首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 46 毫秒
1.
1. In primary parasitoids, significant differences in life history and reproductive traits are observed among parasitoids attacking different stages of the same host species. Much less is known about hyperparasitoids, which attack different stages of primary parasitoids. 2. Parasitoids exploit hosts in two different ways. Koinobionts attack hosts that continue feeding and growing during parasitism, whereas idiobionts paralyse hosts before oviposition or attack non‐growing host stages, e.g. eggs or pupae. 3. Koino‐/idiobiosis in primary parasitoids are often associated with different expression of life history trade‐offs, e.g. endo‐ versus ectoparasitism, high versus low fecundity and short versus long life span. 4. In the present study, life history parameters of two koinobiont endoparasitic species (Alloxysta victrix; Syrphophagus aphidivorus), and two idiobiont ectoparasitic species (Asaphes suspensus; Dendrocerus carpenteri) of aphid hyperparasitoids were compared. These hyperparasitoids attack either the parasitoid larva in the aphid before it is killed and mummified by the primary parasitoid or the parasitoid prepupa or pupa in the dead aphid mummy. 5. There was considerable variation in reproductive success and longevity in the four species. The idiobiont A. suspensus produced the most progeny by far and had the longest lifespan. In contrast, the koinobiont A. victrix had the lowest fecundity. Other developments and life history parameters in the different species were variable. 6. The present results reveal that there was significant overlap in life history and reproductive traits among hyperparasitoid koinobionts and idiobionts, even when attacking the same host species, suggesting that selection for expression of these traits is largely association specific.  相似文献   

2.
Abstract.  1. Parasitoid attack strategy has been divided into two broad categories, koinobiosis and idiobiosis, based on the arrest of host development and the intimacy of larval contact. Koinobionts allow the host to continue developing and larvae usually feed within the host body, whereas idiobionts stop host development and larvae usually feed externally.
2. Comparisons of host ranges from rearings of parasitoids from specific host communities have shown that koinobionts are more host specific than idiobionts. These tests suggested that parasitoid attack strategy influenced specialisation in parasitoid–host interactions within certain host communities.
3. To determine whether this pattern was consistent within a single parasitoid lineage that utilises hosts from many different communities, the host ranges of koinobiont and idiobiont braconid genera of the New World were compared. Koinobiont genera utilised fewer host families than idiobionts, suggesting that parasitoid attack strategy may direct the evolution of host specificity throughout the evolutionary history of parasitoid lineages.  相似文献   

3.
Parasitoid wasps are excellent organisms for studying the allocation of host resources to different fitness functions such as adult body mass and development time. Koinobiont parasitoids attack hosts that continue feeding and growing during parasitism, whereas idiobiont parasitoids attack non-growing host stages or paralyzed hosts. Many adult female koinobionts attack a broad range of host stages and are therefore faced with a different set of dynamic challenges compared with idiobionts, where host resources are largely static. Thus far studies on solitary koinobionts have been almost exclusively based on primary parasitoids, yet it is known that many of these are in turn attacked by both koinobiont and idiobiont hyperparasitoids. Here we compare parasitism and development of a primary koinobiont hyperparasitoid, Mesochorus gemellus (Hymenoptera: Ichneumonidae) in larvae of the gregarious primary koinobiont parasitoid, Cotesia glomerata (Hymenoptera: Braconidae) developing in the secondary herbivore host, Pieris brassicae (Lepidoptera: Pieridae). As far as we know this is the first study to examine development of a solitary primary hyperparasitoid in different stages of its secondary herbivore host. Pieris brassicae caterpillars were parasitized as L1 by C. glomerata and then these parasitized caterpillars were presented in separate cohorts to M. gemellus as L3, L4 or L5 instar P. brassicae. Different instars of the secondary hosts were used as proxies for different developmental stages of the primary host, C. glomerata. Larvae of C. glomerata in L5 P. brassicae were significantly longer than those in L3 and L4 caterpillars. Irrespective of secondary host instar, every parasitoid cluster was hyperparasitized by M. gemellus but all only produced male progeny. Male development time decreased with host stage attacked, whereas adult male body mass did not, which shows that M. gemellus is able to optimally exploit older host larvae in terms of adult size despite their decreasing mass during the pupal stage. Across a range of cocoon masses, hyperparasitoid adult male body mass was approximately 84% as large as primary parasitoids, revealing that M. gemellus is almost as efficient at exploiting host resources as secondary (pupal) hyperparasitoids.  相似文献   

