Abundant Parasitoid Species Research Articles

SPESIES PARASITOID LIPAPHIS ERYSIMI ASAL SUMATERA SELATAN DAN VARIASI PARASITISASINYA PADA TUMBUHAN INANG YANG BERBEDA

Lipaphis erysimi (Hemiptera: Aphididae) is one of the main insect pests on brassicaceous crops. Aphids attack crops by sucking sap from its hosts. Densed population in the initial phase of crop growth could inhibit growing, loss in yield up to 100%. Experiments were aimed to explore and identify species of L. erysimi parasitoid in highland areas of South Sumatra, and to determine potency of the parasitoids to parasitize L. erysimi in laboratory. The highest parasitism level of L. erysimi (72.40%) was found on 200 aphids which reared on B. juncea. While, the second highest parasitism level (65.67%) was found on N. indicum. The number of mummies found on N. indicum was less than on B. juncea. Of all observations, every treatment on every tested plant showed that female D. rapae emerged more than male D. rapae (female bias). The two parasitoids species that parasitized L. erysimi were Diaeretiella rapae and Aphidius sp. Parasitisation at several location in South Sumatera was highly diverse. D. rapae was the most abundant parasitoid species on several high lands at South Sumatera.

Structure and dynamics of the parasitoid community shared by two herbivore species on different host plants

The structure of the parasitoid community on phytophagous insects can be affected by host plant properties, such as chemical compounds, trichomes, and glandular hairs. To clarify effects of host plants on herbivores and the parasitoid community, I examined the structure and dynamics of the parasitoid community associated with two species of Caloptilia moths (Lepidoptera: Gracillariidae) that feed on different Rhododendron species (Ericaceae) for 3 years in a temperate secondary forest in central Japan. Caloptilia azaleella had overlapping generations in summer and overwintered as larvae on leaves of R. macrosepalum. Caloptilia leucothoes also had overlapping generations in summer, but it did not overwinter on the deciduous shrub R. reticulatum. The parasitoid community of C. azaleella larvae and pupae was composed of 18 species, whereas that of C. leucothoes was composed of seven species. Five species of parasitoids attacked both Caloptilia species. The most abundant parasitoid, Apanteles cf. xanthostigma (Hymenoptera: Braconidae), more frequently attacked C. azaleella than C. leucothoes larvae. In contrast, another abundant parasitoid, Acrysocharoides sp. (Hymenoptera: Eulophidae), more frequently attacked C. leucothoes than C. azaleella larvae. This differential parasitism by the most abundant parasitoid species may be responsible for the differential structure and dynamics of the parasitoid community between the Caloptilia species. The host plant of C. azaleella, R. macrosepalum, more frequently trapped and killed parasitoids (of similar size to Acrysocharoides sp.) on the glandular hairs of leaves than did R. reticulatum. The differential effect of host plants on abundant parasitoids may be related to the differential parasitism by the two abundant parasitoids shared by the herbivore hosts.

Plant species loss affects life-history traits of aphids and their parasitoids.

The consequences of plant species loss are rarely assessed in a multi-trophic context and especially effects on life-history traits of organisms at higher trophic levels have remained largely unstudied. We used a grassland biodiversity experiment and measured the effects of two components of plant diversity, plant species richness and the presence of nitrogen-fixing legumes, on several life-history traits of naturally colonizing aphids and their primary and secondary parasitoids in the field. We found that, irrespective of aphid species identity, the proportion of winged aphid morphs decreased with increasing plant species richness, which was correlated with decreasing host plant biomass. Similarly, emergence proportions of parasitoids decreased with increasing plant species richness. Both, emergence proportions and proportions of female parasitoids were lower in plots with legumes, where host plants had increased nitrogen concentrations. This effect of legume presence could indicate that aphids were better defended against parasitoids in high-nitrogen environments. Body mass of emerged individuals of the two most abundant primary parasitoid species was, however, higher in plots with legumes, suggesting that once parasitoids could overcome aphid defenses, they could profit from larger or more nutritious hosts. Our study demonstrates that cascading effects of plant species loss on higher trophic levels such as aphids, parasitoids and secondary parasitoids begin with changed life-history traits of these insects. Thus, life-history traits of organisms at higher trophic levels may be useful indicators of bottom-up effects of plant diversity on the biodiversity of consumers.

