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1.
Masakazu Shimada 《Researches on Population Ecology》1985,27(2):203-216
Summary Effects of niche shift in ecological time scale on the population dynamics of competing species were studied in the experimental
populations of two parasitoid wasp species,Anisopteromalus calandrae andHeterospilus prosopidis (both are solitary parasites), on a host, the azuki bean weevil,Callosobruchus chinensis. Four resource conditions were set up with combination of kind of bean (azuki or black eye), and host distribution (uniform
or clumped). In each resource condition, four developmental stages of hosts were provided as a resource spectrum for parasitoid
wasps.
Population dynamics of the two wasp populations were investigated in each resource condition in Multi-Generation Competitive
Systems (MGCS), in which fresh hosts of four developmental stages were periodically introduced and were parasitized competitively
by the two wasp species. Competitive coexistence of both wasps occurred in the azuki-clumped condition, where the peaks of
the resource utilization curves separated in the two species; pupae inA. calandrae and the early or late fourth instar inH. prosopidis, A. calandrae was eliminated in the azuki-uniform condition andH. prosopidis went extinct in two black eye conditions irrespective of host distributions. The degrees of overlap of the resource utilization
patterns of the two wasp species during population dynamics were not significantly different among resource conditions irrespective
of the results of coexistence or extinction. Even in the azuki-clumped condition, however, extinction ofA. calandrae was observed when resource partitioning could not be realized with only the late fourth instar larvae available to wasps.
Further analytical experiments showed that parasitizing ability ofA. calandrae increased with host density per bean with azuki beans, butA. calandrae could express higher parasitizing ability with black eye beans thanH. prosopidis irrespective of host density per bean.
The flexibility in parasitizing ability byA. calandrae for various host stages under different resource conditions was thought to be the major factor in determining the competitive
coexistence or the extinction of either species under different resource conditions. The present experiments also suggested
that different second-best host stages between competitors could be a major contributing factor to competitive coexistence. 相似文献
2.
Among many stabilizing factors for community dynamics, spatial and temporal heterogeneities have been widely considered in
recent years as two of the most important properties. However, the difference between the two types of heterogeneities have
not been studied, except for Clark and Yoshimura (1993). We evaluated experimentally the effect of temporal and spatial heterogeneities
on the persistence of a biological community. The experimental communities consisted of one parasitic wasp species, one bean
weevil species, and two kinds of bean. Temporal and spatial heterogeneities of experimental communities were generated by
kinds and timing of bean supply. Of all the experimental communities, the most persistent community was a temporally and spatially
homogeneous community with Red Kidney bean as primary resource. Compared to spatially heterogeneous communities, temporally
heterogeneous communities were more persistent. These results were easily explained by considering the attack rate of parasitic
wasps and the difference between arithmetic and geometric means. In order to discuss the relative importance of environmental
heterogeneity and the mode of biological interaction on community persistence, we have to measure the degree of environmental
heterogeneity as the rate of change of the strength of interspecific interactions. 相似文献
3.
Among many stabilizing factors for community dynamics, nonlinear biological interactions such as type III functional response
have been widely considered to be major characteristics. However, most experimental biological communities employed so far
had quite simple structures. Therefore, the possibility that the conclusions in earlier studies were dependent on simple community
structure is undeniable. In this study, using a multiple-species experimental community, we evaluated which combinations of
component species and what kinds of interspecific interactions allow communities to persist and how these contribute to community
persistence. We conducted experimental communities using two species of beans, the adzuki bean (Vigna angularis) and the red kidney bean (Phaseolus vulgaris), two species of bean weevils, the Mexican bean weevil (Zabrotes subfasciatus, Coleoptera: Bruchidae) and adzuki bean weevil (Callosobruchus chinensis, Coleoptera: Bruchidae), and two species of parasitic wasp, Heterospilus prosopidis (Hymenoptera: Braconidae) and Anisopteromalus calandrae (Hymenoptera: Pteromalidae). The outcome of multiple-generation experimental communities was explained by the characteristics
of component species obtained from short-term experiments. In our two resources–two herbivores–one carnivore system, the strong
density-dependent attack ability of one parasitic wasp species (A. calandrae) led to the extinction of C. chinensis. On the other hand, the weak density-dependent attack ability of the other parasitic wasp species (H. prosopidis) led to system persistence. Our overall results show that, in a multiple-species community, the combination of species itself
is more important for community persistence than are the characteristics of the particular species.
