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1.
Kazuo Nakamura Masako Nakamura Tadao Matsumoto Yosiaki It? 《Researches on Population Ecology》1975,16(2):198-206
Summary Population densities of the three grasshopper species onMiscanthus sinensis grassland in the Kawatabi IBP Area, Japan,Parapleurus alliaceus, Mongolotettix japonicus andChorthippus latipennis, were estimated principally by the release-and-recapture method for five years from 1968 to 1972.
The total number of individuals of all three grasshopper species was about 42 per 100m2 in August. The number of individuals ofP. alliaceus adult, the dominant species on this grassland, showed a tendency to decline during the five years, though the amplitude was
not so large. The number of eggs laid was, however, nearly constant and the mortality from the second nymphal instar to adult
was relatively low and constant during the survey period. The weather conditions during the periods of egg and the first instar,
such as snowfall and temperature decreasing, are suggested to be one of the factors causing variation in numbers.
Contributions from JIBP-CT No. 145. A part of this study was supported by the special project, “Studies on the dynamic status
of biosphere”, sponsored by the Ministry of Education. 相似文献
2.
Osamu Iwahashi 《Researches on Population Ecology》1977,19(1):87-98
Summary The sterile insect release method was applied to eradicate the melon fly,Dacus cucurbitae, from the 58.5 km2 island of Kume, in the Okinawa Islands group. Weekly releases of 1 to 1.5 million flies irradiated as pupae with 6–7 kR from
a cobalt-60 source did not decrease the wild melon fly population. Releases of 1.5–2 million pupae per week made from September,
1975 to January, 1976 decreased the percent egg-hatch of females caught on Kume Is., but did not decrease the percent infestation
significantly. The number of pupae released was increased from February, 1976 to accelerate the eradication process. When
the number of pupae released exceeded 3.5 million per week, a rapid increase in the ratio of marked (sterile) to unmarked
(wild) flies, a remarkable decrease in percent egg-hatch, and a decrease in percent infestation of fruits were observed. There
has been no sign of melon fly infestation in wild cucurbit fruits from October, 1976 to the present time (April, 1977), despite
the fact that more than 70,000 fruits were carefully examined. The eradication of the melon fly from Kume Is. was thus achieved
by April, 1977, after the release of 264 million sterile fly pupae. 相似文献
3.
On an outbreak of the citrus flat-headed borer,Agrilus auriventrisE. Saunders in Nagasaki Prefecture
Ryoh-ichi Ohgushi 《Researches on Population Ecology》1967,9(1):62-74
Summary The process of an outbreak of the citrus flat-headed borer,Agrilus auriventris in Nagasaki Prefecture was described with some ecological considerations on causative factors.
This outbreak which showed a typical “Gradation”, initiated around 1958, and terminated in 1963. The peak year was seen in
1961. At first attack by the borer was restricted to old and weak trees, but it was also found in young and healthy trees
in the peak year.
Some environmental conditions in orchards were examined in relation to the intensity of infestation by the borer. Soil management
and drought seemed to have remarkable correlations with the borer's infestations.
Probably, this outbreak was caused by the weakening of citrus tree by gummosis and abnormal defoliation, aging of orchard
trees, and drought in the summer of 1959∼1960. Interrelation between these causes and processes are shown schematically in
Fig. 12. 相似文献
4.
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
5.
R. N. Coulson P. E. Pulley D. N. Pope W. S. Fargo L. J. Edson 《Researches on Population Ecology》1980,22(1):117-135
Summary Infestations ofDendroctonus frontalis
Zimm. are often observed to enlarge continuously by the colonization of new hosts in a pattern similar to a forest fire. This pattern
of infestation growth presents unique problems in quantitatively estimating populations ofD. frontalis. Beetle populations on each infested tree in an infestation go through five processes: attack, oviposition, reemergence,
survivorship, and emergence. These processes, which have been described mathematically in the literature, each take several
days for completion. In order to follow the distribution and abundance ofD. frontalis throughout the course of development of a spot, we need a daily estimate of the number of beetles involved in each process
on every tree. Since it is not practical to sample each tree daily, we developed a procedure whereby quantitative estimation
procedures for within-tree populations were used in combination with the mathematical models for the life processes to produce
a daily record of the number of adults successfully attacking trees, the number of eggs oviposited, the number of beetles
reemerging, number of beetles surviving within the trees, and the number of beetles emerging. These daily estimates were then
summarized for all trees in the spot for the duration of the infestation.