4.
With resistance of insect pests to synthetic pesticides on the increase, the role of parasitoid wasps as biological control agents is expanding in pest and resistance management strategies. One of the predictors of reproductive success of endoparasitoids is the relative size of the wasp at host emergence. While in idiobiont parasitoids, where the host stops feeding after parasitism, the wasp size is determined by the host size at the time of parasitism; the size of koinobiont wasps, where the host continues to feed after parasitism, is dependent on additional factors. Here we show that the host mass and temperature are important factors that determine survival and development of the koinobiont endoparasitoid Venturia canescens in late instar larvae of the flour moth Ephestia kuehniella.  相似文献   

5.
Aim To examine whether island parasitoid faunas are biased towards generalists when compared with the mainland and their species pool, and to evaluate the effects of climate, island characteristics and regional factors on the relative proportions of idiobionts (i.e. generalists) and koinobionts (i.e. specialists) of two parasitic wasp families, Braconidae and Ichneumonidae. Location Seventy‐three archipelagos distributed world‐wide. Methods We used data on the distribution and biology obtained from a digital catalogue and several literature sources. We related level of generalism, measured as the ratio between the number of idiobiont and koinobiont species, to climatic, physiographic and regional factors using generalized linear models. We compared models by means of Akaike weighting, and evaluated the spatial structure of their residuals. We used partial regressions to determine whether the final models account for all latitudinal structure in the level of generalism. Results Islands host comparatively more idiobionts than continental areas. Although there is a latitudinal gradient in the level of generalism of island faunas correlating with both environmental factors and island characteristics, the most important determinant of island community structure is their source pool. This effect is stronger for ichneumonids, where generalism is higher in the Indomalayan region, arguably due to the higher diversity of endophytic hosts in its large rain forests. Main conclusions The level of generalism of island parasitoid faunas is largely constrained by regional factors, namely by the structure of the species pool, which emphasizes the importance of including regional processes in our understanding of the functioning of ecological communities. The fact that generalist species are more predominant in islands with a large cover of rain forests pinpoints the importance of the indirect effects of ecological requirements on community structure, highlighting the complex nature of geographical gradients of diversity.  相似文献   

6.
Takatoshi Ueno 《Oikos》2000,89(2):223-230
In general, ectoparasitoids attack concealed hosts in protected situations whereas endoparasitoids use both concealed and exposed hosts. The difference is assumed to be the consequence of ecological constraints; ectoparasitic larvae are vulnerable both to predation and to climatic factors such as rainfall, and, hence, require some structures to protect themselves. I hypothesized that such ecological constraints should act as a within-species selection pressure to female ectoparasitoids, and hence that females should recognize the degree of concealment of the host and prefer concealed over exposed hosts for oviposition. To test this hypothesis, I examined 1) whether host concealment could influence host acceptance by the ectoparasitoid wasp Agrothereutes lanceolatus and 2) whether host concealment could influence the fitness of the offspring. Female wasps recognized and attacked (probed) both cocooned and exposed host prepupae in equal proportions, but discriminated between them after ovipositor insertion, and preferred the former for oviposition and the latter for host-feeding. They also selected to oviposit on hosts concealed in paper tubes. Thus host concealment was important for host selection in A. lanceolatus . Offspring fitness (measured as survival and size) was much lower on exposed hosts than on cocooned and paper-concealed hosts, even under laboratory conditions. Thus, host concealment influenced the fitness of wasp offspring, and, hence, is a good indicator of host quality for female wasps. Adaptiveness of host selection and host-feeding in A. lanceolatus in relation to host concealment is discussed.  相似文献   

