Parasitoid Community Research Articles

Parasitoid community ecology

PART 1: COMMUNITY SIZE AND STRUCTURE PART 2: HOST RANGES PART 3: TRITROPHIC-LEVEL INTERACTIONS PART 4: TROPICAL COMMUNITIES PART 5: DYNAMICS PART 6: BIOLOGICAL CONTROL PART 7: OVERVIEW

Comparison of Community Composition of Parasitoids that Attack Leaf-Mining Moths (Lepidoptera: Gracillariidae)

Environ. Entomol. 24(4): 879-888 (1995) Parasitoid assemblages associated with Phyllonorycter leaf miners (Lepidoptera: Gracillariidae) were examined on the 2 deciduous oaks, Quercus dentata and Q. mongolica, in Hokkaido, northern Japan, and those on 2 others, Q. acutissima and Q. variabilis, in Nara, central Japan. To address to what extent interspecific competition is important in organizing parasitoid communities, I compared species richness, species composition, and levels of parasitism by guilds at different host immature stages among the parasitoid assemblages. Parasitoids were separated into 5 guilds according to parasitism modes (idiobiosis and koinobiosis) and host immature stages attacked and killed. Pooled data showed that the number of parasitoid species per host leafminer species in Japan (3.1) was similar to that in the United Kingdom (4.1) and that idiobionts (potential generalists) exceeded koinobionts (specialists) in species number (62.5%). A koinobiont guild and 2 idiobiont guilds had an inverse relationship in level of parasitism between 2 assemblages at each study area. These results may suggest that interspecific competition is important in organizing parasitoid communities. Nevertheless, dominant species and guilds varied among the assemblages, resulting in different patterns of percentage of parasitism by guilds in relation to host stage among the assemblages. This implies underuse of hosts at some stages by parasitoids, and interspecific competition is unlikely to be severe. Interspecific competition, therefore, seems to partially contribute to parasitoid community organization.

Parasitoid Guilds: Defining the Structure of the Parasitoid Communities of Endopterygote Insect Hosts

Parasitoids constitute an important component of the biodiversity of terrestrial ecosystems and have become a recent focus for investigations of pattern and process in ecological communities. This article uses parasitoid guilds to characterize the structure of parasitoid communities associated with endopterygote hosts. Parasitoid guilds are defined by three parameters, the host stage attacked, the host stage killed, and the mode of parasitism (internal or external development). A series of 12 guilds are recognized from the patterns of host exploitation by parasitoids; one that utilizes the host egg stage as a resource for parasitoid development, three that utilize the host larva, four that utilize the host prepupa, two that utilize the host pupa, and two that utilize the host adult. A comparison of the parasitoid guilds across endopterygote host orders illustrates the taxonomic diversity of parasitoids in each guild and provides an indication of some of the more frequent parasitoid taxa associated with each guild. The value of the parasitoid guild as an ecological unit that both classifies the functional ecology of parasitoid species and the structure of parasitoid communities is discussed.

Structure, organization, and response of a species-rich parasitoid community to host leafminer population dynamics.

The parasitoid community dynamics of an agromyzid honeysuckle leafminer, Chromatomyia suikazurae (Agromyzidae, Diptera) were studied between 1981 and 1990 in a natural forest in Kyoto, Japan. The parasitoid fauna composed three koinobionts (all larval-pupal solitary parasitoids) and 22 idiodiont species (11 larval solitary, nine pupal solitary and one pupal gregarious). The parasitoid community was dominated by early-attacking oligophagous braconid koinobionts at early periods, but was gradually displaced by late-attacking polyphagous eulophid idiobionts. Accordingly, the diversity index of the parasitoid community peaked at an intermediate point in the intra-generational succession. The succeeding attack-in-waves by the late-attacking idiobionts greatly reduced not only the survival rates of early-attacking parasitoid larvae but also the survival rates of hosts. The density-dependence observed in the host pupal mortality was thought to result from density-dependent host-switching by a keystone polyphagous pupal idiobiont parasitoid, Chrysocharis pubens, whereas high host pupal mortality was potentially attained by an early-attacking koinobiont braconid. Supposed aggregation of polyphagous parasitoids at high host density resulted in intense within-host competition and in an increase of host-feeding attack, both of which contributed to low emergence rates of parasitoids at high host densities. Parasitoid emergence rates were also reduced at low host densities, probably by inter- and intra-specific hyperparasitism among oligophagous parasitoids for limited hosts. The regulation effects of the species-rich parasitoid community upon the host population dynamics are thought to derive from succeeding attack-in-waves by polyphagous late-attacking idiobionts, especially by the keystone species.

