Chalcidoidea

The superfamily, Chalcidoidea in Britain, consists of the following families : Aphelinidae, Chalcididae, Elasmidae, Encyrtidae, Eucharitidae, Eulophidae, Eupelmidae, Eurytomidae, Mymaridae, Ormyridae, Perilampidae, Pteromalidae, Signiphoridae, Tetracampidae, Torymidae, and Trichogrammatidae

Chalcidoidae identification key (pdf)

Description & Statistics

Clausen (1940) stated that "The superfamily Chalcidoidea includes among its different families probably a majority of all entomophagous insects, and their range in form, habits, host preferences, and host relationships is extremely wide. The bulk of the species are entomophagous in habit, and the phytophagous species are distributed in a number of families. The plant-feeding habit in the superfamily has been reviewed by Gahan (1922) and the species listed which develop in that way. The Agaontidae comprise the fig insects, and the members of the subfamily Idarninae of the Callimomidae are associated with them in an uncertain capacity. Numerous other Callimomidae are seed feeders, as are also many Eurytomidae. The latter family also includes a considerable number of species that form plant galls, and a few species of Eulophidae and a single one of the Encyrtidae are stated to be of similar habit. It is generally accepted that the phytophagous habit is the more primitive in the superfamily and that the parasitic relationship is of more recent origin."

"The insect hosts of the parasitic and predaceous members of the superfamily are extremely varied and represent practically all the more common orders, of which the preferred ones are the Lepidoptera, Diptera, Coleoptera, and Homoptera. These groups comprise the bulk of our major crop pests, and their chalcidoid parasites often serve to keep them in check. In biological control work, a considerable number of species have been imported into the different countries and have been successful in reducing the population of the pest species to a noneconomic level."

"The host stages attacked are principally the egg and larva, though a smaller number develop in the pupa, and some of those attacking Homoptera may develop in the adults, also. Certain families are sharply restricted in their choice of host groups or host stages. Thus the Mymaridae and Trichogrammatidae develop exclusively in the eggs of various orders, whereas the Eucharidae occur only upon the larvae and pupae of ants. The great majority of Aphelinidae are parasitic in Homoptera, principally the Coccidae, Aphididae and Aleyrodidae. The parasitic Callimomidae attack mainly the immature stages of gall-making Cecidomyiidae and Cynipoidea; but the Eulophidae are largely governed by the host habitat, and they attack larvae of several orders that form leaf mines or that bore in stems. The manner of attack shows considerable variation. The larvae that feed upon eggs are usually parasitic internally, but some may be true predators. When attacking larvae or pupae, the parasite may develop either internally or externally, and both habits are commonly found within a single genus. Finally, the adult parasites themselves may be predaceous."

"In all probability, the majority of species in the Chalcidoidea are primary parasites, and the known members of the Mymaridae, Trichogrammatidae, Leucospidae and Eucharidae are exclusively so. Other families have a varying proportion that act as hyperparasites, and some species develop indiscriminantly in both roles."

"Many modifications in form are found among the eggs and the larval instars of the Chalcidoidea, a majority of which are definitely adaptive in character. Certain of these are common to whole families, whereas others appear apparently independently in widely separated genera and families. Under these circumstances, they cannot be considered to have a phylogenetic significance and are of limited usefulness in determining the taxonomic position of stages not associated with the adult insects. The first comprehensive study of the early stages of the Chalcidoidea, in which an effort was made to arrange the different groups in accordance with their taxonomic position, was that of H. L. Parker (1924)."

Gibson (1993) included 29 families in Chalcidoidea: Agaonidae, Aphelinidae, Chalcididae, Elasmidae, Encyrtidae, Eucharitidae, Eulophidae, Eupelmidae, Eurytomidae, Leucospidae, Mymaridae, Ormyridae, Perilampidae, Pteromalidae, Rotoitidae, Signiphoridae, Tanaostigmatidae, Tetracampidae, Torymidae and Trichogrammatidae. He distinguished the fully winged chalcidoids from most other Hymenoptera by their reduced forewing venation. At most a single vein complex occurs, composed of the submarginal, marginal, stigmal, and postmarginal veins. Most chalcidoids also have a separate sclerite, the prepectus, partly separating the mesopleuron from a somewhat saddle-like or horseshoe-like pronotum. This is unlike most other parasitic Hymenoptera, which lack an exposed prepectus between the mesopleuron and pronotum, and have the pronotum highly reduced medially so as to be triangular in lateral view. Because a prepectus is present between the pronotum and the mesopleuron in most chalcidoids, the pronotum typically does not extend to the tegula, but how conspicuous this feature is depends on size of the prepectus (Gibson 1993). The position of the mesothoracic spiracle, if visible, also distinguishes chalcidoids from other parasitic Hymenoptera. In chalcidoids the mesothoracic spiracle is at the dorsal margin of the pronotum, usually at the juncture of the pronotum, prepectus, and mesoscutum, but at least between the pronotum and mesoscutum. Other parasitic Hymenoptera have the mesothoracic spiracle located below the dorsal margin of the pronotum, either between the pronotum and the mesopleuron (in some taxa concealed beneath a prominent pronotal lobe) or on the pronotum itself in this same relative position. Thus, the spiracle and mesoscutum are separated by the posterodorsal angle of the pronotum. Almost all chalcidoids also have longitudinal, ridge-like sensory structures (multiporous plate sensilla) on one or more flagellar segments, with the apices of the sensilla projecting above the surface, and often beyond the apex of the segments. Many also have a metallic sheen, which distinguishes them from most other parasitic microhymenoptera. Bou…ek (1988a) gave a comprehensive review of chalcidoid structure.

