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1.
Toshiya Masumoto Shintaro Nomakuchi Kouji Sawada 《Researches on Population Ecology》1993,35(2):241-250
Summary We investigated how the distribution pattern of eggs and larval on the host plant,Turritus glabra, was influenced by the oviposition behavior of the pierid butterflyAnthocharis scolymus. Females searched for the host plants visually and they frequently approached taller host plants with sparse surrounding
vegetation. After encountering host plants, oviposition behavior of females was independent of host plant characteristics
such as height, density, and type of surrounding vegetation. A female laid eggs singly on a host plants. Most females appeared
to lay their eggs regardless of the presense of eggs on the host plant. Consequently egg and larva tended to be abundant on
conspicuous host plants as measured by height or relative isolation from other plants. However, overcrowding of eggs on an
individual host decreased the survival rate of larvae. 相似文献
2.
Keiji Kanamitsu 《Researches on Population Ecology》1965,7(1):16-22
Summary A field population ofEvetria cristata was studied in 10 plots in 1962 and in 6 plots in 1963. These plots were divided into 2 or 3 groups of different population
levels of the shoot moth in respective years. The survival of the insect was then analysed in these different groups of plots.
The survival rate ofE. cristata from eggs to adults in the first generation was found always higher in the group with low population density, which indicates
the existence of some factors that affect the population more severely when the insect is more abundant.Lissonota evetriae andPediobius sp. seemed to have killed more proportion of the hosts where the shoot moth density was high. However, the total effect of
the all natural enemies was not always great in the plots with high density of the moth. The survival of the second generation
of the moth in 1963 was observed to be much higher at any population level than in the other generations. 相似文献
3.
Ishizue Adachi 《Researches on Population Ecology》1989,31(2):343-352
Summary The study was carried out in two (A and B) citrus groves to clarify the spatial distribution patterns of eggs and larvae,
and to analyse the mortality process of eggs. From the analysis by using the mean density and the mean crowding, it was clarified
that the distributions of eggs were contagious and that larvae were more contagiously distributed than eggs. The τ andz indices showed that the operation of egg mortality was inversely density-dependent in both groves, and that the degree of
inverse density-dependence was greater in A than in B grove. The spatial correlations between the emergence holes and the
eggs or larvae in each tree, which were analysed by using ω index, showed that the distributions were more overlapping between
the emergence holes and the larvae than the eggs. As the result of dividing trees into several groups according to the number
of emergence holes, it was clarified that the survival rates of eggs were positively correlated with the number of emergence
holes. In conclusion, inversely density-dependent mortality process was considered to be caused by lower mortality rates of
eggs in the trees with more emergence holes. Especially in A grove, because the trees with more emergence holes were larger
in diameter and more egg oviposition, the inversely density-dependent mortality process was considered to be detected more
conspicuously than in B grove. 相似文献
4.
Summary We studied the interpecific competition between 2 species of predatory aquatic bugs,Diplonychus japonicus andD. major by conducting a field experiment. We set up 3 types of experimental plots in the paddy fields whereD. major predominated. The two plots contained single species of eitherD. japonicus orD. major, respectively, and one plot had both species in equal number. We compared the development and the reproductive performance
between plots in each species.
InD. japonicus, the number of eggs and early instar nymphs were significantly smaller in the plots containing both species than in the monospecific
plots. However, the numbers of late instar nymphs and newly emerged adults were not significantly different between plots.
The proportions of starved nymphs in both plots were larger than those in theD. japonicus's natural habitats. The final densities of adults in both plots were lower than those in the natural habitats. These results
suggest that lower density ofD. japonicus in these paddy fields is due to the lack of available food for nymphs rather than the effects of interspecific competition
withD. major.
InD. major, significant differences were not found in the number of eggs, each instar nymphs and adults. These results suggest that
the effects of interspecific competition did not affect the reproductive performance ofD. major. 相似文献
5.
Demographic attributes of the adults of an introduced herbivorous lady beetleEpilachna niponica (Coleoptera: Coccinellidae) were investigated from 1975 to 1981 in the Botanical Garden of Kyoto University. Population growth
rate varied from 4.8 to 16.8 throughout the study period. Fecundity and mortality in the late larval period contributed most
to annual changes in the population growth rate. Population growth rate was negatively correlated with the density of overwintering
adults. Adult survival from emergence to the reproductive season, which varied from 0.03 to 0.36 throughout the study, was
almost completely determined by survival during the pre-hibernation period. Adult survival to the preproductive season changed
in a size- and sex-dependent manner. Larger adults survived better than smaller individuals; male-biased mortality occurred
from adult emergence to the reproductive age. Severe intraspecific competition among late instar larvae due to host plant
defoliation produced a higher proportion of small-sized adults, resulting in lower adult survival to hibernation. The introduced
population had a higher population growth rate and a lower adult survival to the reproductive season than the source population. 相似文献
6.