Diversity and Abundance of Hymenopterous Parasitoids Associated withAnastrepha fraterculus(Diptera: Tephritidae) in Native and Exotic Host Plants in Misiones, Northeastern Argentina

Some Major host species used by the tephritid fruit flies Anastrepha fraterculus (Wiedemann) and Ceratitis capitata (Wiedemann), including Acca sellowiana (O. Berg) Burret, Campomanesia xanthocarpa O. Berg, Psidium guajava L., Prunus persica (L.) Batsch, Eriobotrya japonica (Thunb.) Lindl., Citrus reticulata Blanco var. Murcott, C. aurantium L., C. paradisi Macfadyen var. Dalan Dan, and C. paradisi var. Sudashi, were sampled for fruit fly larvae between Feb and Dec 2000 in the northernmost section of the Paranaense forest, in the Province of Misiones, NE Argentina. Both A. fraterculus and C. capitata were obtained from these host plant species, with A. fraterculus accounting for 93% of all tephritid puparia identified. Ten species of larval-pupal parasitoids were recovered from A. fraterculus: Doryctobracon areolatus (Szépligeti), D. brasiliensis (Szépligeti), Utetes anastrephae (Viereck), Opius bellus (Gahan), Diachasmimorpha longicaudata (Ashmead) (Opiinae, Braconidae), Odontosema anastrephae Borgmeier, Lopheucoila anastrephae (Rohwer), Aganaspis pelleranoi (Brèthes) (Eucoilinae, Figitidae), Asobara anastrephae (Muessebeck) (Alyssinae, Braconidae), and Aceratoneuromyia indica (Silvestri) (Tetrastichinae, Eulophidae). All these parasitoids, with the exception of D. longicaudata and A. indica, are native to the Neotropical region. No parasitoids were recovered from C. capitata puparia. Asobara anastrephae and O. anastrephae are newly recorded in Argentina, whereas D. brasiliensis, U. anastrephae, and L. anastrephae are newly reported in Misiones. The eucoiline A. pelleranoi was the most abundant parasitoid species. Acca sellowiana and P. guajava harbored the highest parasitoid abundance and diversity.

Liriomyza commelinae (Diptera: Agromyzidae): an alternative host for parasitoids of the leafminer pest Liriomyza huidobrensis

The potential of Liriomyza commelinae (Frost) (Diptera: Agromyzidae) as an alternative host for parasitoids of the pest leafminer Liriomyza huidobrensis (Blanchard) was investigated. We particularly focussed on the specific composition of the parasitoid complex and its impact on L. commelinae, frequency of associations, dependency of parasitism on host density and additive effects of species richness on total parasitism. Mined leaves of Commelina erecta (Commelinaceae) were collected from different localities of Córdoba province (Argentina) from 1991 to 1994, and also from different sites of Córdoba city. In total, 25 species of parasitoids (Hymenoptera) were associated with L. commelinae, of which 13 were shared with L. huidobrensis. Chrysocharis flacilla and Diglyphus websteri (Eulophidae) were the most abundant parasitoid species on L. commelinae, the former being the most frequently associated with the leafminer. Total parasitism, averaging 50%, did not depend on parasitoid species richness. No significant relationship was found between parasitism caused by the main species and host abundance. The potential for using the system C. erecta–L. commelinae in the conservation biological control of L. huidobrensis is discussed.

Seasonal parasitism of hemlock looper (Lepidoptera: Geometridae) eggs in eastern Canada

AbstractA 2-year field study was conducted using sentinel traps to determine the seasonal distribution of the egg parasitoid (Hymenoptera) complex attacking hemlock looper, Lambdina fiscellaria (Guenée), throughout eastern Quebec and western Newfoundland. Hemlock looper populations remained low in all areas over the course of the study. Parasitism of eggs in sentinel traps was generally lower in fall than in spring. Trichogramma Westwood (Trichogrammatidae) as well as Telenomus flavotibiae Pelletier and an unidentified species of Telenomus Haliday (Scelionidae) only parasitized eggs in the fall. Telenomus droozi Muesebeck only parasitized eggs in the spring, whereas T. coloradensis Crawford attacked eggs during both fall and spring. Telenomus coloradensis was the most abundant parasitoid species collected and was far more abundant in spring than in fall collections.