Minimal Community Structure: How Parasitoids Divide Resources

Parasitoid communities show patterns in the distribution and abundance of species that fit predictions of niche partitioning models. These models treat community resources as unit volumes and conceptually treat niche partitioning, or resource division, as breakage of this unit into fractions that correlate with proportional densities of the species controlling that fraction of the resource. Unlike many other communities, parasitoid communities are particularly appropriate for applying these models. We examine four types of niche partitioning models employing three types of breakage algorithms. Of these, the overall best—fit model was unidimensional—niche model using a breakage algorithm in which each subsequent break occurred on the smaller or larger fraction at random. Successful fit of these empirically derived, abundance distributions of parasitoid communities to this theoretically derived, expected distribution supports the hypothesis that these communities are minimally structured by a hierarchical process of random niche partitioning along a single resource axis.

Refuge Theory and Biological Control

An important question in ecology is the extent to which populations and communities are governed by general rules. Recent developments in population dynamics theory have shown that hosts' refuges from their insect parasitoids predict parasitoid community richness patterns. Here, the refuge theory is extended to biological control, in which parasitoids are imported for the control of insect pests. Theory predicts, and data confirm, that the success of biological control is inversely related to the proportion of insects protected from parasitoid attack. Refuges therefore provide a general mechanism for interpreting ecological patterns at both the community level (their species diversity) and population level (their dynamics).

ADAPTATIONS OF GALL WASPS OF THE GENUS DIPLOLEPIS (HYMENOPTERA: CYNIPIDAE) AND THE ROLE OF GALL ANATOMY IN CYNIPID SYSTEMATICS

AbstractAdaptations and attributes of gall-inducing cynipid wasps are reviewed to emphasize that differences in life cycles and anatomical features of their galls are just as useful for systematic purposes as are structural differences in the adult insects themselves. The extent to which cynipid wasps have specialized is illustrated by the genus Diplolepis, all species of which are restricted to native and introduced roses and induce structurally distinct galls. Various aspects of Diplolepis biology including life cycles, host specificity, and gall development and anatomy are reviewed. The biologies of two species of Diplolepis that commonly co-exist in the same habitat in central Ontario are then examined in detail. Diplolepis polita (Ashmead) induces a single-chambered gall on the leaves of Rosa acicularis Lindl. whereas Diplolepis spinosa (Ashmead) induces a multi-chambered gall on the stems of Rosa blanda Ait. Differences in life cycles, distribution, host and organ specificity, oviposition, gall initiation and development, along with differences in the communities of parasitoids and inquilines attracted to the galls, confirm the existence of distinct species and allow some speculation on their ecological and phylogenetic relationships.

Interactions between searching strategies ofDrosophila parasitoids and the polymorphic behavior of their hosts

Two strains of Drosophila melanogaster, “rover” and “sitter,” differing in locomotion while foraging were simultaneously exposed to females of either Leptopilina boulardi or Ganaspis xanthopoda (parasitic Hymenoptera). These two parasitoids show different modes of host-searching behavior, ovipositor searching, or vibrotaxis, respectively. L. boulardi parasitized the sitter host strain significantly more than the rover. In contrast, G. xanthopoda parasitized the rover strain more than the sitter. In one case, L. boulardi selected far more sitters than rovers in population cage experiments. We also describe the frequencies of rovers and sitters in three natural populations where the local parasitoid community may have partially contributed to the differences in rover and sitter frequencies.

