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1.
Takashi Saitoh Nils Chr Stenseth Ottar N. Bj?rnstad 《Researches on Population Ecology》1998,40(1):61-76
Population dynamics of the gray sided-vole,Clethrionomys rufocanus, in Hokkaido, Japan were described on the basis of 225 time series (being from 12 to 31 years long); 194 of the time series have a length of 23 years or longer. The time series were classified into 11 groups according to geographic proximity and topographic characteristics of the island of Hokkaido. Mean abundance varied among populations from 1.07 to 21.07 individuals per 150 trap-nights. The index of variability for population fluctuation (s-index) ranged from 0.204 to 0.629. Another index for population variability (amplitude on log-10 scale) ranged from 0.811 to 2.743. Mean abundance and variability of populations were higher in the more northern and eastern regions of the island. Most populations, except for the southernmost populations, exhibited significant direct density-dependence in population growth. Detection rate for delayed density-dependence varied among groups from 0% to 22.6%. Both direct and delayed density-dependence tended to be stronger in the more northern and eastern populations. The proportion of cyclic populations was higher in the northern-eastern areas than that in the southern-western areas. There was a clear gradient from the asynchronous populations in southwest, to the highly synchronized populations in the northeast. 相似文献
2.
Nils Chr Stenseth Ottar N. Bj?rnstad Takashi Saitoh 《Researches on Population Ecology》1998,40(1):85-95
We interpret gradients in population dynamics of the gray-sided vole from the southwestern part of the island of Hokkaido
to its northeastern part within the framework of a phenomenological model involving the relative length of summer and winter.
In Hokkaido, as in other northern regions, both spring and fall is considered as short transition periods between the two
main seasons — summer (the primary breeding season) and winter (the non-reproductive or secondary breeding season). We show
that the geographic transition in dynamics may be understood as the combined consequence of different patterns of density-dependence
during summer and winter, and geographically varying season lengths. Differences are shown to exist between summer and winter
with respect to strength of density-dependence. Direct density-dependence, in particular, is stronger during winter than during
summer. A model is presented to show how relative lengths of seasons can induce both stable and periodically fluctuating population
dynamics. The results are compared and contrasted with what is otherwise known about the gradient in rodent dynamics in Fennoscandia. 相似文献
3.
Kohji Hirano 《Researches on Population Ecology》1995,37(2):185-195
Temporal changes in the population size of a phytophagous lady-beetle were analyzed to identify mechanisms affecting lady-beetle
population dynamics at different spatial scales. The study area (15 ha) included 18 habitat patches. The major host plants
were potato for first generation larvae and eggplant for second generation larvae. The habitat patches were classified into
three groups according to the major host plants in each patch: P-E patches (both host plants available), P patches (potato
only), and E patches (eggplant only). The winter disappearance of adults in the whole study area, and larval mortality in
E patches were apparently the most important factors disturbing the overall population density. Density-dependent movement
of females appeared to have the greatest stabilizing effect on the yearly fluctuation of population density. Rate of increase
of female adults from the first to the second generation,R, was generally higher on eggplants in E patches than in P-E patches because the adult density of the first generation was
much higher in P-E patches. The yearly fluctuation of adult density in each generation tended to be less in patches with all
habitat components necessary for the full life cycle (P-E patches). However, such patches were not favorable for first generation
females, as indicated by the lower rate of increase from the first to the second generation. The density and stability of
lady-beetle populations is discussed in relation to habitat structure. 相似文献
4.
Masaya Matsumura 《Researches on Population Ecology》1996,38(1):19-25
A population census was conducted to describe the effects of the growth stage of rice on the population dynamics ofS. furcifera, in particular, on immigration, seasonal abundance, population growth rate, and wing-form expression. The number of immigrants
was highest on rice plants 17 to 30 days after transplanting (DAT), which suggested that immigrants prefer to settle or remain
more on rice plants at the tillering stage (approximately 20–30 DAT). Population growth rate from immigration to the 1st generation
decreased with an increase in rice plant age. In contrast, population growth rate from the 1st to 2nd generation was not influenced
by rice plant age and was negatively density-dependent. The percentage of macropters (flyers) was positively related to the
growth stage of rice when rice was in the vegetative or early part of the reproductive stage, and reached 100% at about 10
days before heading (booting stage). Threafter, most adult females molted into macropters regardless of population density.
