历史查询   



 为了更好的帮助您理解掌握查询词或其译词在地道英语中的实际用法，我们为您准备了出自英文原文的大量英语例句，供您参考。 
Summer drought was the main mortality factor in all the microhabitats.


Mean mortality varied greatly by species and within species, anatomical hooking location was the most important mortality factor.


choledochus to be a castrating agent and a serious mortality factor in adult cockle populations.


The bird seems to bean incompletely additive mortality factor acting onthe pest and it can also alter the relativemortalities imposed by the other natural enemies.


Egg disappearance, the major mortality factor, was low in the first four weeks after transplanting and then increased.

 更多 


 The present paper deals with the studies of population dynamics of the 2nd generation of rice leaf roller, Cnaphalocrocis medinalis Guenee, by means of the life table method in Hailing island of Yangjiang county, Guangdong province. The life tables and average life table of 19761981 have been constructed. To summarize, based on the life tables and the models,the present analysis has perhaps been carries enough to show the following results.A)the plan of an integrated control of rice insect pests in Hailing... The present paper deals with the studies of population dynamics of the 2nd generation of rice leaf roller, Cnaphalocrocis medinalis Guenee, by means of the life table method in Hailing island of Yangjiang county, Guangdong province. The life tables and average life table of 19761981 have been constructed. To summarize, based on the life tables and the models,the present analysis has perhaps been carries enough to show the following results.A)the plan of an integrated control of rice insect pests in Hailing island was successful. After the 4thinstar larva stage, the harmful period,the population size of rice leaf roller was lower than the economic damage threshold,and the indices of population trend(Ivalue) of the 2nd generation were decreased to a level lower than 1, in 19761981, being 0.7666, 0.3088, 0.2532, 0.0040, 0.0036 and 0.1243 respectively.B)According to the component analysis of the 6 year's average life table, the Mvalue showed that the natural enemies were playing an important role in controlling the population size of rice leaf rollereIn the component analysis, the Mvalue means that if there were no mortality coused by factor i, the index of population trend I would increase Msi times as against the original Ivalue.Of all mortality factors affecting the population in the 2nd generation,the "predators and other" in the period of the 1stinstar larva stage is the most imortant(MS4 = 2.46). The "predators" of egg period," predators and other" in period of 5thinstar,2ndinstar, 4thinstar, 3rdinstar larva stages are important also (Ms13 = 1.89, Ms8 = 1.87, Ms11 = 1.67, Ms8 = 1.62).The sum total of all "predators"MvalueParasites,Apanteles cypris Nixon, is an important factor also. Its sum total of Mvalue in the periods of the 1stinstar, 2ndinstar and 3rdinstar larvae stages is 1.89(Ms5 Ms7 Ms9 = 1.89)Theoretically, with absence of all the predators, parasites and disease agents, the Ivalue would have increased to 358.69 times of the original, or the population size of the 3rd generation would have been 31.78 times than that of the 2nd generation.C) According to the keyfactor analysis,the data of life tables of the 19761981 showed that the "Predators and other"in the period of the Istinstar larva stage is the key factor affecting the population dynamics of the insect pest in the 2nd generation.Other factors closely related to the population dynamics are "Predators and other" in the periods of the 4thinstar 5thinstar larva stages and "Parasites" in the pupa stage,These results are a basic data for constructing the model for monitoring the population size of rice leaf roller, which will be reported in following paper.  本文应用昆虫生命表方法在阳江县海陵岛研究稻纵卷叶螟种群数量动态问题。试验自1976年开始,至1981年积累了6年第二世代稻纵卷叶螟生命表的数据。通过生命表的组份分析,说明了海陵岛于1976—1981年间贯彻执行的综合防治措施是合理的,是6年来第三世代以后不致达到为害水平的重要原因;说明了天敌对第二世代稻纵卷叶螟种群数量起着重要的抑制作用;通过分析,找出了对稻纵卷叶螟第二世代种群数量起主要作用的因素和对种群数量起关键作用的因素。