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1.
Summary Some calculations were performed usingTang's method as an aid in planning experiments for studying the population dynamics of the Jeffrey pine beetle. The population
dynamics studies were aimed at detecting the importance of specific effects, e. g., tree diameter, tree height. TheTang procedure is a method of estimating the sample size required to detect effects of a given magnitude with analysis of variance
tests. Using this procedure some sample calculations were performed which indicated the sample size needed, and the efficacy
of different strategies of improving the results, e. g., increasing the number of trees sampled versus increasing the area
of the tree sampled. The statistical parameters used in the calculations were estimated from some preliminary sampling data.
Use of this procedure is recommended in insect population studies as a method of optimally planning experiments, and as a
method of making precise conclusions about the significance of specific effects.
This study was supported by Contracts 68-03-0273 and 68-03-2442 with the U. S. Environmental Protection Agency, Corvallis
Environmental Research Laboratory, Corvallis, Oregon. This paper has been reviewed by the Corvallis Environmental Research
Laboratory and approved for publication. Approval does not signify that the contents necessarily reflect the views and policies
of the U. S. Environmental Protection Agency, nor does mention of trade names or commercial products constitute endorsement
or recommendation for use. 相似文献
2.
D. G. Burnell 《Researches on Population Ecology》1977,19(1):99-106
Summary In this paper a dispersal-attack theory for bark beetle attacking trees is developed from a set of simple assumptions, and
the resulting theoretical model is fit to data from four epidemic studies. Implications of the theory are discussed in relation
to the dynamics of lodgepole pine-mountain pine beetle interactions.
Scientific paper #4632, Project #102, College of Agriculture Research Center, Washington State university, Pullman, Washington.
The work reported herein is the result of cooperation between scientists at Washington State University, the University of
Idaho, and the U.S. Forest Service, and is supported by the National Science Foundation (Grant No. GB-341728), through contract
SC 0024 with the University of California (Berkeley). The opinions expressed herein are not necessarily those of California
or NSF. 相似文献
3.
Takayuki Ohgushi 《Researches on Population Ecology》1988,30(1):57-68
Summary The relationships between egg predation of an herbivorous lady beetleEpilachna niponica (Lewis) and its predator, the earwigAnechura harmandi (Burr), were examined in both time and space. In spite of little annual, changes in egg densities, egg mortality due to predation
varied considerably. There was no, clear relationship between the earwig density and the proportionate predation over the
five years. The seasonal occurrence of earwig nymphs on thistle plants, however, was closely synchronized with that of egg
predation. Predator attacks on the beetle occurred in a time-restricted manner. Thus, later cohorts mostly escape from heavy
predatory pressure. No spatially density-depent egg predation was detected at the level of either thistle plants or thistle
patches. Furthermore, there was no indication of aggregative behaviour of the earwig in response to local egg density. The
earwig density was more likely to be associated with particular localities with sandy deposits available for its nest site. 相似文献
4.
Summary Crowding effects of larvae on survival and development were examined for the broad-horned flour beetle,Gnathocerus cornutus (F.). The larvae matured about 3 weeks after hatching regardless of their densities, but pupation was severely hindered by
crowding. There existed an upper limit for the number of the pupae produced and its mechanism was studied by a statistical
analysis of the distribution patterns of pupal cells and the experiment in which glass tubes were artificially supplied in
addition as pupation site. These studies show thatG. cornutus larvae have a habit to construct cells for pupation and this habit leads to a contest competition for pupation site at high
densities. The significance of the contest competition for population regulation was discussed comparing the results onTribolium confusum
Jacqueline duVal. 相似文献
5.
