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1.
Kenji Fujisaki 《Researches on Population Ecology》1985,27(1):125-136
Summary The wing polymorphism of the oriental chinch bug,Cavelerius saccharivorus, was studied in relation to its reproductive strategy. The frequency distribution of wing form in terms of the relative wing
length (R.W.L.) changed with increase in the population density from a single modality biased toward the brachypterous form
to bimodality with both macropterous and more extreme brachypterous forms. Since some evidences in the field showed that fliers
are limited to macropters, such a bimodality of wing form indicated thatC. saccharivorus employs a mixed strategy with some portion of adults staying on in the same habitat, whereas the rest disperse. Moreover,
macropters were larger in body size than brachypters emerging in high density populations, although smaller than brachypters
emerging in low density populations. Larger body size as well as the delay of ovarian maturation in macropters was considered
to be a beneficial trait for migratory behaviour. 相似文献
2.
Kenji Fujisaki 《Researches on Population Ecology》1986,28(2):219-230
Summary Responses to nymphal density in the determination of wing form were compared between the offspring from brachypter x brachypter
crosses and those from macropter x macropter crosses of the oriental chinch bug,Cavelerius saccharivorus.
In the offspring from crosses between macropters, there was a strong tendency for macropters to increase to a rather high
level with increasing nymphal density in both sexes. In contrast to this, in the offspring from crosses between brachypters,
the appearance rate of macropters attained a maximum value in moderately crowded conditions and conversely decreased to a
lower level in more crowded conditions in both sexes. Thus density response patterns concerning the determination of wing
form were quite different between the offspring from different crosses in the wing form, indicating that there is a genetic
basis underlying wing polymorphism in this species.
As for the body size of emerged adults, macropters tended to be larger than brachypters in the same crowded condition. Moreover,
the rate of decrease of body size with nymphal density was lower in the offspring from crosses between macropters than in
the offspring from crosses between brachypters. This indicated that the former offspring are more tolerant of nymphal crowding
than the latter. The difference in such a tolerance against nymphal crowding between the offspring from different crosses
was considered to be related to the difference in the appearance of macropters in the crowded conditions between them. 相似文献
3.
Kenji Fujisaki 《Researches on Population Ecology》1993,35(2):171-181
Summary Reproduction and egg diapause of the oriental chinch bug,Cavelerius saccharivorus, in the subtropical winter season were investigated in relation to its wing polymorphism. Macropterous females collected
from the southern part of Okinawa Is. in the autumn season delayed their oviposition and were less fecund early in the adult
life period, but survived much longer than brachypterous females collected from the same locality. The total fecundity was
not significantly different between wing morphs. The diapause of eggs laid by brachypters tended to be terminated more easily
at a high temperature than that of eggs laid by macropters. This indicated that the eggs laid by macropters were more intense
in their diapause than those laid by brachypters. However, irrespective of the parental wing form, diapause showed considerable
variation in its intensity within and between clutches. 相似文献
4.
Kenji Fujisaki 《Researches on Population Ecology》1993,35(2):317-324
Summary Genetic correlations of the wing form and the relative wing length between females and males were estimated in the oriental
chinch bug,Cavelerius saccharivorus, by calculating the correlation between the sexes of the proportion macropterous or the mean relative wing length in full-sib
families obtained from different wing forms of parents emerged in a high density population. There was a significantly positive
genetic correlation between the sexes in both the proportion macropterous and the mean relative wing length. However, the
appearance rate of macropters tended to be much lower in males than in females under the rearing conditions which promote
the appearance of macropters. This was evident especially in the offspring of brachypterous parents. These indicated that
inC. saccharivorus the wing polymorphism of males is not a simple result of the genetic correlation of wing morphology between the two sexes.
It was considered that both of the female and male fitness advantages to wing reduction, as well as the genetic correlation
between the sexes, would influence the evolution of wing polymorphism in this species. 相似文献
5.
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
6.
Life history traits of the phytophagous ladybird beetle Epilachna yasutomii were compared between a nonpest population feeding on wild blue cohosh and a pest population feeding on cultivated solanaceous
crops, mainly potato. Newly emerged adults of the nonpest population entered diapause early in midsummer when blue cohosh
withered, while adults of the pest population were found in tomato and eggplant fields until late autumn. The pest population
had larger females, a higher population growth rate, a shorter larval developmental period, and reduced longevity of overwintered
females, compared with the nonpest population. ANOVA indicated that all these life history traits were influenced by the food
plant, and that the number of eggs laid per female and the longevity of overwintered females were also affected by the population
type. These findings suggest that the life history pattern of E. yasutomii changed to high fecundity with a short life span from low fecundity with a long life span as a result of the host shift from
wild blue cohosh to cultivated solanaceous crops.