Fusao Nakasuji 《Researches on Population Ecology》1982,24(1):157-173
Summary Survival rates and mortality factors of a migrant skipperParnara guttata were censused in paddy fields in 4 localities of central and western Japan during 1975–1980, and 10 life tables were developed
for 3 generations. Mortality rates of eggs, older larvae and pupae were high but those of younger larvae were very low. The
high mortality rate was caused by parasitoids. Ten primary and 6 secondary parasitoids were recorded. Out of three egg parasitoids,Telenomus sp. was predominant. Larval parasitoids,Apanteles baoris andPediobus mitsukurii which are specific to genusParnara were predominant in wet land habitat, i.e. paddy land. On the other hand, tachinid flies which have a wide host range and
a high searching ability were predominant in dry land habitats. Mortalities of eggs and pupae contribute more to the change
in the total mortality of immature stages than those of other stages. egg parasitoids which are the major mortality factor
of eggs acted density-dependently but larval and pupal parasitoids did not do so. The total mortality of immature stages occurred
more or less density-dependently. Larval density on rice plants scarecely affected the survival rate of larvae. 相似文献
7.
Yosiaki It? Masakazu Shiga Nobuhiko Oho Hitoshi Nakazawa 《Researches on Population Ecology》1977,19(1):33-50
Summary Based on the results of ecological surveys ofAdoxophyes orana and its natural enemies in apple orchards sprayed with the granulosis virus and control plots, we constructed working models
to simulate the population dynamics in three different experimental plots; those treated with chemical insecticides, those
with granulosis virus, and controls. The number of individuals killed by predators, parasitoids and by miscellaneous mortality
factors could be calculated on the assumption of imperfect density relations; that is, relation of the number killed by each
factor with the initial number of larvae was represented by a curve with an upper asymptote. We could estimate the proportion
of virus infection using curves with upper asymptotes. Rate of increase from pupa to middle instar larvae of the next generation
was subject to strong density-effect.
Simulation we proposed in this paper suggests a possibility that a single spray of the virus at 1st generation can reduce
not only the number ofA. orana larvae in the 2nd and 3rd generations but also the degree of fruits injured by this insect. Spray of chemical insecticide
is considered to be ineffective in reducing the pest density and the degree of injury to low levels in subsequent generations,
as compared with untreated plot, where the density of the 1st generation larvae is low. 相似文献
8.
Flower nectar of an autogamous perennialRorippa indica as an indirect defense mechanism against herbivorous insects 总被引:2,自引:0,他引:2
Shuichi Yano 《Researches on Population Ecology》1994,36(1):63-71
This report shows that one of the most important roles of the flower nectar of an autogamous perennialRorippa indica (L.) Hieron is as an attractant for employing some ant species as a defense against herbivorous insects. The plant has flowers
from spring to early winter. Its flower nectar is frequently stolen by some ant species (hereafter cited as ants) which also
feed on small herbivorous insects on the plant. Internations among the tritrophic levels (R. indica, herbivores, ants) were experimentally examined and the followings became clear. (1) Ants were attracted toR. indica in search of its flower nectar. (2) The gradual secretion of flower nectar seemed to detain ants on the plant. (3)Pieris butterfly lavae were the major herbivores onR. indica and were potentially harmful to the plant. (4) The presence of ants reduced the survival rate ofP. rapae larvae onR. indica. (5) The presence of ants reduced the feeding damage toR. indica. (6) The disadvantage of nectar use by ants seemed to be minimal for the plant since the ants did not disturb the other flower
visitors. These facts suggest a mutualistic relationship betweenR. indica and ants. That is, the flower nectar serves as an indirect defense against herbivorous insects. 相似文献
9.