Coexistence, Tritrophic Interactions and Density Dependence in a Species-Rich Parasitoid Community

1. Data from parasitoids attacking galls of Giraudiella inclusa Fr. (Diptera: Cecidomyiidae) from Phragmites australis Trin. were used to assess the factors dictating species richness and coexistence in a community. 2. Species richness of the 14 parasitoids could be related to the high frequency and apparency of both the galls and the Phragmites monocultures. Four non-galling species of Cecidomyiidae attacking P. australis had only 2-3 parasitoid species, presumably due to the less visible and less heterogeneous microhabitat offered to the parasitoids. 3. Distribution of midge galls was due to several plant characteristics with percentage parasitism and parasitoid coexistence determined by the site of gall induction. The stem-boring moth Archanara geminipuncta Haw. (Lepidoptera: Noctuidae) was a key factor for the heterogeneous gall distribution and thereby favoured coexistence of the galls' parasitoid species: Giraudiella-galls induced on side shoots, grown from Archanara-damaged shoots, increased percentage parasitism of two parasitoid species and reduced parasitism of one species. 4. Parasitoid foraging was concentrated on temporally and spatially separated subpopulations with the microscale of host density (gall cluster size per reed internode) influencing percentage parasitism only in two out of eight species, and with the macroscale (gall abundance per habitat) having no effect at all. These findings do not meet expectations for density-dependent host regulation, but support a resource heterogeneity hypothesis. Both midge and parasitoid populations appeared to be 'limited from below' rather than 'controlled from above'. 5. The prediction that host density is negatively correlated with parasitoid diversity was not supported.

Relations Among Assemblage Size, Host Specialization, and Climatic Variability in North American Parasitoid Communities

We classified the parasitoids attacking 628 species of North American herbivorous insects as idiobionts (those that permanently disable their hosts during attack) or koinobionts (those that permit continued host development following parasitization). Using these physiological attributes of parasitoids as estimators of host range, we tested three hypotheses that might explain why average parasitoid assemblage size decreases toward the tropics in complexes associated with exophytically feeding herbivores, whereas it does not in complexes associated with endophytic hosts. We found that the geographical patterns for generalist (i.e., idiobiont) and specialist (i.e., koinobiont) hymenopterous parasitoids and Diptera do not support a host-predation hypothesis or a parasitoid-predation hypothesis and are only partly in accord with the resource-fragmentation hypothesis. We conclude that a modified expression of the resource-fragmentation hypothesis can account for some of the geographical patterns of parasitoid assemblage size, but other forces, as yet unidentified, are also operating.

Über die Bedeutung autochthoner Parasitoidenkomplexe bei der rezenten Arealexpansion von vier Phyllonorycter‐Arten in Europa (Insecta, Lepidoptera, Hymenoptera)

On the Significance of Native Parasitoid Complexes in the Current Range Extension by Four Phyllonorycter Species into Europe (Insecta, Lepidoptera, Hymenoptera)The recently arrived Phyllonorycter species had been originally distributed in different regions: southern Europe (Ph. leucographella, Ph. platani), the Ukraine (Ph. medicaginella), Japan (Ph. issikii). These invading species are being parasitized by many parasitoids. Most of the latter are relatively polyphagous species, usually Eulophidae. They are members of the parasitoid communities preying on indigenous Phyllonorycter species and other leaf miners.The invasion of Ph. plateni has been accompanied by expansion of the gregarious parasitoid, Minotetrastichus platanellus, which is also believed to be native to southern Europe. The other Phyllonorycter species are attacked by resident parasitoids only.The composition of the parasitoid community differs from host to host: each leaf‐miner has its own complex and can be characterized by the relative abundances of the parasitoid species present.The percentage of parasitism varies greatly according to the host. Very low values of parasitoid‐induced mortality are found in the arboricolous and herbaceous species, thus rendering their populations unregulated, at least by parasitoids. Only Ph. leucographella appears to be restricted in population growth by parasitoids. Consequently, the Phyllonorycter populations are increasing and have attained large populations which encourage further expansion. Thus, parasitoids are ineffective in preventing the continuing invasion by their Phyllonorycter hosts.In discussing the reasons for the minor impact of parasitoids, three aspects are emphasized: 1) the degree of relationship among the Phyllonorycter species and the concomitant influence on parasitoid composition and effectiveness; 2) the joint action of idiobionts and koinobionts as the basis of sufficient suppression of the hosts; and 3) the continuing naturalization of “exotic” Phyllonorycter species as a process of their integration into native ecosystems against an ecological and evolutionary background.