Takao Itino 《Researches on Population Ecology》1986,28(2):185-199
Summary I compared life tables between the solitary eumenid waspAnterhynchium flavomarginatum
Smith and the subsocial eumenid waspOrancistrocerus drewseni
Saussure in Kyoto, Japan, during 1980–1983. The subsocial eumenid is parthenogenetic in this study area. There were 9 identified mortality
factors in the solitary eumenid and 7 in the subsocial eumenid, 6 of which were common to the two eumenids. The important
differences of mortality between the two eumenids were seen in the egg, larval, and prepupal stages. In the egg stage, mortality
by the phorid flyMegaselia sp. was much lower in the subsocial eumenid (1.4%) than in the solitary eumenid (15.0%) likely because of the matenal care
of the subsocial eumenid (progressive provisioning and other related behavior), which reduced predation pressure. In the larval
stage, mortality by the miltogrammine flyAmobia distorta was also lower in the subsocial eumenid (8.1%) than in the solitary eumenid (23.8%) also probably because of the maternal
care of the subsocial eumenid. A comparison of mortality in the two eumenids between the stable, long continuing natural nest
sites and the additional temporal ones showed that the phorid fly remained near its birth place and parasitized stable nest
sites. The miltogrammine fly followed returning eumenid wasps and parasitized those nest sites that have a high host density.
In the prepupal stage, mortality by endogenous death was higher in the subsocial eumenid than in the solitary eumenid. Mortality
due to the rhipiphorid beetle was also higher in the subsocial eumenid probably due to more frequent flower-visits by the
subsocial eumenid.
The defense mechanism of the subsocial eumenid was discussed in relation to the evolution of subsociality.
Contribution to the ecological studies of the eumenid wasps. I. 相似文献
6.
Kazuyuki Fujita 《Researches on Population Ecology》1983,25(2):387-399
Summary An acarine predator-prey system in a circular stepping-stone environment was described with a simulation model to elucidate
the factors responsible for persistence of the system. The main assumptions in this model are: (1) The prey are inevitably
eliminated in patches in which predators exist. (2) The density of prey declines and becomes extinct by plant defoliation
due to feeding by prey. In this regard this model is different from the models which mimickedHuffaker's (1958) experiments and assumed stable plant-prey relations.
Analyses showed that the critical factor in persistence of the predator-prey system was the plant-prey relations, at any combination
of other parameters involved in the model. The predator-prey system did not persist long under the unstable relationship of
prey and plant. Otherwise the system persisted longer especially when I used a larger number of patches, a larger amount of
plant in each patch, and long-distance-migrations of the prey. In particular, frequent emigration of the prey regardless of
plant conditions was most effective. 相似文献
7.
Summary Time-specific life tables were constructed for three pea aphid,Acyrthosiphon pisum (Harris) (Homoptera: Aphididae), populations using a modification ofHughes' analytical procedure. All populations were studied on second-growth alfalfa (mid-June to mid-July) in south central Wisconsin;
data for two populations were collected during 1980, and data for the third population were collected during 1982. The intrinsic
rate of increase (r
m) estimated on a physiological time (day-degree) scale under field conditions but in the absence of natural enemies, provided
a reliable estimate of potential population growth rate and was used in preference toHughes' approach of estimating potential population growth rates directly from stage structure data. Emigration by adult alatae and
fungal disease were the major sources ofA. pisum mortality in each of the three populations studied. These factors were most important because of their impact on reducing
birth rates within the local population. Parasitism was never greater than 9 percent. Mortality attributable to predation
ranged from 0.0 to about 30.0%; however, even at the highest predator densitiesA. pisum populations increased exponentially. 相似文献
8.
Naoya Osawa 《Researches on Population Ecology》1989,31(1):153-160
Summary Sibling (cannibalism among siblings) and non-sibling cannibalism (cannibalism among non-siblings) were studied in a natural
population of a lady beetle,Harmonia axyridis
Pallas.