Effects of urbanisation on the parasitoid community of a leafminer

Urbanisation may have detrimental effects on communities of parasitoids, affecting their species richness, abundance, and species dominance. Here we investigated the influence of the degree of urbanisation on parasitoid communities of Liriomyza commelinae (Frost) (Diptera: Agromyzidae), a leafminer of Commelina erecta L. (Commelinaceae), in the city of Córdoba, Argentina. To study changes in species richness, the specific composition of parasitic complexes and their degree of impact on the leafminer, 18 sampling sites from the centre to the outskirts of the city were selected and different variables indicative of urbanisation were quantified in each site. During January and February of 2005 and 2006, all mined leaves found in each plant patch were collected and the following variables were estimated: proportion of mined patches, abundance of the leafminer, total parasitoid species richness, total parasitism rates and parasitism due to the most abundant parasitoid species. The percentage of mined patches and leafminer abundance increased with urbanisation degree. Estimates of parasitoid species richness were not influenced by urbanisation degree but increased with species richness of mined plants. Changes in the specific composition of species along the urbanisation gradient were observed. Although parasitism by one of the species studied was higher in more urbanised sites of the city, the total parasitism rate of L. commelinae was not affected by urbanisation degree, species richness of mined plants or leafminer abundance. It appears that urbanisation benefits the herbivore species here studied but not through altering parasitoid activity. Changes in parasitoid community composition reflex dissimilar tolerance to environmental conditions displayed by different parasitoid species.

Aphids (Aphididae) and their parasitoids in selected vegetable ecosystems in Slovenia

Sucking insects, which representatives are also aphids, can cause important economic damage on cultivated and wild-growing plants in vegetable ecosystems. Our research was based on the aim of biological control, which is to limit or to control the pests with the use of their natural enemies. From April to November 2006 living aphids and their mummies were sampled together with their host plants in four locations in Slovenia. The samples have been taken from vegetables, weeds, within-crops plants and from the plants in the field borders. The occurrence of 18 aphid species was confirmed - 14 of them were parasitised. In our research 365 parasitoid specimens (17 species from 8 genera - Aphidius, Binodoxys, Diaeretiella, Ephedrus, Lipolexis, Lysiphlebus, Monoctonus, and Praon - of the family Aphidiidae) were recorded and identified. The most abundant parasitoid species were Aphidius matricariae (32.2 %) and Lysiphlebus fabarum (29.3 %). Parasitoid L. fabarum had the widest range of hosts; it parasitised aphids on the plants from 7 different botanical families. Sex ratio in our research confirmed the known fact, that in natural ecosystems female parasitoids are more numerous than the male parasitoids; this ratio in our research was 71 % : 29 %.

Aphids (Aphididae) and their parasitoids in selected vegetable ecosystems in Slovenia

Sucking insects, which representatives are also aphids, can cause important economic damage on cultivated and wild-growing plants in vegetable ecosystems. Our research was based on the aim of biological control, which is to limit or to control the pests with the use of their natural enemies. From April to November 2006 living aphids and their mummies were sampled together with their host plants in four locations in Slovenia. The samples have been taken from vegetables, weeds, within-crops plants and from the plants in the field borders. The occurrence of 18 aphid species was confirmed - 14 of them were parasitised. In our research 365 parasitoid specimens (17 species from 8 genera - Aphidius, Binodoxys, Diaeretiella, Ephedrus, Lipolexis, Lysiphlebus, Monoctonus, and Praon - of the family Aphidiidae) were recorded and identified. The most abundant parasitoid species were Aphidius matricariae (32.2 %) and Lysiphlebus fabarum (29.3 %). Parasitoid L. fabarum had the widest range of hosts; it parasitised aphids on the plants from 7 different botanical families. Sex ratio in our research confirmed the known fact, that in natural ecosystems female parasitoids are more numerous than the male parasitoids; this ratio in our research was 71 % : 29 %.

Relative abundance of parasitoids reared during field exposure of sentinel larvae of the leafminers Liriomyza trifolii (Burgess), L. sativae Blanchard, and Chromatomyia horticola (Goureau) (Diptera: Agromyzidae)

In order to examine the relative abundance of indigenous parasitoids against three leafminer species, Liriomyza trifolii, L. sativae and Chromatomyia horticola, kidney bean plants infested with larvae of each species were exposed in vegetable gardens or grassland to different seasonal conditions (spring, summer and fall). Abundant parasitoid species were Chrysocharis pentheus, Diglyphus isaea and D. minoeus in spring or fall, and Neochrysocharis formosa, D. albiscapus and D. pusztensis in summer. Also, abundant parasitoid species varied among the different field conditions; however, within the same season and field the dominant parasitoid species were similar in all three leafminer species tested. Our findings indicate that the dominant parasitoid species did not exhibit any strong preference in the field between the three host species, namely L. trifolii, L. sativae or C. horticola.