Received: September 29, 1997 / Accepted: October 5, 1998 相似文献
4.
The relation of the within-season and between-season patterns of shoot growth were compared in a clonal grass with long-lived
shoots,Festuca rubra, in a mown mountain grassland. The growth rate of shoot length from spring to summer in a year was almost constant for each
shoot irrespective of spring shoot length each year. The annual shoot growth rate from spring to spring was negatively correlated
with the shoot length in the first spring. Shoots of different length and age therefore tended to converge over time to a
population of identical shoot size, suggesting an equalizing effect of growth pattern on size structure. Shoot size (shoot
length and number of leaves) influenced the fates of shoots. Larger shoots showed an increased incidence of both flowering
and formation of intravaginal daughter shoots and a decreased incidence of death in the subsequent time period. The fates
of shoots were independent of their age. Although the negatively size-dependent springto-spring annual shoot growth rate acted
to decrease shoot size variation, the remaining variation within the shoot population was still sufficient to generate different
fates of shoots. These fates were not related to the previous life history of individual shoots. There was a significantly
positive effect of the shoot size at initiation on its life expectancy. This was mainly attributable to the positively size-dependent
survival rate of shoots in the early stage (<1 year old) of shoot life history. Later on (> 1 year old), shoot size had little
effect on the survival rate of shoots. Once small young shoots have survived this early stage (< 1 year old) in life history,
they can grow vigorously, little affected by competition regardless of shoot size, and converge to a stable size structure
of shoots of similar size. Only shoot size in the early stage ( < 1 year old) of life history is important for the persistence
of a shoot population. 相似文献
5.
Tamito Sakurai 《Researches on Population Ecology》1998,40(1):167-172
This study examines the relationship between the number of sperm in the seminal receptacle (spermatheca) and the receptivity
of female remating in the bean bugRiptortus clavatus Thunberg. On the 21 st day after the first mating when receptivity to remating was > 70%, females receptive to remating had
significantly fewer sperm ( < 40 on average) in the spermathecae than females reluctant to do (about 150 on average). However,
averages of the number of eggs laid by receptive and reluctant females within 21 days were almost same. The proportion of
fertilized eggs for receptive females at 15–21 days after copulation was significantly lower than that for reluctant females.
Spermatozoa transferred from a male to a female’s spermatheca were detected 5 min after copulation and then increased continuously
to about 500 with the first hour. When copulation durations were manipulated artificially, the shorter the copulation period
(=females had less sperm in their spermathecae), the higher the remating rate became. Females may perceive the number of sperm
in their seminal receptacles and then determine whether they copulate or not. These results support the hypothesis that females
mate multiply in order to replenish inadequate sperm supplies to fertilize all eggs produced. 相似文献
6.
Takatoshi Ueno 《Researches on Population Ecology》1999,41(1):47-57
Charnov's host-size model explains parasitoid host-size-dependent sex ratio as an adaptive consequence when there is a differential
effect of host size on the offspring fitness of parasitoid males versus females. This article tests the predictions and the
assumptions of the host-size model. The parasitoid wasp Pimpla nipponica Uchida (Hymenoptera: Ichneumonidae) laid more female eggs in larger or fresher host pupae when choice among hosts of different
sizes or ages was allowed. Then, whether an asymmetrical effect of host size and age on the fitness of females versus males
existed in P. nipponica was examined. Larger or fresher host pupae yielded larger wasps. Larger females lived longer, whereas male size did not influence
male longevity. Large males mated successfully with relatively large females but failed with small females, whereas small
males could mate successfully either with small or with large females. Thus, small-male advantages were found, and this held
true even under male–male competition. Ovariole and egg numbers at any one time did not differ among females of different
sizes. Larger females attained higher oviposition success and spent less time and energy for oviposition in hosts. Larger
females produced more eggs from a single host meal. Taken together, females gained more, and males lost more, by being large.