Chalcidoids are found in all zoogeographic regions and in all habitats from equatorial forests to the northernmost tundra, from deserts to ponds (Gibson 1993). Although they occur almost everywhere, they are one of the poorest known groups of parasitic Hymenoptera, in part because of their small size (most are 3-5 mm or less in length), morphological and biological diversity, and numerical abundance. About 3,300 nominal genera and 22,500 nominal species have been described, of which circa 2,000 genera and 18,500 species are considered valid (Noyes 1990a). The number of species certainly represents only a fraction of the true diversity, and estimates of 60,000-100,000 chalcidoid species do not seem unreasonable (Noyes 1978, Gordh 1979). Noyes (1990a) gave the approximate number of genera and species for each family.

Bou…ek (1988a), Gauld & Bolton (1988) and Bendel-Janssen (1977) reviewed the biological diversity of chalcidoids. Most chalcidoids are parasitoids or, rarely, predators of the immature stages or, very rarely, of adults of 12 orders of Insecta, 2 orders of Arachnida (Araneae and Acari), and one family of Nematoda (Anguinidae). This represents about the same number of orders that are parasitized by the rest of the parasitic Hymenoptera combined. Few chalcidoids are phytophagous, either as gall formers or seed eaters, or as inquilines within the galls of other species.

Gibson (1986a) defined Chalcidoidea on the basis of three external, putatively synapomorphic attributes. Because members of Mymarommatidae lack these three attributes but share other putative synapomorphies with chalcidoids, they were thought to be a sister group. Gauld & Bolton (1988) and Naumann (1991) classified mymarommatids as a family in Chalcidoidea, while Delvare & Aberlenc (1989) and Noyes & Valentine (1989b) classified them as a superfamily separate from Chalcidoidea.

Bou…ek (1988b) gave an extensive review of the history of chalcidoid classification. Since 1952 from 9 to 24 families have been recognized. Current workers have still not reached a consensus as to family level classification or relationships. Many of the families cannot be defined by any unique attribute or even combination of attributes if the world fauna is treated. Also, using combinations of attributes to key out family level taxa results in often endless, although often rare, exceptions of intermediate forms. These problems have long been acknowledged by specialists in their taxonomy. Gordh (1979) stated that classifications are based on external morphology, and chalcidoids are exceeding plastic morphologically. This has resulted in differences of opinion over the limits of higher taxa because various workers have interpreted the significance of characters differently. Grissell (1980) noted that characters used to delimit higher taxa often work well for only one sex and generally are not disjunctive, i.e., they intergrade and crop up on occasion where least expected. The result is that many of the chalcidoid families likely represent taxa of convenience, based on overall similarity, more than they represent monophyletic evolutionary lineages.

Family classification used in this report follows that of Bou…ek (1988a). Gibson (1993) nevertheless followed Heraty & Darling (1984) for delineating Perilampidae and Eucharitidae. Because many family diagnoses cannot be made strictly differential, diagnostic attributes of the most inclusive definable unit within each family (usually subfamily, rarely tribe) are given, except for Pteromalidae, which generally is considered to be the paraphyletic dumping ground of the Chalcidoidea. Family diagnoses are arranged primarily by degree of structural similarity between members, which may or may not reflect phylogenetic relationships (Gibson 1993).

Gibson (1993) provided a key to the families of Chalcidoidea of the world. Regional keys are Nikolskaya (1952) and Medvedev (1978) for the European USSR; Peck, Bou…ek & Hoffer (1964), Europe; Graham 91969), Europe; Riek (1970), Australia; Alayo & Hernandez (1978), Cuba; Prinsloo (1980), Ethiopian region; Yoshimoto (1984), Canada; Subba Rao & Hayat (1985), India and adjacent areas; Bou…ek (1988a), Australasian region; Gauld & Bolton (1988), Britain; Delvare & Aberlenc (1989), tropical Africa and America; Noyes & Valentine (1989b), New Zealand; Grissell & Schauff (1990), Nearctic region; Naumann (1991), Australia.

Specific Geographic Areas

NEARCTIC (CANADA).-- Yoshimoto (1984) discussing Chalcidoidea stated that "The superfamily Chalcidoidea, commonly called chalcids or chalcid flies, is a large group of mostly small parasitic or phytophagous insects within the suborder Apocrita of the Hymenoptera. It is an economically important group of insects, because most of the larvae eat insects, thus helping to control or suppress insect pest populations on forest and agricultural crops (Clausen 1940)."

"The superfamily is recognized as among the numerically largest insect groups and is an extremely diverse assemblage, united mainly on the structure of the pronotum and very reduced wing venation (Riek 1970). The chalcidoids now equal the number of described species of Ichneumonidae and are estimated at over l00,000 species by current workers. The number of world genera of Chalcidoidea has been estimated at 2000 (Noyes 1978). In America north of Mexico, there are about 2000 species known from 466 genera and 18 families (Bou…ek in Peck et al. 1964), or 11 families (Burks in Krombein et al. 1979). In Canada alone, there are about 380 genera and 800 species (Peck 1951, 1963; Burks 1958, 1967, 1979; Yoshimoto 1979)."

On chalcidoid biology, Yoshimoto (1984) noted that "Most female chalcidoids parasitize the eggs, larvae, or pupae of other insects and the eggs or juveniles of arachnids. Others feed on plant tissues of stems, leaves, seeds, or flowers, or stimulate the host plant to develop abnormal vegetative growths, called galls. Many are parasitic, and this behavior is distributed throughout the families of Chalcidoidea, with a few plant-feeding exceptions. The female searches for the host insect by the use of her olfactory, optical, and tactile senses. Chalcidoids are holometabolous. They develop through egg, larval, pupal, and adult stages. The egg is laid either outside or inside the host with the use of the ovipositor, which may be narrow and long as in the Torymidae or short and stubby as in the Eulophidae. Either the egg or the newly hatched larva may be deposited. The position and age of the host are important factors in the choice of host."

"In some chalcidoids such as those of the family Eurytomidae, the larva feeds on plant tissues and it is frequently associated with galls on foliage and stems of many kinds of plants. In the family Torymidae, the members of the genus Megastigmus feed on plant seeds."

