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1.
Summary Until now, mathematical models of parasitoid-host interactions have not incorporated the tendency for destructively host-feeding
parasitoids to partition their feeding and oviposition behaviour in relation to different host stages. A literature survey
reveals a trend for female parasitoids to feed preferentially or exclusively on earlier host stages and to oviposit preferentially
or exclusively in/or later ones.
We explore the relative advantages to host-feeding parasitoids of a number of possible host stage selection strategies. We
develop hypotheses, formalizing and testing them using modifications to our earlier simulation model of host-feeding strategies
(Jervis and Kidd, 1986).
We conclude from our modelling that the advantage to be gained from feeding on early host stages and ovipositing in late ones
is likely to be associated with: 1) reduced handling times when feeding on early stage hosts; 2) reduced wastage of progeny
from mortality factors other than host-feeding by the parent parasitoid, achieved by confining oviposition to late host stages;
and 3) reduced probability of progeny mortality resulting from the parent's host-feeding activities. 相似文献
2.
T. S. Bellows Jr. 《Researches on Population Ecology》1985,27(1):65-76
Summary Oviposition rates and related behaviours were quantified forLariophagus distinguendus
F?rster attackingCalosobruchus chinensis (L.) andC. maculatus (F.). Oviposition rates varied with parasitoid age; parasitoids aged 1–7 days laid approximately twice as many eggs per day
as those aged 8–14 days. Similar differences were noted in search rates and handling times; younger parasitoids had higher
attack rates and lower handling times than older parasitoids. Search rates and handling times also varied with the host stage
available for attack. Search rates were higher and handling times were lower on larger stages. The results are discussed with
reference to their impact on the dynamical behavior of insect parasitoid-host populations. 相似文献
3.
Combining pheromone-baited and food-baited traps for insect pest control: Effects of additional control by parasitoids 总被引:1,自引:0,他引:1
Hugh J. Barclay 《Researches on Population Ecology》1991,33(2):287-306
Summary Two age-structured population dynamic models are analyzed in which pheromone-baited trapping and food-baited trapping are
used simultaneously to eradicate an insect pest. The pest species is assumed to be under partial control by a host-specific
parasitoid species. The two models assume that density-dependent population regulation is accomplished either by host larval
competition or by means of oviposition interference among the parasitoids. The two trap types interact in a positive synergistic
manner and this combination appears to be very promising as a useful combination of pest control methods. Several features
of the system are examined; the feature which appears to cause the greatest problem is the possibility of the parasitoids
being attracted to the pheromone or the food traps. In either case, the degree of attraction does not have to be very great
to undermine the control effort. It is seen that food trapping becomes indispensible if host pheromone is used by the parasitoids
as a host-locating kairomone. If odor in the food traps is used by the parasitoids as kairomone, then the situation appears
more optimistic, as the reduction in efficiency of the food traps appears much less than with the pheromone traps when pheromone
acts as kairomone. 相似文献
4.
T. S. Bellows Jr. 《Researches on Population Ecology》1985,27(1):55-64
Summary The effects of host age on parasitoid reproductive capacity are studied using the pteromalid parasitoidLariophagus distinguendus
F?rster and its bruchid hosts,Callosobruchus chinensis (L.) andC. maculatus (F.). A series of experiments were performed to investigate relationships between age and size of host parasitized and the
developmental period of pre-imaginal progeny, sex ratio, female size, longevity, fecundity and oviposition rate. There was
no effect of host size on preimaginal parasitoid developmental period. Sex ratio varied from less than 5% females from young
(small) hosts to 60% females from mature (large) hosts. Adult size, female longevity, fecundity, and oviposition rate were
also positively related to host age. Females provided mature hosts lived longer than those provided either young hosts or
no hosts, possibly because of an increased ability to host-feed from the larger hosts. The implications of these findings
to parasitoid population reproductive capacity and host-parasitoid synchrony are discussed. 相似文献
5.
