Host-parasitoid Associations Research Articles

Parasitoid complex associated with the flea weevil Orchestes alni L. (Coleoptera: Curculionidae) in Bulgaria and a review of host–parasitoid interactions of genus Orchestes Illiger

ABSTRACT Leaves of field elm, Ulmus minor, with mines of Orchestes alni, were collected at four sites in Sofia city during 2018, 2019 and 2023, and kept under laboratory conditions to observe and count emerging parasitoid adults. Results revealed that the parasitoid complex included 22 hymenopteran species belonging to five families: Braconidae (two species), Ichneumonidae (one species) (Ichneumonoidea), Eulophidae (14 species), Eupelmidae (three species) and Pteromalidae (two species) (Chalcidoidea). The most abundant species was Pnigalio agraules (27%), followed by Minotetrastichus platanellus (18%) (Eulophidae) and Trichomalus inscitus (Pteromalidae) (14%). Nine host–parasitoid associations are reported as new. Tetrastichus miser is reported from Bulgaria for the first time. These findings are discussed in relation to the known host–parasitoid associations of the genus Orchestes. The identification of the host species, O. alni, was supported by both morphological and molecular methods.

A molecular approach to unravel trophic interactions between parasitoids and hyperparasitoids associated with pecan aphids.

Advances in molecular ecology can overcome many challenges in understanding host-parasitoid interactions. Genetic characterization of the key-players in systems helps to confirm species and identify trophic linkages essential for ecological service delivery by biological control agents; however, relatively few agroecosystems have been explored using this approach. Pecan production consists of a large tree perennial system containing an assortment of seasonal pests and natural enemies. As a first step to characterizing host-parasitoid associations in pecan food webs, we focus on aphid species and their parasitoids. Based on DNA barcoding of field-collected and reared specimens, we confirmed the presence of 3 species of aphid, one family of primary parasitoids, and 5 species of hyperparasitoids. By applying metabarcoding to field-collected aphid mummies, we were able to identify multiple species within each aphid mummy to unravel a complex food web of 3 aphids, 2 primary parasitoids, and upward of 8 hyperparasitoid species. The results of this study demonstrate that multiple hyperparasitoid species attack a single primary parasitoid of pecan aphids, which may have negative consequences for successful aphid biological control. Although further research is needed on a broader spatial scale, our results suggest multiple species exist in this system and may suggest a complex set of interactions between parasitoids, hyperparasitoids, and the 3 aphid species. This was the first time that many of these species have been characterized and demonstrates the application of novel approaches to analyze the aphid-parasitoid food webs in pecans and other tree crop systems.

Description of a new species of the genus Atanycolus Foerster (Hymenoptera: Braconidae) parasitizing Lamprodila nobilissima bellula (Lewis) (Coleoptera: Buprestidae) in China

Atanycolus yangi sp. nov. (Hymenoptera, Braconidae), a new species parasitizing the flatheaded wood borer, Lamprodila nobilissima bellula (Lewis) (Coleoptera: Buprestidae), is described. Lamprodila nobilissima bellula is a serious wood boring pest of Rosacea trees in North China. We collected adult specimens of A. yangi sp. nov. searching for hosts on infested tree trunks and confirmed the host-parasitoid association by dissecting parasitized hosts from infested trees in the field and rearing the parasitoid from L. nobilissima bellula -infested host tree logs in the laboratory. Adult images for both sexes of the new parasitoid species are provided. A morphological identification key to Oriental and Palaearctic species similar to A. yangi sp. nov is also presented.

Redescription of Apanteles mimoristae (Hymenoptera, Braconidae), a parasitoid of the native pyralid cactus moth Melitara cf. nephelepasa in central Mexico