"Parasitism is categorized on the basis of where the egg is laid and how the larva feeds. Most species attack the host directly, and the egg is either laid on the host and the larva develops externally (ectoparasitism), or deposited internally and the larva develops inside the host (endoparasitism) (e.g., family Eulophidae). The female eucharid and perilampid deposit the first-instar larva (planidium) directly onto the vegetation where the larva searches for hosts. In the eucharids, the planidium attaches itself to an ant worker and is carried into the nest. The eucharids are parasites only of larvae and pupae of ants. Certain families such as Mymaridae and Trichogrammatidae attack eggs of the host. Most aphelinids attack the nymphs of Homoptera. The torymids attack primarily the larvae in cecidomyiid and cynipid galls; others are secondary parasites on lepidopterous cocoons or dipterous puparia, and a few are phytophagous. Eulophids attack leaf-mining Coleoptera, Diptera and Lepidoptera."

"In the aphelinids, the development of the male and female in the reproductive phase is expressed by the following terminology. The situation in which females develop as primary parasites and males as secondary parasites on their own larval female is known as autoparasitism. When males develop as hyperparasites on females of their own species, this is known as obligate adelphoparasitism, and when males develop on females of different species, this is known as facultative adelphoparasitism. When the female maintains the direct, indirect, or primary relationship and the male becomes a secondary parasite on the female larva or pupa of the same species, this is known as obligate autoparasitism. Much of the reproductive behavior is dependent on the mated or unmated condition of the female (DeBach 1964)."

"In the family Encyrtidae and in some species of Eulophidae, parthenogenesis is common. There are three types of parthenogenesis in chalcidoids, namely, arrhenotoky, deuterotoky, and thelytoky. Most species of parasitic Hymenoptera exhibit facultative parthenogenesis. The eggs may develop either parthenogenetically or zygogenetically, depending on the occurrence of fertilization. In the case of fertilized eggs (zygote), they are diploid and give rise to females, whereas unfertilized eggs (azygote) are haploid and give rise to males. This type of parthenogenesis is known as arrhenotoky. If the unfertilized eggs develop into both sexes (uniparental), this is known as deuterotoky. In obligatory parthenogenesis, each generation consists almost entirely of females, and this phenomenon is known as thelytoky (DeBach 1964)."

"The host rage of a species of chalcidoid varies from a single host species to a large number of species. Hence we may refer to monophagy (a parasite that lives on one host species), oligophagy (a parasite that lives on different species of the same genus), or pleophagy (a parasite that lives on species which belong to different but related families (Bendel-Janssen 1977)."

"When the primary parasite becomes parasitized by another parasite, the condition is known as secondary parasitism, or hyperparasitism. The secondary parasitism may develop into tertiary parasitism, which, in turn, may develop into quarternary parasitism. The primary, secondary, or tertiary parasite, which may itself become a host, may either live in its primary, secondary, or tertiary host at the time it becomes parasitized or it may already have left the host for its own further development (Bendel-Janssen 1977)."

"The larvae of chalcidoids are minute, often only 0.2-0.5 mm long. The greatest variation in larval form occurs in the first-instar larva with 14 types (Clausen 1940; Hagen in DeBach 1964: 179). The development thereafter (3-5 instars), tends to change to the usual hymenopterous type with a full complement of 10 spiracles, 12 or 13 visible segments, the greatest body width in the region of the thorax and first abdominal segment, and the lack of sculpturing, or segmented, processes on the first abdominal segment."

Host lists may be found in Peck (1963) and Burks (in Krombein et al. 1979). Clausen (1940) and Bendel-Janssen (1977) provide details on general biology and host/parasitoid relationships.

On economic importance, Yoshimoto (1984) stated that "The more important groups of chalcidoids, such as Aphelinidae, Eulophidae, Trichogrammatidae, Mymaridae, Encyrtidae, Eurytomidae, and Pteromalidae, are widely used in controlling or suppressing economic pests, both of forest and agricultural crops and those of public health importance. The use of these parasites is an important means of control alternate to chemicals, pathogens, or predators. The practice of integrated control using the above methods is being widely used to suppress target pests of great economic diversity, especially where chemical control measures are not feasible (DeBach 1964; Huffaker & Messenger 1976; Kilgore & Doutt 1967)."

On distribution, Yoshimoto (1984) commented that "Chalcidoids are found in all zoogeographical regions, in all terrestrial habitats except for oceanic islands and islands separated from the "continental mass." Despite the great abundance of numbers and species of chalcidoids, the taxonomy is poorly known (Gordh 1979)."

On fossil records, Yoshimoto (1984) noted that "The oldest fossil records of Chalcidoidea are placed in the Cretaceous period (70-100 million years ago) (Yoshimoto 1975; Rasnitsyn 1980). The ancestral chalcidoids probably flourished about 100 million years ago. They are about half as old as the Xyelidae, the earliest hymenopterous fossils from the Lower Triassic period (Riek 1970). Because of their small size, most of the fossil chalcidoids are represented in amber material. These are placed in nine families with fewer than 70 species; they represent only a small fragment of the present chalcidoid fauna."

Yoshimoto (1984) discussing classification, noted that "The superfamily Chalcidoidea contains moderately small (20 mm) to minute (0.2 mm) insects, many of which are either black or brilliant metallic green. Most of the species are parasitic or hyperparasitic on other insects, spiders, mites, or other arthropods. A few are phytophagous, some of them making plant galls (Ferričre & Kerrich 1958)."

