一种模拟昆虫种群动态的改进的变维矩阵模型

提出了一种模拟昆虫种群动态的改进的变维矩阵模型,该模型以发有历期为维数,采用分解与合成的方法变维,并考虑了个体间的发育差异。经模拟检验,模型模拟结果略优于徐汝梅等（1981）变维矩阵模型的结果。     

稻纵卷叶螟(Cnaphalocrocis medinalis Guene''e)种群生命系统模型的研究

经过五年来对稻纵卷叶螟自然种群生命表的研究,组建了预测种群动态的生命系统模拟模型。本模型为一变维矩阵组合模型。除能随环境温度而改变矩阵维数外,采用生理年龄为矩阵步长。每一虫期内各个体的发育不一致,矩阵中各元素均为某些环境因素的函数,共组建有18个子模式。在输入起始日期,预测期限,水稻生育期,环境温、湿度和初始种群各年龄向量后,即可自动打印出逐日种群年龄向量及总虫量。计算机模拟曲线与实测曲线基本吻合。本模型可用来预测南京地区稻纵卷叶螟二代迁入峰后种群的发展以至第三代种群各虫态的起始虫量和发生期。     

广义LESLIE矩阵模型的稳定年龄结构及其性质

〔1〕提出了一个描述生物种群动态的矩阵模型——广义Leslie矩阵模型。这个模型是Leslie矩阵模型的一个推广,它考虑了昆虫发育过程中个体在虫态发育历期上的差异。因此与普通Leslie矩阵模型相比,该模型更适于描述昆虫种群的动态。〔2〕对广义Leslie矩阵模型的渐近性质做了分析,给出了相应的稳定年龄结构的表达式,同时从马氏链的观点出发,给出了种群年龄结构渐近稳定或周期变化的充要条件。本文是〔2〕的继续,将给     

昆虫种群动态模拟方法的一点改进──三化螟种群动态模拟模型的研究

以Ｒｕｅｓｉｎｋ（１９７６）的模型为基础,根据昆虫个体一般不同步地进入下一发育阶段的状况,当昆虫各虫态发育到完成该虫态发育所需要的最低年龄级数后,假定各年龄级的昆虫种群均以一定的概率分布函数值进入下一个发育阶段,同时根据有效积温向前推进。据此,对昆虫种群动态模拟方法作了一点改进。该方法综合了已有的种群模型的优点,因而较Ｒｕｅｓｉｎｋ（１９７６）和ＣｈｉＨｓｉｎ等（１９８５）提出的方法更真实地反映了昆虫种群动态的变化规律。根据三化螟自然种群生命表的资料,分析和确定逐日存活率、逐日发育率和逐日生殖率,对三化螟种群进行逐日动态模拟和预测,同时引入环境因素对种群的控制作用,研究不同环境条件下的种群动态,经验证,模型基本能够反映田间三化螟的发生规律。     

褐飞虱种群动态的模拟模型(英文)

本文根据种群生命系统的概念和分析,组建了模拟褐飞虱(Nilaparvata lugens St(?)l)种群动态的计算机模型。该模型包括一个多列矩阵和一组差分方程。多列矩阵用于描述褐飞虱种群的龄期重叠现象及其年龄——虫态结构;差分方程用于计算种群的增长过程。在建模时,我们把10日度作为褐飞虱发育的一个年龄,用天作为模拟的时间步长,同时利用了褐飞虱特定龄期的发育速率,根据生命表数据计算的特定龄期存活率、长翅型成虫的迁飞类型及数量、雌成虫的生殖力等有关资料。经过采用福建省龙海、福州和沙县三个地方1896—1990的实际观测资料与模型的预测结果进行比较,验证了该模型的有效性和准确性;通过改变模型的主要输入变量,得到了各种不同的输出结果,由此对模型的行为及真实性作了分析。笔者认为该模型可用于进一步研究褐飞虱的生物学、生态学以及综合治理的基础,稍作改进,也可用于描述其它昆虫的种群生命系统。     

稻纵卷叶螟种群系统动态模拟

本文组建了稻纵卷叶螟种群系统模似模型,它由系统亚模型和总模型二个部分组成.系统亚模型包括发育、死亡和繁殖三个子模块.系统总模型是作者提出的新模型,它综合了前人所提出的种群模型的优点,以差分方程形式给出,以生理时间为单位,考虑了种群内个体间发育速率的差异,不仅能模拟种群数量动态,而且能模拟种群年龄结构,同时能预测发生期.模型有效性检验表明,模拟结果基本上能吻合实测结果.文中还对5个影响因子进行了灵敏性分析.     

稻纵卷叶螟种群系统动态模拟

本文组建了稻纵卷叶螟种群系统模似模型,它由系统亚模型和总模型二个部分组成.系统亚模型包括发育、死亡和繁殖三个子模块.系统总模型是作者提出的新模型,它综合了前人所提出的种群模型的优点,以差分方程形式给出,以生理时间为单位,考虑了种群内个体间发育速率的差异,不仅能模拟种群数量动态,而且能模拟种群年龄结构,同时能预测发生期.模型有效性检验表明,模拟结果基本上能吻合实测结果.文中还对5个影响因子进行了灵敏性分析.     

