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1.
A. J. Hayes 《Researches on Population Ecology》1988,30(1):13-24
Summary The numerical response of adult femaleT. pyri feeding on different levels of ERM larvae, and at a range of temperatures was examined. The duration of the pre-oviposition
period decreased as larval consumption increased, and the rate of oviposition was linearly related to the rate of consumption
of larvae. Mathematical models were used to describe these relationships in terms of temperature and consumption of ERM larvae.
The results were discussed in relation to the nature of theT. pyri/ERM interaction in New Zealand apple orchards. 相似文献
2.
Hideki Ueno 《Researches on Population Ecology》1994,36(1):121-124
Heritabilities and genetic correlations for body size characters and development period in a coccinellid beetle,Harmonia axyridis were estimated by a sib-analysis experiment. Positive genetic correlations were detected between size characters and development
rate. If this is upheld in the field, genetic variation would be eliminated, as the loci affecting the characters are supposed
to be fixed. However, the results indicated moderate heritabilities for all characters. Possible explanations for the results
are discussed. 相似文献
3.
K. Tanaka T. Watanabe H. Higuchi K. Miyamoto Y. Yusa T. Kiyonaga H. Kiyota Y. Suzuki T. Wada 《Researches on Population Ecology》1999,41(3):253-262
To examine density dependence in the survival, growth, and reproduction of Pomacea canaliculata, we conducted an experiment in which snail densities were manipulated in a paddy field. We released paint-marked snails of
15–20 mm shell height into 12 enclosures (pens) of 16 m2 at one of five densities – 8, 16, 32, 64, or 128 snails per pen. The survival rate of released snails was 95% and was independent
of snail density. The snail density had a significant effect on the growth and egg production of individual snails. This density
dependence may have been caused by reduced food availability. The females at high density deposited fewer and smaller egg
masses than those at low density, and consequently produced fewer eggs. The females at densities 8 and 16 deposited more than
3000 eggs per female, while the females at density 128 oviposited only 414 eggs. The total egg production per pen was, however,
higher at higher snail density. The survival rates of juvenile snails were 21%–37% and were independent of adult density.
The juvenile density was positively correlated with the total egg production per pen and hence was higher at higher adult
density. However, the density of juveniles larger than 5 mm in shell height, i.e., juveniles that can survive an overwintering
period, was not significantly different among density treatments. These results suggest that snail density after the overwintering
period is independent of the density in the previous year. Thus, density dependence in growth and reproduction might regulate
the population of P. canaliculata in paddies.
Received: October 23, 1998 / Accepted: July 16, 1999 相似文献
4.
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
5.
Keizi Kiritani 《Researches on Population Ecology》1964,6(2):88-98
Summary Based on the results of five-year study on theNezara population, it was concluded that the level of abundance of the insect was determined partly by the combination and relative
adundance of the host plants and partly by the climatic factors. The endless increase of the population was checked by the
deleterious effects associated with the overpopulation which occurred locally. The degree of such overpopulation was determined
by the relative abundance of host plants to the current level of the population. Therefore, even when the general level ofNezara population seemed to be low, there still exists the possibility of overpopulation in some areas.
Winter was the critical period which threatened the persistence ofNezara population. The survival of the hibernating adults was partly dependent on the physiological state of adults which was determined
in the period of pre-hibernation. But when the severity of a winter exceeded the tolerance limit of the insect, the only safety-valve
which prevented the elimination ofNezara was the heterogeneity of hibernacula. Therefore,Milne's theory (1957) was closest to the known facts. 相似文献
6.
Summary Development periods were determined for eggs and juvenile stages of the predatory phytoseiid miteTyphlodromus pyri at four constant temperatures and three feeding levels. For the non-feeding stages (eggs and larvae) power curve functions
were fitted to development rate in terms of temperature. The results are compared to the general arthropod response to temperature.
A non-linear model was fitted to nymphal development rate in terns of temperature and food, in which the weight gain over
an instar is assumed to be a linear function of daily food consumption. Examples of the same shape development rate—food relationship
are given for two more phytoseiid mites and for other arthropods. The results are discussed with respect toT. pyri as an integrated control agent. 相似文献
7.
David Wool 《Researches on Population Ecology》1969,11(1):40-44
Summary The effect of larval age range on survival of twoTribolium castaneum strains in mixed cultures was studied in an experimental situation in which other selective forces were reduced to a minimum.