"Within the Hymenoptera, adults of this superfamily are recognizable by the posterior margin of the pronotum touching the tegula, as in some species of Mymaridae and Mymarommatidae, or not touching the tegula (in the latter case, the pronotum is separated from the tegula by the prepectus); the anterior margin of the pronotum usually separated from the neck region by a carina; the venation of the fore wing reduced to a few veins (submarginal, marginal, postmarginal, and stigmal); the propodeum usually bearing plicate (lateral carinae) and a median carina; the prepectus occasionally reduced to a long, narrow projection as in Mymaridae or fused to the pronotum as in most eucharitids and perilampids. The chalcidoids are also the only Hymenoptera where the prothoracic spiracle is situated at or above the level of the tegula."

"Most species of the group have five-segmented tarsi, although the tarsi are three-segmented in the Trichogrammatidae, and four-segmented in most Eulophidae as well as in some Mymaridae, Aphelinidae, and Encyrtidae."

"Many chalcidoids are active jumpers, the stronger ones using their middle legs, which are modified with enlarged tibial spurs and with dense padlike hairs and rows of spines for gripping the surface on the underside of the tarsus. The enlarged mesothoracic muscles evidenced by the inflation of the mesepimeron in such families as Encyrtidae and Aphelinidae, are correlated with this ability to jump. The hind legs with enlarged hind femur seen in Elasmidae sometimes cllassified as a sub family Elasminae in Eulophidae, Chalcididae, and some Torymidae and Pteromalidae are also used in jumping. The hind femur is toothed in at least some members of the last three of these families (Riek 1970)."

"In the recent classification of Chalcidoidea, Ashmead (1904) first proposed the use of 14 families. Nikol'skaya (1952) elevated this number to 24 families, and Bou…ek in Peck et al. (1946) and Graham (1969) reduced it to 18 families including the Mymarommatidae and the Tetracampidae. Riek (1970) recognized only nine families, and Burks in Krombein et al. (1979) recognized 11 families. The following have been treated by some authors as subfamilies: Leucospidinae (Chalcididae); Eupelminae, Signiphorinae, Aphelininae (Encyrtidae); Eucharitinae, Ormyrinae, Perilampinae (Pteromalidae); Agaoninae (Torymidae); and Elasminae (Eulophidae) (excluding Tetracampidae and Mymarommatidae)."

Yoshimoto (1984) follows the classification of Graham (1969) Burks in Krombein et al. (1979), and in part Bou…ek in Peck et al. (1964). Yoshimoto (1984) stated that "The families and subfamilies seem to exhibit coherent morphological and phylogenetic relationships to form a natural grouping. The classification of higher taxa, however, depends upon the opinion of each worker with regard to weight placed on individual character states. The Canadian fauna includes all the Nearctic families with the exception of the Agaonidae."

On anatomy, Yoshimoto (1984) employed the terminology of Graham 91959, 1969) and Richards (1956), and included reference to Hedqvist (1963), Snodgrass (1910, 1935) and Matsuda (1965, 1970).

Yoshimoto (1984) described the various structures as follows:

Head.-- "The compound eyes, which generally occupy the greater part of the side of the head, are the most obvious landmark. The ocelli, typically three, lie at the top of the head between the eyes in a more or less triangular arrangement. The central ocellus is the anterior (median) ocellus, and the outer ocelli are the posterior (lateral) ocelli. The distance between the posterior ocellus and eye margin is the ocellar-ocular line (OOL), and the distance between the posterior ocelli is the postocellar line (POL). Behind the posterior ocelli there is usually a transverse carina, the occipital carina. The region of the head posterior to this is the occiput. The area of the head located between the occipital carina, the inner orbits (margins) of the eyes, and the anterior ocellus is the vertex, and the region posterior to the eye on either side of the vertex is the temple. The area between the ventral margin of the eye and base of the mandible is the gena, and the distance between the ventral edge of the eye and mandibular articulation is the malar space. Often a suture, the malar groove, is present."

"The most obvious structures on the frontal aspect of the head are the antennae. The antennal toruli are the sockets of the antennae. The prominent carina between the toruli is known as the interantennal crest. The area of the head between the toruli, the inner orbits of the eyes and the anterior ocellus is the frons (defined by Graham 1969), and the area between the toruli, the eyes, and the clypeal edge is the face. The clypeus often is a poorly defined mesal region above the oral margin and demarked by the epistomal suture. The scrobes are one or two depressions often present on the frons in which the antennal scape lies at rest."

"The prothorax consists largely of the dorsal sclerite, the pronotum which is variable in shape, an important distinguishing character at the family level. The lateral edges of the pronotum invariably are reflexed ventrally to cover most of the lateral part of the prothorax. The lateral metapleuron, like the mesopleuron, is usually separated into metapisternum and metepimeron by a metapleural suture."

"As noted previously, the first abdominal segment has become fused with the thorax and is known as the propodeum. it bears a pair of spiracles near its lateral edges and often a number of taxonomically important carinae. These are the median carina, plica (lateral carina), and costula (horizontal carina). The apex of the propodeum where it is attached to the gaster may be slightly projected; this projection is known as the nucha. The lateral area of the propodeum laterad of the spiracles is the callus."

Wings.-- "The venation of the fore wing of winged chalcidoids is reduced to a single composite vein, which generally consists of the submarginal, marginal, and postmarginal veins, and often a small stigmal vein projecting between the marginal and postmarginal veins. The stigmal vein often is expanded into a knoblike structure at its apex, the stigma, and this may have a hook, the uncus. The thickened region of the submarginal vein adjacent to the marginal vein is the parastigma. Other obsolescent veins may be indicated on the wing by ridges or hairlines, in particular the basal vein and cubital vein. The speculum, a bare region, is present posterior to the parastigma and bounded in part by the basal and cubital veins. A radial cell may be delineated by the stigmal vein and macrotrichia extending from the stigma toward the apex of the wing. A row of setae below and parallel with the marginal vein are the admarginal hairs. The central part of the wing is the disc."