Of all the eggs laid (n=2269), 24.76% (n=562) were killed by sibling cannibalism and 36.10% (n=819) were killed by non-sibling cannibalism. Sibling cannibalism occurred constantly and intensively in most egg batches
throughout the entire oviposition period. On the other hand, non-sibling cannibalism was more intense in the middle and late
oviposition periods, and when the egg batches were close to an aphid colony. This may be due to the high density ofH. axyridis larvae relative to aphid density in the middle and late oviposition periods and also the larvae searching intensively near
an aphid colony. 相似文献
9.
Kazuyuki Fujita 《Researches on Population Ecology》1984,26(2):379-388
Summary I propose a new method for anlysing predatorprey interactive systems in discontinuous environments. The basic index used here
is a generalized version ofLloyd's (1967) “interspecies mean crowding”, which is defined as the number of individuals of one species existing in a given patch
per that of the other species in either the same or different patches at either the same or different times. Four indices
are derived from different combinations of the numbers of the prey and the predator in habitat patches. Then, the correlation
coefficients between the numbers of individuals in patches in both different locations and times are derived by modifying
the above new indices. Using this technique, dynamical changes of the joint distributions of the numbers of predators and
prey which reflect variation in local conditions, can readily be described. As an example, this method was applied to an analysis
of the outcomes of a multi-patch version of theLotka-Volterra model of predator-prey interactions. 相似文献
10.
Katsumi Togashi 《Researches on Population Ecology》1990,32(1):1-13
Summary Newly-emerged adults ofMonochamus alternatus aged 1 to 5 days were code-numbered with lacquer paint and released by placing them on the trunks of one or two trees in
aPinus thunbergii stand at weekly intervals during the beetle emergence period from 1980 to 1983. Beetles were captured at weekly intervals
from one week after the first day of release. Determinations were made on the distance and direction of beetle dispersal during
a week after release and analysed by a method of Inoue (1978). When the stand canopy was closed, the rate of beetle’s stay
on trees was 0.56 per week. The beetles dispersed at random by walk and flight. When the pine stand was sparse, the rate of
beetle’s stay on trees was 0.02–0.30 per week. They dispersed at random by flight. The average distances traversed were estimated
to be 7.1–37.8 m for the first week after emergence. Using other method, the average distance traversed was estimated to be
10–20 m for each week through the first 3 weeks after release. The results of stepwise multiple regression analysis and a
simple field experiment suggested that the dispersal of newly-emerged beetles was affected by stand density, number of beetles
emerging from individual dead trees, maximum air temperature, and precipitation. 相似文献
11.
Summary The virgin female introduced pine sawfly,Diprion similis (Hartig), produces a powerful sex pheromone capable of attracting males. Pending chemical identification of the substance, a pilot
study in male annihilation is under consideration. A mathematical model was developed to assess the feasibility of population
suppression using pheromone-baited traps. Departure from preexisting population models resulted chiefly from the arrhenotokous
nature of the sawfly. The model predicts alternating sawfly generations which undergo first a large shift in the sex ratio
but no population reduction, followed by a large decrease in population size with a moderating sex ratio. Four generations
of intensive trapping would theoretically be sufficient to eliminate the sawfly from an isolated area. 相似文献
12.
Summary This paper has examined the effect of within-stage mortality on the estimation of stage-specific survival rates bySouthwood's (1978, p. 358) method. As pointed out bySouthwood, both the severity and timing of mortality affect the mean duration of a life stage, and consequently the estimate of the
number of individuals entering that stage. Knowledge of the form of the survivorship curve permits correction of the estimate
under certain circumstances. The use ofSouthwood's method with two overlapping stages having different rates and patterns of mortality leads to complex errors in the estimation
of survival for the first stage. The nature of these errors is examined analytically and via a simulation model.Southwood's method is fairly robust, with moderate differences in mortality rates leading to acceptable errors in estimating survival
for the first stage. When both the rate and pattern of mortality in both life stages are the same, then the survival estimate
is made without error. Precise estimates of stage-specific survival will not usually be possible withSouthwood's method because of the errors introduced by the very parameters being measured. Direct measurement of mortality rates and
survivorship patterns (seeSouthwood, 1978, p. 309) is strongly advised, at least in preliminary work. 相似文献
13.