Host size and age thus asymmetrically affected the fitness of offspring males versus females through the relationships between
host size or hast age and wasp size, which means the basic assumption of the host-size model was satisfied. Therefore, sex
ratio control by P. nipponica in response to host size and age is adaptive.
Received: November 13, 1998 / Accepted: January 18, 1999 相似文献
7.
Masakazu Shimada 《Researches on Population Ecology》1999,41(1):69-79
Population dynamics and variability were examined in one-host–two-parasitoid experimental systems with different resource
distributions: resource-clumped and resource-sparse conditions. The system consists of a seed beetle host, Callosobruchus chinensis, and two parasitoid wasps, Anisopteromalus calandrae (Pteromalidae) and Heterospilus prosopidis (Braconidae). In the resource-clumped condition, suitable hosts for parasitism (the late fourth-instar larvae and pupae)
were clumped in 1 large resource patch, but they were scattered evenly among 16 small patches in the resource-sparse condition.
Population censuses were conducted at 10-day intervals in long-term cultures, renewing 10 g of azuki beans (Vigna angularis). In both resource conditions, the first period was a single-species system of C. chinensis only, and A. calandrae was added in the second period. The one-host–one-parasitoid system with C. chinensis and A. calandrae showed stable population dynamics with small fluctuations. After addition of H. prosopidis in the third period, two of three replicates persisted to day 800 in each resource condition, although one replicate in each
went to extinction at an immediate outbreak of the H. prosopidis population after the introduction. Population variabilities of C. chinensis and H. prosopidis were significantly higher and the mean population size of A. calandrae was significantly smaller in the resource-sparse condition than that in the resource-clumped one. A short-term experiment
on parasitism efficiencies revealed that H. prosopidis parasitized significantly more at a low host density in the resource-sparse condition than in the resource-clumped one. Mutual
interference of H. prosopidis was weak enough at low parasitoid densities but became abruptly stronger with high densities. Providing fresh hosts in a
mixture of already parasitized ones, host-searching behaviors of a parasitoid were recorded by video for 3 h and were compared
between the two wasp species. H. prosopidis could parasitize fresh hosts more efficiently than A. calandrae through frequent long-distance walks (walking to distant beans at one bout or outside a clump of beans with hosts and back
soon on a distant bean of the clump) after reencounters with parasitized hosts. Considering all the experimental results,
populations were judged to be more fragile and more likely to go to extinction in the resource-sparse condition than in the
resource-clumped one. A higher attacking efficiency of H. prosopidis destabilized population dynamics more in the resource-sparse condition.
Received: December 23, 1998 / Accepted: January 20, 1999 相似文献
8.
Motoaki Kinoshita Eiiti Kasuya Tetsukazu Yahara 《Researches on Population Ecology》1998,40(2):239-242
The sex ratio of the pollinator fig wasp,Blastophaga nipponica Grandi (Agaonidae), was examined in an experiment manipulating the number of foundresses. The sex ratio ofB. nipponica was conditional on the number of foundresses and corresponded to the qualitative prediction of the local mate competition
(LMC) theory that the proportion of males increases as foundress number increases. However, the sex ratio ofB. nipponica was consistently more female-biased than predicted by extended LMC theories that incorporated effects of inbreeding, and
these deviations were statistically significant. Plausible factors that would make predictions more female-biased are discussed. 相似文献
9.
Summary The populations of native male adult oriental fruit flyDacus dorsalis (Hendel) and artocarpus fruit flyD. umbrosus (F.) in two selected site (BU and SD) were estimated weekly by the capture-recapture technique using live traps baited with
methyl eugenol. In BU where many varieties of fruit trees were grown, the estimated population densities ofD. dorsalis were between 980 and 3100 male flies per ha between May and July, 1984. During the same period, in SD where there were fewer
number and varieties of fruit trees, the estimated population densities were between 300 and 1000 flies per ha. The estimated
population densities ofD. umbrosus over the same period were between 570 and 1290 flies per ha in BU; and between 5 and 95 flies per ha in SD.