7.
Tachinids are usually considered as koinobionts as none of them kills or paralyzes the host when first entering it. These parasitoids, however, do not fit well into the koinobiont/idiobiont dichotomy because only some species show a high degree of physiological adaptation to the host, whereas the larvae of other species grow quickly following attack and kill the host rapidly, thus behaving more as idiobionts. The in vitro rearing technique provides further evidence for the poor adequacy of the koinobiont/idiobiont dichotomy for tachinids. In fact, while typical koinobionts are known to be difficult to culture on artificial media, some tachinids displaying non-synchronized development with the host have been successfully reared in vitro on insect material-free artificial media, thus behaving similarly to idiobionts. I therefore suggest not to use the koinobiont/idiobiont classification for tachinids and to class them instead only on the basis of the presence or absence of developmental synchrony with their hosts.  相似文献   

8.
Parasitoid wasps have long been favored organisms for fundamental studies on reproductive strategies and life-history evolution. Progeny allocation models designed with parasitoids in mind assume that offspring develop by consuming most or all of the resources available from a single host, and that size is the most important factor affecting offspring fitness. Many parasitoids exhibit host usage patterns consistent with these assumptions, but our recent observations suggested that endoparasitic wasps in the family Braconidae often do not. To investigate how differences in host usage patterns might affect developmental strategies, we compared two related braconids with contrasting host usage patterns. Apanteles carpatus consumed virtually all host tissues during immature development, whereas Microplitis demolitor fed exclusively on host hemolymph and consumed a relatively small proportion of available host resources. Development time of M. demolitor was unaffected by host size, whereas development time of A. carpatus was much longer in small hosts than in large hosts. On the other hand, offspring size in M. demolitor correlated strongly with host size, but it correlated only weakly with host size in A. carpatus . Our results collectively suggest that selection has favored rapid development at the potential cost of reduced size in M. demolitor , and increased size at the potential cost of increased development time in A. carpatus . Tissue feeding appears to be more prevalent among parasitoids overall, but hemolymph feeding is the predominant pattern of host usage in several subfamilies of endoparasitic braconids. We argue that the relative importance of offspring size and development time will be influenced by host ecology and the effects of selected traits on parasitoid survival.  相似文献   

9.
Parasitic Hpenoptera attacking Phyllonorycter species mining leaves of oak and birch were studied at a Cheshire locality during 1974. The host developmental stages killed, and attacked, by each parasite species are analysed. Smaller species and males tend to kill earlier Phyllonorycter instars than do larger species and females, and certain of the endoparasites as well as the ectoparasites must discriminate between small hosts which receive haploid eggs and large hosts which receive diploid eggs. Host-feeding is very widely practised, and facultative hyperparasitism is engaged in by all except the braconids and a few specialized chalcids. The biology of a parasite species generally allows its allocation to one of three groups according to the size of host larva that it attacks, whether it is endoparasitic or ectoparasitic, whether or not the host continues to develop after parasitization, the extent of its hyperparasitic behaviour, its reproductive capacity, and the width of its host range. Different strategies, together with different specific host and habitat preferences, provide the basis for parasite complexes of high species diversity.  相似文献   

