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Summary Difficulty arises in applying marking-and-recapture methods to insects when the probability of recapture of marked individuals
is changed with advancing age, either due to detachment of the mark by moulting (in the case of larvae) or to changes in their
survival rate or their behaviour. A modification of the re-recapture method (Leslie
et al., 1953) has been devised to analyze the capture-recapture data of the 5th-instar larvae and adults ofNezara viridula L. Estimation of the rate of moulting to the adult stage is made with the aid of additional information on larval survival.
Migration rates of the larvae between the two halves of the census field is estimated byIwao's (1963) method. Through these analyses, the dynamic feature of the population during transition from the 5th instar to, adult
is revealed. Several problems involved in the application of marking-and-recapture methods to insect populations are discussed.
Contribution from the Entomological Laboratory, Kyoto University No. 392. 相似文献
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3.
Summary A simulation model of the green rice leafhopper-spiders system was presented. The validity of this model for simulation purpose
was tested by comparing the calculated values with observed ones (Fig. 4). The effectiveness of various control measures against
leafhoppers was evaluated by computer simulations. The computer simulation demonstrated that the wrong use of selective insecticide,
contrary to expectation, brought an increase in the pest density, i. e., that the egg densities of leafhoppers in the 2nd
and 3rd generations are increased by the insecticidal application in February, while they are decreased by the July application
(Table 2). To obtain satisfactory control by sterile-male release, 320,000 sterile-male per square kilometer should be released
even in the combined use with insecticides (Fig. 5). The escape of leafhoppers from predation by spiders was demonstrated
by the simulation. It is suggested that spiders are able to suppress the leafhopper populations at a low density when there
is a very favorable balance between spiders and leafhoppers, and this condition may be realized by sophisticated use of selective
insecticides (Fig. 6). Factors and/or processes which have to be involved in a more improved systems model are discussed.
A part of this research was supported by science research fund from the Ministry of Education. 相似文献
4.
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
5.
Summary An epidemiological system model was developed to evaluate the role of factors which were responsible for the prevalence of
rice dwarf virus (RDV) transmitted by the green rice leafhopper,Nephotettix cincticeps. Simulation tests were conducted by varying values of the following three parameters: the vector density, the coefficient
of the efficiency of feeding acquisition of RDV of the vector, and that of efficiency of RDV transmission by the vector. The
effect of each parameter was assessed in terms of changes in percentages of infected insects and of infected rice hills.
Both the percentages of infected insects and of infected rice hills increased rapidly with increasing vector density within
a range of low vector density. The former increased linearly when the acquisitive coefficient was increased. But the percentage
of infected rice hills was affected to a lesser extent. The percentage of infected insects and that of infected rice hills
increased exponentially with increasing values of the transmission coefficient. The results obtained from the simulation tests
were discussed in relation to the ecological factors which caused the recent prevalence of RDV.
A part of this research was supported by science research fund from the Ministry of Education. 相似文献
6.
Summary A predator-prey system involvingLycosa pseudoannulata as predators and both the green rice leafhopper,Nephotettix cincticeps and the brown planthopper,Nilaparvata lugens as prey was studied in an experimental paddy field. Daily predation rates on the prey and weekly disappearance rates ofLycosa females were related to densities of both predators and prey by multiple regression. During the off-season of reproduction
for predators and prey, it proved possible to simulate the interaction betweenLycosa and its prey. 相似文献
7.
Summary A simple experiment of simulation was done to analyze the natural mortality process of young larval colonies and egg masses
of the southern green stink bug. In this experiment, a degree of contagiousness
was allowed in regard to the action of a mortality factor, and
was defined as the mean number killed per a colony or an egg mass by the mortality factor within a unit time and the number
killed per a colony was assumed to follow the Poisson series with the mean
. Thus each component of the Poisson series was opposed to each colony or egg mass which was taken at random from 162 egg
masses, 135 and 117 colonies of the first and the second instar larvae, respectively.
It was revealed that mortality factors in the field did not act with a small degree of contagiosness, e. g.
, on all colonies or egg masses, but acted with a large degree of contagiousness, e. g.
, on some of the colonies or egg masses. Thus differential survival somewhat in all or none way occurred among the insect
colonies irrespective of their initial sizes. These results were well explained by taking actual mortality factors into account. 相似文献
8.
Keizi Kiritani 《Researches on Population Ecology》1970,12(1):19-34
Summary Polymorphism in adult colour pattern ofNezara viridula is determined on the genetic basis. The basic colour patterns of adult are classified into four types, i. e. G, O, R and
F. No appreciable differences between these types were observed in respect to various physiological traits of nymphs and adults,
except that type G seems to be superior in reproductive ability but to be inferior in ability of surviving winters at least
to types R and F.
Inter-generation changes in percentage frequency of G type were examined from 1959 to 1967 covering more than 30 generations.
Percentage frequencies of G types prior to the severe winter of 1962–3 fluctuated greatly around a mean of 87.9%, while they
did to a lesser extent than before with a mean of 85.0% after the winter. Unexpected high percentages of G type were recorded
frequently in summer generations, viz. 1st and 2nd. On the other hand, the relative frequencies of G and O types decreased
after hibernation in contrast to the increases in those of F and R. This sort of changes in genetic composition related to
the winter of 1962–3 was observed in several populations segregated from each other.
This seasonal alternation of selective activity in the environments is considered to be responsible for retention of the polymorphism.
Alternative possible causes, i. e. difference in habitat preference, non-random mating and selective predation by predators
among polymorphs, may safely be rejected as irrelevant to the mechanism in maintaining polymorphism.
The polymorphism of this insect seems to be in a transient state rather than balanced one contributing little to population
regulation, but the persistence ofN. viridula in the periphery range may be assisted by retention of the polymorphism. 相似文献
9.
Summary Population behaviour of adults and 5th-instar nymphs ofNezara viridula L. was analysed by means of the marking-and-recapture method in an early-planted paddy field. The field contained five varieties
of rice which differend in growth states. It was estimated that a total of more, than 7,000 adults of the first generation,
in which at least 3,000 were females, invaded the field from early July to middle August. Egg-mass census data, however, indicated
that only 10 per cent or less of the females participated in egg-laying. This was largely due to the, low rate of adult survival.
The adults preferred younger plants, for both feeding and oviposition.
The method described byIwao
et al. (1966) permitted estimate that 3,300–3,400 of the 5 th-instar nymphs and 1,100–1,200 of the adults of the second generation
were produced from 298 egg-masses (25, 700 eggs); while 95–6 per cent of the individuals were thought to have died before
reaching adulthood. Most of the 5 th-instar nymphs moved less than 4 m in three days as long as the condition of food plants
remained suitable, but they tended to move more towards younger plants when those on which they lived became too mature. The
apparent survival rate of the second generation adults was very low, probably due both to a rapid emigration and a high mortality
of newly-emerged adults. 相似文献
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