日本托特螨的生物学特性

日本托特螨（Tortonia sp.）是盗寄生性携播型螨类的一种。本研究通过室内人工饲养观察,对来源于日本的日本托特螨的形态特征进行了描述;并明确了此螨是营生于授粉昆虫——角额壁蜂（Osmia cornifrons（Radoszkowski））的巢筒育房中,属于盗寄生兼腐生性的螨类。在日本,此螨的年生活相有3相,以Ⅲ相中的幼螨、第1和第3若螨、成螨以及携播型第2若螨的虫态在壁蜂育房内过冬;成螨雌雄性比为1：1,无孤雌生殖,雌螨一生产卵量为（264.0±34.0）粒;各螨态在16～32℃温度条件下总发育历期为（52.1±5.5）～（14.7±2.0）d;此螨以寄主壁蜂贮存的食粮——花粉团和壁蜂的粪便为食料,26℃条件下取食这两种食料的发育历期虽有差异,但都能顺利生长发育并完成世代。本研究为日本托特螨的识别和防控提供了依据。     

3种不同柑桔中间砧在树体矿质营养含量上的双重效应

以纽荷尔脐橙/3种不同中间砧/枳为试材进行田间试验研究不同中间砧对接穗叶片矿质营养含量的影响。结果表明，3种中间砧对接穗叶片N、P、Ca、Fe和Zn含量年变化趋势的基本特征无明显影响；而对叶片K、Mg和Mn含量的年变化趋势特征在一定变化阶段上有明显影响。在年周期的不同时期里，叶片K和Mn含量在3种不同中间砧之间存在显著或极显著差异；而其余矿质营养含量在3种不同中间砧之间只在部分时期里存在显著或极显著差异；而在各矿质营养含量存在显著或极显著差异的不同时期间，该矿质营养含量在3种不同中间砧之间的相对高低差异趋势不全相同。     

转基因植物对农业、农民和生态发展的意义

转基因植物商业化生产10年以来,尽管遇到各种各样的阻力,仍以前所未有的速度发展。长期积累的数据表明,在经济利益上,采用转基因植物的农民获得了显著的经济效益。由于采用转基因植物,农药特别是高毒农药使用量减少,减少了农田环境和水环境的化学毒素毒物的残留。由于转基因抗虫植物虫害减少,在粮食产品中有害微生物及其毒素毒物残留大大降低。这表明,在现有技术基础上,转基因植物商业化有利于农民生活质量的提高和环境的改良。     

The ecology of extinction: population fluctuation and decline in amphibians

Even among widespread species with high reproductive potentials and significant dispersal abilities, the probability of extinctions should be correlated both with population size variance and with the extent of population isolation. To address how variation in demographic characteristics and habitat requirements may reflect on the comparative risk of species decline, I examined 617 time series of population census data derived from 89 amphibian species using the normalized estimate of the realized rate of increase, ΔN, and its variance. Amphibians are demonstrably in general decline and exhibit a great range of dispersal abilities, demographic characteristics, and population sizes. I compared species according to life-history characteristics and habitat use. Among the populations examined, census declines outnumbered increases yet the average magnitudes for both declines and increases were not demonstrably different, substantiating findings of amphibian decline. This gives no support for the idea that amphibian population sizes are dictated by regimes featuring relatively rare years of high recruitment offset by intervening years of gradual decline such that declines may outnumber increases without negative effect. For any given population size, those populations living in large streams or in ponds had significantly higher variance than did populations of completely terrestrial or other stream-dwelling amphibians. This could not be related to life-history complexity as all the stream-breeding species examined have larvae and all of the wholly terrestrial species have direct development without a larval stage. Variance in ΔN was highest amongst the smallest populations in each comparison group. Estimated local extinction rates averaged 3.1% among pond-breeding frogs, 2.2% for pond-breeding salamanders, and negligible for both stream-breeding and terrestrial direct-developing species. Recoveries slightly exceeded extinctions among European pond-breeding frogs but not among North American pond-breeding frogs. Less common species had greater negative disparities between extinctions and recoveries. Species with highly fluctuating populations and high frequencies of local extinctions living in changeable environments, such pond- and torrent-breeding amphibians, may be especially susceptible to curtailment of dispersal and restriction of habitat.     