Novel trophic associations have sometimes resulted in fortuitous and significant biological control. After the invasion of North America by the South American cactus moth, Cactoblastis cactorum (Berg) (Pyralidae: Phycitinae), it is pertinent to characterize the assemblage of local natural enemies that could utilize this moth in new host-parasitoid associations. Herein we report on Apanteles mimoristae Muesebeck (Braconidae: Microgastrinae), a North American gregarious endoparasitoid wasp attacking the caterpillar of the phycitine cactus moth Melitara cf. nephelepasa (Dyar) (Pyralidae: Phycitinae, also known as zebra worm), also native to North America; both collected in Opuntia ficus-indica (L.) Mill. (Cactaceae) cultivated fields at rural areas of Mexico City. We provide an updated morphological account for A. mimoristae visualized with light microscopy and scanning electron microscope (SEM); a fragment of its cytochrome oxidase subunit I (COI) gene sequence data is reported for the first time. Additionally, we analyze its taxonomical position relative to other Apanteles species from the Americas including those attacking cactus-feeding moths. Our analyses place A. mimoristae (from Mexico) in a clade with A. esthercentenoae Fernández-Triana (from Costa Rica), a parasitoid of both Cromarcha stroudagnesia Solis (Pyralidae) and Palpita venatalis (Schaus) (Crambidae) (non cactus-feeding), and in a sister clade to A. opuntiarum Martínez & Berta (from Argentina) and A. alexanderi Brèthes (from Argentina and Uruguay), parasitoids of the cactus-feeding phycitines Cactoblastis and Tucumania respectively. Finally, we provide an updated key for the identification of Apanteles species recorded parasitizing cactus moth caterpillars in the American continent.

New host-parasitoid association and the Trojan horse strategy adopted by the cuckoo wasp Elampus bidens with two vectors of Flavescence Dorée: Scaphoideus titanus and Orientus ishidae

New host-parasitoid association and the Trojan horse strategy adopted by the cuckoo wasp Elampus bidens with two vectors of Flavescence Dorée: Scaphoideus titanus and Orientus ishidae

Molecular identification of the brown marmorated stink bug’s egg parasitoids by species-specific PCR collected from Beijing, China

Brown marmorated stink bug (BMSB), Halyomorpha halys (Stål) (Hemiptera: Penta-tomidae), is a highly polyphagous and invasive insect pest with more than 300 plant species as hosts, including a wide range of economic crops. To date, several egg parasitoid species are reported to attack BMSB. In this study, two species of Trissolcus (Hymenoptera: Platygastridae) and one Anastatus (Hymenoptera: Eupelmidae) were recovered from field exposed BMSB sentinel eggs in Beijing, China. The wasps’ small size of only 1.5 mm and 4 mm in length make them difficult to identify morphologically and required taxonomist for identification of specific species. In addition, these parasitoids have morphology sibling species and have been misidentified several times in China. To overcome these problems, a molecular method with species-specific primers designed for the COI gene has been developed to identify Trissolcus, Anastatus and their host samples from field collected samples. After successful morphological confirmation with experts, DNA extractions were carried out from these samples. PCR amplification using published primers for T. japonicus, A. japonicus and BMSB specimens confirmed the species. As for T. cultratus, species specific primers TCYF and TCYR were developed which produce 340-bp PCR products length while no positive amplifications found in other wasps and host. Sensitivity analysis of markers revealed that TCYF and TCYR primers could detect as low a DNA template concentration as 0.00025 ng/μL. This indicates that PCR with these primers specifically and sensitively differentiates T. cultratus specimens from other similar wasp species. All the primers tested in this study could discriminate between parasitized and non-parasitized BMSB eggs. This molecular identification method shows promise for conveniently identifying Trissolcus and Anastatus species in host-parasitoid associations and accurately evaluating parasitism rates in the field.

Description of the Male of Psyllaephagus saxaulicus Sugonjaev (Hymenoptera: Encyrtidae) Parasitising the Olive Psyllid, Euphyllura straminea Loginova (Hemiptera: Liviidae) in Iran, with Notes on Its Hyperparasitoids

The parasitoid wasp, Psyllaephagus saxaulicus Sugonjaev, 1968 (Hym.: Encyrtidae) is newly reported from Iran. It was reared from the olive psyllid, Euphyllura straminea Loginova (Hem.: Liviidae) on the olive tree, Olea europaea L. (Oleaceae), which is considered as a new host-parasitoid association. Here, the male of P. saxaulicus is described and illustrated for the first time and a redescription is provided to facilitate the recognition of its female. Furthermore, other new associations, Marietta picta (André) (Hym.: Aphelinidae) and Chartocerus kurdjumovi (Nikol`skaya) (Hym.: Signiphoridae) as hyperparasitoids are recorded.