Received: May 22, 1998 / Accepted: January 13, 1999 相似文献
7.
Frank J. Sonleitner 《Researches on Population Ecology》1977,19(1):10-32
Summary A model is described for investigating the interactions of age-specific birth and death rates, age distribution and density-governing
factors determining the growth form of single-species populations. It employs Monte Carlo techniques to simulate the births
and deaths of individuals while density-governing factors are represented by simple algebraic equations relating survival
and fecundity to population density. In all respects the model’s behavior agrees with the results of more conventional mathematical
approaches, including the logistic model andLotka’s Law, which predicts a relationship betwen age-specific rates, rate of increase and age distribution.
Situations involving exponential growth, three different age-independent density functions affecting survival, three affecting
fecundity and their nine combinations were tested. The one function meeting the assumptions of the logistic model produced
a logistic growth curve embodying the correct values orr
m
andK. The others generated sigmoid curves to which arbitrary logistic curves could be fitted with varying success. Because of
populational time lags, two of the functions affecting fecundity produced overshoots and damped oscillations during the initial
approach to the steady state.
The general behavior of age-dependent density functions is briefly explored and a complex example is described that produces
population fluctuations by an egg cannibalism mechanism similar to that found in the flour beetleTribolium.
The model is free of inherent time lags found in other discrete time models yet these may be easily introduced. Because it
manipulates separate individuals, the model may be combined readily with the Monte Carlo simulation models of population genetics
to study eco-genetic phenomena. 相似文献
8.
Masami Hasegawa 《Researches on Population Ecology》1990,32(1):119-133
Summary The demography of the lizardEumeces okadae was studied for 4 years on Miyake-jima, in the Izu Islands, central Japan. Most males matured at 3 years of age with a mean
snout-vent length of 77.5 mm. Females matured at 3–4 years with a mean SVL of 77.8 mm, and reproduced biennially thereafter.
Growth continued after maturity with a decreasing rate. In females, annual growth was negligible in reproductive years, but
resumed markedly in non-reproductive years. Clutch size increased with SVL and was used to construct a fecundity schedule.
Population density (exclusive of hatchlings) was estimated to be ca. 4000 individuals/ha in August, an exceptionally high
density for lizards. Before introduction of the weasel onto Miyake-jima, low predation pressure had allowedE. okadae to maintain a high population density. Estimated annual survival rates were 36% for hatchlings, 56% for yearlings, 80% for
2-year-olds, 63% for adult males and 76% for adult females. The cohort generation time (6.95 years) was so long that theE. okadae population can be characterized by a combination of low natality and slow turnover. 相似文献
9.
Koichi Tanaka 《Researches on Population Ecology》1995,37(2):197-202
Within a population of the web-building spiderAgelena limbata, the weight of the first instar nymphs ranged from 1.187 to 6.559 mg. Both intraclutch and interclutch variation were recorded.
The mean weights were different among clutches and the coefficients of variation within a clutch ranged from 3.3 to 29.2%.
Variation in the nymphal weight was certainly derived from variation in the egg weight because there was a high correlation
between the two weights. Factors affecting interclutch variation in nymphal weight were examined by multiple regression analysis.
Nymphal weight was positively correlated with the body size and food conditions of female parents, and negatively correlated
with the clutch size. Among these three factors, the food conditions of female parents had the largest apparent effect on
the interclutch variation. The results suggest that females with larger body size and more food produce larger offspring,
and that there is a trade-off between offspring size and clutch size. Heavier nymphs had larger body size (carapace width)
and may have larger energy reserves. Heavier nymphs survived experimental starvation for a significantly longer period. 相似文献
10.
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
11.
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
12.
Summary The population growth of the green rice leafhopper,Nephotettix cincticeps, in the paddy field was analyzed based on the life table data accumulated for six years.