The daily record of populations ofD. frontalis, used with information on infestation geometry, were suggested to be of value in describing and elucidating several important
facets of population dynamics including dispersal patterns within infestations, between tree beetle loss (mortality), and
time lags among the various population processes. The information reported can be used to develop simulation models of population
dynamics or to validate existing models.
Texas Agric. Experiment Stn. TA No. 14689. 相似文献
6.
The relationship between the infestation rate of carambola fruits byBactrocera carambolae Drew and Hancock was investigated in a carambola orchard. Phenology of the fruits was found to influence percentage infestation
of fruits byB. carambolae. The proportion of unbagged or susceptible fruits infested varied with time of year and tended to decrease with the increase
of unbagged fruits available on the tree. The number of ovipunctures per fruit varied with fruit size and was also found to
be indicative of the number of adult insects (B. carambolae and parasitoids) that will emerge from each fruit. Higher number of susceptible fruits available on each tree also decreased
both the number of ovipunctures per fruit and the number of eggs laid per fruit, which could possibly be due to the strategy
of spreading the risk adopted by the femaleB. carambolae or a result of random selection with more hosts available. The main parasitoids recorded wereBiosteres vandenboschi (Fullaway) andB. arisanus (Sonan). The mean percentage of parasitism was 38.3% and it followed roughly that of infestation of fruits. 相似文献
7.
Katsumi Togashi 《Researches on Population Ecology》1991,33(2):245-256
Summary To understand the mechanism of spread of pine wilt disease caused by the pinewood nematode,Bursaphelenchus xylophilus, which is vectored by a cerambycid,Monochamus alternatus, the spatial distribution of trees weakened by the nematode was examined within aPinus thunbergii stand from June to October for 4 years. The weakened trees were distributed in a clumped pattern in 1980 and 1981, at an
early stage of infestation. In many cases, they showed a double-clumped pattern. The degree of aggregation was higher in June
or July than after August. They were uniformly distributed in June or July 1982 and in June 1983 whereas they showed a double-clumped
pattern after August. The trees were frequently weakened in June or July when they were near the trees weakened during the
previous year. At quadrat sizes of more than 25 m2, spatial overlapping was pronounced between trees weakened during June–July of the current year and those weakened in the
previous year. The seasonal changes in spatial distribution of weakened trees were explained by the interaction amongM. alternatus, B. xylophilus andPinus trees. 相似文献
8.
Sibling cannibalism in the ladybird beetleHarmonia axyridis: Fitness consequences for mother and offspring 总被引:1,自引:0,他引:1
Naoya Osawa 《Researches on Population Ecology》1992,34(1):45-55
Summary The adaptive significance of sibling cannibalism was analyzed in the ladybird beetleHarmonia axyridis at two prey densities. Possible costs and benefits were considered from three points of view: the mother, the cannibal and
the victim. Cannibals ate both infertile and fertile eggs, thereby increasing in body length and survival rate with the intensity
of sibling cannibalism. The cannibalistic trait was clearly beneficial to the cannibal when aphid density was low. However,
it was not always beneficial when aphid density was high and the victims were full siblings. The altruistic behavior of being
a victim was beneficial only when the victim was cannibalized by full siblings at low aphid density. The mother attained almost
equal fitness at low aphid density, regardless of the intensity of sibling cannibalism. This suggests that sibling cannibalism
is not maladaptive for the mother. At high aphid density, however, mother’s fitness decreased with the intensity of sibling
cannibalism, indicating that sibling cannibalism is maladaptive for the mother when larval food availability is high. 相似文献
9.