Legs.-- The legs are composed of the coxa, trochanter, femur, tibia, and tarsus. The trochanter is two-segmented in all chalcidoids except the Mymarommatidae in which the parts have coalesced into a single segment. The tibia apically has one or two tibial spurs; the number of spurs on the fore, middle, and hind legs is known as the tibial formula, e.g., 1-1-1, 1-1-2, 1-2-2. The tarsus is three- to five-segmented; the number of segments is an important distinguishing character at the family level."

Gaster.-- The gaster comprises the abdominal segments posterior to the propodeum, including the petiole, which connects the gaster to the propodeum. In many chalcidoids the petiole may be reduced to an inconspicuous ringlike segment, broader than long, in which case the gaster is said to be "sessile." If, however, the petiole is relatively long and conspicuous, longer than broad, the gaster is said to be "petiolate."

"There are seven gastral segments posterior to the petiole, although not all may be visible, and the ultimate segment is actually the fused remnants of the apical four abdominal segments. The dorsal sclerite of each segment is the tergite, whereas the ventral sclerite is the sternite. The penultimate tergite (t6) bears the only pair of functional spiracles on the gaster. The ultimate gastral tergite bears a small pair of fine hairs, the pygostyli (cerci). The apical segment also has a dorsal and ventral arch, the epipygium and hypopygium, respectively. In most females a pair of ovipositor sheaths, which protect the ovipositor when at rest, project from the apex of the gaster. The degree to which these project is an important distinguishing character for some families."

PALEARCTIC (EUROPEAN former USSR).-- Medvedev (1978/1987), as translated from the Russian, stated that "The superfamily includes 19 families of parasitic hymenopterans, of which only one (the family Tanaostigmatidae) is note represented in the fauna of the Soviet Union. Chalcids are 2.0 to 3.0 mm long. The smallest of them, the egg parasite Alaptur magnanimus Annecke, is one of the smallest insects, with a body length of about 0.2 mm. Larger species reach more than 10 mm in body length. Chalcids are almost always differentiated by the venation of their forewings; only a few veins have been retained, which have been tentatively named as follows: marginal, postmarginal, and radial or stigmal. Sometimes the postmarginal or marginal veins are absent and the radial vein highly reduced, but usually the general pattern of venation of the forewings of chalcids is maintained. Some proctotrupoids have a similar venation, especially those of the subfamily Telenominae. However, unlike proctotrupoids, in chalcids the pronotum does not reach the tegulae because the unique postspiracular sclerites are located here. Adults lead a unique mode of life. By and large they are poor fliers and generally confined to their host habitats. They either feed on the nectar of flowers or sweet secretions of suctorial insects such as coccids, aphids, and psyllids; female chalcids often feed on the hemolymph of their host after killing it with their ovipositor. The chalcid larvae are ecto- or endoparasites of various arthropods, predominantly insects. Predators are rare among them, while in some families (Eurytomidae and Torymidae) phytophagous species are common (even serious pests are present, for example, eurytomids of the genus Tetramesa and seed chalcids). All Agaonidae are phytophages and develop in the influorescences of the genus Ficus. Many chalcids live at the cost of other parasitic hymenopterans, constituting second and third order parasites. The number of species in the superfamily Chalcidoidea is very large; estimates reach dozens of thousands and far from all have been described and classified. Those of arid regions and the tropics in particular have not been studied well."

"The chalcid families are neither equal in volume nor economic importance, although each exhibits fairly distinctive biological characteristics. The families Pteromalidae and Eulophidae predominate in the European part of the USSR, and are primarily parasites of flies, Lepidoptera, and beetles, and even secondary parasites. The population strength and species variability of the family Eurytomidae increase in a southerly direction. Eurytomids are parasites of the most varied insects, especially those inhabiting stems and galls of plants; many eurytomids are secondary phytophages. The number of species of the family Encyrtidae also increases southward. Encyrtids constitute a highly specialized family, primarily associated with suctorial insects, mainly coccids. In northern regions encyrtids prefer dry habitats (slopes with a southern exposure, sand, and limestone deposits). Like encyrtids, members of the family Aphelinidae are also common parasites of coccids (and aphids); nevertheless this family is not related to encyrtids but to eulophids; the similarity in body dimensions of encyrtids and aphelinids is convergent. The fairly large family Torymidae includes parasites of gall-forming insects, Lepidoptera, eggs in the oothecae of the praying mantis, and seed chalcids. The subfamily Toryminae is richly represented in the forest zone and Monodontomerinae in the steppes and deserts. Practical entomologists are well acquainted with the egg parasites of the genus Trichogramma, which are used in the biological control of Lepidoptera pests; this genus belongs to the widespread, but poorly studied, family Trichogrammatidae, which comprises very minute egg parasites. Larvae of the family Mymaridae also develop exclusively in the eggs of insects, but the inclusion of this family in the superfamily Chalcidoidea is still a controversial issue. The family Chalcididae is rarely seen in the northern regions of the European part of the USSR, but quite common in the south. Chalcidids are larger, with highly thickened hind femora, and mainly primary and secondary parasites of Lepidoptera and flies. The family Eupelmidae is quite unique in that these species arch their body upward and forward; eupelmids are also common in the southern European part of the USSR."

"In addition to the more or less widespread families of Chalcidoidea mentioned above, another eight smaller families of this superfamily are represented in the Soviet Union: Perilampidae, Eucharitidae, Leucospididae, Tetracampidae, Elasmidae, Ormyridae, Signiphoridae, and Agaonidae. Some of these families thrive in tropical regions and hence only a fraction of their fauna, meager offshoots, have been found here."

"The affinity between the various families of the superfamily Chalcidoidea is not well understood. Almost all the families reveal a more or less high degree of morphological and biological evolution. Nevertheless, some can be separated into rather definitive groups. The families Tetracampidae, Eulophidae, Elasmidae and Aphelinidae may be combined into the eulophid group which, possibly, could also include the family Trichogrammatidae. The families Pteromalidae, Tanaostigmatidae, Eupelmidae and Encyrtidae constitute the pteromalid group. The present volume includes 555 genera with 2,489 species of Chalcidoidea."