农村大龄未婚男性的生活质量及其影响因素分析——以冀北地区调查为基础 总被引:1,自引:0,他引:1
利用2010年冀北C县农村调查数据,借鉴生活质量的概念和研究框架,分析农村大龄未婚男性的生活质量现状及影响因素。研究结果表明,与已婚男性相比,未婚男性的客观生活质量和主观生活质量均明显偏低;居住方式和父母在世情况显著影响他们所获得的生活支持,工作、收入和社会保障显著影响他们的经济满意度;年龄、生理、心理和收入是影响未婚男性生活总体满意度的重要因素。经济满意度和生活总体满意度之间具有显著的正向相关关系,社会交往满意度和生活总体满意度之间的关系不显著。分析农村大龄未婚男性的生活质量有利于把握其生存状态,也有利于理解其对社会公共安全的影响。 相似文献
14.
Summary The functional response ofPseudogonatopus flavifemur E & H (Hym., Dryinidae) was investigated by offering hosts (brown planthopper) at densities ranging from 8 to 160 per cage.
The response curve was found to be sigmoid, i. e.Holling's (1959) Type III curve. In experiments involving 310 hosts per cage distributed unevenly in 5 densities (10, 20, 40, 80
and 160 per hill), and a different female parasite density each time (viz. 1, 2, 4, 8 or 16 per cage), the behavioral response
was described well by the “random predator equation” ofRoyama (1971) andRoger (1972), which is a convex exponential curve. The area of discovery (a) decreased with an increase in female parasite density (P), and the relationship was described by the equation: loga=−1.0099−0.3638 logP. There was an apparent increase in handling time per host as the number of female parasites increased. Superparasitism, a
rare phenomenon under natural conditions, was often observed in the laboratory. The potential ofP. flavifemur as a biocontrol agent of the brown planthopper is discussed. 相似文献
15.
B. F. J. Manly 《Researches on Population Ecology》1979,21(1):30-39
Summary Various aspects of a model for key factor analysis (Manly, 1977a) are discussed. Equations for estimating the parameters of the model are given. The jackknife method is suggested
for obtaining standard errors for estimators. The case of circular populations (where the adults in one generation produce
all the individuals alive at the start of the next, generation) is considered. A computer program is described.
Varley
et al.’s (1973) data on the winter moth is used for illustrative purposes. 相似文献
16.
Hidenori Ubukata 《Researches on Population Ecology》1984,26(2):285-301
Summary Females of an odonate species in which oviposition sites overlap with mating sites may adopt one or more of the following
strategies when they lay eggs except when they ‘trade’ mating for access to suitable oviposition sites or for services (guarding,
etc.) provided by males: (1) ovipositing at hidden places; (2) ovipositing at a time when males are neither patrolling nor
watching; (3) indicating non-receptivity by a behavioral display. The density of ovipositing females of the dragonfly,Cordulia aenea amurensis
Selys which was studied between 1970 and 1983 at a pond (H?rai-numa, Sapporo, Hokkaido) had a high negative correlation with the
distance from ‘entrance’ (a part of shore at which the arrival of most adults seems to have occurred). On the other hand,
oviposition was rarely observed at a sector being distant from entrance in spite of the inference that larval survivorship
was probably high at this sector. Most females oviposited among emergent vegetation in which approach of males to them was
difficult, and they scarcely traveled across the open water in search of oviposition sites. Therefore, most females of the
population studied were considered to adopt the first strategy. The second and third strategy were not adopted by the population
studied. Finally, the influences of some environmental factors and traits possessed by a species on the adoption of these
tactics or on the execution of the ‘trades’ were discussed.
Ecological studies ofCordulia aenea amurensis
Selys, VII.
