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Akio Takafuji 《Researches on Population Ecology》1986,28(1):91-101
Summary Two types of the citrus red mite,Panonychus citri (M.) occur in some pear orchards in the intermediate latitudal areas in Japan during a certain period of the year (Takafuji andMorimoto, 1983): one is a diapausing type (DP) and the other a non-diapausing type (C). These two types are incompatible: no adult females are produced from the crosses between them (Takafuji andFujimoto, 1985). In the present study, females of each type were doubly crossed, first with a male of the other type, and then with
a male of the same type, to examine the effectiveness of the second mating. In the females of the DP type, the second mating
with a male of the same type was almost totally ineffective. In contrast, for the females of the C type the effectiveness
of the second mating depended on the durations of the first and second matings: the famles produced female offspring only
when the duration of the first copulation with a male of the DP type was brief and the second copulation with a male of the
C type lasted relatively long. The results suggested that if the two types coexist, the intercrossing between them will favour
the C type over the DP type. 相似文献
3.
Summary Reproductive compatibility was studied among populations of different types of the citrus red mite,Panonychus citri (McGregor), i.e., the diapausing type from pear (DP), the non-diapausing type from citrus (C) and that from pear (NP).
Copulation was also observed between mates of different types (DP and C). Only in crosses between C ♀ and DP ♂, was copulation
occasionally broken off prematurely; duration of copulation varied considerably between pairs and the average duration was
much shorter than that between DP ♀ and C ♂ and than that in crosses between mates of the same types.
No F1 adult females were produced at all from crosses between DP and C, showing that there was a complete reproductive isolation
between the two types. There was a significant reciprocal difference in the egg hatchability and survival rate of immatures
in the F1 progeny; mortality in the eggs and that in the immature stage were significantly higher in crosses between DP ♀ and C ♂,
as compared to those in the reciprocal cross. This suggested that fertilization may have occurred in the former cross, whereas
it seemed that eggs were not fertilized in crosses between the C ♀ and DP ♂.
The NP was compatible with the C, whereas it was completely incompatible with the DP. Thus, there was a complete reproductive
incompatibility between the diapausing and non-diapausing type ofP. citri.
This work was supported in part by Grant-in-Aid No. 60560049 from the Ministry of Education, Science and Culture, Japan. 相似文献
4.
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
5.
Summary The life cycle of a non-diapausingT. urticae population was studied in a pear orchard in the southern part of Okayama Prefecture, western Honsh?, Japan. The mites overwintered
only on biennial weeds in the orchard without entering diapause, started to increase in number in early spring on them and
then moved to other weeds as they emerged. The occurrence of the mites on pear began in early May several weeks after the
unfolding of pear leaves and the population on pear was initiated by the migrants from the weeds around the base of pear trees.
The population on pear showed two distinct peak occurrences, one in June and the other in mid-autumn. After pear leaves dropped
in late autumn, the mites returned to biennial weeds for overwintering.
This work was supported in part by Grant-in-Aid No. 00556033 from the Ministry of Education, Science and Culture, Japan. 相似文献
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Ping-Man So 《Researches on Population Ecology》1991,33(2):229-243
Summary I sampledTetranychus urticae Koch (Acarina: Tetranychidae) regularly from four rose gardens in Kyoto and Nara Prefectures in 1988–1990. When mite density
was low,T. urticae showed an uneven vertical distribution, being more abundant in the lower third and absent from the upper third of the plants.
Mite density was less variable within than between plants, suggesting that a sampling plan which includes more leaves from
different plants rather than from different levels of a plant is favourable. Spatial distribution ofT. urticae was nonrandom and followed the negative binomial distribution. In addition, both the Taylor’s power law and the Iwao’s patchiness
regression described the distribution well. An empty-sample method for estimating mite density from the proportion of empty
sampling units was developed. Sampling plans for determining the sample size required to reach a predetermined precision level,
based on this method and by directly counting the mites, were designed. The counting method was more accurate than the empty-sample
method. However, when the time factor was taken into account, the latter was more favourable, because it was faster than the
former at a density range of 1.5–300 mites leaf−1, which was most commonly encountered in the field. 相似文献
8.
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
9.
Summary We compared the removal by solution, the represented count-area method and the beating, for the purpose of estimating the
number of the Cryptomeria red mite.