Seasonal abundance of hymenopteran parasitoids of the leafminer Chromatomyia horticola (Diptera: Agromyzidae) and the impact of insecticide applications on parasitoids in garden pea field

The seasonal abundance of hymenopteran parasitoids reared from the agromyzid leafminer Chromatomyia horticola was monitored on garden pea in Shizuoka, central Japan, for 17 months between 2004 and 2005. The leafminer was abundant during the cool seasons (December to May) but parasitoid populations generally lagged behind the leafminer by approximately two months. Twenty-one parasitoid species were reared from C. horticola, and the most abundant parasitoid species were Diglyphus isaea, D. minoeus and Chrysocharis pentheus, comprising ca. 90% of the total number caught. Diglyphus isaea and D. minoeus were abundant during the cool season (December to May), while C. pentheus was abundant in the warm season (May to June). Other common parasitoid species were Dacnusa nipponica, Neochrysocharis formosa and Halticoptera circulus. The effects of two insecticides, malathion and tralomethrin, on parasitoid populations were investigated both in the cool and warm seasons. The insecticides caused a reduction in the density of most parasitoid species for at least one month and resulted in resurgence of the leafminer. However, the density of H. circulus increased after insecticide applications, suggesting that this parasitoid was tolerant to both insecticides but H. circulus could not reduce C. horticola populations when insecticide applications were made to the crop. These studies provide insight into the development of integrated control strategies of leafminer pests in field and glasshouse crops.

Survey of brown soft scale Coccus hesperidum L. parasitoids in southern California citrus

The parasitoid complex of brown soft scale, Coccus hesperidum L., a multivoltine soft scale, was determined in southern California citrus over the period February 2004–March 2006. The survey was conducted by placing brown soft scale-infested yucca leaves in the canopy of citrus trees and subsequently rearing individually isolated parasitized scales in the laboratory. A total of 14 species parasitized brown soft scale in the field, the most abundant ones belonging to the genus Metaphycus Mercet (75%). The most abundant parasitoid species was Metaphycus angustifrons Compere (38% parasitism), and this is a new record of establishment for this species in California. Coccophagus species accounted for only 11% parasitism. There were important spatio-temporal differences across the parasitoid complex survey locations. We also found that the five most abundant encyrtid parasitoid species showed preferences for scales of different sizes. Our results have implications for biological control of citricola scale, Coccus pseudomagnoliarum (Kuwana), an important pest of citrus in the San Joaquin Valley of central California. Notably, this species is nearly absent in southern California. Brown soft scale is considered to be an alternate host for parasitoids of citricola scale, a univoltine soft scale, at times when the latter species is unavailable for parasitism.

Habitat modification alters the structure of tropical host–parasitoid food webs

Global conversion of natural habitats to agriculture has led to marked changes in species diversity and composition. However, it is less clear how habitat modification affects interactions among species. Networks of feeding interactions (food webs) describe the underlying structure of ecological communities, and might be crucially linked to their stability and function. Here, we analyse 48 quantitative food webs for cavity-nesting bees, wasps and their parasitoids across five tropical habitat types. We found marked changes in food-web structure across the modification gradient, despite little variation in species richness. The evenness of interaction frequencies declined with habitat modification, with most energy flowing along one or a few pathways in intensively managed agricultural habitats. In modified habitats there was a higher ratio of parasitoid to host species and increased parasitism rates, with implications for the important ecosystem services, such as pollination and biological control, that are performed by host bees and wasps. The most abundant parasitoid species was more specialized in modified habitats, with reduced attack rates on alternative hosts. Conventional community descriptors failed to discriminate adequately among habitats, indicating that perturbation of the structure and function of ecological communities might be overlooked in studies that do not document and quantify species interactions. Altered interaction structure therefore represents an insidious and functionally important hidden effect of habitat modification by humans.