Midori Tuda 《Researches on Population Ecology》1998,40(3):293-299
In an insect host (the cowpea weevilCallosobruchus maculatus)- parasitoidHeterospilus prosopidis) experimental system, the population densities of the component species oscillated for the first 20 generations and then
abruptly stabilized as the parasitoid density decreased. Examination of the host and parasitoid after the 40th generation
in the long-term experiment showed that (1) host larvae exhibited contest-type competition (killing other larvae inhabiting
the same bean), in contrast to the founder population being scramble-type competitors and (2) the parasitoid attack rate on
the host did not change. There was also an evolutionary trade-off between body size and the rates of larval survival and development,
suggesting a cost of contest competition on larval survivorship and development. I tested model predictions (Tuda and Iwasa
1998) that (1) host equilibrium population size should gradually decrease as the proportion of the contest type increases
and that (2) random attacks of the parasitoid on the host should reduce the rate of increase in proportion of the contest
type, and the effect should become manifest especially during the first 20 generations. Two of three host-only replicates
showed significant decrease in population sizes. Although the density of emerging adults per bean did not differ between replicates
of the host-only and host-parasitoid systems, comparison of the host body size between them on day 270 (at the 13th generation)
showed that the host was more contest-type in the host-only system than in the host-parasitoid system, as the model predicted,
and later on day 650 the effect of the parasitoid had disappeared. 相似文献
6.
Makoto Kato 《Researches on Population Ecology》1996,38(1):27-40
Population dynamics of a leafminer,Chromatomyia suikazurae (Agromyzidae, Diptera) and its parasitoid community were studied for ten years at seven natural populations along an altitudinal
gradient in Japan. This species which mines leaves of a forest shrub,Lonicera gracilipes (Caprifoliaceae), was attacked by 25 hymenopterous parasitoid species. Annually, the parasitoid community structure varied
less within a population than among populations. The seven parasitoid communities were clustered into three groups corresponding
to the altitudinal gradient: (a) lowland communities dominated by late-attacking, generalist pupal idiobiont eulophids and
with highest species diversity, (b) hillside communities dominated by an early-attacking, specialist larval-pupal koinobiont
braconid and (c) highland communities dominated by an early-attacking, generalist larval idiobiont eulophid. Annual changes
of the host larval densities among the local populations were largely synchronous rather than cyclic. Among these populations,
host density levels and mortality patterns greatly varied. By analyzing these inter-populational differences of host mortality
patterns, the following conclusions were drawn: (1) The host mortality patterns were determined by the host utilization patterns
of the locally dominant species. (2) The host pupal mortality but not larval mortality was related to species diversity but
not to species richness itself of each parasitoid community. (3) Density dependence was detected only in pupal mortality at
a lowland population dominated by late-attacking pupal parasitoids. These results suggest that interspecific interactions
of parasitoids add additive effects to host population dynamics dissimilarly among local populations with different parasitoid
communities. 相似文献
7.
Indirect interactions between populations of different species can be important in structuring natural communities. Indirect
effects are either mediated by changes in population densities (trophic or density-mediated effects) or by changes in the
behavior of species that are not trophically connected (behavioral or trait-mediated effects). We reviewed the literature
on aphids and their parasitoids to explore the various possible indirect interactions that can occur in such communities.
The review was motivated by our study of a particular aphid–parasitoid community in a natural (i.e., nonagricultural) habitat,
and by the wealth of information that exists about aphid–parasitoid systems in agricultural settings. We focused our review
on aphid–parasitoid interactions, but considered how these were influenced by the other aphid natural enemies and also by
aphid mutualists and host plants. We conclude that indirect effects are likely to have a major effect in structuring aphid–parasitoid
communities, and that the latter are a valuable model system for testing ideas about community interactions.
Received: December 20, 1998 / Accepted: January 12, 1999 相似文献
8.
Yoshihiro Yamada 《Researches on Population Ecology》1988,30(2):235-249
1. | a mathematical model is presented which predicts the expected optimal-patch-use strategy for solitary parasitoids with a limited fecundity. |
2. | The model predicts that the quality of the patches is determined by the proportion of unparasitized hosts and not by the density of those hosts, and that throughout the searching period the parasitoids should maintain the level of parasitism equal in all the patches irrespective of the host density per patch. |
3. | The spatial pattern of parasitism among field patches by a parasitoid with a low fecundity,Praestochrysis shanghaiensis, was in agreement with the prediction of the model, i.e., a similar level of parasitism in different patches was observed when the ratio of female parasitoids to hosts in the whole study area exceeded 0.07. When the ratio was less than 0.05, however, the level of parasitism per patch showed an inverse relation to the host density, and was positively correlated with the female parasitoid-host ratio. |
4. | The model assumes that the parasitoids move between patches without cost and have perfect information about patch quality. Consideration of the cost of moving and sampling bridges the gap between the observed and predicted rates of parasitism found when the female parasitoid-host ratio in the whole study area was low |
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.