A new gregarious parasitoid species, Microplitis idreesae (Hymenoptera, Braconidae, Microgastrinae) reared from Mythimna sp. (Lepidoptera, Noctuidae), with a key to the species of Microplitis in the Kingdom of Saudi Arabia

A new species of parasitoid wasp (Braconidae, Microgastrinae) from the kingdom of Saudi Arabia (KSA) is described, Microplitis idreesaesp. nov. The genus is reported for the first time in the Eastern province of the KSA. This is the first host-parasitoid association for Microplitis documented in the country. The new species attacks Mythimna Ochsenheimer (Lepidoptera, Noctuidae). Natural history information is provided such as the association of males with females, geographical location, possible food plants, and details of wasp cocoons. In addition, a fragment of the mitochondrial cytochrome b gene is presented. A taxonomic key to the species of Microplitis reported from the KSA is provided. Characters of this new species and its affinities with the three previous species described from the KSA and four of the closely related to Palaeartic species are also discussed.

A new species of Aphanogmus Thomson (Hymenoptera: Ceraphronidae) parasitising predatory cecidomyiids in mite-induced galls of Pongamia pinnata in India

ABSTRACT Ceraphronidae is one of the small, commonly collected families of parasitoid Hymenoptera. Aphanogmus cecidovorus Ranjith sp. n. is described here as a parasitoid of the acarivorus cecidomyiid Microdiplosis pongamiae Mani. This is the first host–parasitoid association of Aphanogmus parasitising an acarivorus cecidomyiid reported from outside the Nearctic and Palaearctic regions. The new species is described and compared with related species and those with a similar association. Taxonomic placement of the new species and host–parasitoid association are commented on briefly. http://www.zoobank.org/urn:lsid:zoobank.org:pub:93C143DF-D8C0-489B-9251-948E9BE9EC0A

Synoptic catalogue of insect parasitoids associated with Lixinae (Coleoptera: Curculionoidea: Curculionidae)

The first host-parasitoid catalogue for Lixinae is presented. This survey is based on literature search (~300 references) and followed by two parts, firstly one of the Lixinae, and secondly one of parasitoids with distinguishing numbers of their Lixine hosts. There are at least 221 species recorded as parasitoids on 108 lixine species. Records on 12 host-parasitoid associations seem to be questable or based on misidentifications. Most common hosts are species of two genera: Lixus (112 parasitoid species) and Larinus (43). All actually known parasitoids of Lixinae are dipterans (belonging to three families) and hymenopterans (15 families). The latter listed as parasitoids of no less than 102 lixine species (94.4%) and 22 hosts (19.4%) associated with Diptera. Six lixine species associated with dipterans only. Most common parasitoids are braconids. Four parasitoid species have the most extensive list of the hosts: Exeristes roborator (at least 29 host species), Cerceris tuberculata (12), Bracon urinator (11) and Zeuxia cinerea (10). Parasitoid complex of some hosts can include more than 10 (to 44!) species. Information contained in catalogue will be helpful for programs of effective biological control of economic important pests and weeds.

Nonreproductive effects are more important than reproductive effects in a host feeding parasitoid

When female host feeding parasitoids encounter a potential host, they face a complicated trade-off between either laying an egg for investing in current reproduction or feeding on or killing the host for future reproduction. Few studies have measured these behavioral shift patterns in a given host-parasitoid association thus far. We systematically assessed the behavioral shifts and life history traits of a host feeding parasitoid, Necremnus tutae, on different instars of its host Tuta absoluta. N. tutae females, as idiobiont host feeding parasitoids, can act on the 1st–4th instar larvae of T. absoluta by either host feeding, parasitizing or host killing. Moreover, a significant behavioral shift was observed on different instar hosts. N. tutae preferred to feed on the young hosts (1st and 2nd instars), lay eggs on middle-aged hosts (3rd instars) and kill old hosts (4th instars) by ovipositor-mediated stinging. The offspring of N. tutae showed a significant female-biased sex ratio, with the number of instars of T. absoluta larvae that were parasitized increasing. Specifically, nonreproductive host mortality induced by host feeding and host killing accounted for high percentages of the total mortality (ranging from 70% on 3rd instar hosts to 88% on 1st instar and 4th instar hosts). We hypothesize that N. tutae could be not merely a parasitoid but also a predator. Our results shed light on the nonreproductive abilities of a host feeding parasitoid that should be given further attention, especially when evaluating the efficacy of parasitoids.