Among them the solution procedure provided the smallest standard error as per cent of the mean. 0.25 per cent unheated solution
of sodium hydroxide is used for the summer generation, and also 0.25 per cent boiling one for the winter eggs. The mean proportion
removed±standard error for the summer eggs and the winter eggs were 0.8770±0.0316 and 0.7920±0.0281 respectively, while 0.9894±0.0050
for the mites. 相似文献
10.
Natural hybridization among wingless carabid beetles of the subgenusOhomopterus (Carabidae, genusCarabus) is reviewed, and its significance in the evolution of this subgenus discussed. Natural hybridization occurs between parapatric
species of similar size. Two case studies of natural hybridization suggest that natural hybridization could have affected
the evolution of this subgenus in different ways. When there is a large difference in genital morphology between hybridizing
species, interspecific copulation often results in genital injuries that causes mortality of copulating individuals, and hence
reduces the fitness of hybridizing individuals greatly. In such a case, hybridization may be effective in maintaining the
parapatric distribution of the two species, and in the long term, may promote reinforcement selection for traits which are
effective in prezygotic reproductive isolation. When the morphological difference in genitalia is not so large as to cause
genital injury, a hybrid population may be established at the intermediate zone between two parental species, provided that
the immigration rates of the two species into the intermediate zone are small. Thus, natural hybridization may have contributed
to both divergence and reticulate evolution in this subgenus. 相似文献
11.
Myron P. Zalucki 《Researches on Population Ecology》1983,25(2):353-365
Summary A model simulating the movement and oviposition of monarch butterflies over a female's life time is presented. The model's
predictions compare favourably with observed data and suggest that females who lay eggs in an optimal fashion should have
low directionalities in areas with high host plant density (patches and single plants) and high directionalities in areas
with low host plant density. The model also provides one means of combining individual animal processes and spatial heterogeneity
into population dynamics. 相似文献
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Summary Effects of starvation on the suryival period and the respiratory rate in adults of a wolf spider,Pardosa astrigera (L. Koch), were investigated. The spiders used were divided into four groups: well-fed, starved and two limited food groups; in the
latter two, each spider was supplied with one leafhopper every second or third day. Adult males and females ofP. astrigera could survive for a long time; 28.8±2.7 days and 54.4±18.9 days, respectively, without any food. The longevities shown here
were 73.8% for males and 78.6% for females of those of well-fed spiders, indicating thatP. astrigera adults have a strong tolerance to starvation. The respiratory rate of well-fed adults showed no tendency to increase or decrease
with their aging; the mean respiratory rates were 4.86×10−4 mg CO2/mg f.w. (fresh body weight)/hr for males and 3.80×10−4 mg CO2/mg f.w./hr for females. The respiratory rates of starved spiders increased during the first two days of starvation but decreased
markedly from the third to the twelfth day, and thereafter retained an almost constant level for each sex. The mean respiratory
rates after the twelfth day of starvation were 2.49×10−4 mg CO2/mg f.w./hr for males and 2.76×10−4 mg CO2/mg f.w./hr for females; these values were respectively 48.4% and 63.0% of those prior to starvation. The fresh body weight
of starved spiders decreased linearly with time but the rate was small. The respiratory rates of the limited food groups tended
to decline with time and thereby their weight losses were minimized. The decrease in the respiratory rate under starvation
was considered not to be due to spider exhaustion or senescence but due to an intrinsic change in behaviour and/or metabolism,
because when the spiders were supplied with ample food for five days after starvation, the respiratory rate and the body weight
rapidly recovered to near the levels prior to starvation. It is suggested that starved spiders use a higher ratio of fat as
catabolic substrate than normally fed or satiated ones. Feeding strategies of poikilo-therm predators are discussed.
This work was partially supported by the Nippon Life Insurance Foundation Research Fund and Grant-in-Aid (No. 56480039) from
the Ministry of Education, Science and Culture, Japan. 相似文献
14.
Barundeb Banerjee 《Researches on Population Ecology》1980,21(2):308-316
Summary A marked variation exists in the numbers and distribution of East African red legged millipedeMetiche tanganyciense
Kraus on the surface and in the lower layer (15 cm) of the soils. Stadia 5 cm and lesser in length are found in the lower layer
and those 5 cm and above on the surface soil. Adults are common in varying numbers in both the habitats.
It is suggested that after becoming surface active during March–August, and mating, adults migrate to lower layer during September
to oviposit. Eggs and early developmental stages are passed here, and when they are 5 cm in length, the stadia move to the
surfface soil to complete their development. In keeping with this behaviour, spatial distribution of the adults may change
from non-aggregation on surface soil to aggregation in the lower layer. The simulataneous presence of adults and developing
stadia in the two habitats suggests and overlapping of generations.