Increasing the difference in larval age setween the strains by one day resulted in a reduction of survival of the faster-developing
mutant strain, because more of its earlier pupae were cannibalized by the larvae. General aspects of the effects of pupal
cannibalism by larvae on the outcome of intra-specific competition (sensu lato) inTribolium are discussed. 相似文献
8.
9.
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
10.
Summary We studied settling-site selection and the resulting survival of two sessile scale insects,Ceroplastes rubens andC. ceriferus, in the citrus tree,Citrus unshiu, in central Japan.
C. rubens preferred 0-year-old twigs most as a settling-site; the density of nymphs settling on 0-year-old twigs was significantly
higher than those on ≥1-year-old twigs, and few nymphs settled on ≥3-year-old twigs. The mean survival rates from settling
until reproduction in the next year were significantly higher on more preferred twigs than on less preferred ones. InC. ceriferus, nymphs significantly preferred 1- and 2-year-old twigs to 0- and ≥3-year-old ones, and the mean survival rates on the more
preferred 1- and 2-year-old twigs were significantly higher than those on less preferred ≥3-year-old twigs. However, the survival
rate on less preferred 0-year-old twigs was slightly higher than those on 1- and 2-year-old ones. Thus, in both species of
scale, it was the preferred twigs which were more profitable sites for survival after settling, except for less preferred
0-year-old twigs forC. ceriferus.
In both scale species, most mortality was due to growth cessation, which is believed to be related to the twig quality as
a food source. Predators and parasitoids were minor mortality factors.
Both species showed constant survival rates until the density of settled nymphs exceeded double the “upper-limit” density,
whereupon they decreased drastically.
Nymphs ofC. rubens settling on twigs of high scale density showed a spacing-out distribution, those ofC. ceriferus did not. InC. rubens, an increase in preference for originally less profitable twigs at the later stage of the settling season was observed, but
not inC. ceriferus. Accordingly, individuals ofC. rubens showed a stronger tendency to avoid conspecifics than didC. ceriferus.
Although nymphs of the two scales clearly preferred more profitable sites, their settling-site selection did not agree with
the predictions from the ideal free distribution theory (Fretwell and Lucas, 1970). The discrepancies were (1) frequent settling
on less profitable sites at the early stage of the settling season, (2) insufficient utilization of the most profitable twigs,
and (3) virtually 100% mortality on overcrowded twigs under conditions where unoccupied profitable twigs still remained. These
discrepancies are thought due to the limited dispersal time of nymphs.
Contribution to the ecological studies of scale insects 2. 相似文献
11.
Takayoshi Nishida 《Researches on Population Ecology》1993,35(1):45-56
Summary Spatial relationships of mate acquisition probability for individuals of both sexes of a gregariously-mating coreid bug,Colpula lativentris, were studied in relation to aggregation size. Operational sex ratio was always strongly male biased. Mate acquisition probability
of females was rather constant and independent of aggregation size, as predicted by an ideal free distribution. Moreover laboratory
experiments showed that both multiple mating and rearing density little affected female fecundity, suggesting ideal free distribution
of females in terms of reproductive success. On the other hand, mate acquisition probability of males was higher in larger
aggregations, where more receptive females were available. This male discrepancy from an ideal free distribution was similar
to the patterns predicted by an ideal free distribution under perceptual constraints (Abrahams, 1986), but not by that under
unequal competitive ability. 相似文献
12.
Tamotsu Kusano 《Researches on Population Ecology》1982,24(2):329-344
Summary The postmetamorphic growth and survival of the salamanderHynobius nebulosus tokyoentis
Tago were surveyed in the study site located in Habu village of Hinodemachi, a suburb of Tokyo City, during 1975–1981. A laboratory
experiment on the growth rate of juveniles was conducted in parallel with the field survey. The result indicated that this
salamander grew at the rate of 8,mm in s.v.l. per year during the juvenile stage, but its growth rate decreased markedly as
low as 1.8 mm for males and 1.1 mm for females, once it had attained sexual maturity. According to the “capture-recapture”
procedure the annual survival rate after metamorphosis was found to be quite high; that is, approximately 0.7. By using the
growth rate of juveniles and the difference between the sizes at metamorphosis and sexual maturity, the age at first reproduction
was estimated to be 4 year for males and 5 year for females.
From the data obtained in this study, the intrinsic rates of increase (r) were calculated for various values of age at first reproduction under different survival schedules, and the relationship
between the age at first reproduction and fitness as measured byr was examined. The result indicated that an optimal age maximizing fitness always existed under respective survival schedules,
and the observed age at first reproduction of this salamandei was found to coincide well with the predicted optimal age. 相似文献
13.