Interspecific interaction between Anagyrus fusciventris and Tetracnemoidea brevicornis for controlling Pseudococcus calceolariae

ABSTRACT Anagyrus fusciventris and Tetracnemoidea brevicornis (Hymenoptera: Encyrtidae) are solitary endoparasitoids of Pseudococcus calceolariae and P. longispinus (Hemiptera: Pseudococcidae), major pests of many horticultural crops. The interspecific interaction relate to host-parasitoid association between these two parasitoid species was tested in the laboratory. To test the hypothesis that both species prefer the same life stages of P. calceolariae, first instar to adult mealybugs were exposed to female parasitoids of both species for either 24 h or 10 days. The parasitism by each parasitoid species of eggs and newly emerged or late first instar P. calceolariae was individually tested. A sequential test was also carried out, where mealybugs were exposed to either of the two parasitoid species with 24-h intervals between the exposure to the first and second parasitoid species. Regardless of the time or order of exposure, T. brevicornis females produced a larger proportion of parasitoid progeny within their short adult lifespan (< 10 days). The maximum daily reproductive output of T. brevicornis (32) was higher than A. fusciventris (8). Egg to adult development period of A. fusciventris was shorter (20 ± 1.6 (SD) days) than T. brevicornis (36.6 ± 4.6 (SD) days). A complementary effect of the two species on mealybug suppression was highlighted in our findings, due to their species-specific host stage preference, A. fusciventris prefer older life stages while T. brevicornis prefer younger life stages. Therefore both species together could provide stable control of the pest population more effectively than one species alone.

A Coordinated Sampling and Identification Methodology for Larval Parasitoids of Spotted-Wing Drosophila.

We provide recommendations for sampling and identification of introduced larval parasitoids of spotted-wing drosophila, Drosophila suzukii (Matsumura) (Diptera: Drosophilidae). These parasitoids are either under consideration for importation (aka classical) biological control introductions, or their adventive (presumed to have been accidentally introduced) populations have recently been discovered in North America and Europe. Within the context of the ecology of D. suzukii and its parasitoids, we discuss advantages and disadvantages of estimating larval parasitism levels using different methods, including naturally collected fruit samples and sentinel baits. For most situations, we recommend repeated sampling of naturally occurring fruit rather than using sentinel baits to monitor seasonal dynamics of host plant-Drosophila-parasitoid associations. We describe how to separate Drosophilidae puparia from host fruit material in order to accurately estimate parasitism levels and establish host-parasitoid associations. We provide instructions for identification of emerging parasitoids and include a key to the common families of parasitoids of D. suzukii. We anticipate that the guidelines for methodology and interpretation of results that we provide here will form the basis for a large, multi-research team sampling effort in the coming years to characterize the biological control and nontarget impacts of accidentally and intentionally introduced larval parasitoids of D. suzukii in several regions of the world.

Cerambyx miles (Coleoptera: Cerambycidae) and Oobius rudnevi (Hymenoptera: Encyrtidae): a new host–parasitoid association revealed by laboratory tests and sentinel eggs in the wild

Summary The parasitism of the encyrtid wasp Oobius rudnevi (Nowicki, 1928) on the eggs of the longhorn beetle Cerambyx (Cerambyx) miles Bonelli, 1812, is recorded for first time through field and laboratory trials. Field trials with sentinel eggs of C. miles were conducted in SW Spain oak forests in which O. rudnevi was known to occur, using as positive controls sentinel eggs of both Cerambyx (Cerambyx) cerdo Linnaeus, 1758, and Cerambyx (Cerambyx) welensii (Küster, 1845), the only two O. rudnevi hosts known to date. Laboratory assays were conducted using non-choice tests and choice tests (C. miles vs. C. cerdo). Results showed that C. miles eggs were attacked and successfully parasitised by O. rudnevi in the wild, uncorrected parasitism rates (PU) being similar to those of C. cerdo and C. welensii (2.2–5.2%), and net parasitism rates (PN) even significantly higher in C. miles (8.9%) than in C. welensii (3.3%). Interestingly, C. miles sentinel eggs were parasitised in holm oak forests in which C. miles was unknown to occur, suggesting that egg-derived volatile cues were important in host location. In the laboratory, non-choice tests showed no differences in PN among C. miles, C. cerdo and C. welensii (80–88%), signifying that O. rudnevi performed alike in the three hosts. Choice tests showed that O. rudnevi did not exhibit host preference between C. miles (53%) and C. cerdo (47%). Similar tests proved that eggs of Cerambyx (Microcerambyx) scopolii Fuessly, 1775, and Prinobius myardi Mulsant, 1842, were never selected as hosts by O. rudnevi. Our results and the chorological, ecological and phylogenetic available evidence suggest that O. rudnevi behaves as an oligophagous egg parasitoid, which could be associated to other Cerambyx (s. str.) species over the Western Palaearctic realm.