The roles of host plant age and crowding effect on the population dynamics ofS. furcifera are discussed. 相似文献
5.
建设和谐社区,抓住外来人口管理的战略环节——以成都市金牛区为试点 总被引:1,自引:0,他引:1
本文采用实证分析的方法,在对四川省最大外来人口聚居地成都金牛区进行全方位调研的基础上,探讨了金牛区外来人口的基本状况及其对城市外来人口管理的新挑战,并提出了建设“和谐社区”这一外来人口管理服务的新模式。 相似文献
6.
Tuyosi Sugimoto 《Researches on Population Ecology》1978,19(2):197-208
Summary The present paper studies how the female parasite ofKratochviliana sp. visits and attacks its host larvae of Ranunculus leaf mining fly,P. ranunculi at a single leaf visit. The parasite visited its hosts at random on the leaf. The frequency of host visits was independent
of the host density and the proportion of hosts survived from the parasite attack, in a leaf and its distribution was expressed
as a single straight line. It almost always attacked living hosts at the first host visit after isolated from them for one
day but with the rate of about 0.5 at the subsequent visits. In consequence, the relationships of the number of host attacks
and killed hosts to the host density drew satulated curves in each. A model of host attack by this parasite at its single
leaf visit was formulated by modifyingBakker
et al.'s model (1972) basing upon these observations and the attack avoidance by the parasite to already attacked hosts previously
reported.
Ecological studies on the relationship between Ranunculus leaf mining fly,Phytomyza ranunculi
Schrank (Diptera; Agromyzidae) and its parasite,Kratochviliana sp. (Hymenoptera; Eulophidae) from the viewpoint of spatial structure II.
This paper constitutes a part of the Doctoral Thesis presented to the College of Agriculture, Kyoto University by the present
author. 相似文献
7.
Yoshihiro Yamada 《Researches on Population Ecology》1990,32(2):365-379
1. | Analysis of life tables of the oriental moth,Monema flavescens, obtained for 8 generations over 4 years, disclosed that the cocoon parasitoid,Praestochrysis shanghaiensis, acted as a density-disruptive factor. |
2. | The density of the host cocoon remained stable (max./min.=3.2), whereas that of the host adult varied (max./min.=14.3) although both showed similar fluctation patterns. |
3. | Stability of the host population was associated with the density-dependence in the ratio of first generation cocoons to overwintered generation moths, which was the key factor for the rate of change throughout the year. Chrysidid parasitism among the first generation cocoons ranged from 37.7 to 70.1%, and that among the second generation cocoons from 16.7 to 63.2%, each showing an inverse density-dependence and acting as the main determinant (key-factor) of the between-year variation in the density of the adult moths. |
4. | The density-dependence of the rate of change from overwintered generation adults to first generation cocoons was so strong that the parasitism on the second generation hosts had not effect on the cocoon density of the first generation. On the other hand, the density-dependence of the rate of change from first generation adults to second generation cocoons was weak, and the parasitism on the first generation hosts became the key factor for the between-year variation of the second generation cocoons. |
5. | It is suggested that the stability of the parasitoid-host system will be disrupted without three parasitism-restricting factors: asynchrony in the parasitoid attack on the second generation hosts, high mortality among parasitoid larvae of the second generation, and the high proportion of those first generation parasitoids that enter diapause. These factors are considered to be effective only in cooler parts of the distribution of the parasitoid. |
8.