具有时间依赖转移率的昆虫种群的稳定性理论

研究Leslie种群的稳定性一直是种群动态研究中的重要课题。近几年,这项工作已得到比较完满的解决。考虑到昆虫个体在发育历期上的差异,〔1〕对Leslie模型进行了推广,提出了广义Leslie矩阵模型。〔2〕在转移率为常数的情况下,讨论了有关广义Leslie种群的渐近稳定性等方面的问题。本文将研究具有时间依赖转移率的广义Leslie种群的稳定性,给出一个具有时间依赖转移率的昆虫种群渐近于一个稳定的年龄分布的充分条件。     

烟青虫种群动态模型的研究

在对烟青虫Ｈｅｌｉｃｏｖｅｒｐａａｓｓｕｌｔａ实验种群研究的基础上,应用变维矩阵综合差分方程,建立了烟青虫种群动态模拟模型,模型采用分块矩阵的方式,以实际日龄为步长,通过适当增加矩阵维数,对虫期（态）向量实行按矩阵维数的变化而伸缩的形式,使模型不但适合于变温条件,而且能够表示烟青虫个体发育的差异,该理论模型有待于地方化。     

陕西不同地区栓皮栎种群年龄结构动态模型的研究

栓皮栎种群动态模型能阐明其自然种群动态的规律,揭示种群的内在机制和对种群行为进行预测。矩阵模型是一种i状态分布方法,依靠矩阵形式来处理种群的特征分布,可以模拟和预测种群中各个年龄组的数量动态和年龄结构的变化,它能够从目前已知的年龄结构及种群的生存率和生育率,来推测种群的未来年龄结构。在研究栓皮栎种群动态时,也借用该模型对栓皮栎种群各年龄组的结构和数量动态作出预测。Leslie矩阵模型就是该模型中的一种,利用该模型的理论和方法,对栓皮栎种群的自然变化过程进行了模拟和预测。结果发现,从分布中心到分布边缘,随着生境的差异,栓皮栎种群产生幼苗的年龄级、内禀增长率、生育力和幼苗的数量都发生变化,预测结果与实际反映的情况基本一致,表明Leslie矩阵模型是一种较为理想的反映种群动态的模型。模型表达形式简单,参数生态学意义确切,应用精度高,从而达到准确预测栓皮栎种群动态的目的。     

Age and size at maturity: A quantitative review of diet‐induced reaction norms in insects

Optimality models predict that diet‐induced bivariate reaction norms for age and size at maturity can have diverse shapes, with the slope varying from negative to positive. To evaluate these predictions, we perform a quantitative review of relevant data, using a literature‐derived database of body sizes and development times for over 200 insect species. We show that bivariate reaction norms with a negative slope prevail in nearly all taxonomic and ecological categories of insects as well as in some other ectotherm taxa with comparable life histories (arachnids and amphibians). In insects, positive slopes are largely limited to species, which feed on discrete resource items, parasitoids in particular. By contrast, with virtually no meaningful exceptions, herbivorous and predatory insects display reaction norms with a negative slope. This is consistent with the idea that predictable resource depletion, a scenario selecting for positively sloped reaction norms, is not frequent for these insects. Another source of such selection—a positive correlation between resource levels and juvenile mortality rates—should similarly be rare among insects. Positive slopes can also be predicted by models which integrate life‐history evolution and population dynamics. As bottom‐up regulation is not common in most insect groups, such models may not be most appropriate for insects.     

Food limitation and insect outbreaks: complex dynamics in plant-herbivore models

1. The population dynamics of many herbivorous insects are characterized by rapid outbreaks, during which the insects severely defoliate their host plants. These outbreaks are separated by periods of low insect density and little defoliation. In many cases, the underlying cause of these outbreaks is unknown. 2. Mechanistic models are an important tool for understanding population outbreaks, but existing consumer-resource models predict that severe defoliation should happen much more often than is seen in nature. 3. We develop new models to describe the population dynamics of plants and insect herbivores. Our models show that outbreaking insects may be resource-limited without inflicting unrealistic levels of defoliation. 4. We tested our models against two different types of field data. The models successfully predict many major features of natural outbreaks. Our results demonstrate that insect outbreaks can be explained by a combination of food limitation in the herbivore and defoliation and intraspecific competition in the host plant.     