DISPLACEMENT OF BATHYPLECTES CURCULIONIS (THOMS.) (HYMENOPTERA: ICHNEUMONIDAE) BY B. ANURUS (THOMS.) IN EASTERN ONTARIO POPULATIONS OF THE ALFALFA WEEVIL, HYPERA POSTICA (GYLL.) (COLEOPTERA: CURCULIONIDAE)

AbstractBathyplectes anurus (Thoms.) has displaced B. curculionis (Thorns.) as the main larval parasitoid in populations of the alfalfa weevil, Hypera postica (Gyll.), in eastern Ontario. Following its belated spread to the Bay of Quinte dairy belt, it used a combination of r and K strategies to assert its superiority: a greater reproductive capacity, more rapid search and handling, and more aggressive behaviour. Also, it is not subject to encapsulation by the host and reduces direct competition with the entomopafhogenic fungus Zoophthora phytonomi (Arthur) by laying its eggs in older hosts that have a greater probability of escaping death from disease. Taken together, these factors have enabled it to perform better than B. curculionis and to displace it in the host–parasitoid community. Moreover, it may have the potential to stabilize weevil populations during years when the fungus is enzootic.

Influences of host feeding‐niche and foodplant type on generalist and specialist parasitoids

Abstract. 1. We classified the parasitoids of 185 British herbivorous insect species as being koinobionts (which should tend to be specialists) or idiobionts (potential generalists) to examine the influences of host feeding‐niche and foodplant type on the numbers of parasitoid species attacking individual host species.2. The majority of parasitoid species of exophytic hosts are koinobionts, whereas endophytic hosts support mainly idiobionts.3. Parasitoid assemblage size increases with host foodplant size and complexity; for endophytic hosts this is due to an increase in idiobionts on hosts on large plants, but for exophytic hosts it is the number of koinobionts that increases with foodplant size.4. Comparison of these patterns with those predicted under a competition hypothesis suggests that parasitoid communities associated with endophytic hosts may be commonly limited by interspecific competition, whereas those of exophytic hosts probably are not.

Are galling insects better protected against parasitoids than exposed feeders?: a test using tenthredinid sawflies

ABSTRACT. Data mostly from the published literature were used to assess the effect of galling on the number of parasitoid species per host species in the phylogeny of nematine sawflies from free external feeders (colonial and solitary) to leaf gallers and shoot gallers. The strongest effects of galling were the total elimination of the species‐rich cocoon‐attacking guild of parasitoids, and eonymphal parasitoids, from the parasitoid community on shoot gallers, all of which are in the genus Euura. All tachinid larval parasitoids were also eliminated by the galling habit. The cumulative effects of these exclusions resulted in a decline in mean number of parasitoid species per host species from almost sixteen species on external colonial feeders to 4.0 species on shoot gallers. General patterns in per cent parasitism by non‐tachinid and tachinid larval parasitoids, eonymphal and cocoon parasitoids, on exposed feeders to shoot gallers, showed declines in non‐tachinid attack and elimination of tachinid, eonymphal and cocoon parasitoids. But leaf gallers tended to be attacked more than exposed feeders by non‐tachinid larval parasitoids. The galling habit had a long‐term impact by reducing the number of parasitoid species attacking nematine sawfly gallers and per cent mortality inflicted, so that natural enemies may have been important as a selective factor in the evolution of galling nematine sawflies.