Summary Population dynamics ofHeliothis virescens (F.) andHeliothis zea (Boddie) (Lepidoptera: Noctuidae) eggs and larvae were studied for two years in a small plot of cotton,Gossypium hirsutum (L.). Due to morphological and ecological similarities, the pooledHeliothis population was considered for most of the analyses. Two generations ofHeliothis eggs and larvae were completed during each year. Stage recruitment was estimated for the eggs and larval instars 2–6, and
recruitment variances were estimated by a Monte Carlo method. A modified form of the Weibull distribution was developed and
used as a model to characterize survivorship curves for each of the fourHeliothis generations. A Type I survivorship curve (mortality rate increasing with age) was inferred for both Generation 1 (early season)
data sets, whereas a Type II survivorship curve (mortality rate constant and thus independent of age) was inferred for both
Generation 2 (late season) data sets. The shapes of the survivorship curves for the individualH. virescens andH. zea populations were inferred to be the same as those for the pooled populations. Analysis of the contributions of various factors
toHeliothis stage-specific mortality indicated that natural enemies (predators and parasites) and the availability of food for larvae
were responsible for between-generation differences in survivorship patterns. 相似文献
10.
Contest competition inDrosophila subobscura 总被引:1,自引:0,他引:1
T. H. Jones ?. Langefors M. B. Bonsall M. P. Hassell 《Researches on Population Ecology》1996,38(1):105-110
The role of larval intraspecific competition in laboratory populations ofDrosophila subobscura was investigated. Mortality is density-independent during the first 3 days after hatching but becomes density dependent as
development proceeds to pupation. Although total biomass per patch was independent of initial egg density, competition betweenDrosophila larvae leads to the formation of smaller pupae. This resulted in a population that was dominated by suppressed individuals.
Development rate ofD. subobscura larvae was not affected by high larval densities. Smaller pupae give rise to females with fewer eggs in their ovarioles.
A simple simulation model, predicting the effects of intraspecific competition on the fecundity of the nextDrosophila generation is described. 相似文献
11.
Tatsuto Kajimura I Nyoman Widiarta Kazuya Nagai Kenji Fujisaki Fusao Nakasuji 《Researches on Population Ecology》1995,37(2):219-224
The reproduction ofSogatella furcifera was investigated in a chemically fertilized rice field and an organically farmed field. In the latter, the density of immigrants
was significantly higher, while the settling rate of female adults and the survival rate of immature stages of ensuing generations
were lower. The number of eggs laid by a female of the invading and following generations was smaller, and the percentage
of brachypterous females in the next generation was also lower. Consequently, the density of nymphs and adults in the ensuing
generations decreased in the organically farmed field. For an experimental comparison, potted rice plants were cultivated
using seedlings and soil from the chemically fertilized or the organically farmed fields. WhenSogatella furcifera was reared on these plants, both the reproductive rate and the appearance rate of brachypterous female adults were lower
in the organic treatment. Egg hatchability was also lower in the organic treatment. This experiment suggested that a specific
nutritional condition in rice plants suppressed the population ofS. furcifera in the organically farmed field. 相似文献
12.
《Researches on Population Ecology》1983,25(2):336-352
Summary Numerical changes and distribution patterns of the pine needle gall midge,Thecodiplosis japonensis
Uchida etInouye, were studied during the period from 1978 to 1979 in a young plantation ofPinus thunbergii in Shiga Prefecture, Japan. The survivorship curve of this species was characterized by a low mortality of larvae in galls
and two high mortalities before the formation of galls and during the overwintering period in soil.
The within and between-trees distributions of eggs and larvae in galls were examined by using the
regression method. The egg distribution per shoot was aggregative both within and between host plants. The within-tree variations
in numbers of eggs per shoot were related to the differences in the abundance of available needles for oviposition per shoot
among the canopy layers. The between-tree variations reflected the heterogeneous emergence of adult females in the study plot.
The degree of aggregation increased from egg to gall stage in both within- and between-tree distributions and the increase
was explained by the different mortality of larvae within trees and the inversely density-dependent mortality between trees.
The distribution patterns in the soil habitat stages were examined by the patchness index (
). This species showed aggregative distributions in soil stages. There was a correlation in spatial patterns of adult emergence
between the successive generations.
The distribution properties of this species were discussed in connection with the population dynamics and the availability
of host plants in the study plot. 相似文献
13.
K. Tanaka T. Watanabe H. Higuchi K. Miyamoto Y. Yusa T. Kiyonaga H. Kiyota Y. Suzuki T. Wada 《Researches on Population Ecology》1999,41(3):253-262
To examine density dependence in the survival, growth, and reproduction of Pomacea canaliculata, we conducted an experiment in which snail densities were manipulated in a paddy field. We released paint-marked snails of
15–20 mm shell height into 12 enclosures (pens) of 16 m2 at one of five densities – 8, 16, 32, 64, or 128 snails per pen. The survival rate of released snails was 95% and was independent
of snail density. The snail density had a significant effect on the growth and egg production of individual snails. This density
dependence may have been caused by reduced food availability. The females at high density deposited fewer and smaller egg
masses than those at low density, and consequently produced fewer eggs. The females at densities 8 and 16 deposited more than
3000 eggs per female, while the females at density 128 oviposited only 414 eggs. The total egg production per pen was, however,
higher at higher snail density. The survival rates of juvenile snails were 21%–37% and were independent of adult density.