Of a total 6828 markedD. dorsalis flies released only one fly (released 6 weeks earlier in BU) was caught in a different site. 相似文献
10.
Wolbachia bacteria are obligatory intracellular parasites of arthropods and have been detected in about 70 species of parasitic wasps
and three parasitoid flies. Wolbachia are transmitted cytoplasmically (maternally) and modify host reproduction in different ways to enhance their own transmission:
parthenogenesis induction (PI), cytoplasmic incompatibility (CI), or feminization (F) of genetic males. Only PI and CI are
known in parasitoids. PI-Wolbachia cause thelytoky in otherwise arrhenotokous parasitoids by generating diploid (rather than haploid) unfertilized wasp eggs.
CI-Wolbachia cause incompatibility of crosses between infected males and uninfected females because the paternally derived chromosomes
fail to decondense and are destroyed after syngamy. More complex situations arise when hosts harbor multiple infections, which
can lead to bidirectional incompatibility and may be involved in parasitoid speciation. The relative fitness of infected and
uninfected hosts is important to the population dynamics of Wolbachia, and more data are needed. Evolutionary conflict should be common between host genes, Wolbachia genes, and other "selfish" genetic elements. Wolbachia-specific PCR primers are now available for several genes with different rates of evolution. These primers will permit rapid
screening in future studies of spatial and temporal patterns of single and multiple infection. Molecular phylogenies show
that CI- and PI-Wolbachia do not form discrete clades. In combination with experimental transfection data, this result suggests that host reproductive
alterations depend on the interaction between attributes of both Wolbachia and host. Moreover, Wolbachia isolates from closely related hosts do not usually cluster together, and phylogenies suggest that Wolbachia may have radiated after their arthropod hosts. Both results support considerable horizontal transmission of Wolbachia between host species over evolutionary time. Natural horizontal transmisson between parasitoids and their hosts, or with
entomoparasitic nematodes or ectoparasitic mites, remains a tantalizing but equivocal possibility.
Received: November 27, 1998 / Accepted: January 15, 1999 相似文献
11.
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
12.
Pollination and factors limiting fruit set of chasmogamous flowers of an amphicapric annual,Polygonum thunbergii (Polygonaceae) 总被引:1,自引:0,他引:1
Summary We observed phenology and insect visitors of chasmogamous flowers of an amphicarpic annual,Polygonum thunbergii (Polygonaceae) in Kyoto, Japan, and clarified limiting factors for fruit set by bagging and hand-pollination experiments.
Flowering season was one month from late September. Flowers were visited by various insect groups (total 30 families and 64
species) and effective pollinators were lower bees (Halictidae) and wasps (Vespidae) in the early flowering season, and middle-sized
flies (Syrphidae and Calliphoridae) in the later season. Nectar was secreted at a constant rate (0.013mg sugar/hour) throughout
a day and >90% of it was consumed by insects. The average number of flowers per ramet was 122, of which 95% were pollinated
in the natural conditions. Bagging experiments showed that 47% of flowers were self-pollinated even under no pollinator visits.
Despite of a high probability of cross pollination, the probability of fruit set within the ramet was 0.30 due to resource
limitation. We discussed possible adaptive significance of cleistogamous flowers under the condition that seeds could be produced
by chasmogamous flowers through self-pollination even under pollinator limited conditions. 相似文献
13.
Midori Tuda 《Researches on Population Ecology》1996,38(2):133-140
The effects of spatial structure in terms of local capacity, or the maximum number of larvae surviving competition at resource
patches, and temporal structure in terms of the period vulnerable to parasitoid attack in host populations on the persistence
of host-parasitoid systems were quantitatively evaluated by laboratory experiments and well-parameterized model analyses.