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.
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
12.
Incorporating physiology into parasitoid behavioral ecology: the allocation of nutritional resources 总被引:3,自引:0,他引:3
A critical problem faced by most theoretical studies of parasitoid behavior and population dynamics has been the paucity
of empirically obtained information about the pattern of resource allocation to egg production and metabolic maintenance in
relation to adult diet in female parasitoids. This review calls for a shift from traditional manipulative feeding studies
to studies that quantify the energetic budget of parasitoids and which take into account the dynamic nature of metabolic processes.
As guidelines, we highlight the advances made along these lines with other insect groups and some of the simplest tools already
available today for fulfilling this goal.
Received: December 22, 1998 / Accepted: January 12, 1999 相似文献
13.
Michael F. Antolin 《Researches on Population Ecology》1999,41(1):29-37
Parasitoid sex ratios are influenced by mating systems, whether complete inbreeding, partial inbreeding, complete inbreeding
avoidance, or production of all-male broods by unmated females. Population genetic theory demonstrates that inbreeding is
possible in haplodiploids because the purging of deleterious and lethal mutations through haploid males reduces inbreeding
depression. However, this purging does not act quickly for deleterious mutations or female-limited traits (e.g., fecundity,
host searching, sex ratio). The relationship between sex ratio, inbreeding, and inbreeding depression has not been explored
in depth in parasitoids. The gregarious egg parasitoid, Trichogramma pretiosum Riley, collected from Riverside, CA (USA) produced a female-biased sex ratio of 0.24 (proportion of males). Six generations
of sibling mating in the laboratory uncovered considerable inbreeding depression (∼ 20%) in fecundity and sex ratio. A population
genetic study (based upon allozymes) showed the population was inbred (F
it = 0.246), which corresponds to 56.6% sib-mating. However, average relatedness among females emerging from the same host egg
was only 0.646, which is less than expected (0.75) if ovipositing females mate randomly. This lower relatedness could arise
from inbreeding avoidance, multiple mating by females, or superparasitism. A review of the literature in general shows relatively
low inbreeding depression in haplodiploid species, but indicates that inbreeding depression can be as high as that found in
Drosophila. Finally, mating systems and inbreeding depression are thought to evolve in concert (in plants), but similar dynamic models
of the joint evolution of sex ratio, mating systems, and inbreeding depression have not been developed for parasitoid wasps.
Received: November 13, 1998 /Accepted: January 8, 1999 相似文献
14.
Summary The zygaenidPryeria sinica
Moore and the ichneumonidAgrothereutes minousubae
Nakanishi form a one host—one parasitoid system in nature. Their seasonal life cycles were investigated by laboratory experiments and
field observations, and the life-cycle adaptation of the parasitoid to its host was examined.
The moth is univoltine. The larva hatches from mid-February to mid-March and feeds on leaf buds and young leaves of ever greenEuonymus japonicus
Thunb. The thermal constants for completing the 1st, 2nd, 3rd, 4th larval instars and prepupal stage were 85.6, 80.5, 85.2, 177,0
and 197.6 degree-days, respectively. The prepupa and pupa vulnerable to the attack by the parasitoid occurred from mid-April
to early May and from mid- to late May, respectively.
Diapause in the parasitoid is facultative and occurs in the eonymphal stage. The photoperiodic response for this diapause
was a long-day type with a critical photoperiod of 13 hr 40 min at 20°C, but it was not expressed at 25°C, most larvae entering
diapause irrespective of photoperiod. About 19, 120, 82 and 112 degree-days above 7°C were required to complete the egg, larval,
prepupal and pupal development, respectively. These data were superimposed on the photothermograph of Fukuoka, and it is predicted
that the 1st adult eclosion would occur in late April and the partial 2nd adult eclosion in early June. The prediction was
supported by field observations.
The adult eclosion of the parasitoid synchronized well with the apperance of prepupae and pupae of the moth. The parasitoid
has two types of seasonal life cycle, one generation and two generations a year. Both types have an extremely long dormant
period of 10–11 months due to aestivo-hibernation. This seasonal life cycle enables the parasitoid to maintain its population
when the host is in short supply. 相似文献
15.