The juvenile density was positively correlated with the total egg production per pen and hence was higher at higher adult
density. However, the density of juveniles larger than 5 mm in shell height, i.e., juveniles that can survive an overwintering
period, was not significantly different among density treatments. These results suggest that snail density after the overwintering
period is independent of the density in the previous year. Thus, density dependence in growth and reproduction might regulate
the population of P. canaliculata in paddies.
Received: October 23, 1998 / Accepted: July 16, 1999 相似文献
14.
Kohji Yamamura 《Researches on Population Ecology》1999,41(2):177-182
The relationship between plant density and the abundance of arthropods was examined by planting cabbages in four densities
(0.25, 1, 4, or 8 plants per square meter). Four herbivorous species were examined: the small white butterfly Pieris rapae crucivora Boisduval, the diamondback moth Plutella xylostella (Linnaeus), the beet semi-looper Autographa nigrisigna (Walker), and the green peach aphid Myzus persicae (Sulzer). The number of spiders and the number of eggs of syrphid flies were also examined. The number of individuals per
unit ground area increased curvilinearly with increasing plant density for most arthropods. To clarify the mechanism causing
such a curvilinear increase, the oviposition behavior of Pieris rapae crucivora was examined. The oviposition process of a female was divided into three components: (1) entering the field, (2) alighting
on a plant to bend her abdomen, and (3) attaching an egg on the leaf. The first and the second components curvilinearly increased
with increasing plant density, while the third component was not influenced by the plant density. The analysis of the flight
path of P. rapae crucivora indicated that the curvilinear increase in the frequency of abdominal bending behaviors occurs since a female flies at least
about 1.3 m between successive abdominal bending behaviors, irrespective of the plant density, when the plant density is sufficiently
high.
Received: October 23, 1998 / Accepted: February 15, 1999 相似文献
15.
Minoru Murai 《Researches on Population Ecology》1979,21(1):153-163
Summary The distribution of sugarcane bugs,Cavelerius saccharivorus is remarkably patchy at time of the peak emergence of the first generation adult in early summer. In population near carrying
capacity 70% of adults become macropterous, and they move to sparse populations or vacuum areas.
The experiment on the reproductive difference between females from field populations with different densities, showed that
the overcrowding restricted their oviposition. On the further experiment it was shown that reproductive ability of macropterous
adults or dispersers was not much inferior to that of brachypterous from sparse populations. Overcrowding at time of the peak
emergence is reduced by the dispersal. Hence the intraspecific competition is a transient condition. The oviposition is at
first restricted in residents of dense populations as compared with brachypterous adults of sparse populations, but the difference
becomes small as the former density decreases by the emigration.
The last section considers the relation of the reproductive rate and dispersal risk to the rate of dispersal with the simple
model, which explains the characteristic dispersal of this species. 相似文献
16.
Duncan A. Mackay 《Researches on Population Ecology》1985,27(1):87-98
Summary OvipositingE. editha butterflies display post-alighting discrimination among patches ofCollinsia torreyi, one of their major hosts in the General's Highway (GH) population at a montane site in California. Females tended to accept
(i.e. oviposit on) dense patches of this host and to reject sparse patches. Possible behavioural mechanisms underlying this
tendency are discussed. The consequences of this non-random pattern of oviposition for egg and larval survivorship were investigated
and no differences were found in the survivorship of larvae on acceptable and unacceptable collinsias. 相似文献
17.
Summary A field work with two plots of grid, a snap trap being set on each station spaced 5 m apart, was executed in the summer of
1968 to evaluate prebaiting in census trapping by comparing the result in one plot, prebaited for three days, with that in
the other not prebaited. Since the population was as high as some 230 per acre on the average in density and formed of the
vole,Microtus montebelli, alone, sufficient samples were gathered irrespective of the plot size as small as 50×50 m.
Owning to the circumstances, multiple collisions inflicted so intense influence on sampling especially in the prebaited plot
thatz-equation for census adjusted to the effect was well applicable to the data in either plot. In sampling, the fact that small
voles are apt to be caught later than large voles was statistically evidenced in either sex, and yet any proof that males
tend to be caught prior to females was not offered. It was ascertained in either plot that the daily catch was realized according
to the same rule through the whole period of trapping in both external belt and internal square within the plot; hence it
follows that no considerable immigration occurred.