NEW RECORDS OF CERCERIS TUBERCULATA (VILLERS, 1787) (HYMENOPTERA: CRABRONIDAE) FROM UKRAINE, WITH NOTES ON ITS PARASITOIDS AND PREY

Present paper reports observations on the digger wasp Cerceris tuberculata (Villers, 1787) (Hymenoptera: Crabronidae), listed in Red Data Book of Ukraine, its parasitoids and prey. The observations revealed two parasitoids associated with this wasp: a cuckoo wasp Hedychrum virens Dahlbom, 1845 (Chrysididae) and velvet ant Nemka viduata viduata (Pallas, 1773) (Mutillidae). The host-parasitoid association of this velvet ant and C. tuberculata is provided for the first time. Four species of weevils were registered as a prey of C. tuberculata, three of them are given for the first time herein. New records of the species from Zaporizhzhya and Kherson Regions are provided; the species is reported from Zaporizhzhia Region for the first time.

Differential temperature responses between Plutella xylostella and its specialist endo-larval parasitoid Diadegma semiclausum-Implications for biological control.

Understanding the thermal dynamics of host-parasitoid interactions is crucial to predicting how biological control of pest insects by parasitoids might be affected by geographic location and climate change. We compared performance traits of Plutella xylostella (Lepidoptera: Plutellidae) and its solitary endo-larval parasitoid Diadegma semiclausum (Hymenoptera: Ichneumonidae), over a wide range of constant rearing temperatures (10-30°C). Parasitoids reared at 30°C experienced reductions in pupation rate, pupal mass, egg load, and adult life span when compared with those reared at lower temperatures. Our analyses of the fate of parasitoids and their hosts and intergenerational population growth at different rearing temperatures show that D. semiclausum and P. xylostella respond differently to temperature, leading to divergent outcomes under different temperature conditions. Some parasitoid larvae could not complete development at 30°C, the temperature at which the host biomass was least and the metabolic demands of the parasitoid could be high, suggesting that parasitoid development might be constrained by lack of host resources at higher temperatures. We discuss the potential mechanisms of parasitoid susceptibility to elevated temperatures, which likely explain the pronounced seasonal dynamics of D. semiclausum in subtropical regions and its failure to establish in lowland tropical regions, where P. xylostella is a serious pest. Similar interactions in other host-parasitoid associations would constrain the efficacy of parasitoids as biological control agents as global temperatures increase.

Eco-climatic matching to guide foreign exploration and optimal release strategies for biological control agents of Rastrococcus iceryoides in Africa and Asia

Rastrococcus iceryoides (Green) (Homoptera: Pseudococcidae) is a major invasive pest of several horticultural crops [in Africa and Asia, outside its native range in India], with damage levels ranging from 30% to complete crop failure. Due to lack of effective co-evolved parasitoids in the invaded regions, maximum entropy (MaxEnt) and genetic algorithm for ruleset production (GARP) were used to identify climatically suitable areas in India for foreign exploration. Based on the outcome of the predictive models, an extensive survey was conducted in 15 major mango growing regions in the state of Tamil Nadu, India. Thereafter, both models were used to identify climatic compatibility habitats in the invaded regions of R. iceryoides. Our results revealed ten host plants belonging to eight families with considerably low levels of infestation. The percentage parasitism established using mummified R. iceryoides was relatively high ranging between 16.7 ± 1.4 to 91.3 ± 3.7%. Both old and new host-parasitoid associations were recorded with eleven parasitoid species described. Eight of the parasitoids recorded were new records of R. iceryoides. Among these parasitoids, Praleurocerus viridis Agarwal, Anagyrus chryos Noyes & Hayat and Neoplatycerus tachikawai Subba Rao were the most dominant and widespread parasitoid species, highly specific to R. iceryoides with percent parasitism of 53.2 ± 5.4, 31.3 ± 2.7 and 8.8 ± 2.9%, respectively. Using the occurrence data of the parasitoids, both models successfully identified optimal suitable habitats in Africa and Asia. Both models showed optimal performances with the value of the average area under the curve (AUC) of 0.98 for MaxEnt and 0.95 for GARP. However, the percentage contribution of the predictor variables that influenced the current and future predictions in the native and invaded range varied considerably. These findings demonstrate the importance of predictive modelling as novel tools to support future classical biological control program targeting R. iceryoides in the invaded regions. Our results provide important information to guide strategic planning for future classical biological control programmes.