The paddy field population, which stems from the invading adults of the first generation (G-I), repeats two complete generations,
and the hatchlings of the fourth generation (G-IV) enter diapause and overwinter as the fourth instar nymphs in fallow paddy
fields. It was clarified that the density dependent reduction in the mean longevity and oviposition rate of adult females
in G-II and III played a primary role in stabilizing the annual population densities. The annual average of the mean longevity
of G-II females (3.9 days) was much shorter than that of G-III ones (7.7 days) and thus the density dependent reduction in
the mean longevity induced a more prompt regulatory effect on the oviposition of G-II females compared with G-III ones. As
the result, two equilibrium densities of eggs were obtained,e.g., ca 100 and 700 eggs per hill in G-III and IV, respectively. Density dependent decrease in the proportion of mature females in
the adult population was especially conspicuous in G-II, and this was closely associated with the density dependent reduction
in the mean longevity and fecundity. Thus, the density dependent dispersal (emigration) of the adult females by flight in
G-II and III was the most convincing factor in the process of population regulation. The density dependent dispersal of the
adult females is effective in avoiding the deleterious effects of nymphal crowding in a breeding habitat unit (a paddy field),
and may result in a more even distribution of the population over a continuous habitat units in a locality than otherwise. 相似文献
13.
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
14.
Hiroichi Sawada Ayi Kusmayadi S. W. Gaib Subroto Edi Suwardiwijaya Mustaghfirin 《Researches on Population Ecology》1993,35(1):113-137
Summary Population dynamics of the brown planthopper (BPH),Nilaparvata lugens St?l, were investigated in paddy fields in the coastal lowland of West Java, Indonesia, where rice is cultivated twice a
year, in the wet and dry cropping seasons. Distinct differences in the basic features of population dynamics were detected
between the two rice cropping seasons: (1) In the wet season, BPH populations multiplied rapidly in the period from initial
to peak generation, reaching quite often the destructive level despite the low density of initial immigrants. However, in
the dry season, the population growth rate and the peak population density were much lower than those in the wet season. The
abundance of natural enemies such as arthropod predators played a major role in determining such a difference in seasonal
population development. (2) The density at the peak generation or the occurrence of outbreaks in each field was predictable
in the wet season with fairly high accuracy on the basis of the density at the initial or previous seasonal generations. In
the dry season, however, the rate of population growth and the peak population density widely varied among the fields depending
on the water status in each field. (3) Density-dependent processes to regulate the population density were detected in both
cropping seasons. In the wet season, the regulatory processes were only detected in such high densities as cause the considerable
deterioration of host plants, which suggested that the processes were largely attributable to intra-specific competition.
In the dry season, however, the regulatory processes operated at a much lower density in the earlier stages of the crops.
The results of an analysis of adult longevity or residence period suggested that the density-dependent dispersal of macropterous
adults played an important role in stabilizing the population fluctuation among the fields in the early dry season. 相似文献
15.
Summary The dynamics of Angoumois grain moth,Sitotroga cerealella (Olivier), and maize weevil,Sitophilus zeamais
Motschulsky, populations breeding in a small bulk (initially 5.36 t) of shelled corn were studied over an 8-year period by monthly sampling.
The weevil population showed wide fluctuations in density superimposed on a general decline with time. The moth population
showed no upward or downward trend for the first 60 months, although it fluctuated widely. Following a decline that occurred
between 56 and 60 months, the moth population fluctuated within a much narrower range, and there was a general decrease in
density with time. The decline of the weevil population paralleled deterioration of the corn as did that of the moth population
after ca 60 months, and the decline of both species probably resulted from increasing scarcity of suitable breeding sites.
Both populations exhibited seasonal variation in density with minima in late summer and early fall, following periods of adversely
high temperatures in the storage shed. The populations increased during the fall, leveled off or declined slightly during
the winter months, and then increased to maximum levels in late spring or early summer. It thus appears that high temperatures
had a greater adverse effect on the populations than low temperatures. The grain moth and the maize weevil both tended to
be randomly dispersed at low population levels and moderately aggregated at intermediate and high levels, although the degree
of aggregation was not correlated with population density when low population levels were considered separately, and the maize
weevil showed a greater tendency for aggregation than did the grain moth. Analysis of individual samples at fixed points in
time showed a conspicuous bias for negative correlation between numbers of the two species within sampling quadrats, suggesting
a tendency for the two species to segregate within the grain mass. This process could have resulted from behavioral differences
or from the destruction of one species by the other. Competitive displacement of the grain moth by the maize weevil has been
demonstrated in laboratory experiments but has rarely been observed under natural conditions, and in our study the two species
coexisted for 8 years in a relatively small grain bulk. 相似文献
16.
