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1.
I Nyoman Widiarta Tsuyoshi Ikeda Kenji Fujisaki Fusao Nakasuji 《Researches on Population Ecology》1993,35(1):23-29
Summary Dispersal propensity of green leafhoppers was compared between a tropical species,Nephotettix virescens, and a temperate species,N. cincticeps. The flight ability was measured with tethered flight technique under laboratory conditions (25°C, 16L-8D). The pre-flight
period was shorter and the flight duration was longer inN. virescens than inN. cincticeps in both sexes. No significant correlations were found between the flight activity and morphometric characters for either
of the two species. The results suggested that dispersal propensity ofN. virescens is higher than that ofN. cincticeps. 相似文献
2.
I Nyoman Widiarta Yoshito Suzuki Hiroichi Sawada Fusao Nakasuji 《Researches on Population Ecology》1990,32(2):319-328
Summary The population dynamics ofNephotettix virescens, a vector of rice tungro virus disease was investigated in a synchronized transplanting area at Jatisari (1984–1986), West
Java and in a staggered transplanting area at Sidan (1986–1988), Bali, Indonesia. The FARMCOP suction sampler was employed
for population censuses ofN. virescens and its natural enemies. The population growth pattern was affected by transplanting pattern: In the staggered transplanting
area, the population density increased from the immigrant generation to the first generation, and sharply decrease thereafter,
while in the synchronized transplanting area the population density often reached the highest peak in the second generation.
The degree of contageousness in the spatial distribution ofN. virescens was negatively correlated with population density of the immigrant generation.
Contribution from Indonesia-Japan Joint Program on Food Crop Protection 相似文献
3.
Eizi Kuno 《Researches on Population Ecology》1963,5(1):31-43
Summary The frequency distribution of the number of nymphs per hill of rice plant were analyzed for three species of rice leaf- and
planthoppers,Nilaparvata lugens, Delphacodes striatella and Nephotettix cincticeps, based on the sampling data obtained during their last generations in the paddy field.
For every species concerned, individual distributions were proved to be contagious and to fit well to the negative binomial
distribution. Further, it was found that the value of negative binomial parameterk is so stable for same species that a single value ofk is applicable for a series of counts with different means, whereas thatk differs remarkably among different species: if the reciprocal of the weighted estimate of commonk which is an adequate index measuring degree of contagiousness of the distribution, is compared among different species, it
is higher in the order ofNilaparvata, Delphacodes andNephotettix.
The ecological and practical implication of constancy and heterogeneity within and among species was discussed respectively
as to the value of parameterk. 相似文献
4.
The outbreak mechanisms of the green rice leafhopper,Nephotettix cincticeps Uhler, in northern Japan
Intraspecific regulatory processes keep the population ofNephotettix cincticeps stable at a low density in southern Japan. In northern Japan, however, the yearly population density of the insect fluctuates
violently, and large outbreaks occasionally take place. To clarify the difference in the population dynamics between the two
regions, we analyzed light-trap and sweep-net sampling records from prefectural and national agricultural experimental stations.
The survival rate of the overwintering population decreased with increases in the period of continuous snow cover (PCSC) in
the north, and initial population densities in the years of long PCSC were too low for populations to reach equilibrium density
by the end of the active breeding season. This made yearly population fluctuations in the north much larger than in the south.
The equilibrium density in the north was higher than in the south. The higher equilibrium density presumably permits the higher
population density and larger yearly population fluctuations in the north. A major factor responsible for the difference in
equilibrium densities between the two regions is the difference in heading dates of the host plant (rice). Qualitative differences
among rice plant varieties, and among biotypes ofN. cincticeps, may also be important. 相似文献
5.
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
6.
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
7.
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
8.
Kazuo Nakamura Yosiaki It? Kazuyoshi Miyashita Akira Takai 《Researches on Population Ecology》1967,9(2):113-129
Summary The population parameters of green rice leafhopper,Nephotettix cincticeps in hibernated generation was estimated by the capture-recapture method on the gramineous weeds of resting paddy field from
late in April to mid-May, 1962–1965.