INDIA & ENVIRONS.-- Subba-Rao & Hayat (1985) discussing Chalcidoidea, noted that this is one of the six superfamilies of the order Hymenoptera whose members are mostly parasitoids: parasitic in their pre-imaginal stages and free-living as adults. They state that "Chalcidoids are the most difficult among the Hymenoptera to identify, not only because of their minute to small size, but also due to lack of useful keys to families, tribes, genera and species. The literature on chalcids is vast, but scattered; and most of it is not meant for the beginner. Therefore, students who take up for study the taxonomy of any chalcid group may find the going very hard and difficult. We, however, do not claim that this work will take that initial burden off the beginners' intellectual shoulders. It should at least tell them the present state of knowledge on Chalcidoidea of India and the adjacent countries, and should additionally help them identify the known fauna from the region."

"The study of 'chalcids', as the members of this superfamily are generally known, may have begun with Carl Linnaeus who described several taxa under Ichneumon, Cynips, etc. Subsequently, biologists like Swederus, Fabricius, Dalman, Dahlbom, Thomson, Mayr, Foerster, Motschulsky, Haliday, Westwood, Walker, and a few others described many genera and species. Yet, the real foundation for serious taxonomic studies of chalcids was laid by Ashmead (1904) who for the first time brought all the known information together and presented keys to families, subfamilies, tribes and genera of Chalcidoidea."

"Chalcidoids are of world-wide distribution and are found in all zoogeographical regions. Taxonomically, the western Palaearctic fauna is better known because of the works of early European and some recent taxonomists (Z. Bou…ek, M.W.R. de V. Graham, V. A. Trjapitcyn), followed by the fauna of the Nearctic and the Neotropical regions; the latter mainly due to the contributions of L. De Santis. Whatever is known of the Australian chalcids is entirely due to the monumental yet, the most confusing contributions of A. A. Girault. The Ethiopian (= Afrotropical) and the Oriental fauna are relatively less known."

"Large as the chalcidoid fauna is, their numerical dimensions can only be speculated. Noyes (1978 & pers. com.) estimated about 20,000 species that constitute the Chalcidoidea of the world as we know them today. Again, there is no doubt, that this number is only a fraction of what is yet to be encountered."

"Chalcidoids have diverse feeding habits, exhibiting both entomophagy and phytophagy. While a majority of these develop as endo- or ecto-parasites of other insects, some develop in the seeds and some form galls. The phytophagous species are known among Eurytomidae, Torymidae and Tanaostigmatidae and some Pteromalidae. Chalcidoids parasitize a great number of insect species in more different taxonomic categories than any other group of insect parasites like ichneumonids and braconids. Some encyrtids are known to attack ticks and also eggs of spiders. Some mymarids and trichogrammatids are capable of diving into the water, search for hosts which are invariably aquatic insects and parasitize them."

"Parthenogenesis is common among Hymenoptera and chalcids demonstrate arrhenotoky, thelytoky and deuterotoky in their reproduction. Arrhenotokous type of reproduction is the most common among chalcidoids, in which males develop from unfertilized eggs. Thelytokous form of reproduction is not uncommon, where males are not known at all, or occasionally a male or two may be encountered among the population, that too in several generations. Deuterotokous form of reproduction is also met with in which males and females are produced from fertilized eggs [authors probably meant unfertilized eggs]. Polyembryony, a phenomenon in which several to several hundred or even thousands of imagines emerge from a singe egg, is met with in several genera of the family Encyrtidae."

"Because of these diverse parasitic habits, chalcidoids have been utilised, and mostly with encouraging results, for the control of insect and other arthropod pests of agricultural and horticultural crops. It is this aspect of the chalcidoid habit that makes them economically important, and that provides the excuse, if an excuse is needed, for a scientific study of these 'pygmies' of the insect world."

AUSTRALASIA.-- Bou…ek (1988) discussing the characteristics of a chalcid stated that "All chalcids have the wing venation greatly reduced, generally to one linear vein, without any closed cells, but such reduction is found also in some other groups. Another important feature is found on the anterior part of the thorax; the prepectus. It is a subtriangular sclerite between the lateral panel of the pronotum and the tegula. The prepectus is absent in the proctotrupoid families which otherwise in venation resemble chalcids. In chalcids the prepectus is reduced very rarely (in Rotoita and in some Macromesus), but then the mesothoracic spiracle can be found at the dorso-lateral margin of the mesoscutum. In the proctotrupoid groups this spiracle is always situated much lower. The chalcidoid antennae are almost always elbowed between the scapus and the rest (indistinctly so in some Eucharitidae)."

"Other chalcidoid characters may be difficult to see. They include longitudinal placoid sensilla on at least some segments of the flagellum, the second abdominal segment, i.e. the one immediately after the propodeum, transformed into the petiole and always differentiated from the rest of the abdomen, which is here called the gaster. The gaster bears one pair of spiracles, on the sixth tergite (eighth abdominal tergite). Another feature is the form of the ovipositor and its components."

Chalcid Biology.-- On this subject, Bou…ek (1988) stated that "The biology of chalcids is unusually diverse and often fascinating. Studies of life history, ecology, behaviour, physiology or any other facet of life are often undertaken in universities as a part of general biological projects. Such studies are also a necessity for the economic entomologist focussing his interest on a particular pest or its natural enemies. For the taxonomist the biological attributes are often a test of his taxonomic hypotheses and supplement the morphological characteristics, i.e. they may provide confirmation of his conclusions or a signal that something needs a deeper study. In some cases a discordance of opinion suggests biological variation within a species, but more often a process of biological specialisation, speciation, which is not yet reflected sufficiently in the morphological characters. Such hardly detectable entities may be reproductively isolated (sibling species) and have to be taken into account in biological control. In such cases our concept of species is inadequate, especially in conjunction with the restrictive use of nomenclature. Its rules (Code) accept only the species and subspecies categories but not all gradual states of speciation which apparently exist in the evolution of perhaps every species."