Effect of different hosts onThaumetopoea pityocampa populations in northeast Portugal

A study was carried out at the Natural Park of Montesinho, NE Portugal, in order to evaluate the effect of different pine species (Pinus pinaster Ait.,P. nigra Arn. andP. sylvestris L.) onThaumetopoea pityocampa populations. The structure of the egg batches, the impact of the egg parasitoids on natural mortality of the pest and the species of parasitoids present, as well as their emergence dynamics, were analyzed. The length of the egg batches varied among pine species with the longest ones onP. nigra. The mean number of eggs per batch differed betweenP. sylvestris and the two other hosts studied, with fewer eggs per batch on the first. No differences were found in the size of eggs among pine species. The egg mortality varied between 25.8% and 33.0%, with no differences among hosts. Parasitism was the main cause of death.Baryscapus servadeii (Mercet.) was the most abundant parasitoid species, followed byOoencyrtus pityocampae (Dom.) andTrichogramma embryophagum Htg.B. servadeii dominated in the egg batches collected fromP. pinaster andP. nigra, whereasO. pityocampae was most frequent onP. sylvestris. The emergence ofB. servadeii started in the middle of March and continued until August, with the emergence peak at the end of May. The emergence ofO. pityocampae started at the end of April and continued throughout September, with maximum values in June.

Aphids and parasitoids on willows and poplars in southeastern Europe (Homoptera: Aphidoidea; Hymenoptera: Braconidae, Aphidiinae)

Aphid and aphid parasitoid associations on willows (Salix spp.) and poplars (Populus spp.) in southeastern Europe are reviewed. In total 13 aphid parasitoid species were reared from aphids on these plants. The specific parasitoid complex of Acyrthosiphon cf. malvae (Mosley) on Salix retusa and the aphids and parasitoids composition on willows and poplars are discussed. The most frequently sampled and the most abundant parasitoid species in poplar aphid-aphid parasitoid associations was Adialytus salicaphis Fitch. Furthermore, Lysiphlebus confusus Tremblay & Eady was the most abundant species collected on willow-feeding aphids, whereas A. salicaphis, Euaphidius cingulatus (Ruthe) and Binodoxys heraclei (Haliday) were the most frequently sampled parasitoid species on willows. Trophic connections between aphids and parasitoids associated with willow agroecosystems are also discussed. A key for the identification of aphid parasitoids associated with aphids on willows and poplars in southeastern Europe is provided.

Conservation biological control in urban landscapes: Manipulating parasitoids of bagworm (Lepidoptera: Psychidae) with flowering forbs

Abstract We conducted field experiments to test the hypothesis that regulation of herbivorous pests in urban landscapes can be enhanced with forbs that provide floral resources for adult natural enemies. The herbivore was bagworm, Thyridopteryx ephemeraeformis (Haworth) (Lepidoptera: Psychidae), which is attacked by a guild of hymenopterous parasitoids. We established host shrubs in common garden plantings, encircling some with flowering forbs, released bagworm larvae on shrubs, and assessed survivorship. The hypothesis was supported: parasitism rates of bagworm were 71% higher in shrubs that were surrounded by flowering forbs than in shrubs that lacked flowers. This study also suggested that white-footed mice and European sparrows were important predators of bagworms. The most abundant parasitoid species was the exotic ichneumonid Pimpla (=Coccygominus) disparis (Vierick), an introduced biological control agent of gypsy moth. In a second experiment, parasitism rates were at least three times higher in shrubs encircled by a high density of forbs compared to those having fewer or no forbs. In a third experiment, parasitism rates exceeded 70% in shrubs that were adjacent to a central bed of flowering forbs, but less than 40% in shrubs that were farther away. We conclude from these studies that flowering forbs have a localized effect on host-searching behavior of female parasitoids, encouraging them to parasitize bagworms in the immediate vicinity. This study provides further evidence that ecological methods of pest management can be integrated into the design of urban landscapes to improve regulation of herbivorous pests.

Relationships among abundance of galls, survivorship, and mortality factors in a cynipid wasp, Andricus moriokae (Hymenoptera: Cynipidae)

We describe the relationships among patterns of abundance of galls, survivorship, and mortality factors in the sexual generation of a cynipid wasp, Andricus moriokae, and detail the impacts of abundant parasitoid species on the survivorship of the cynipid in relation to the abundance patterns of galls. The mean number of galls per shoot, the frequency distribution of number of galls on a single shoot, and the mean number of galls per shoot in respective shoot size classes (the number of leaves per shoot) did not differ significantly between two sample trees. The relative impacts of the three mortality factors differed between trees, having different consequences for the survivorship of the cynipid. The rate of parasitoid attack, the main cause of mortality, was higher in the tree on which the cynipids survived better. On the other hand, the mortalities caused by gall predation and gall abortion were higher in the tree with the lower survival rate of the cynipid. Galls appeared more frequently on larger shoots on both trees. However, the survival rate and the mortality rates caused by three mortality factors did not differ among shoot size classes within each tree. The species composition of the parasitoid assemblage changed with shoot size, but the patterns of change differed between trees with similar abundance patterns of galls. Thus, the survivorship and mortality factors of the cynipid were probably not related to the abundance patterns of galls.