M. Kato Akihiro Shibata Takaya Yasui Hidetoshi Nagamasu 《Researches on Population Ecology》1999,41(2):217-228
The Bonin (Ogasawara) Islands are oceanic islands located in the northwest Pacific, and have ten native (nine endemic) bee species, all of which are nonsocial. The European honeybee (Apis mellifera), which was introduced to the islands for apiculture in the 1880s, became naturalized in a few islands shortly after introduction. To detect the impact of the honeybees upon native bee diversity, we analyzed pollen harvest by honeybees and surveyed the relative abundance of honeybees and native bees on flowers on several islands. Both hived and feral honeybee colonies were active throughout the year, harvesting pollen of both native and alien flowers and from both entomophilous and anemophilous flowers. Honeybees strongly depended on the alien plants, especially during winter to spring when native melittophilous flowers were rare. From June to November, honeybees exhaustively utilized native flowers, which had originally been utilized and pollinated by native bees. On Chichi and Haha Islands, where human disturbance of forests has been severe, both native and alien flowers were dominated by honeybees, and native bees were rare or extinct even in well-conserved forests. In contrast, on Ani Island and Haha's satellite islands where primary forests were well conserved and honeybees were still uncommon or absent, native bees remained dominant. These results suggest that competition for nectar and pollen of the native flowers between honeybees and native bees favors honeybees on the disturbed islands, which are thoroughly invaded by alien nectariferous, sometimes aggressive, weedy plants. Received: May 8, 1998 / Accepted: May 6, 1999 相似文献
9.
10.
N. A. C. Kidd 《Researches on Population Ecology》1990,32(2):189-208
Summary The large pine aphid,Cinara pinea lives exclusively onPinus species, where it feeds on the foliated shoots of the current and previous year. The paper describes the development of a
computer model designed to simulate the aphid’s population dynamics on saplings in the controlled environment of the laboratory,
i.e. in the absence of natural enemies. The model was able to account for about 80% of the variation in aphid numbers within
and between trees over a three month period. Sensitivity analysis revealed that the number of pine aphids is limited primarily
by nymphal emigration, the operation of which is sensitive both to density and to plant quality as reflected in aphid growth
rates. Of secondary importance are changes in reproduction acting through increased reproductive delay, again a result of
altered growth rates and adult size. Development, too, has an important secondary influence. Contrary to expectation and conventional
belief, however, alate production proved to be of negligible importance, either in limiting or regulating population numbers.
Alatae are produced in too few numbers and for too short a period to significantly alter the pattern of population change. 相似文献
11.
K. L. Heong 《Researches on Population Ecology》1981,23(1):177-191
Summary The functional response parameters of the parasitoid,Anisopteromalus calandrae (Howard) to the third instar, the fourth instar and the pupae ofCallosobruchus maculatus (F.) were estimated from the Random Parasitoid Equation. By modifying this equation for a two host situation and using the
parameters estimated above, a no switch model could be obtained. This model was then used to test for switching. In the preference
experiments where two stages of the host were presented to the female parasitoid, a definite preference for the fourth instar
followed by the pupa and the third instar, respectively was shown. There was, however, no evidence of switching. There was
also no evidence that the data fitted the no switch models which suggests that when the parasitoid is searching in an environment
with two or more hosts, its searching behaviour is more complex. 相似文献
12.
Tadashi Miyashita 《Researches on Population Ecology》1992,34(1):143-153
Summary Field studies were conducted to clarify whether variation in food availability among habitats influences population density,
and whether population density has a negative effect on foraging success in the orb-web spider,Nephila clavata.
Lifetime food consumption per individual (i.e., foraging success) strongly correlated with mean body size of adult females
and mean fecundity in populations. Also, there was a positive correlation between foraging success and population density.
Since foraging success reflected potential prey availability in the habitat, food resource appeared to be a limiting factor
for populations in this spider. Mean fecundity per individual correlated with population density of the following year, suggesting
that decreased reproduction is a major component of food limitation on population density. Consistent defferences in mean
body size between particular sites were observed over years, while such difference was less obvious in density. Thus, ranking
of food abundance among habitats seems to be predictable between years. A field experiment revealed that an artificial increase
in population density had no negative effect on the feeding rate of individuals, suggesting that intraspecific competition
for food is not important in this species. 相似文献
13.