The role of evolutionary dynamics in understanding host–parasitoid interactions is interlinked with the population dynamics
of these interactions. Here, we address the problems in coupling evolutionary and population dynamics of host–parasitoid interactions.
We review previous theoretical and empirical studies and show that evolution can alter the ecological dynamics of a host–parasitoid
interaction. Whether evolution stabilizes or destabilizes the interaction depends on the direction of evolutionary changes,
which are affected by ecological, physiological, and genetic details of the insect biology. We examine the effect of life
history correlations on population persistence and stability, embedding two types, one of which is competitively inferior
but superior in encapsulation (for parasitoid, virulence), in a Nicholson–Bailey model with intraspecific resource competition
for host. If a trade-off exists between intraspecific competitive ability and encapsulation (or virulence, as a countermeasure)
in both the host and parasitoid, the trade-off or even positive correlation in the parasitoid is less influential to ecological
stability than the trade-off in the host. We comment on the bearing this work has on the broader issues of understanding host–parasitoid
interactions, including long-term biological control.
Received: November 10, 1998 / Accepted: January 18, 1999 相似文献
16.
Summary Dispersions and resource utilization of primary and secondary parasitoids developing in non-depletable primary host populations
were determined for an aphid-parasitoid community occurring on strawberries. Analyses of dispersions based onGreen's coefficient andLloyd's Patchiness Index indicated parasitized aphids were highly aggregated initially, became less aggregated as density increased,
and remained aggregated following collapse of the aphid populations. The “index of aggregation” values calculated usingTaylor's Power Law concurred with results from the other indices, and the similarity of the regression coefficients from both seasons
suggests that the index of aggregation may be characteristic for communities as well as species. Analysis withIwao's regression of mean crowding on the mean generated similar results when population data were stratified temporally, and
also indicated that the individual was the basic unit of the population.
In a non-depletable environment, oviposition of individuals exhibiting an aggregated dispersion pattern within clumps of hosts
provides primary parasitoids with a suitable trade-off between energy utilization or genetic potential, and losses associated
with hyperparasitism. 相似文献
17.
Norio Yamamura 《Researches on Population Ecology》1996,38(2):211-218
In geological history, rapid speciation, called adaptive radiation, has occurred repeatedly. The origins of such newly developing
taxa often evolved from the symbiosis of different species. Mutualistic symbioses are generally considered to evolve from
parasitic relationships. As well as the previous model of host population with discrete generations, a differential equation
model of host population with overlapping generations shows that vertical transmission, defined as the direct transfer of
infection from a parent host to its progeny, is an important factor which can stimulate reduction of parasite virulence. Evolution
of the vertical transmission rate from both points of view, the parasite and the host, is analyzed. There is a critical level
of the rate, below which an evolutionary conflict arises (the parasite would want an increase in the rate while the host would
not), and above which both species would correspond to increase the rate. Therefore, once the parasite dominates the evolutionary
race so as to overcome this critical level, one-way evolution begins toward a highly mutualistic relationship with a high
vertical transmission rate, possibly creating a new organism through symbiosis with perfect vertical transmission. Changes
in other parameters may decrease the critical level, initiating one-way evolution. However, changes in traits, probably developed
through a long interrelationship in parasitism, do not necessarily induce the evolution of mutualism. Establishment of the
ability to make use of metabolic and digestive wastes from the partner certainly facilitates the evolution of mutualism, while
improvements in reproductive efficiency of parasites and reduction of negative effects from exploitation in hosts on the contrary
disturb mutualism. 相似文献
18.
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
19.
This paper introduces the special issue of this journal, which is devoted to parasitoid ecology. We provide a brief review
of the role that parasitoids have played in research in population, community, and behavioral ecology and speculate on their
future importance to the subject.
Received: January 11, 1999 / Accepted: January 19, 1999 相似文献
20.
Duncan A. Mackay 《Researches on Population Ecology》1985,27(1):87-98
Summary OvipositingE. editha butterflies display post-alighting discrimination among patches ofCollinsia torreyi, one of their major hosts in the General's Highway (GH) population at a montane site in California. Females tended to accept
(i.e. oviposit on) dense patches of this host and to reject sparse patches. Possible behavioural mechanisms underlying this
tendency are discussed. The consequences of this non-random pattern of oviposition for egg and larval survivorship were investigated
and no differences were found in the survivorship of larvae on acceptable and unacceptable collinsias. 相似文献