The difficulty of applying the capture-recapture method to this insect is caused from the low density and the low activity
of the leafhopper, so that it is necessary to make the suitable plan of capture-recapture series and to construct the special
method to detect the population parameters.
The number of adults differed greatly among the years and among the plots in the same year. But, in general, the density was
relatively high late in April, and decreased rapidly in May. The number of males was higher than that of females late in April,
but decreased rapidly to become lower in May.
The sampling efficiency with sweep-net depends upon the many factors, such as weather and floristic conditions; especially
the atmospheric temperature and the force of wind are considered to affect greatly to the efficiency. In general, low temperature
and strong wind are the cause of low sampling efficiency.
Contribution from JIBP-PT No. 20. 相似文献
9.
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
10.
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
11.
Summary Responses of laboratory population of the azuki bean beetleCallosobruchus chinensis to temperature conditions of 30°C and 32°C are compared. Equilibrium population size was found to be lower at 32°C. A one-generation
process examined by reproduction-curve experiments is divided into two consecutive life stages specified by different habitats,
i.e., outside and inside beans. Modified logistic difference equations are used to describe these population-level responses
at each life stages. Sensitivity analysis is used to determine parameters of importance, thus determining the main cause of
the reduced equilibrium population size at 32°C. The reduction resulted from the decrease in maximum population size of emerged
adults which have experienced inside-bean process. The application and limitation of this population-level analysis to different
levels 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.
Eizi Kuno 《Researches on Population Ecology》1991,33(1):33-39
Summary In some situations the logistic equation in the usual expression, dN/dt=r(1−N/K)N, exhibits properties that are biologically unrealistic. For example, whenr≦0 the population can no longer show any normal, negative response in per-capita growth rate to increasing density. Also,
when the equation is employed in the Volterra's competition model, a familiar but incredible conclusion is derived which says
that the outcome of competition is entirely independent of the reproductive potentialr of each species. It is shown that all such strange properties are mere artifacts arising peculiarly in thisr-K model from its misleading implicit supposition thatK could be independent ofr, and they can be readily removed by alternative use of a plainer, classical form of the model, dN/dt=(r−hN)N. 相似文献
14.
Summary Populations of the two-spotted spider mite,Tetranychus urticae Koch collected from various localities and from various host plants in Japan showed wide variations in diapause attribute.
Diapause percentages at 18°C/9L15D varied from nearly 100% in the north to 0% in the south-west. At intermediate latitudes
the mites showed wide inter-population variations. Populations on herbaceous hosts in vinyl- or glass-houses gave significantly
lower incidence of diapause than those on roses and deciduous fruit trees. Presence of winter hosts and better host quality
under protected environments seemed to favour non-diapausing mites.
The temperature threshold for diapause expression also varied widely among local populations. Northern populations consistently
had higher and less variable thresholds than populations at intermediate latitudes with thresholds between 15 and 18°C. Inbred
lines derived from a population in Kyoto exhibited a wide variation in diapause percentage at 18°C. These results show that
diapause inT. urticae is a quantitative threshold trait and that populations in central Japan consist of a variety of genotypes with different
diapause traits. This might provide a genetic source for adaptation to local and temporal variations in environmental conditions. 相似文献
15.
Summary An epidemiological system model was developed to evaluate the role of factors which were responsible for the prevalence of
rice dwarf virus (RDV) transmitted by the green rice leafhopper,Nephotettix cincticeps. Simulation tests were conducted by varying values of the following three parameters: the vector density, the coefficient
of the efficiency of feeding acquisition of RDV of the vector, and that of efficiency of RDV transmission by the vector. The
effect of each parameter was assessed in terms of changes in percentages of infected insects and of infected rice hills.
Both the percentages of infected insects and of infected rice hills increased rapidly with increasing vector density within
a range of low vector density. The former increased linearly when the acquisitive coefficient was increased. But the percentage
of infected rice hills was affected to a lesser extent. The percentage of infected insects and that of infected rice hills
increased exponentially with increasing values of the transmission coefficient. The results obtained from the simulation tests
were discussed in relation to the ecological factors which caused the recent prevalence of RDV.
A part of this research was supported by science research fund from the Ministry of Education. 相似文献
16.
