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1.
Summary The population dynamics ofPryeria sinica was investigated in an undisturbed area in 1976–1979. We analyzed the process stabilizing the local population by the life
table approach for immature stages and the mark-recapture method for the adult stage. Females usually layed about 130 eggs
in an egg-mass. The shape of the survivorship curve was convex and was characterized by a relatively low mortality in the
egg and larval stages and by a relatively high mortality in the prepupal and pupal stages. The low mortality in the early
stage seemed to be not only due to the peculiar life cycle of this species (larvae develop in early spring when natural enemies
are not active) but due to their protective nest-webs, larval warning coloration and repellent smell. The high mortality after
cocooning was caused by severe parasitization byAgrothereutes minousubae. The number of adult in the population varied by 2.10-fold, which was less than that of other gregarious moths. The life
table data and field observations suggest that adult female dispersal would have acted as a stabilizing factor, andA. minousubae as a conditioning factor on the dynamics of the moth population. 相似文献
2.
Takao Itino 《Researches on Population Ecology》1986,28(2):185-199
Summary I compared life tables between the solitary eumenid waspAnterhynchium flavomarginatum
Smith and the subsocial eumenid waspOrancistrocerus drewseni
Saussure in Kyoto, Japan, during 1980–1983. The subsocial eumenid is parthenogenetic in this study area. There were 9 identified mortality
factors in the solitary eumenid and 7 in the subsocial eumenid, 6 of which were common to the two eumenids. The important
differences of mortality between the two eumenids were seen in the egg, larval, and prepupal stages. In the egg stage, mortality
by the phorid flyMegaselia sp. was much lower in the subsocial eumenid (1.4%) than in the solitary eumenid (15.0%) likely because of the matenal care
of the subsocial eumenid (progressive provisioning and other related behavior), which reduced predation pressure. In the larval
stage, mortality by the miltogrammine flyAmobia distorta was also lower in the subsocial eumenid (8.1%) than in the solitary eumenid (23.8%) also probably because of the maternal
care of the subsocial eumenid. A comparison of mortality in the two eumenids between the stable, long continuing natural nest
sites and the additional temporal ones showed that the phorid fly remained near its birth place and parasitized stable nest
sites. The miltogrammine fly followed returning eumenid wasps and parasitized those nest sites that have a high host density.
In the prepupal stage, mortality by endogenous death was higher in the subsocial eumenid than in the solitary eumenid. Mortality
due to the rhipiphorid beetle was also higher in the subsocial eumenid probably due to more frequent flower-visits by the
subsocial eumenid.
The defense mechanism of the subsocial eumenid was discussed in relation to the evolution of subsociality.
Contribution to the ecological studies of the eumenid wasps. I. 相似文献
3.
InMenida scotti aduts which mate during hibernation, we examined the effect of photoperiod on diapause induction in terms of the developmental
degree of reproductive organs and corpora allata. In a hibernating population, mating season and physiological changes related
to dipause were investigated. When newly emerged adults were reared under long- or short-day conditions, reservoir of the
ectodermal accessory gland and corpora allata in males developed, while the developments of ovary and corpora allata in females
were suppressed under both conditions. This suggests that diapause of this species is induced only in females independently
photoperiodic conditions during adult stage. In a hibernating population, mating was observed from early to late November
and from late March to early May. Observations of the development of reproductive organs and corpora allata suggest that diapause
is induced only in females in the former period, while both sexes are not in diapause in the latter period. 相似文献
4.
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
5.
We studied seasonal changes in the larval population structure, adult size, and autogeny (egg production without a bloodmeal)
of the mosquitoAedes togoi on the seacoast of northern Kyushu, Japan. The effects of temperature, photoperiod and food conditions on larval development,
adult size and autogeny were studied in the laboratory.Aedes togoi overwintered in both the egg and larval stages and was multivoltine. Adult size was greater in spring and autumn and smaller
in summer. Autogeny occurred in spring and autumn but not in summer. Autogenous females were larger than anautogenous females,
and larger autogenous females produced more eggs. Laboratory experiments showed that autogeny was promoted under low temperature
and short-day conditions which corresponded with spring/autumn conditions in the field. Experimental food limitation in the
larval stage greatly reduced adult size and autogenous egg production. In the field, large inter-pool variations in adult
size and autogeny rate probably resulted from variations in nutrient and crowding conditions. Seasonal autogeny ofAedes togoi was discussed in terms of life-history strategy under fluctuating environmental conditions where relative advantages of autogenous
and anautogenous reproduction alternate seasonally. 相似文献
6.