This work was supported in part by a Grant-in-Aid for Special Project Research on Biological Aspects of Optimal Strategy and
Social Structure from the Japan Ministry of Education, Science and Culture. 相似文献
17.
TABRAP (TArget Birth Rate Acceptor Program) is a computer programmed model that provides a direct solution to the problem of determining the total annual numbers of contraceptive acceptors required to achieve a prescribed crude birth rate target path. Applied to an initial population for which age structure, the fertility schedule, and expected trends in life expectancy and age-specific proportions of females married are known, TABRAP incorporates the following factors: age at acceptance, with acceptors drawn from currently married nonusers; age-method-specific attrition rates of users; a potential fertility schedule of acceptors that allows for aging and sterility; and allowance both for postpartum anovulation and nine months for gestation to time properly the averted births. TABRAP generates annual data on acceptors, couple-years of use, births averted and age-specific fertility rates that meet the crude birth rate target. Resulting changes in population size, age structure and crude vital rates, also yielded, are invariant with respect to acceptor age and method mix. Assuming a target to reduce the crude birth rate from 45 to 30 in ten years, TABRAP is illustrated for seven mixes of acceptor age-method combinations applied to a population approximately that of Thailand, circa 1965. 相似文献
18.
Summary Interrelations between natural arthropod fauna and their environment were studied in 1964 from 165 samples collected from
the same number of boxcars each containing about 54 tons of stored grain originating from various parts of Western Canada.
Applications of several multivariate procedures, such as principal component and maximum likelihood factor analyses (unrotated,
rotated and oblique solutions) were applied to 6 biotic and 3 environmental variates to obtain the clearest picture of interrelations
among these variates.J?reskog’s computational procedure and computer programs were used for unrotated, rotated and oblique maximum likelihood solutions.
A 3-factor hypothesis was developed; of the 3 factors the first 2 were significantly correlated (Correlation coefficient=0.78±0.15).
The final confirmatory factor analysis revealed that: 1) the first factor indicates that acarine variates,Glycyphagus andCheyletus, were correlated positively to each other but negatively with the insect Psocoptera, 2) the second factor indicates that
the acarine variateTarsonemus is correlated to moisture, dockage and the entomological variate Psocoptera, 3) the third factor indicates that the environmental
factors are correlated to each other, and 4) the correlations between the third factor and the other factors are statistically
different from zero.
Contribution no. 420 from the Research Station, Canada Department of Agriculture, Winnipeg, Manitoba. 相似文献
19.
Motivated by long-standing debates between abstinence proponents and sceptics, we examine how socio-economic factors influence premarital first births via: (i) age at first sexual intercourse and (ii) the risk of a premarital first birth following the onset of sexual activity. Factors associated with an earlier age at first intercourse will imply more premarital first births owing to increased exposure to risk, but many of these same factors will also be associated with higher risks of a premarital first birth following onset. Our analyses confirm previous findings that women from disadvantaged backgrounds are younger at first intercourse and have higher premarital first-birth risks than women from more advantaged backgrounds. However, differences in onset timing have a strikingly smaller influence on premarital first-birth probabilities than do differences in post-onset risks. Our findings thus suggest that premarital first births result primarily from differences in post-onset risk behaviours as opposed to differences in onset timing. 相似文献
20.
How powerful is demography? The Serendipity Theorem revisited 总被引:1,自引:1,他引:0
Introduced by Samuelson (Int Econ Rev 16(3):531–538, 1975), the Serendipity Theorem states that the competitive economy will converge towards the optimum steady-state provided the
optimum fertility rate is imposed. This paper aims at exploring whether the Serendipity Theorem still holds in an economy
with risky lifetime. We show that, under general conditions, including a perfect annuity market with actuarially fair return,
imposing the optimum fertility rate and the optimum survival rate leads the competitive economy to the optimum steady state.
That Extended Serendipity Theorem is also shown to hold in economies where old adults work some fraction of the old age, whatever
the retirement age is fixed or chosen by the agents. 相似文献