10.
The larval host associations and mode of parasitism of Bombyliidae (bee flies) are summarized and analysed within an evolutionary framework. We discuss difficulties in extracting information from the (almost 1000) host records, noting that most observations are made by chance, often imprecise, and distributed unevenly across bombyliid taxa. These caveats aside, the vast majority of Bombyliidae are ectoparasitoid; endoparasitoids are known in only three tribes belonging to two distandy related subfamilies, the Toxophorinae (Gerontini and Systropodini) and Anthracinae (Villini). The recorded host range of Bombyliidae spans seven insect Orders and the Araneae; almost half of all records are from bees and wasps (Hymenoptera). No Bombyliidae have evolved structures to inject eggs directly into the host as is the case in many hymenopterous parasitoids. Bombyliid larvae usually exhibit hyper-metamorphosis, and contact their host while it is in the larval stage. Bee fly larvae consume the host when it is in a quiescent stage such as the mature larva, prepupa or pupa. Records of hyperparasitism by Bombyliidae are uncommon, most occurring in genera of the Anthracinae. All bombyliids recorded as hyperparasitoids do not appear to have evolved in any close association with the primary host, and are best termed pseudohyperparasitoids. Both facultative and obligate pseudohyperparasitism has been recorded. Bombyliidae are difficult to place in the koinobiont/idiobiont classification used most extensively in Hymenoptera but they share most features of koinobionts. Provision-directed cleptoparasitism has been recorded in one genus. We propose an evolutionary scenario progressing from an ancestral substrate-zone free-living predator to ectoparasitoid, a broadening of host range to include the consumption of orthopteran egg pods, and the independent development of endoparasitism in two lineages. The suggestion that host range narrows as the intimacy of encounter between female parasitoid and host increases is supported in the Bombyliidae. Amongst the basal subfamilies which are parasitoids, host range is narrowest in the Toxophorinae. In the more derived subfamilies host range is generally broad, and is dictated by ecological context rather than host phylogeny. Bombyliidae violate the prediction of increased species richness in parasitic groups, and the broad host range of most bee flies is a possible explanation.  相似文献   

11.
Biological control ofstalkboring Lepidoptera often has beensuccessful when the braconid parasitoids in thegenera Cotesia and Apanteles werethe natural enemies of choice. Constraints inusing these gregarious, koinobiont,endoparasitoids have included host suitability,especially as influenced by the host's immuneresponse. The suitability of a novel host, theNew World stalkborer Diatraeaconsiderata (Lepidoptera:Pyralidae), for parasitization by three OldWorld braconids, Cotesia chilonis, C. flavipes and C. sesamiae (Hymenoptera: Braconidae), wascompared to the suitability of another NewWorld novel host, Diatraea saccharalis. D. considerata was less suitable for allthree parasitoids than was D.saccharalis. The frequent occurrence ofparasitized D. considerata larvae thatdid not yield parasitoids, or pupate within anappropriate time interval, suggestedencapsulation of the parasitoid progeny, whichwas visible through the host cuticle. Giventhe suitability results, these threeparasitoids would not be appropriate candidatesfor use against D. considerata. Theresults also have important implications forthe narrow host range expressed by theseparasitoids.  相似文献   

12.
1. Despite the profusion of Lepidoptera and other potential hosts in the tropics, the Ichneumonidae are not more species-rich in the lowland tropics than in temperate communities. Alternate but partially complementary hypotheses emphasizing resource fragmentation, predation, or chemical defence have been proposed to explain this paradox.
2. Because different diversity gradients occur in the various subgroups of the Ichneumonidae, as well as among their hosts, general explanations are unlikely to account for this 'anomalous diversity.' Hypotheses of ecological causation are best tested at the taxonomic level where the pattern of interest applies.
3. Phylogenetic trends in the distribution, abundance, and palatability of butterflies (Papilionoidea), a group that increases dramatically in species richness towards the tropics, are presented as a case study for evaluating hypotheses of parasitoid species richness. Evidence is presented that supports the 'nasty host hypothesis' as an explanation for the lack of diversity of associated parasitoids.
4. An examination of hypotheses and the approaches used to test them suggests that the nasty-host hypothesis is best supported by the limited evidence available, while evidence in favour of other hypotheses is either lacking or ambiguous. In particular, use of the koinobiont/idiobiont dichotomy and parasitoid assemblage-size comparisons may result in contradictory conclusions.  相似文献   