J. N. Ayertey 《Researches on Population Ecology》1980,22(1):101-116
Summary This paper describes a series of experiments conducted to determine whySitophilus zeamais
Mots. andSitotroga cerealella (Oliv.) could not survive together in maize cultures in the laboratory. The effect ofS. zeamais on different developmental stages ofS. cerealella was investigated. The presence of adultS. zeamais slightly affected moth copulation, egg laying and moth eggs in a mixed culture, but large numbers of developing moths inside
maize grains were killed by the adult weevil through feeding on the grains. The major cause of elimination ofS. cerealella byS. zeamais from mixed cultures was therefore found to be damage to the immature moths in grain and such moth mortality increased as
the developing moths became bigger in the grains. A weevil: grain ratio of approximately 1.4∶1 was found to be the critical
weevil density at which the moth disappeared from the mixed cultures. 相似文献
7.
Summary Life tables for worker honeybees covering all life span, and those for adults, were prepared for three seasonal cohorts,June bees, July bees andwintering bees. Survivorship curves forJune andJuly bees show a convex type being exceptional for insects, with relatively high mortality at egg and feeding larval stages and at
later adult stage after most bees became potential foragers. Adult longevity greatly lengthens inWinteriing bees and survivorship curve drops approximately with the same rate. A remarkable similarity of survivorship curves for men and
honeybees was demonstrated, apparently due to highly developed social care in both. Some comments were given on mortality
factors. The importance of life tables for population researches was shown by applying our result to the population growth
curve made byBodenheimer, based upon the data byNolan. At the asymptote of the uncorrected curve, the ratio of total population estimated by uncorrected curve to that by corrected
curve reaches about 3∶2.
Contribution No. 821 from the Zoological Institute, Faculty of Science, Hokkaido University, Sapporo, Japan.
Contributions from JIBP-PT No. 45. This study was in part supportod by a grant in aid from the Ministry of Education for the
special project research, “Studies on the dynamic status of biosphere.”
Population and bioeconomic studies on the honeybee colonies. II.
We express our sincere thanks to Dr. YosiakiIt?, National Institute of Agricultural Sciences, Tokyo, for his kind stimulation and advices to the present work. 相似文献
8.
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
9.
Yoshihiro Yamada 《Researches on Population Ecology》1990,32(2):365-379
1. | Analysis of life tables of the oriental moth,Monema flavescens, obtained for 8 generations over 4 years, disclosed that the cocoon parasitoid,Praestochrysis shanghaiensis, acted as a density-disruptive factor. |
2. | The density of the host cocoon remained stable (max./min.=3.2), whereas that of the host adult varied (max./min.=14.3) although both showed similar fluctation patterns. |
3. | Stability of the host population was associated with the density-dependence in the ratio of first generation cocoons to overwintered generation moths, which was the key factor for the rate of change throughout the year. Chrysidid parasitism among the first generation cocoons ranged from 37.7 to 70.1%, and that among the second generation cocoons from 16.7 to 63.2%, each showing an inverse density-dependence and acting as the main determinant (key-factor) of the between-year variation in the density of the adult moths. |
4. | The density-dependence of the rate of change from overwintered generation adults to first generation cocoons was so strong that the parasitism on the second generation hosts had not effect on the cocoon density of the first generation. On the other hand, the density-dependence of the rate of change from first generation adults to second generation cocoons was weak, and the parasitism on the first generation hosts became the key factor for the between-year variation of the second generation cocoons. |
5. | It is suggested that the stability of the parasitoid-host system will be disrupted without three parasitism-restricting factors: asynchrony in the parasitoid attack on the second generation hosts, high mortality among parasitoid larvae of the second generation, and the high proportion of those first generation parasitoids that enter diapause. These factors are considered to be effective only in cooler parts of the distribution of the parasitoid. |
10.
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