Roles of gall morphology in determining potential fecundity and avoidance of parasitoid attack in Aphelonyx glanduliferae

This study addresses the relationship between gall morphology and some fitness components in the agamic generation of Aphelonyx glanduliferae. Larger A. glanduliferae adults that showed higher potential fecundity developed in larger galls. No fewer than 60% of A. glanduliferae individuals were attacked by parasitoids, and cynipids in smaller galls suffered more parasitoid attacks. Thus, large galls are likely to provide considerable food resources and avoidance of parasitoid attack for A. glanduliferae. Both thickness of gall walls (barrier to the parasitoid attack) and diameter of larval chamber (open space for the cynipid larva to move away) were positively correlated with gall size. Mean gall-wall thickness was significantly larger in galls harboring a living cynipid than in those harboring a living parasitoid, but the difference in the mean larval-chamber diameter was not significant. These results suggest that gall-wall thickness plays an important role in avoiding parasitoid attacks. However, the mean ovipositor length of the abundant parasitoid species exceeded the maximum gall-wall thickness, indicating that these parasitoids are potentially able to attack large galls. The higher rate of parasitoid attack in smaller galls suggests that (1) an individual of A. glanduliferae, even if it grows in a small gall, is large enough to be a host for parasitoids, and (2) parasitoids can oviposit more easily on smaller galls of A. glanduliferae, which have thinner walls.

Looks are important: parasitic assemblages of agromyzid leafminers (Diptera) in relation to mine shape and contrast

Summary We test the hypothesis that leaf mine appearance can affect the risk of leafminers being discovered by parasitoids, and therefore influence parasitic assemblages, using a comparative study of parasitic complexes associated with 28 agromyzid species in Central Argentina. Analyses were based on size, structure (defined as the number of species in host‐range categories) and impact (percentage parasitism) of parasitic complexes on leafminers. Mine appearance was defined in terms of shape (linear, linear‐blotch, blotch) and colour (high or low contrast with the leaf lamina). Irrespective of the agromyzid species involved, significant differences were found in the structure of the parasitoid complexes: specialists were more abundant and generalists rarer than expected in blotch and cryptically coloured mines. There were no differences in average parasitoid species richness and parasitism rates among differently coloured or shaped galleries. However, mine appearance significantly affected parasitic assemblage structure, with shape driving generalist species richness and contrast influencing that of specialists. Mine shape also affected parasitism rates, which were highest for generalists in linear mines, and for specialists in blotch mines. The existence of a gradient of discovery from the cryptically coloured blotch mines to the most apparent highly contrasting linear ones was supported by significant correlations of this gradient with richness and parasitism rates of generalist and specialist parasitoids. Taxonomic composition of parasitic complexes (analysed through parasitoid species abundance) was separated significantly according to host mine shape. An even more significant classification of assemblages was achieved when the combination of mine shape and colour was considered in the discoverability gradient. Our results suggest that despite leaf mines being an ecologically homogeneous resource, their morphology might offer varying degrees of refuge against different parasitoids.

Spatial and temporal variation in the parasitoid assemblage of an exophytic polyphagous caterpillar

Abstract 1. Over 3400 larvae of the polyphagous ground dwelling arctiid Grammia geneura were sampled and reared over seven generations in order to characterise its parasitoid assemblage and examine how and why this assemblage varies over time and space at a variety of scales.2. The total parasitoid assemblage of 14 species was dominated both in diversity and frequency by relatively polyphagous tachinid flies.3. Both the composition of the parasitoid assemblage and frequency of parasitism varied strikingly among and within sampling sites, seasons, and years.4. Overall rates of parasitism increased consistently over the duration of caterpillar development.5. Within sampling sites, parasitism rates were non‐random with respect to habitat structure and caterpillar behaviour for the most abundant parasitoid species.6. The large variability in parasitoid assemblage structure over space and time in this system may be a function of local host population abundance, habitat‐specific parasitism, and indirect interactions between G. geneura and other Macrolepidoptera through shared oligophagous and polyphagous parasitoids.