13.
Parasitoid wasps have long been considered as model organisms for examining optimal resource allocation to different fitness functions, such as body size and development time. Unlike insect predators, which may need to consume many prey items to attain maturity, parasitoids generally rely on a limited amount of resources that are obtained from a single source (the host). This review discusses a range of ecophysiological constraints that affect host quality and concomitantly the evolution of development strategies in parasitoids. Two macroevolutionary differences in host usage strategies (idiobiosis, koinobiosis) are initially described. Over many years, particular attention has been paid in examining a range of quantitative host attributes such as size, age, or stage, as these affect idiobiont and koinobiont parasitoid development. Parasitoids and their hosts, however, constitute only a small part of an ecological community. Consequently, host quality may be affected by a broad range of factors that may operate over variable spatial and temporal scales. Intimate factors include aggressive competition with other parasitoids and pathogens for access to host resources, whereas less intimate factors include the effects of toxic plant compounds (allelochemicals) on parasitoid performance as mediated through primary and/or secondary hosts. It is suggested that future experiments should increase the levels of trophic complexity as these influence the evolution of life history and development strategies in parasitoids. This includes integration of a suite of direct and indirect mechanisms, including biological processes occurring in different ecological realms, such as above‐ground and below‐ground interactions.  相似文献   

14.
  • 1 For their larval development, parasitoids depend on the quality and quantity of resources provided by a single host. Therefore, a close relationship is predicted between the size of the host at parasitism and the size of the emerging adult wasp. This relationship is less clear for koinobiont than for idiobiont parasitoids.
  • 2 As size differentiation in host species exhibiting sexual size dimorphism (SSD) is likely to occur already during larval development, in koinobiont larval endoparasitoids the size of the emerging adult may also be constrained based on the sex of the host caterpillar.
  • 3 Sex‐specific growth trajectories were compared in unparasitised Plutella xylostella caterpillars and in second and fourth instar hosts that were parasitised by the solitary larval koinobiont endoparasitoid Diadegma semiclausum. Both species exhibit SSD, where females are significantly larger than males.
  • 4 Healthy female P. xylostella caterpillars developed significantly faster than their male conspecifics. Host regulation induced by D. semiclausum parasitism depended on the instar attacked. Parasitism in second‐instar caterpillars reduced growth compared to healthy unparasitised caterpillars, whereas parasitism in fourth‐instar caterpillars arrested development. The reduction in growth was most pronounced in hosts producing male D. semiclausum.
  • 5 Parasitism itself had the largest impact on host growth. SSD in the parasitoid is mainly the result of differences in growth rate of the parasitoid–host complex producing male and female wasps and differences in exploitation of the host resources. Female wasps converted host biomass more efficiently into adult biomass than males.
  相似文献   

15.

Background  

The parasitic Platyhelminthes (Neodermata) contains three parasitic groups of flatworms, each having a unique morphology, and life style: Monogenea (primarily ectoparasitic), Trematoda (endoparasitic flukes), and Cestoda (endoparasitic tapeworms). The evolutionary origin of complex life cyles (multiple obligate hosts, as found in Trematoda and Cestoda) and of endo-/ecto-parasitism in these groups is still under debate and these questions can be resolved, only if the phylogenetic position of the Monogenea within the Neodermata clade is correctly estimated.  相似文献   

16.
In this study we examined the relationship between clutch size and parasitoid development of Muscidifurax raptorellus (Hymenoptera: Pteromalidae), a gregarious idiobiont attacking pupae of the housefly, Musca domestica (Diptera: Muscidae). Host quality was controlled in the experiments by presenting female parasitoids with hosts of similar size and age. This is the first study to monitor the development of a gregarious idiobiont parasitoid throughout the course of parasitism. Most female wasps laid clutches of one to four eggs per host, although some hosts contained eight or more parasitoid larvae. In both sexes, parasitoids completed development more rapidly, but emerging adult wasp size decreased as parasitoid load increased. Furthermore, the size variability of eclosing parasitoid siblings of the same sex increased with clutch size. Irrespective of clutch size, parasitoids began feeding and growing rapidly soon after eclosion from the egg and this continued until pupation. However, parasitoids in hosts containing five or more parasitoid larvae pupated one day earlier than hosts containing one to four larvae. The results are discussed in relation to adaptive patterns of host utilization by gregarious idiobiont and koinobiont parasitoids.  相似文献   