Summary The effects of food supply and population density on the nocturnal behaviour ofArion ater andAriolimax columbianus were investigated. Density did not significantly affectA. ater's level of activity or short-term movement, resting, or feeding.A. columbianus was more active and moved, rested, and fed more frequently when slug density was high.A. ater foraged and rested more often, but fed less when good food was unavailable.Ariolimax's only response to the food regime was to feed more when good food was available. Seasonal changes in the level of activity
and behaviour ofArion were evident, whereasAriolimax's activity and behavioural repertoire were not similarly affected.Arion ater's nightly activity appeared to be mainly food oriented, whileAriolimax columbianus seemed most responsive to slug density during its nocturnal activity periods. 相似文献
14.
Samples of shoots ofPistacia lentiscus carrying galls of the aphid,Aploneura lentisci, were collected at three localities in Israel.
Shoots growing near pruning scars carried more galls than elsewhere on the plant, but these galls weighed less and contained
fewer aphids (smaller clones). The proportion of empty galls increased with gall density. Crowding of galls at such sites
may be due to the early burst of buds at the time of aphid emergence from the overwintering eggs, and not to active search
for preferred sites. 相似文献
15.
16.
Summary Crowding effects of larvae on survival and development were examined for the broad-horned flour beetle,Gnathocerus cornutus (F.). The larvae matured about 3 weeks after hatching regardless of their densities, but pupation was severely hindered by
crowding. There existed an upper limit for the number of the pupae produced and its mechanism was studied by a statistical
analysis of the distribution patterns of pupal cells and the experiment in which glass tubes were artificially supplied in
addition as pupation site. These studies show thatG. cornutus larvae have a habit to construct cells for pupation and this habit leads to a contest competition for pupation site at high
densities. The significance of the contest competition for population regulation was discussed comparing the results onTribolium confusum
Jacqueline duVal. 相似文献
17.
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
18.
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
19.
Peter B. Shaw 《Researches on Population Ecology》1985,27(1):1-23
Summary A detailed sensitivity analysis of a model of a predator-prey system comprised ofTetranychus urticae andPhytoseiulus persimilis was performed. The aim was to assess the relative importance of the life history parameters of both species, the functional
response, and the components of the numerical response. In addition, the impact of the initial predator-prey ratio and the
timing of predator introduction were tested. Results indicated that the most important factors in the system were relative
rates of predator and prey development, the time of onset of predator oviposition, and the mode of the predator's oviposition
curve. The total oviposition of the predator, the effect of prey consumption on predator oviposition, and predator searching
were important under some conditions. Factors of moderate importance were the adult female predator's functional response,
total prey oviposition, the mode of the prey's oviposition curve, abiotic mortality of the pre-adult predator, and the effect
of prey consumption on predator development and on the immature predator's mortality. Factors of least importance were the
variances of the predator's and prey's oviposition curves, the abiotic mortality of the adult predator, the abiotic mortality
of the pre-adult and adult prey, the functional response of the nymphal and adult male predators, and the effect of prey consumption
on adult predator mortality. The sex ratios had little effect, except when the proportion of female predators was very low.
The initial predator-prey ratio and time of predator introduction had significant impacts on system behavior, though the patterns
of impact were different. 相似文献
20.
Summary Experiments were conducted to determine if slug density, or food quantity and quality could cause dispersal by slugs.Arion ater dispersed quickly from overcrowded areas, where high mortality was incurred by this species. Poor food conditions, caused
more dispersal than good food conditions, but food had no effect on the mortality ofA. ater. Neither food nor density factors had significant effects on the dispersal ofAriolimax columbianus. However, moreA. columbianus died in the high- than low-density treatments.A. columbianus mortality was unaffected by the food factor. DispersingArion were heavier than non-dispersers, but there was no difference between the weights of dispersing and non-dispersingAriolimax. There were significant seasonal changes in the dispersal rate, mortality and weight of dispersingArion, whereas only the mortality ofAriolimax changed significantly during the experiments.
SinceArion ater did not markedly reduce its activity during unsuitable weather it was able to leave areas of poor food and high slug density
fairly rapidly.Ariolimax columbianus' large size allowed it to remain inactive during unfavourable weather and permitted this species to be relatively unresponsive
to the experimental treatments. 相似文献