中国昆虫生态学研究的透视

<正> 昆虫生态学在我国是通过几十年来密切结合农、林、牧实际,解决生产中不断提出的重大问题而发展起来的。随着研究问题不断深入,交叉学科不断渗透,使昆虫生态学在生物学宏观领域中成为迅速发展的一门学科。现将7个主要领域研究的动态加以评述。     

Population dynamic models of the spread of Wolbachia

Wolbachia are endosymbionts that are found in many insect species and can spread rapidly when introduced into a naive host population. Most Wolbachia spread when their infection frequency exceeds a threshold normally calculated using purely population genetic models. However, spread may also depend on the population dynamics of the insect host. We develop models to explore interactions between host population dynamics and Wolbachia infection frequency for an age-structured insect population regulated by larval density dependence. We first derive a new expression for the threshold frequency that extends existing theory to incorporate important details of the insect's life history. In the presence of immigration and emigration, the threshold also depends on the form of density-dependent regulation. We show how the type of immigration (constant or pulsed) and the temporal dynamics of the host population can strongly affect the spread of Wolbachia. The results help understand the natural dynamics of Wolbachia infections and aid the design of programs to introduce Wolbachia to control insects that are disease vectors or pests.     

Intraguild predation: fiction or reality?

Intraguild predation has become a major research topic in biological control. Quantification of multipredator interactions and an understanding of the consequences on target prey populations are needed, which only highlights the importance of population dynamics models in this field. However, intraguild predation models are usually based on Lotka–Volterra equations, which have been shown not to be adequate for modeling population dynamics of aphidophagous insects and their prey. Here we use a simple model developed for simulation of population dynamics of aphidophagous insects, which is based on the type of egg distribution made by predatory females, to estimate the real strength of intraguild predation in the aphidophagous insects. The model consists of two components: random egg distribution among aphid colonies, and between-season population dynamics of the predatory species. The model is used to estimate the proportion of predatory individuals that face a conflict with a heterospecific competitor at least once during their life. Based on this, predictions are made on the population dynamics of both predatory species. The predictions are confronted with our data on intraguild predation in ladybirds.     

Developmental database for phenology models: related insect and mite species have similar thermal requirements

Two values of thermal requirements, the lower developmental threshold (LDT), that is, the temperature at which development ceases, and the sum of effective temperatures, that is, day degrees above the LDT control the development of ectotherms and are used in phenology models to predict time at which the development of individual stages of a species will be completed. To assist in the rapid development of phenology models, we merged a previously published database of thermal requirements for insects, gathered by online search in CAB Abstracts, with independently collected data for insects and mites from original studies. The merged database comprises developmental times at various constant temperatures on 1,054 insect and mite species, many of them in several populations, mostly pests and their natural enemies, from all over the world. We show that closely related species share similar thermal requirements and therefore, for a species with unknown thermal requirements, the value of LDT and sum of effective temperatures of its most related species from the database can be used.     

Persistence of pyrophilous insects in fire-driven boreal forests: population dynamics in burned and unburned habitats

Several boreal insect species respond to smoke and heat generated by forest fires and use recent burns to reproduce in high numbers. Some of these species are rare or uncommon in undisturbed forests, and the contribution of recently burned habitats to their population dynamics has been deemed crucial by some to their long-term persistence. Consequently, the severe decline seen in some species in Fennoscandia has been frequently linked with fire suppression. In this paper, we explore some aspects of the spatial dynamics of pyrophilous insect populations in relation to the expected relative contribution of burned and unburned habitats to their global population dynamics. Forest fires are, throughout the boreal forest biome, generally highly aggregated in some years while rare in most other years. The low connectivity between fire events and the typical life cycle seen in these species make it improbable that recent burns act as significant population sources. This leads us to suggest that populations of pyrophilous species may be more limited by the adequacy of the unburned matrix than by the occurrence of fire events. Moreover, by combining an age-class distribution model and a dead wood availability model, we show that the quality of the unburned matrix increases in landscapes with longer fire cycles, in which pyrophilous insects should persist at higher population levels. We conclude that the degradation of the unburned habitat better explains the decline of pyrophilous insects than fire suppression alone.     

Demographic consequences of inflorescence-feeding insects for Liatris cylindracea, an iteroparous perennial

While floral herbivores and predispersal seed predators often reduce plant reproductive output, their role in limiting plant fitness and population growth is less clear, especially for iteroparous perennial plant species. In this study we experimentally excluded floral herbivores and predispersal seed predators (insecticide spray versus water control) over a 2-year period to examine the effect of inflorescence-feeding insects on levels of seed production, seedling emergence, and juvenile establishment for Liatris cylindracea, an iteroparous perennial plant. In addition, we collected detailed demographic data on all life stage transitions for an additional set of individuals in the same population over 4 years. We used the experimental and demographic data to construct stochastic individual-based simulations to evaluate the overall effect of inflorescence-feeding insects on adult recruitment per maternal plant (a fitness component) and population growth rate. The insect exclusion experiments showed that damage due to insects decreased seed production, seedling emergence, and juvenile establishment for both years' experiments. These results indicate that recruitment was seed-limited through juvenile establishment, and that inflorescence-feeding insects influenced the degree of seed limitation. Results of the individual-based simulation models, which included individual demographic and temporal stochasticity, showed that inflorescence-feeding insects negatively affected the number of adult offspring per maternal plant recruited into the population and population growth rate for both years' experiments. Taken together, the results of the experimental exclusions and the individual-based models indicate that inflorescence-feeding insects can influence population growth rate, and have the potential to act as a selective force for the evolution of traits in this plant species.