-wide cropping patterns on insect pest populations have not been well studied. This paper reviews the empirical literature and develops a theoretical framework for these effects. Changes in regional cropping patterns do affect insect populations, and in at least one case, the presence of fence rows and thickets provide a net benefit to the nearby agro-ecosystem. Of the 17 studies reviewed here, 15 discuss cotton or wheat. With cotton, increased monoculture leads to increases in 13 pest populations and a decrease in two. With wheat, increases occurred in only three populations, while seven were not affected or decreased. Most of the insect populations that were not affected or decreased are multivoltine and oligophagous or polyphagous. All of the populations that increased are monophagous on the crop in the region in which they were studied. A higher proportion of the wheat fauna is multivoltine and oligophagous or polyphagous than the cotton fauna. This may explain the difference between the response of the wheat fauna and the cotton fauna to changes in the extent of monoculture. Additional factors may be insect vagility, host-finding ability, and the response of the predators and parasitoids.     

环境的不确定性对声纳作用距离预报的影响

由于海洋环境的复杂性,声速梯度存在一定的不确定性.用蒙特卡洛方法对声速梯度进行模拟统计,并用WKBZ方法计算传播损失,得出各个距离上传播损失的概率分布直方图,由此可以导出声纳作用距离的概率分布直方图.相对于传统的声纳作用距离预报结果,文中给出的作用距离预报结果是一个满足某一分布的随机变量,而非某一个单一确定的值,为作用距离的预报提供了概率的依据.     

上海环城林带植物群落景观美学评价

以上海环城林带为对象,采用美景度评判法进行不同植被类型的景观评价,评价分为林内景观和林外景观2个空间层次,分别在春、夏、秋、冬4个季节进行。结果表明,林内景观平均值和林外景观的美景度都表现为夏季最高,冬季最低。在不同植被类型的林内景观中,落叶针叶林在不同季节均表现出最高的美景度,竹林的美景度最低;针叶林中,常绿针叶林的美景度四季均低于落叶针叶林;阔叶林中,落叶阔叶林的美景度在春季和夏季高于常绿落叶林,常绿阔叶林在秋季和冬季高于落叶阔叶林;混交林中,除秋季外,针阔混交林的美景度均高于常绿落叶阔叶混交林。     

苔藓植物资源保护利用中的生态环境效应研究进展

苔藓植物资源丰富、种类繁多、分布广泛,是一类以孢子繁殖,由水生向陆生过渡的高等植物。苔藓植物的结构相对简单,对环境变化的反应较为敏感,被广泛应用为环境污染的指示植物。苔藓植物生长与所处的环境有关,而它的生长对土壤结皮形成、水土保持、生态小环境改善等方面又发挥着重要的促进作用。综述了苔藓植物的资源分布、苔藓植物对环境污染的响应、苔藓植物的生态效应等方面的研究进展,但是目前的研究领域及其研究角度还存在着各自的不足。随着经济建设快速发展,世界各地大量的矿山开采、水电开发等工程建设对土地、自然环境的破坏日益严重,非农业建设以及农产品需求不断增加造成了农田的生态结构与功能发生着不断变化。针对各地经济社会发展以及城乡建设现状,积极开展工程建设领域以及农田生态系统苔藓植物的生态环境效应研究是今后值得十分重视的研究方向。     

苔藓植物资源保护利用中的生态环境效应研究进展

苔藓植物资源丰富、种类繁多、分布广泛,是一类以孢子繁殖,由水生向陆生过渡的高等植物。苔藓植物的结构相对简单,对环境变化的反应较为敏感,被广泛应用为环境污染的指示植物。苔藓植物生长与所处的环境有关,而它的生长对土壤结皮形成、水土保持、生态小环境改善等方面又发挥着重要的促进作用。综述了苔藓植物的资源分布、苔藓植物对环境污染的响应、苔藓植物的生态效应等方面的研究进展,但是目前的研究领域及其研究角度还存在着各自的不足。随着经济建设快速发展,世界各地大量的矿山开采、水电开发等工程建设对土地、自然环境的破坏日益严重,非农业建设以及农产品需求不断增加造成了农田的生态结构与功能发生着不断变化。针对各地经济社会发展以及城乡建设现状,积极开展工程建设领域以及农田生态系统苔藓植物的生态环境效应研究是今后值得十分重视的研究方向。