One of two bruchid beetles,Callosobruchus maculatus andC. phaseoli, were used as a host with Heterospilus prosopidis used as the parasitoid.C. maculatus, in which few larvae survive competition to become adults in each bean, andC. phaseoli, in which many larvae become adults in each bean, along with two kinds of beans, the mung and the azuki, were combined to
construct four (2×2) resource-herbivorous host-parasitoid systems that differed in local capacity and vulnerable period. The
mung-C. maculatus system with the parasitoid was the most persistent, i.e., took the longest time for extinction of either the host or parasitoid
to occur. Since this resource-herbivorous host combination exhibited the lowest local capacity and the shortest vulnerable
period, these two conditions possibly promoted the persistence of the system. A model incorporating the host population structure
supported the observed persistence. Furthermore, the possible contribution of the timing of density-dependent competition
of the host on the host-parasitoid persistence is predicted. 相似文献
14.
David Abramson F 《Population studies》1973,27(2):235-242
Abstract Studies of birth intervals have generally separated the process into: (1) the period of infertility following a pregnancy termination; (2) the length ofthe interval from the end of the infertile period to the next conception (which reflects the probability of conception), and (3) the average duration of pregnancy for both live births and foetal deaths.(1) Empirically derived intervals between successive live births average from 19 to 30 lunar months(2) (Table 1), depending upon the population studied and the birth order.(3) Estimates of conception rates using birth intervals data require some estimate of the extent to which foetal wastage increases the birth interval. 相似文献
15.
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
16.
Keisuke Nakata 《Researches on Population Ecology》1989,31(2):185-209
Summary Changes of the components of reproduction were analyzed quantitatively in a two-year cyclic population (which has two peaks
in alternate years during a five-year census) of the red-backed vole,Clethrionomys rufocanus bedfordiae, with reference to its regulatory mechanism: (1) Variation in sex ratios was not associated with population phase or density,
although a higher percentage of females in mature individuals was observed in the increase phase. (2) Females attained to
sexual maturity at younger age and at lighter body weight than did males. All the youngest mature individuals were found in
the low and the increase phases. Age and size at maturity became older and larger as the population went toward the peak phase.
(3) Maturation rate was strongly associated with population phase and density; this component is an important and good parameter
to predict population trend. Maturation rates were in the order, the low phase>the increase phase>the peak phase>the decline
phase; the differences in the rates among these phases were significant. Maturation rate was somewhat depressed when the population
density exceeded about 40 individuals/ha. Changes in age at maturity and in maturation rate are interpreted as derivative
phenomena related to the population density and the capacity of the number of mature voles per unit area. (4) The maximum
number of mature individuals were 26 males/ha and 29 females/ha; there was almost no increase of the number of mature voles
at higher population densities over about 40 individuals/ha. The number of exclusive home ranges per hectare calculated from
the observed range lengths did not differ much from the maximum number of mature voles of either sex. (5) Length of breeding
period was shorter in the high-density years than in the low-density years; the breeding started earlier and ended earlier
in the former than that in the latter. In the increase phase a few voles reproduced in winter. (6) The percentage of pregnant
females was significantly lower in the peak phase than those in the other phases. 相似文献
17.
Takao Itino 《Researches on Population Ecology》1992,34(1):203-211
Summary There are, at least, three possible ways in which similar species coexist; resource partitioning, interference competition,
and exploitation competition. Here, I investigated which way contributed to the coexistence of leafroller-hunting eumenid
wasp species. Resource partitioning and, in addition, differential diet breadths proved to promote species coexistence in
this case.
First, I analyze the prey records and diet overlap of four eumenid species in a local area. The larger two eumenids hunted
similar-sized prey items and had similar potential taxonomic prey uses. But the diet breadth of the subsocial eumenid was
much wider than that of the solitary one. As a result, the diet overlap between the two large eumenids decreased. This was
because the solitary eumenid attend repeatedly to the same hunting site inhabited by one abundant prey species, while the
subsocial one made random hunting. On the other hand, the two medium-sized eumenids partitioned resources according to prey
size.