Athayde Tonhasca Jr. John C. Palumbo David N. Byrne 《Researches on Population Ecology》1994,36(2):181-186
Early season infestations of the sweet potato whitefly,Bemisia tabaci (Gennadius), on cantaloupes,Cucumis melo L., were determined by counts of the number of adults per leaf in fields near Yuma, Arizona. We used these data to develop
binomial sampling plans based on the relationship between mean densities of whiteflies per leaf,m, and proportion of leaves infested with more thanI whiteflies,P
I, according to the empirical model lnm=a′+b′ ln[−ln(1−P
I)]. The models were developed for the presence-absence approach (I=0) and for a cutoff value of three whiteflies per leaf (I=3). Four independent data sets were used to evaluate the models. Both methods yielded reliable predictions at low infestation
levels, but some of the higherm values were overestimated. As the tentative economic threshold forB. tabaci is three adults per leaf, which corresponds to lowP
I values, results of the binomial sampling were satisfactory for pest management purposes. 相似文献
10.
Takayuki Ohgushi 《Researches on Population Ecology》1988,30(1):57-68
Summary The relationships between egg predation of an herbivorous lady beetleEpilachna niponica (Lewis) and its predator, the earwigAnechura harmandi (Burr), were examined in both time and space. In spite of little annual, changes in egg densities, egg mortality due to predation
varied considerably. There was no, clear relationship between the earwig density and the proportionate predation over the
five years. The seasonal occurrence of earwig nymphs on thistle plants, however, was closely synchronized with that of egg
predation. Predator attacks on the beetle occurred in a time-restricted manner. Thus, later cohorts mostly escape from heavy
predatory pressure. No spatially density-depent egg predation was detected at the level of either thistle plants or thistle
patches. Furthermore, there was no indication of aggregative behaviour of the earwig in response to local egg density. The
earwig density was more likely to be associated with particular localities with sandy deposits available for its nest site. 相似文献
11.
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
12.
One hundred and thirty carcasses of the red fox were collected in Tochigi Prefecture, by the Tochigi Prefectural Museum, from
1981 to 1991. The young/adult ratio of the sample was 1.60, which suggests that the hunting pressure has been relatively low
in this area. Six percent of the animals were 5 years or older which compares to those taken in Hokkaido, but is higher than
those in Europe and North America. The sex ratio for all specimens had a tendency towards male bias (0.587), but this bias
was higher for the adult (0.605) than for the young (0.576). Among young (0 year-old) foxes, more individuals were killed
on roads than by trapping or shooting (P<0.02, chisquare test). This mortality pattern was caused by high mortality of young males (P<0.02). The proportions of adults killed by the three mortality factors were similar, though only one of the 14 foxes older
than 4 years old was shot, probably due to age-linked activity patterns. Most road-kills of young foxes occurred in May when
juveniles began exploiting and in November when sub-adults began dispersal. The ratios of road-kills for the whole sample
and for adults alone were 42% and 34%, respectively. These high rates of road-kills suggest that the mortality pattern in
Tochigi has been affected by factors characteristic of urban environments. 相似文献
13.
In the early twentieth century, the cotton-growing regions of the U.S. South were dominated by families of tenant farmers. Tenant farming created opportunities and incentives for prospective tenants to marry at young ages. These opportunities and incentives especially affected African Americans, who had few alternatives to working as tenants. Using complete-count Census of Population data from 1900–1930 and Census of Agriculture data from 1889–1929, we find that increases in tenancy over time increased the prevalence of marriage among young African Americans. We then study how marriage was affected by one of the most notorious disruptions to southern agriculture at the turn of the century: the boll weevil infestation of 1892–1922. Using historical Department of Agriculture maps, we show that the boll weevil’s arrival reduced the share of farms worked by tenants as well as the share of African Americans who married at young ages. When the boll weevil infestation altered African Americans’ opportunities and incentives to marry, the share of African Americans who married young fell accordingly. Our results provide new evidence about the effect of economic and political institutions on demographic transformations. 相似文献
14.
Mathematical procedures are given to estimate infestation totals and daily life stage arrivals, departures, and mortality
ofDendroctonus frontalis
Zimmermann for an infested tree in the field. These estimates are based on minimal sample data and are designed to utilize all available
information. Daily arrival estimates for larvae, pupae, and callow adults are obtained by indirect analysis without direct
observation of these stages. The procedures are applied to 147 infested trees, and the results are transformed to a common
time basis to obtain daily expectations by life stage for an “average” tree. These expectations suggest optimal times for
field sampling or relative times of sampling when optimal times are missed. Expected daily arrival distributions by life stage
for a single egg and a single attacking adult are given. Procedures are given for utilizing collateral information to obtain
an infestation total and daily arrival estimates for a boundary life stage. The results of this study are applicable to anyD. frontalis field study, and the procedures given are applicable to any bark inhabiting insect having similar habits. 相似文献
15.