This investigation was done while I was in the Department of Entomology, University of Nairobi. 相似文献
15.
Reproductive behaviors related to habitat utilization were studied in males of the damsefly,Mnais nawai, which has two male forms, territorial orange-winged males (nawai) and non-territorial pale-orange-winged males (sahoi), at the upper part of a mountain stream where they partiallycoexist with a related species,Mnais pruinosa, which also has two male forms, territorial orange-winged males (esakii) and non-territorial hyaline-winged males (strigata). These two species showed parapatric distribution; the lower part of the stream was occupied byM. nawai, and the upper part byM. pruinosa. In the present study, cross-matings occurred between bothMnais species, although normal intraspecific matings occurred more frequently than cross-matings. Territorial males of both species copulated
with conspecific females that entered their territory and guarded the ovipositing females, probably to avoid sperm displacement
resulting from subsequent copulations. Severe competition for oviposition sites by territorial males even occurred between
the two species. On the other hand, non-territorial males of both species have alternative mating strategies (including several
tactics such as sneaking, takeover and interception). The possible benefits from conflict among territorial males of both
species is discussed. 相似文献
16.
K. L. Heong 《Researches on Population Ecology》1981,23(1):177-191
Summary The functional response parameters of the parasitoid,Anisopteromalus calandrae (Howard) to the third instar, the fourth instar and the pupae ofCallosobruchus maculatus (F.) were estimated from the Random Parasitoid Equation. By modifying this equation for a two host situation and using the
parameters estimated above, a no switch model could be obtained. This model was then used to test for switching. In the preference
experiments where two stages of the host were presented to the female parasitoid, a definite preference for the fourth instar
followed by the pupa and the third instar, respectively was shown. There was, however, no evidence of switching. There was
also no evidence that the data fitted the no switch models which suggests that when the parasitoid is searching in an environment
with two or more hosts, its searching behaviour is more complex. 相似文献
17.
Hiroshi Sakata 《Researches on Population Ecology》1995,37(2):159-164
The antLasius niger was observed collecting honeydew and preying on the two aphid speciesLachnus tropicalis andMyzocallis kuricola on the chestnut treesCastanea crenata. Observation determined how the antL. niger controlled their predation on the aphids in response to the density and honeydew-productivity of the aphids.Lachnus tropicalis was a better honeydew source thanM. kuricola forL. niger in terms of the amount of honeydew collected per unit time by the ants. The number of foraging workers on a tree increased
with the number ofL. tropicalis on the tree, but not with the number ofM. kuricola. The density ofL. tropicalis perL. niger worker on a tree had a positive effect on the predation activity ofL. niger on both aphids, whereas the density ofM. kuricola per ant did not have any significant effect. The predation pressure by the ant which increased withL. tropicalis density, however, directed toM. kuricola rather than toL. tropicalis. These facts suggest (1) thatL. niger control their predation activities on aphids with regards to the densities of the attended aphids per worker, and (2) that
the ants prey on the aphid species producing less honeydew. The effects of the ant predation on aphids and the importance
of these predation effect in antaphids interactions were discussed. 相似文献
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Ei''ichi Shibata 《Researches on Population Ecology》1995,37(2):229-237
The inner bark of Japanese cedar,Cryptomeria japonica D. Don., is the main food of the sugi bark borer,Semanotus japonicus Lacordaire, but may also be involved in resistance to attack by the borer. I used newly hatched larvae to inoculate cedar
logs that had been cut 2-weeks to 12-months earlier, and undamaged living cedar trees. On living trees, all larvae were killed
by resin flow from the traumatic resin canals between the outer- and inner bark or between the inner bark and cambium. In
logs that were cut more than 4 months prior to inoculation, larvae were unable to complete development. In logs cut 2 weeks
prior to inoculation, almost all larvae were able to reach the adult stage but they were smaller in size than adults from
living trees damaged by this borer. These results suggest that poor nutrient conditions in the inner bark of logs affected
development and survival of the borer. Because of its nutritional advantage, living cedars provide a better environment for
the sugi bark borer. However, all larvae are killed by resin flow, suggesting that this insect is “in between” being primary
and secondary with respect to living trees, or a “weak” primary insect. The sugi bark borer seems to develop early in the
season so that early instar larvae encounter reduced amounts of resin flow and so that late-instar larvae feed mostly in summer
when nutrient levels in the inner bark are at their highest. 相似文献