Host-parasitoid associations in marine planktonic time series: Can metabarcoding help reveal them?

In this study, we created a dataset of a continuous three-year 18S metabarcoding survey to identify eukaryotic parasitoids, and potential connections to hosts at the Long-Term Ecological Research station Helgoland Roads. The importance of parasites and parasitoids for food web dynamics has previously been recognized mostly in terrestrial and freshwater systems, while marine planktonic parasitoids have been understudied in comparison to those. Therefore, the occurrence and role of parasites and parasitoids remains mostly unconsidered in the marine environment. We observed high abundances and diversity of parasitoid operational taxonomic units in our dataset all year round. While some parasitoid groups were present throughout the year and merely fluctuated in abundances, we also detected a succession of parasitoid groups with peaks of individual species only during certain seasons. Using co-occurrence and patterns of seasonal occurrence, we were able to identify known host-parasitoid dynamics, however identification of new potential host-parasitoid interactions was not possible due to their high dynamics and variability in the dataset.

Competition between Diachasmimorpha kraussii and Fopius arisanus in Bactrocera tryoni: does native parasitoid-host association matter?

In Australia Fopius arisanus (Sonan) is an established, but exotic fruit fly egg-larval-pupal parasitoid which co-occurs with Diachasmimorpha kraussii (Fullaway), a native larval-pupal fruit fly parasitoid: both attack the native fruit fly Bactrocera tryoni (Froggatt). In interactions involving evolutionary novel host-parasitoid associations, F. arisanus consistently out-competes other parasitoid species, including D. kraussii. However, in fruit fly-parasitoid systems where there is co-evolutionary history between parasitoids and their hosts, competitive hierarchies can vary. In this study we investigated the outcome of competition between F. arisanus and D. kraussii within B. tryoni, to test whether the close evolutionary relationship between D. kraussii and B. tryoni might circumvent the competitive advantage of F. arisanus. Consistent with previous research, and despite the evolutionary relationship, dissection of multiparasitized B. tryoni larvae showed that D. kraussii was invariably suppressed by F. arisanus. A total of 47% and 74% of the eggs of D. kraussii in presence of F. arisanus were killed within a span of 24 h and 48–72 h, respectively. However, parasitoid emergence from fruit fly hosts exposed sequentially to F. arsianus and D. kraussii suggest that D. kraussii females are able to discriminate hosts already parasitized by F. arisanus. Results show that the co-evolutionary relationship between B. tryoni and D. kraussii does not help overcome the early-acting advantage of the egg parasitoid F. arisanus. Though F. arisanus may not have completely displaced D. kraussii in its native habitat, simultaneous inundative releases of these two parasitoid species (currently under consideration) might not help increase B. tryoni parasitism levels.

How to escape from insect egg parasitoids: a review of potential factors explaining parasitoid absence across the Insecta.

The egg is the first life stage directly exposed to the environment in oviparous animals, including many vertebrates and most arthropods. Eggs are vulnerable and prone to mortality risks. In arthropods, one of the most common egg mortality factors is attack from parasitoids. Yet, parasitoids that attack the egg stage are absent in more than half of all insect (sub)orders. In this review, we explore possible causes explaining why eggs of some insect taxa are not parasitized. Many insect (sub)orders that are not attacked by egg parasitoids lack herbivorous species, with some notable exceptions. Factors we consider to have led to escape from egg parasitism are parental egg care, rapid egg development, small egg size, hiding eggs, by e.g. placing them into the soil, applying egg coatings or having thick chorions preventing egg penetration, eusociality, and egg cannibalism. A quantitative network analysis of host-parasitoid associations shows that the five most-speciose genera of egg parasitoids display patterns of specificity with respect to certain insect orders, especially Lepidoptera and Hemiptera, largely including herbivorous species that deposit their eggs on plants. Finally, we discuss the many counteradaptations that particularly herbivorous species have developed to lower the risk of attack by egg parasitoids.