Influences of life history, environmental gradients, and disturbance on riparian tree regeneration in Western Oregon

In two related field studies: (1) a multiscale riparian forest inventory and (2) a comparative study of natural forest gap and nongap environments, we explored regeneration patterns of native riparian trees in relation to large- and small-scale ecological drivers in four western Oregon watersheds spanning a climatic gradient from dry to wet. Twenty-three tree species were classified by life history traits into five functional groups that differed in shade and drought tolerance; distribution and abundance of tree regeneration were analyzed by group. For most groups, seedling abundance varied substantially across the large scale climate gradient. In particular, drought tolerant species decreased sharply in abundance from the drier to wetter watersheds. Overall seedling frequency and diversity also decreased from the driest to wettest watersheds, while nurse log use increased. Regeneration of most, but not all, species was greater in gaps.Principal conclusions are that life history information was useful for categorizing species and quite predictive of regeneration behavior overall, yet for many species contextual factors such as climate, forest structure, and adjoining species were also very important. Species appeared to regenerate opportunistically wherever local conditions fell within their environmental tolerances and competitive abilities. Management or restoration of riparian forests, therefore, requires knowledge of site conditions, the life history of the riparian trees present, and in particular an understanding of the species’ environmental tolerances, disturbance responses, and competitive abilities relative to one another.     

Using process-based modelling to analyse earthworm life cycles

To understand the life cycle of an organism, it is important to understand the physiological processes that govern growth and reproduction. In this paper, we re-analyse a life-cycle data set for the earthworm Eisenia veneta, using a process-based model. The data set comprises measurements of body size and cocoon production over 200 days, at two temperatures (15-25 °C) and two densities (five and 10 worms per container, but with the same worm:soil weight ratio). The model consists of a set of simple equations, derived from Dynamic Energy Budget (DEB) theory. The dynamics of growth and reproduction are simultaneously described by the model, using very few parameters (five parameters for four curves). This supports the use of this model for efficient analysis of earthworm life-cycle data, and to interpret the effects of stressors. However, there was considerable inter-individual variation in the response, hampering the interpretation of the temperature and density effects. A temperature increase corresponded to an increase in the rate constants for growth and reproduction (with the same factor), without affecting the other parameters, as expected from DEB theory. Changing the earthworm density hardly affected the growth curves, but had an unexpected effect on reproduction: at higher densities, the worms start to produce cocoons at a larger body size and the maximum reproduction rate was lower. This study confirms the use of DEB as a reference model for earthworms, and using this model, we can recognise that temperature has a predictable effect on the life cycle of E. veneta. Furthermore, this analysis reveals that the effects of density are less clear and may involve a change in energy allocation that requires further study.     

杂交稻二化螟自然种群生命表

以常规稻作对照,研究了杂交稻二化螟自然种群生命表。结果表明:二化螟存活率和种群趋势指数因世代不同而异。同一世代,杂交稻二化螟世代存活率和种群趋势指数高于常规稻二化螟。杂交稻二化螟主要死亡虫期是蚁螟孵出至侵入期,其次是3、4龄期,影响种群变动的关键虫期是蚁螟孵出至侵入期。     

芦笋十四点负泥虫发生规律与防治技术初探

十四点负泥虫是北京市新发现的一种为害芦笋的害虫。通过田间观察试验,了解了该虫的形态特征和生物学特性,明确了在北京地区一年发生3～4代,提出了应用农业防治、生物防治和化学农药防治等控制该虫的方法。     

黄杨绢野螟生物学特性研究

摘要本文阐述了黄杨绢野螟[Diaphania perspectalis(Walker)]在上海地区年发生3代,并以3～4龄幼虫在黄杨木叶片上结苞越冬。翌年3月中下旬开始活动为害;经过2个世代后,第三代幼虫于9月中旬起陆续结茧越冬。同时对该虫的各虫态发育历期、生物学特性等进行了研究,为指导防治提供依据。     

柑桔臀纹粉蚧的研究

柑桔臀纹粉蚧在上海地区常规栽培管理的十字景天上一年发生3代,以受精雌成虫或产卵雌成虫越冬。本文报导了此虫的年生活史及各虫态的生活习性、发育进程与历期,并测得其卵的发育起点温度为11.49±0.53℃;有效积温为73.11±3.39日度。以15%铁灭克颗粒剂根施;40%氧化乐果10O倍液浇灌,防治效果在97%以上.