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
17.
Omar Muhamad Ritsuko Tsukuda Yoko Oki Kenji Fujisaki Fusao Nakasuji 《Researches on Population Ecology》1994,36(1):53-62
The larvae ofPlutella xylostella were fed on five wild crucifers,Capsella bursa-pastoris, Lepidium virginicum, Cardamine flexuosa, Rorippa indica, R. islandica and a crop, cabbage. The developmental period of the immature stages, adult longevity, preoviposition period, fecundity and
morphometrical characters of the adults were measured. The flight activity of the adults was also measured by the tethered
flight method. All the wild plants except forR. islandica were less suitable host plants than cabbage, and larvae which were fed on these less suitable plants emerged as smaller adults
with shorter wings. The smaller female adults had lower fecundity but a higher flight activity. Smaller adults measured in
terms of their pupal weight among individuals fed on the same host plant had longer wings. These smaller adults with longer
wing flew more actively. 相似文献
18.
Summary Seasonal changes in the percentage of macropterous individuals in natural population ofMicrovelia douglasi in permanent habitats were investigated in Shimane, western part of Japan. Macropterous forms of 5th instar nymphs occurred
most frequently from late June to early July. However, the seasonal appearance of macropterous adults differed between habitats
and years. There were significant effects of density, temperature, photoperiod and food availability on the percentage of
macropters under laboratory conditions. The percentage of macropterous forms generally increased with density, but the mode
of the response was modified by temperature, photoperiod and food availability. When insects were reared under long day photperiod
(16L8D) with abundant food (0.5–1.0 g/container/day), the percentage of macroptery varied most among the different density
treatments at the intermediate temperature (24°C) and the difference was reduced at higher temperature (28° and 32°C). Effects
of temperature were small under the short day photoperiod (12L12D). Under 12L12D photoperiod sensitivity of density responses
were higher at 32°C and lower at 24°C than those under 15L8D photoperiod. When the insects were supplied with food every other
day, the density response became obscure. Ecological significance of environmental responses in the wing morph determination
was discussed in relation to the heterogeneous environment of water surface. 相似文献
19.
Shefali Begum Ritsuko Tsukuda Kenji Fujisaki Fusao Nakasuji 《Researches on Population Ecology》1996,38(2):257-263
The wild crucifers,Rorippa indica andLepidium virginicum, are known to serve as host plants for the diamondback moth (DBM),Plutella xylostella, but they are less suitable than the preferred cultivated cruciferous plant, cabbage, in terms of adult body size and fecundity.
The life history traits and flight activity of DBM adults grown on various host plants were investigated. The adults thus
reared on each host plant were divided into three size groups (small, medium and large). In general, female adults grown on
the wild crucifers were less fecund and lived longer than those reared on cabbage. Flight activity was higher in adults grown
on wild crucifers than in those reared on cabbage. Male adults flew longer than females. Fecundity, longevity, flight activity
and morphometrical characters of adults were positively correlated with pupal weight in individuals reared on the same host
plant. A negative relationship was found between fecundity and flight activity in females of the same size group, but a positive
one was observed in females reared on the same host plant. 相似文献
20.
Minoru Murai 《Researches on Population Ecology》1975,17(1):51-63
Summary The change in population density ofCavelerius saccharivorus was studied in the sugar cane field and theMiscanthus habitats around it. This species spent 2 (or partly 3) generations a year. It was suggested that the density rose in the
sugar cane field where the density had been low enough, when the population density increased in the nearby sugar cane fields.
Likely, the density in theMiscanthus habitat increased with the density in the nearby sugar cane field. It seems that these are mainly due to flying movement
of adults, and that the movement takes place in every season.
It was found through the investigation in the sugar cane field that the percentage of long-winged adults increased with the
population density. These adults seemed to emmigrate to the nearby sugar cane fields andMiscanthus habitats. The remarkable increase in the percentage of long-winged adults in the sugar cane field was probably due to the
immigration into there. In theMiscanthus habitat the adult population was consisted mainly of long-winged ones. Through all the observations, it was suggested that
the adult movement was associated with the population regulation and performed chiefly by long-winged adults. 相似文献