Secondly, I related these results to prey choice by several other species of eumenid obtained from literature sources. Ten
Japanese common eumenids were divided into four groups according to their prey size. In each of the four groups, 2 to 3 wasp
species differentiated the habitat (1 group) or coexisted by means of differential diet breadths (parallel with differential
sociality, 2 groups).
Contribution to the ecological studies of the eumenid wasps. III. 相似文献
18.
Makoto Kat? 《Researches on Population Ecology》1984,26(1):84-96
Summary The mining pattern of the honeysuckle leaf-minerPhytomyza lonicerae which feeds onLonicera gracilipes was analyzed with special reference to the avoidance of parasitoids' attacks. The leaf-miner makes the linear mine with branches
and crosses by turning and branching, off the backtracking mine. Both average numbers of turnings and branchings were about
4. The speed of mining was 1.5 times faster in backtracking than in advancing. The mine width increased as the mining larva
grew and total volume of consumed plant tissue was nearly constant independent of variability of the number of turnings and
other characteristics of the mine. The majority of larval mortality were due to attacks by parasitoid wasps (Chrysochairs pentheus andDiglyphus minoeus), which locate the present position of leaf-miners, by tracing mine tracks, and wasps attack leaf-miners at a higher rate
in backtracking than in advancing. The adaptive significance of branching and crossing by leaf-miners was discussed in terms
of the reduction of parasitoids' attacks. 相似文献
19.
Summary Studies on the population dynamics of the fall webworm,Hyphantria cunea have been carried out at three survey stations and along selected roads in the urban area of Tokyo since 1966. Twelve survivorship
curves obtained during two years and 8 life tables show that the mortality rate in early developmental stages of the fall
webworm is remarkably low as compared with that of other lepidopterous defoliaters and the mortality rate in later developmental
stages is compensatory high. The low mortality rate in early stages is considered to be due to the protective role of the
nest-web and the lack of egg and larval parasites. All but one parasitic species emerge from prepupae and pupae. Spiders living
in the nest-web of the fall webworm play an important role in reducing the number of young larvae. Direct observations and
caging experiments showed that relatively high mortality during later larval stages is mainly due to predation by birds (in
the first generation) and wasps (in the second generation). The generation mortality in the survey stations always exceeded
the level where the population is kept at the steady state, and the outbreak of this moth is considered to be continued by
the immigration of adults from large trees growing in gardens on which the larvae can escape from predation pressure.
Contributions from JIBP-PT No. 51. A part of this study was supported by the special project research, ‘Studies on the dynamic
status of biosphere’, sponsored by the Ministry of Education. 相似文献
20.
Summary To determine the effectiveness of a pest management system that uses pesticides at a low level, we censused populations of
seven insect pests and three plant diseases from 1980 to 1989 in a citrus orchard which was managed with a pesticide-reduced
and pesticide-free protocols, in Wakayama Prefecture, Japan. In the orchard, we controlled the pests solely by spraying petroleum
oil once a year from 1980 to 1985, by not spraying insecticide in 1986, and spraying only germicide in 1987. The arrowhead
scale population remained much lower level at which citrus trees begin to wither when petroleum oil was sprayed, whereas it
rapidly increased and began to wither trees during the years without spraying petroleum oil. The Indian wax scale population
rapidly increased only during a 2-year period and then declined. Although the infection level of the sooty mold was unusually
high on the trees where the density of the scale was high, this pathogen did little damage to citrus trees. The population
of the red wax scale gradually increased throughout the census period but did not reach the level at which citrus trees begin
to be damaged. Other pests also caused negligible damages to citrus trees. The results indicated that the pesticide-reduced
pest management system which was proposed by Inoue and Ohgushi (1976, 1977) is valid for the prevention of the outbreak of
the arrowhead scale, and that is has the sufficient control efficiency for the other pests in citrus orchards.
Contribution to the ecological studies of scale insect 3. 相似文献