该项研究为进一步建立海陵岛第二世代稻纵卷叶螟为害期的数量预测和第三世代卵期的数量预测模型提供基础。关于数量预测模型将在下文介绍。  Based on the studies of life tables of diamondback moth (DBM),Pbatella xylostella (L.),"perasitization" at the pupae stage were established as the most important mortality factor for the population of DBM.The new style of insecticides (chitin synthesis inhibiting insecticide) IKI7899 which was sprayed at the concentration of 50 ppm were promised to be favourable to the parasites,and could provide effective control of the DBM,with 98.80%of the control efficency for the larvae and 0.0009 of the population... Based on the studies of life tables of diamondback moth (DBM),Pbatella xylostella (L.),"perasitization" at the pupae stage were established as the most important mortality factor for the population of DBM.The new style of insecticides (chitin synthesis inhibiting insecticide) IKI7899 which was sprayed at the concentration of 50 ppm were promised to be favourable to the parasites,and could provide effective control of the DBM,with 98.80%of the control efficency for the larvae and 0.0009 of the population trend index (I),while conventional insecticides cypermethrin (200 ppm) and dichlorvos (1600 ppm),which were mixed used for four sprays at an interval of 45 days,in the whole generation were harmful to the enemies and could not effecctively control the DBM,with 62.82% of the control efficency and 9.2769 of the trend index (I).  通过对小菜蛾种群生命表的研究,确定蛹期“寄生”是影响小菜蛾种群的重要因子。昆虫生长调节剂IKI—7899对小菜蛾蛹期寄生天敌安全,以50ppm的剂量喷施后,小菜蛾幼虫各虫期累积死亡率达98.80％,并显著抑制种群的增长(种群趋势指效Ⅰ值为0.0009);常规药剂氯氰菊酯(200ppm),DDVP(1600 ppm)杀伤天敌,一个世代连续混合喷施4次,幼虫期累积死亡率仅为62.82％,种群显著增长(Ⅰ值为9.2769)。常规药剂的费用是IKI—7899的5倍多。  Controllability and observability, two important concepts in engineering cybernetics, are useful in studying animal population systems. An insect population system is comprised of: 1) the subject population and 2) the environment factors affecting the pupulation. If the whole system is to be manipulated, the input variables (such as mortality factors) that affect the population must be controlled. Similarly, information necessary for understanding the internal system, is seen through the output... Controllability and observability, two important concepts in engineering cybernetics, are useful in studying animal population systems. An insect population system is comprised of: 1) the subject population and 2) the environment factors affecting the pupulation. If the whole system is to be manipulated, the input variables (such as mortality factors) that affect the population must be controlled. Similarly, information necessary for understanding the internal system, is seen through the output variables (such as insect life stages) of that system. Based on the state space model of a dynamic system, the present paper gives a short review of the concepts of controllability and observability and of some necessary and sufficient conditions which the system must fulfil in order to have these properties. An application of these conceps to the population system of spruce budworn, Choristoneura fumiferana (Clemens), is shown. Controllability of this system requires that the input variables (mortality factors) have an effect on all life stages. If a given control strategy affects only the mortality of one life stage, it is difficult to manipulate the population because the other stages will remain fluctuate. This system is observable because all information about its population dynamics can be obtained from visible life stages. Thus, controllability and observability of an insect population system must be analyzed before developing an optimal management strategy.  能控性和能观性是工程控制论中２个重要的新概念，它们在研究动物种群系统时是很有用的．昆虫种群系统是由对象种群和影响该种群的环境因素组成的，因此，只有当影响对象种群的输入变量（如死亡因子）是可控的，整个系统才是能够控制的；只有当与系统内部状态有关的输出变量（如昆虫的发育阶段）是可观的，整个系统才是能够观测的．本文在描述动态系统状态空间模型的基础上，简述了系统能控性和能观性的概念及其充分和必要条件，同时运用这２个基本概念及其分析方法研究了云杉卷叶蛾种群系统的能控性和能观性问题．结果表明，满足云杉卷叶蛾种群系统能控性的充分和必要条件是系统的输入变量（防治对策）必须对种群的各个虫态或龄期起到控制作用，因为一种防治对策如果只能控制一个虫态或龄期，其余虫态或龄期的数量仍然得不到控制而任意波动，在这种情况下，该系统就是不可控系统．云杉卷叶蛾种群系统是能观系统，因为该系统的内部状态与输出变量有联系，有关种群动态的信息可以通过各个虫态或龄期来观测．研究昆虫种群系统的能控性和能观性，是寻求系统优化控制对策的必要前提   << 更多相关文摘 
相关查询  