"Such situations come to light only in very detailed biological studies, in particular those concerning the host-specificity and host-acceptance of some species tested for suitability for biological control, be it for weeds or insect pests. Normally only much cruder information is accumulated, especially in the relatively little known groups which are the subject of the present study."

"In Australasia various biological details have been studied in relatively few species of chalcids, mainly by Noble (1932-1941). However, much more information concerning the same groups is available from other parts of the world. Extensive reviews, especially on the parasitic species, are found particularly in Clausen (1940b), shorter summaries in Doutt (1959), Askew (1971) and Gauld & Bolton (in press). Especially useful information on many entomophagous species studied in conjunction with pest insects was compiled by Clausen (1956, and especially 1978), wider aspects connected with biological control by DeBach & Schlinger (1964). Some general information can be gained from works on the Australasian Ichneumonidae (e.g. Gauld, 1984). Several special subjects attracted some attention, e.g. hyperparasitism (Rosen, 1981; Sullivan, 1987) and the mating behaviour or courtship. The latter was earlier studied only occasionally in chalcids, but recently an important centre specialising in the subject has developed in Leiden, founded by Dr. van den Assem. The courtship of a number of species of Melittobia (Eulophidae) was compared (Assem & al., 1982 [van den Assem in references]); this provided a biological basis for a taxonomic revision of the genus (Dahms, 1984a). Information is gradually accumulating on various groups, sometimes resulting in suggested modifications of the phylogeny of the groups studied (see Assem, 1974, 1976; Assem & Al.: Bosch & Assem)."

"Reproduction of chalcids is mostly bisexual and, as generally in Hymenoptera, the males are haploid, i.e. have only half of the chromosomes of females which are diploid. Normally the fertilised egg produces a female and the unfertilised egg a male (arrhenotoky). The sperm is kept in a spermatheca and the female can lay either unfertilised or fertilised eggs, as is well known in the honeybee. In parasitic species the males are usually smaller than females and can develop on a smaller host. The pteromalid Lariophagus distinguendus lays unfertilised male eggs onto a small larva of the granary weevil, Sitophilus granarius, and female eggs (fertilised) on larger older larvae of the host (Assem & al., 1984). In some species parthenogenetic reproduction, i.e without mating, is widespread and mostly females are produced (thelytoky). Sometimes populations introduced outside the area of their original distribution consist only of females. For instance Macroneura vesicularis in New Zealand and North America is thelytokous and found only as females, whilst in Europe both sexes readily occur; hence Europe is regarded as the country of origin of the species." [this is not a valid criterion for judging point of origin, given that bacterial infection is now known to cause thelytoky].

[This is not true for all strains of a species]. "In gregarious species, where many individuals emerge in a sheltered situation, as for example in a fig syconium (many fig-wasps) or in cells of large hosts under bark or a cavity in wood (Melittobia) or some other restricted niche (Nasonia), the males may be brachypterous or wingless and mate with their sisters. The latter are fully winged and disperse after mating in search for hosts. In most species males search for females, then sometimes the females may be shortwinged but the males are always fully winged. brachyptery and especially aptery (complete absence of wings) are always associated with great differences between the wingless sex and the winged one, in an evident dimorphism. Such extreme dimorphism is found in some Pteromalidae (e.g. Diparinae), most Agaonidae, many Eupelmidae, and Encyrtidae, but rather rarely in other families, and no brachypterous or apterous forms are known in Chalcididae, Leucospidae, Torymidae, Perilampidae, Eucharitidae, Signiphoridae and Tetracampidae. In some Agaonidae (e.g. Camarothorax) the females may be macropterous and the males are apterous or brachypterous (trimorphism). Otherwise sexual dimorphism is commonplace, exhibited at least in the form of the gastral apex and the antennae; there are very few exceptions to this, e.g. some Euplectrus (Eulophidae)."

"The adults are generally not very good fliers, although there are some exceptions. For instance agaonid females are often found dozens of miles away from any fig and where the suitable fig species has a very dispersed distribution it is necessary for the agaonid to travel long distances."

"The larvae of Chalcidoidea have so far attracted only casual attention, except for the excellent paper by Parker (1924). His study was based on various European species but belonging to genera mostly also represented in Australasia. His work shows, however, how little is available for an eventual appraisal of the chalcid larval morphology. There is little hope that its analysis will provide such a useful tool for classification as has been found in larval morphology of Ichneumonidae and Braconidae."

"As normal in Hymenoptera, the chalcid pupa has free limbs (pupa libera), but in Entedoninae (Eulophidae) the pupal surface is fused as in pupa obtecta (as in Lepidoptera). Before pupating the chalcid larvae do not spin any cocoon, except for a loose cocoon prepared by the gregariously ectoparasitic larvae of Euplectrini (Eulophidae). Another exception is the pteromalid genus Systasis (see Askew, 1971: 140)."

"Adult chalcids sometimes live a short time (e.g. some Eucharitidae) and do not take any food, but most species, at least the females, live for weeks or months and then have to take at least some water. Many species also take nectar and honeydew and consequently visit flowers offering them accessible nectar, or plants with aphid colonies. The females of many species get proteins by 'host-feeding,' ie. they lick oozing body fluid after piercing the skin of the host. This sometimes happens after oviposition but often the parasite makes a wound solely in order to obtain these nutrients and does not lay an egg in the host. The host insect may die from the infection in the wound, or even from loss of the body fluid. If the host so attacked is in a shelter, e.g. within a cocoon, a tube is constructed by a secretion coming from the ovipositor, as described and figured by Fulton (1933) for Pteromalus cerealellae (see also Clausen, 1940b: 123). The population of pest species may be strongly reduced by host-feeding of the parasites."