Osamu Imura 《Researches on Population Ecology》1986,28(2):281-293
Summary The population fitness in terms of the intrinsic rate of increaser
m was measured in eight pure (homogenic) strains ofEphestia kühniella
Zeller with different larva color at an optimal temperature of 25°C, and in three strains at unfavorble temperatures of 15, 17,
28, and 30°C, to understand a mechanism of maintenance of a larval color variation found in wild populations. The survival
rate, hatchability, and gross rate of reproduction were poorly correlated with the fitness but the mean generation time and
net reproduction rate were correlated with the fitness significantly at 25°C. Intermediate color (pink) strain(s) grew faster,
initiated reproduction earlier and had shorter longevities than other strain(s) under the range of 15 and 28°C; the fitness
was highest in the intermediate larval color strains except at 30°C in which all strains had a negative rate of increase.
The results were discussed with reference to the relationship between the larval color and fitness along with a maintenance
mechanism of the variation. 相似文献
17.
Akio ?take 《Researches on Population Ecology》1966,8(1):62-68
Summary Light-trap records on the green rice leafhopper,Nephotettix cincticeps, were dealt with to study its population fluctuations in the Hokuriku district. Crude data were modified for distinguishing
years of the low intensity of infestation by the insect from the rest of years. It is then clearly demonstrated that the low
intensity of infestation were ordinarily preceded by heavy snowfall, although heavy snowfall could not be regarded as the
only factor checking the vigorous multiplication of the populations. 相似文献
18.
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
19.
Competitive exclusion through reproductive interference 总被引:6,自引:0,他引:6
Eizi Kuno 《Researches on Population Ecology》1992,34(2):275-284
Summary A simple differential equation model was developed to describe the competitive interaction that may occur between species
through reproductive interference. The model has the form comparable to Volterra's competition equations, and the graphical
analysis of the outcome of the two-species interaction based on its zero-growth isoclines proved that: (1) The possible outcome
in this model, as in usual models of resource competition, is either stable coexistence of both species or gradual exclusion
of one species by the other, depending critically upon the values of the activity overlapping coefficientc
ij
; (2) but, for the samec
ij
-values, competitive exclusion is much more ready to occur here than in resource competition; (3) and moreover, the final
result of the competition is always dependent on the initial-condition due to its non-linear isoclines, i.e., even under the
parameter condition that generally allows both species to coexist, an extreme bias in intial density to one species can readily
cause subsequent complete exclusion of its counterparts. Thus, it may follow that the reproductive interference is likely
to be working in nature as an efficient mechanism to bring about habitat partitioning in either time or space between some
closely related species in insect communities, even though they inhabit heterogeneous habitats where resource competition
rarely occurs so that they could otherwise attain steady coexistence. 相似文献
20.
Summary When there exist two species such that one is a parasite on fruit and the other exploits the parasitized fruits, they must
compete for a limited resource with each other. The relation betweenDacus cucurbitae andAtherigona orientalis is an example of such a situation. We raise a question whether the population of a parasite on fruit can be stabilized by
the existence of the cleptoparasite of the parasite on fruit.
The changes in their population densities are represented as a differential equation with time delayed parameters, which is
deduced from the context of life histories of the two species. An index representing degree of overlapping of generations
(g) is defined as an average oviposition period devided by the average preoviposition period, and the value is assumed to be
the same in the two species.
The stability of the system is classified by three parameters: the reproductive rate of the parasite on fruits (R), the survival probability of it through competition against the cleptoparasite (p), and the generation overlapping index (g).
For small values ofg, e.g. less than some 0.5, the stability is determined mainly by a product ofRp: the values larger than 1 result in no equilibrium and infinite increase of both species, the values near 0 lead to large
amplitude oscillations, and the intermediate values make stable equilibria or regular small oscillations. Asg takes the larger values, the stability region in the space (p, R) occupies the larger area.
The model presented here is well adjusted to the fluctuating pattern of the population ofD. cucurbitae on Okinawa Is., and would also be applied to analysis of both hyperparasitisms and inquilin.
This study was supported partly by Science Research Fund (No. 574092) from the Ministry of Education, Japan. 相似文献