Organization of a parasitoid community associated with a complex of galls on Atriplex spp. in southern California

Abstract. 1. Atriplex canescens (Pursh) Nuttall and A.polycarpa (Torrey) Watson (Chenopodiaceae) support twelve morphologically distinct gall types in southern California. Thirty‐seven common species of parasitoids, predators and inquilines are associated with these galls.2. The galls incited by eight members of the Asphondylia atriplicis Cockerell (Diptera: Cecidomyiidae) species complex are linked into a single, interacting community through shared hymenopterous parasitoids and inquilines.3. Cluster analysis (UPGMA) grouped the fifteen most common species of Chalcidoidea into three host guilds of five species each: (1) specialists in tumour stem and blister leaf galls on A.canescens, (2) specialists in woolly stem galls on A.poiycarpa, and (3) generalists that attack all galls. Guild 1 dominated the galls with which it was primarily associated, while guild 3 dominated the remainder.4. The abundances of the parasitoids of the tumour stem and blister leaf galls were negatively correlated with the abundances of two organizer species, a gall‐forming inquiline, Tetrastichus cecidobroter Gordh and Hawkins, and an internal, larval—pupal parasitoid, Tetrastichus sp. B. The abundances of nine of the twelve most common chalcidoids were not correlated with the abundances of all coaccurring species in six other galls.5. Host seasonality partly determines parasitoid population dynamics and guild structure. Parasitoid dominance increased with gall duration, suggesting that parasitoid competition depends on resource stability. The two continuously available galls were dominated by their specialist guild, while all seasonal galls were dominated by generalists. The subdominant specialists of woolly stem galls may represent competitively inferior species that utilize those galls opportunistically, because of the gall's widespread distribution and 9–10 month yearly availability.6. Sites in the Colorado Desert and chaparral that supported several gall types showed stable relative abundances of the major parasitoid species, whereas sites in the Mojave Desert that supported only woolly stem galls had unpredictable parasitoid species assemblages.7. The competitive success of Atriplex gall parasitoids may depend primarily on voltinism (multivoltine species dominated univoltine species) and mode of feeding (phytophagous, mixed entomophagous—phytophagous and facultatively hyperparasitic species in general dominated strict primary parasitoids).

Community patterns of nectivorous adult parasitoids (Diptera, Bombyliidae) on their resources.

Highly diverse assemblages of nectivorous bee flies (Diptera: bombyliidae) occur at desert sites in California presenting an opportunity to investigate the ecology of this little-known group. This study compared communities of adult bee flies visiting flowers at two sites, one in the Mojave Desert (Darwin Plateau) and one in the Great Basin (Mono Basin), during periods of higher and lower resource abundance. The range of resources used by single species varied inversely with the number of species present, with the greatest number of species and smallest niche breadths occurring at the Darwin Plateau. Adult bee flies did not visit flower resources at random. Rather the two major divisions of the family exhibited contrasting patterns of specialization on plant species. Results of this study support the hypothesis that resources were limiting for adult bee flies in the period of lower food abundance at the Darwin Plateau and not limiting at the Mono Basin during this study. Bee flies at the Mono Basin exhibited lower densities per flower (despite higher densities per unit area), lower frequency of feeding, a lower degree of specialization, and less pronounced phenological changes than bee flies at the Darwin Plateau. The data suggest that episodes of population regulation in the non-parasitic (i.e. adult) stage, due to short supply of the adults' food, contribute to determining the structure of parasitoid communities.