I Gusti Ngurah Aryawan I Nyoman Widiarta Yoshito Suzuki Fusao Nakasuji 《Researches on Population Ecology》1993,35(1):31-43
Summary Population dynamics ofNephotettix virescens was studied in 17 paddy fields transplanted at intervals of about 1 month in 1988–1990. The adult density was highest either
in the immigrant or the 1st generation and sharply decreased to the 2nd generation. The survival rate of the 1st generation
was lowest in the transition season when areal population density increased. Key factor analysis revealed that the nymphal
and adult mortality of the 1st generation (kn) was the principal source of population fluctuations. No significant correaltion
was found between kn and natural enemy density, natural enemy density/healthy egg density, or the precipitation during the
nymphal period. On these bases adult emigration was suspected to be the key factor. Areal population build-up ofN. virescens in the transition season was considered to occur as a result of increasing immigration to young stages of rice.
Contribution from Indonesia-Japan Joint Program on Food Crop Protection (ATA 162), which was implemented by the Directorate
of Food Crop Protection, Ministry of Agriculture, Indonesia and Japan International Cooperation Agency, Japan. 相似文献
14.
Summary The consequences of infestation of stored wheat by the rusty grain beetle,Cryptolestes ferrugineus (Stephens) was determined for 222 d at 30°C in 70-1 drums containing wheat at 13.5% moisture content. Temperature, grain
moisture, seed damage, germination and weight, dust weight, fat acidity values (FAV), published data on growth, reproduction,
survival and cannibalism rates and energy budget were used to develop a computer simulation model to simulate the population
dynamics ofC. ferrugineus at 30°C. In the insect-free control system, the fungi,Alternaria alternata decreased,Aspergillus glaucus group andPenicillium spp. increased, probably causing a rise in FAV of the grain. In the insect-infested system,C. ferrugineus could only eat the wheat germ of kernels that had a broken bran layer; 35.7% of the wheat germ or 914.6 J per 100 kernels
was consumed. Within two generations after initial introduction,C. ferrugineus reached a peak in numbers and biomass polluting the ecosystem with excreta and remains, and accelerating the deteriorative
process observed in the insect-free control system by increasing respiration temperature, FAV and reducing grain germination.
After 87 d, the insect population declined to low levels. The simulation model provided a close match between the observed
and predicted numbers of insect life stages and bioenergetic variables during the insect population growth phase. Simulation
trials suggested that cannibalism of larger compared with smaller immature stages would be more wasteful of developmental
time and energy, reducing the number of individuals reaching reproductive age, and that density-dependent fecundity was probably
not an important regulatory mechanism ofC. ferrugineus population dynamics in this study.
Contribution No. 1314 from Agriculture Canada Research Station, Winnipeg, Manitoba, R3T 2M9, Canada 相似文献
15.
Effects of population fluctuation of the gray-sided vole(Clethrionomys rufocanus) on the prevalence (infection rates) of the parasiteEchinococcus multilocularis in red fox(Vulpes vulpes) populations was investigated from 1985 to 1992 in eastern Hokkaido (Abashiri, Nemuro, and Kushiro area), Japan. This parasite
needs two hosts to complete its life cycle; the gray-sided vole as its intermediate host and the red fox as its final host.
We found that: (1) Infection rates in foxes depended on the current-year abundance of voles in all three study areas, particularly
in Abashiri. (2) In addition to this direct density-dependence, delayed density-dependence between the infection rate and
the prior-year abundance of voles was detected in Nemuro and in Kushiro. (3) The regional differences in density-dependence
pattern were related to regional differences in the winter food habits of red foxes: in Abashiri the proportion of voles in
the fox’s diet greatly decreases in winter, while the proportion remains high in winter in Nemuro and in Kushiro, probably
because of shallower snowpack. These results suggest that infection rates in foxes in Abashiri were less influenced by the
prior-year prevalence, since the infection cycle might be interrupted in winter, when voles became less important in fox’s
diet. In contrast, the state of the prevalence may carry over from year to year in Nemuro and in Kushiro, because red foxes
continue to eat a considerable amount of voles throughout year. The regionally contrasted results for the relationship between
infection rate in foxes and vole abundance were parallel to the regional difference in fluctuation pattern of vole populations,
which are highly variable in Abashiri area, but less variable in Kushiro-Nemuro area. Drastic change in vole populations appears
to affect the host-parasite system. 相似文献
16.