17.
Arabica coffee was sampled from two sites in the central highlands of Kenya (Rurima, Ruiru) and one site on the western side of the Rift Valley (Koru). Three species of ceratitidine Tephritidae, Ceratitis capitata (Wiedemann), C. rosa Karsch and Trirhithrum coffeae Bezzi, were reared from sites in the central highlands, and an additional species, C. anonae Graham, was recovered from the western-most site. Ten species of parasitic Hymenoptera were reared from these tephritids. The parasitoid assemblage was dominated by koinobionts. Eight of the species are koinobiont endoparasitoids, but only one idiobiont larval ectoparasitoid was reared, and only one idiobiont pupal endoparasitoid. The effects of sampling bias on determination of parasitoid assemblage size associated with concealed hosts are discussed. The potential for use of these parasitoids in biological control is also discussed. Most of the parasitoid species recovered during this study are capable of developing on C. capitata, while several also attack C. rosa. Both flies are notorious pests of tropical and subtropical fruits.  相似文献   

18.
The impact of low levels of spinosad on the obliquebanded leafroller, Choristoneura rosaceana Harris (Lepidoptera: Tortricidae), and the koinobiont endoparasitoid, Apophua simplicipes Cresson (Hymenoptera: Ichneumonidae), was assessed when the parasitoid was in the larval stage within second‐ and fourth‐instar hosts. These are developmental stages that would be exposed to spring orchard treatments of the insecticide. Oral spinosad LC50 levels for unparasitized obliquebanded leafroller hosts were <1% of the recommended orchard treatment levels. Apophua simplicipes survival was significantly reduced within parasitized spinosad‐treated second‐ and fourth‐instar larval hosts. Both the leafroller host and parasitoid were much more susceptible (ca. 65‐fold) to spinosad when larval hosts fed on spinosad‐treated leaf material as opposed to being treated topically. When hosts were exposed to extremely low doses of spinosad, a small percentage of parasitoids was able to survive to emerge as adults. These laboratory trials predict that applications of spinosad may reduce biological control of C. rosaceana populations by ichneumonid endoparasitoids developing within treated hosts.  相似文献   

19.
The six known Costa Rican species of the campoplegine ichneumonid genus Cryptophion Viereck are described and keyed. The distribution of species throughout Costa Rica is detailed based on data gathered by an intensive Malaise trap survey of the ichneumonids of the country. Five new species are recognized: C. espinozai. C. guillermoi, C. manueli. C. moragai and C. tickelli , and a sixth, C. inaequalipes (Cresson) redescribed. The monophyly of the genus is demonstrated and the phylogeny of the Costa Rican species reconstructed. Host relationships have been established for all species in Costa Rica; they develop as koinobiont endoparasitoids of first to third instar larvae of Sphingidae or Saturniidae. Analysis of the host relationships from a phylogenetic perspective suggested that the genus first evolved using macroglossine sphingid larvae feeding on rubiaceous understorey plants as hosts, and subsequently diversified to utilize sphingine sphingids and ceratocampine saturniids feeding on a variety of food-plants. Most species appear to be monophagous and oligophagy is apparently a derived feature of one sister-species pair, C. espinozai and C. manueli . In Santa Rosa National Park, Costa Rica, only a small proportion of the species of Saturniidae and Sphingidae present are used as hosts by Cryptophion species. No one host species is parasitized by more than one Cryptophion species. No species of Cryptophion is known to parasitize more than one host species feeding on any one plant species. The monophagous species C. inaequalipes is only known to develop in its sphingid host when that host is feeding on one of its two alternative food-plants.  相似文献   

20.
We reared six idiobiont braconids, Bracon asphondyliae, B. sunosei, B. tamabae, Simplicibracon curticaudis, Testudobracon longicaudis and T. pleuralis from 22 identified species and 11 unidentified segregates of Asphondyliini (Diptera: Cecidomyiidae) in Japan. A total of 22 cecidomyiid species and segregates were newly recorded as hosts of the braconids. Analysis of cytochrome oxidase subunit I (COI) did not show any evidence of host races among the braconids. Bracon sunosei, which was synonymized with B. asphondyliae, is restored to a valid species. The host range of the braconid species seemed to be related to the lineage of host genera within Asphondyliini.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号