One of the beneficial effects of prebaiting is sure to be that the probability of capture was markedly enhanced in the prebaited
plot, and a second is supposed, though inconclusively, to be that a good sampling could be executed consistently through the
census period giving rise to no inordinate catches perhaps due to heterogeneous sampling as was seen in earlier days in the
not prebaited plot. The supposition has derived from the condition that most of the whole population is trappable, which is
established by interrelation among population density, size of home range and trap spacing. It was suggested that the effect
of prebaiting should be evaluated from the view-point of the interrelation, because the basic utility of prebaiting consists
in that it may help to our utlimate purpose to estimate the whole population.
Contribution from JIBP-PT No. 55, carried out by the grant from the expenditure of Education Department to the specific study
on “Dynamics of Biosphere” 相似文献
18.
Summary Two experiments on the nymphal predation ofPodisus maculiventris were conducted usingSpodoptera litura larvae as prey.
First experiment: The predator nymphs divided into three groups were reared individually from second instar to adult in a
small vessel. Each nymph in the groups 1, 2 and 3 was allowed to attack the serially growing larvae (these were supplied at
the rate of one per day) from 3-, 5- and 7-day old after hatching, respectively. The first prey used for the group 1 was so
small that it was not only insufficient to satiate the predator but also was difficult to be searched out. But these disadvantages
were soon recuperated due to the rapid growth of the prey and all nymphs could survive to adults. The survival rate of third
and fourth instar nymphs in the group 3 was severely affected by vigorous counterattack of older prey larvae.
Second experiment: The predator nymphs were individually reared either in a small vessel or in a large one at various rates
of food supply (the prey larvae of 7-day old were used). The functional response curves obtained for each instar of the predator
took a saturation type within a certain range of the prey density. The saturation level specific to each instar was generally
higher for the predator reared in the large vessel than in the small one. The functional response of fourth and fifth instar
nymphs was accelerated at a high prey density,viz. 16 larvae per vessel. Even at the low rate of food supply,viz. one larva per day per predator, the predator nymphs could survive to adults, but the size of resultant adults were abnormally
small. 相似文献
19.
Midori Tuda 《Researches on Population Ecology》1998,40(3):293-299
In an insect host (the cowpea weevilCallosobruchus maculatus)- parasitoidHeterospilus prosopidis) experimental system, the population densities of the component species oscillated for the first 20 generations and then
abruptly stabilized as the parasitoid density decreased. Examination of the host and parasitoid after the 40th generation
in the long-term experiment showed that (1) host larvae exhibited contest-type competition (killing other larvae inhabiting
the same bean), in contrast to the founder population being scramble-type competitors and (2) the parasitoid attack rate on
the host did not change. There was also an evolutionary trade-off between body size and the rates of larval survival and development,
suggesting a cost of contest competition on larval survivorship and development. I tested model predictions (Tuda and Iwasa
1998) that (1) host equilibrium population size should gradually decrease as the proportion of the contest type increases
and that (2) random attacks of the parasitoid on the host should reduce the rate of increase in proportion of the contest
type, and the effect should become manifest especially during the first 20 generations. Two of three host-only replicates
showed significant decrease in population sizes. Although the density of emerging adults per bean did not differ between replicates
of the host-only and host-parasitoid systems, comparison of the host body size between them on day 270 (at the 13th generation)
showed that the host was more contest-type in the host-only system than in the host-parasitoid system, as the model predicted,
and later on day 650 the effect of the parasitoid had disappeared. 相似文献
20.
Summary
Luehdorfia butterflies lay eggs in clusters. Clones of their host plants (Asiasarum andHeterotropa) are distributed pacthily among the understory of deciduous forests. Groups ofLuehdorfia larvae often exhaust the clones and may wander over the forest floor seeking new clones. The highest mortality observed is
during this wandering period. To elucidate whyLuehdorfia butterflies lay eggs in clusters, a simulation experiment was made for hypothetical populations which lay eggs in clusters
or singly. Field data on larval mortality, consumption, density of host clones and leaf weight forLuehdorfia japonica were incorporated into the model. The predictions of the simulation were: (1) When the egg density is low, the single egg
type could leave many more pupae than the egg clustering type, but when the egg density is high, the former might leave smaller
number of pupae than the latter; and (2) There are optimal sizes of egg clusters for different egg densities and the optimal
size becomes larger as the egg density increased.
This work was supported in part by Grant-in-Aid No. 439017 and No. 56480039 from the Ministry of Education, Science and Culture,
Japan. 相似文献