Parasitoids, Patches, and Phenology: Their Possible Role in the Local Extinction of a Cynipid Gall Wasp Population

The cynipid gall wasp Xanthoteras politum (Bassett) and its associated chalcid and inquiline parasitoid community were studied from 1976 to 1978 at a postfire site near Lake Oswego in the New Jersey Pine Barrens. X. politum and two other cynipid species selectively attacked new sucker shoots growing from larger fire—damaged trees. Chalcid and inquiline parasitoid attack was the major mortality factor in the population in all 3 yr. In each successive year a higher frequency of the host population was killed by parasitoid attack, and by 1978 on 76 host galls occurred at the site. Inquiline cynpids were minor parasitoid elements the 1st yr of the gall outbreak, but dominated the parasitoid guild in subsequent seasons. Their dominance is attributed to two major factors. First, they attack galls earlier than other parasitoids, and those galls attacked remained at a smaller size and were not chosen for oviposition by later arriving chalcids. Secondly, inquilines did not emerge in spring and infest other gall species as did the chalcid parasitoids. These inquilines remained in the leaf litter and reinfested the next asexual generation of X. politum which appeared on trees in mid—July. The parastioid community displayed neither strong stability nor consistent composition. The apparent overexploitation of the host population by parasitoids may be to their selective advantage as phenological changes in host plants eventually eliminate X. politum from postfire sites anyway.

Do Parasites of Lepidoptera Larvae Compete for Hosts? No Evidence

Previous articleNext article No AccessNotes and CommentsDo Parasites of Lepidoptera Larvae Compete for Hosts? No EvidenceJohn M. Dean and Robert E. RicklefsJohn M. Dean Search for more articles by this author and Robert E. Ricklefs Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The American Naturalist Volume 116, Number 6Dec., 1980 Published for The American Society of Naturalists Article DOIhttps://doi.org/10.1086/283677 Views: 2Total views on this site Citations: 3Citations are reported from Crossref Copyright 1980 The University of ChicagoPDF download Crossref reports the following articles citing this article: 10.1007/BF02380670, CrossRef Listing of Deleted DOIs 56 (Jan 2011).https://doi.org/10.1007/BF02380670F. A. N. Alebeek, D. Rojas-Rousse, L. Leveque Interspecific competition between Eupelmus vuilleti and Dinarmus basalis, two solitary ectoparasitoids of Bruchidae larvae and pupae, Entomologia Experimentalis et Applicata 69, no.11 (Apr 2011): 21–31.https://doi.org/10.1111/j.1570-7458.1993.tb01724.xBRADFORD A. HAWKINS, RICHARD D. GOEDEN Organization of a parasitoid community associated with a complex of galls on Atriplex spp. in southern California, Ecological Entomology 9, no.33 (Aug 1984): 271–292.https://doi.org/10.1111/j.1365-2311.1984.tb00851.x

New Rashes for Old

<h3>ABSTRACT</h3> Parasites in aquatic systems are highly diverse and ubiquitous. In marine environments, parasite-host interactions contribute substantially to shaping microbial communities, but their nature and complexity remain poorly understood. In this study, we examined the relationship between Perkinsea parasitoids and bloom-forming dinoflagellate species. Our aim was to determine whether parasite-host species interactions are specific and whether the diversity and distribution of parasitoids are shaped by their dinoflagellate hosts. Several locations along the Catalan coast (NW Mediterranean Sea) were sampled during the blooms of five dinoflagellate species and the diversity of Perkinsea was determined by combining cultivation-based methods with metabarcoding of the V4 region of 18S rDNA. Most known species of Parviluciferaceae, and others not yet described, were detected, some of them coexisting in the same coastal location, and with a wide distribution. The specific parasite-host interactions determined for each of the studied blooms demonstrated the host preferences exhibited by parasitoids in nature. The dominance of a species within the parasitoid community is driven by the presence and abundances of its preferred host(s).The absence of parasitoid species, often associated with a low abundance of their preferred hosts, suggested that high infection rates are reached only under conditions that favour parasitoid propagation, especially dinoflagellate blooms.