B. Leroi 《Researches on Population Ecology》1972,13(2):201-215
Summary The study of the population dynamics of the celery leaf-miner,Philophylla heraclei, must take into account the fact that the host-plant is not present permanently and that it develops between the two annual
generations of the insect. This development affects in particular the quality and quantity of the leaves fed upon by the mining
larvae. It is possible to know the numerical change of the populations from one annual generation to the next (bivoltine insect)
and from one year to the next by counting the populations in the various larval instars, responsible for the injury caused
to celery.
An accurate method of counting of larval numbers, taking into account their change parallel with that of the host-plant, is
described in this text. It makes it possible to know with accuracy the duration and importance of the infestations in relation
to external factors and to factors inherent to the host-plant itself. Certain traits of larval behaviour, particularly the
transfer of a larva from its original mine to a secondary mine as a result of food shortage can thus be established and estimated
quantitatively. 相似文献
17.
Summary We studied the stopping rule obeyed by the female parasitoid,Chrysocharis pentheus, in deciding when to leave the leaflet on which she is searching for larvae ofPhytomyza ranunculi. She seemed not to employ some stopping rules that have been suggested; i.e., a fixed-number rule and a fixed-time rule and
others. The stopping model formulated forDapsilarthra rufiventris parasitic on the same host species fitted well to the results. The model assumes that the searching female will deposit a
marking pheromone on the leaflet at a rate proportional to the search speed and will leave the leaflet when the amount of
the pheromone that has accumulated on the leaflet reaches the threshold,L. In this model,L denotes the amount of search effort spent on the leaflet. A comparison of the observed results with the predictions from
the model suggested thatL increased markedly at the first encounter with the mine (host), but less at later encounters.C. pentheus appears to employ a mixed strategy of a fixed search-effort and an area-concentrated search. This would confer an adaptive
advantage in foraging forP. ranunculi larvae, which are distributed in clumps among leaflets in the field. 相似文献
18.
19.
Yasuyuki Sirota 《Researches on Population Ecology》1978,19(2):170-180
Summary Experiments for analyzing the movement and dispersal of larvae ofC. pipiens molestus were made and preliminaly simulation models were constructed. The models were based on two distributions, the distance and
direction of movements between 1 minute intervals. The distribution of distance is represented by a unimodal curve, and that
of angle by a bimodal one. The results of simulation reasonably depicted the actual process of movements. Nevertheless, the
simulated time-dispersal curves overestimated the number of dispersed individuals. This might be due to mutual attraction
among the larvae.
Contribution No. 68 from the Lab. of Entomol. Fac. Agric. Hirosaki Univ. 相似文献
20.
Takahisa Miyatake 《Researches on Population Ecology》1998,40(3):301-310
Quantitative genetic studies for life history and behavioral traits are important in quality control for insect mass-rearing programs. Firstly, a brief history of quality control in mass-reared insects is described. Next, the differentiation of many traits of wild and mass-reared melon flies,Bactrocera cucurbitae, in Okinawa is reviewed, and the factors which have caused variation in these traits are considered. As artificial selection pressures are thought to be more important than inbreeding depression and genetic drift in the mass-reared strain of the Okinawan melon fly, two artificial selection experiments were conducted to evaluate genetic variations and genetic correlations among life history and behavioral traits. These are divergent selections for age at reproduction and for developmental period. The genetic relationship among 5 traits, i.e. longevity, age at reproduction, developmental period, circadian period, and time of mating was clarified and discussed in relation to genetic changes of traits during the mass-rearing. The results suggest that the genetic trade-off relationships between traits should be taken into account in mass-rearing programs. 相似文献