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
16.
Kazuyoshi Miyashita 《Researches on Population Ecology》1964,6(1):37-42
Summary A relationship between outbreaks of the oriental tussock moth,Euproctis flava, in Akita Prefecture and weather conditions have been analyzed in the present paper. The results obtained are summarized
as follows:
Outbreaks were, in most cases, observed at intervals of 7–9 years, and the population fluctuation was considered to be regular,
when small rises of population density were taken into consideration. The condition of low temperature and decreased percentage
of sunny hours in spring and summer has a great influence upon the occurrence of outbreaks, and a big outbreak seems to come
when a peak of the intrinsic population fluctuation occurs just simultaneously with such a weather condition. 相似文献
17.
This paper reports on projections of the United Kingdom’s ethnic group populations for 2001–2051. For the years 2001–2007
we estimate fertility rates, survival probabilities, internal migration probabilities and international migration flows for
16 ethnic groups and 355 UK areas. We make assumptions about future component rates, probabilities and flows and feed these
into our projection model. This model is a cohort-component model specified for single years of age to 100+. To handle this
large state space, we employed a bi-regional model. We implement four projections: (1) a benchmark projection that uses the component inputs for 2001; (2) a trend projection where assumptions beyond 2007 are adjusted to those in the UK 2008-based National Population Projections (NPP);
(3) a projection that modifies the NPP assumptions and (4) a projection that uses a different emigration assumption. The projected UK population ranges between a low of 63 millions in 2051 under the first projection to a high
of 79 million in the third projection. Under all projections ethnic composition continues to change: the White British, White
Irish and Black Caribbean groups experience the slowest growth and lose population share; the Other White and Mixed groups
to experience relative increases in share; South Asian groups grow strongly as do the Chinese and Other Ethnic groups. The
ethnic minority share of the population increases from 13% (2001) to 25% in the trend projection but to only 20% under our
modified emigration projection. However, what is certain is that the UK can look forward to be becoming a more diverse nation
by mid-century. 相似文献
18.
Economic disadvantage,perceived family life quality,and emotional well-being in Chinese adolescents: A longitudinal study 总被引:1,自引:0,他引:1
Daniel T. L. Shek 《Social indicators research》2008,85(2):169-189
Over three consecutive years, Chinese secondary school students experiencing and not experiencing economic disadvantage (n = 280 and 2,187, respectively) responded to measures of perceived family life quality (parenting attributes and parent-child
relational quality) and emotional well-being (hopelessness, mastery, life satisfaction and self-esteem). While participants
experiencing economic disadvantage generally had more negative perceptions of parenting quality and parent-child relational
quality than did adolescents not experiencing economic disadvantage, the differences were more pronounced for the father-adolescent
dyad than for the mother-adolescent dyad. Emotional well-being was also different in adolescents with and without economic
disadvantage. Although adolescents experiencing different intensity of economic disadvantage differed on some paternal parenting
processes, no related differences were observed for other measures of family life quality and emotional well-being. The present
study fills the research gap pertinent to the relationship between economic disadvantage and family as well as emotional quality
of life in early adolescence in the Chinese culture.
This work was financially supported by the Research Grants Council of the Government of the Hong Kong Special Administrative
Region, Hong Kong (Grant CUHK4293/03H) and Wofoo Foundation. The author wishes to thank Britta Lee and Joyce Chow for their
assistance in collecting the data. 相似文献
19.
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
20.
Summary The frequency distributions in sex ratios of offspring from 4 fieldTetranychus kanzawai populations were examined. No significant difference was observed between average sex ratios of the 4 populations, although
there was a great variability within each population, especially in the population fromPueraia lobata. Using the population fromP. lobata, inbred lines with high (H) and low (L) sex ratios were selected. Crossing experiments between H and L showed that sex ratio
is determined by the genotype of mothers. It seemed that sex ratio is cointrolled by several genes, with no cytoplasmic factor
involved. 相似文献