"Chalcids belong to Hymenoptera Parasitica but not all of them are parasites, however. Some of them develop, partly or exclusively on a vegetarian diet, i.e. are phytophagous, whilst others are entomophagous."

Phythphagous Chalcids.

"Phytophagy is found in Eurytomidae, Torymidae, Agaonidae, Pteromalidae, Tanaostigmatidae and Eulophidae (e.g. Gahan 1922a; now rather out of date). it appears in a number of groups, some of which seem to be rather old, primitive and therefore in them phytophagy may be the primary way of life. In Eurytomidae, however, the Rileyinae, perhaps the oldest group, seem to include only entomophagous species and the phytophagous ones are found only in the more derived Eurytominae. Certain genera are wholly phytophagous (e.g. Tetramesa), others only partly so (e.g. Eurytoma). In the latter genus several species are known to develop as parasites on the phytophagous larvae of Tetramesa and at least in one case it was proved that if a young host larva is attacked, it is soon consumed and the 'entomophagous' Eurytoma larva then turns to the surrounding plant tissue (in a grass stem) and completes its development as a 'phytophagous' one. This suggests a secondary phytophagy. The explanation seems easy but a generalisation should be made with some caution. it seems, that the feeding habit of Tetramesa and of many other groups, is primarily phytophagous.

"Another well known example is the pollinating fig-wasps, Agaoninae. Apart from the pollination by the adult, which is regarded as a high specialisation, the fig-wasp larva causes excessive growth of the ovarium of the fig flower and is actually a gall-causer. Gall-producing chalcids are found amongst Eurytomidae, Agaonidae, Pteromalidae, Tanaostigmatidae and Eulophidae. Some other species use the gall tissue as food bud do not cause galls themselves. These are the inquilines; they often co-exist with the gall-causers but in the past they were often labelled as 'parasites,' although probably most of them develop solely on plant tissues. Some of them, as recently discovered about Epichrysomalinae and Otitesellinae (of fig wasps), gall the female florets of figs as do the pollinating Agaoninae."

"The association of chalcid with plant galls is generally widespread. In Australasia, more than in most other regions, some species are known and others are suspected to be gall-makers. Tetramesa for instance is a cosmopolitan genus causing swelling, shortening and other deformations of grass stems, but the genus is relatively poorly represented in the region. A number of forms are associated with galls on eucalypts and acacias. The eulophids of the genus Ophelimus (earlier Rhicnopeltella) are suspected causers of small globular galls on leaves and other fresh growths on eucalypt species introduced from Australia to New Zealand, because no other insects were reared from the galls (Valentine, 1970; Somerfield, 1976). Species of another eulophid genus, Quadrastichodella, cause small seed-like galls in eucalypt flowers and these galls may then be introduced, mixed with seeds, to various countries, despite quarantine measures (Flock, 1957; Bou…ek, 1977b). A number of Australian pteromalids are gall-causers, especially the Ormocerinae. One of them, the bud-galling Trichilogaster acaciaelongifoliae, was recently introduced in the Cape Province of South Africa and proved very efficient in control of the earlier introduced Acacia longifolia growing as a weed. The galling of the acacia buds is so massive that it prevents the plant from producing any seed. Another gall-producing pteromalid is the peculiar, Austrosystasis developing in 'bullet-galls' on Eleocarpus. Many other Ormocerinae and Coelocybinae probably are phytophagous inquilines in the galls, as shown for Coelocyba aurocincta by Noble (1941). The torymids of the genus Xenostigmus gall buds of Hakea. Also tanaostigmatids, or at least some of them, are generally gall-causers, although there is so far no reliable regional evidence, apart from a rather confusing statement about Tanaostigmodes velasquezi (Girault, 1933 [440]: (5))."

"Another group of phytophagous species are the seed-eaters (some Eurytomidae, Torymidae and Eulophidae). They feed on the rich seed tissues but do not produce a noticeable deformation. The above-mentioned genus Eurytoma also includes seed-eaters, but most species of that genus are clearly entomophagous and so far these habits have been found to bear little relationship to the taxonomy of the genus, except perhaps at the species-group level. It seems that in some other eurytomids the seed-eating habit is more consistently associated with the generic classification, especially in Bruchophagus, Systole and allied forms. Systole, as understood here, is confined to seeds of Cruciferae (Daucaceae), but Bruchophagus includes not only species feeding in seeds of Papilionaceae (Viciaceae) (including clover and lucerne) but also causing galls or developing in galls on various other plants, (e.g. Bruchophagus fellis and B. muli on Citrus). In other groups the torymids classified in Bootania are seed-eaters in Pandanus, some of those of Bootanelleus in Casuarina, some pteromalids of the genus Systasis develop in grass-seeds, etc."

Parasitoids (Entomophagous Chalcids).

"Most chalcids develop by feeding on other insects, rarely on some other arthropods (spiders, mites), and are called entomophagous. They are regarded as parasites in the broad sense, but because in general only the larval stages of chalcids feed this way, they are called either protelean parasites (e.g. Askew, 1971) or parasitoids. The meaning of the latter term has not been always well defined (see e.g. Doutt, 1959: 161) but most recently its use is spreading. In the present work the term parasite is preferred, because it enables us to use other derived terms, such as to parasitise, parasitic Hymenoptera, hyperparasitism, etc. It would be cumbersome to use derivatives of 'parasitoid.'"

"A parasite is understood to develop on one individual of its host, in distinction from a predator which consumes more individuals (called prey). The difference between the two is sometimes not easy to define. A larva of certain Eupelmus species attacking pockets of cicadid eggs embedded in plant tissue, may devour one or several eggs to complete development. On the contrary, if the host is much larger than the parasite, several eggs may be laid and the chalcid parasite is gregarious instead of solitary (if one parasite develops on one host). Some pupal parasites are gregarious. A special case of gregarious parasites are the polyembryonic encyrtids of several genera related to Copidosoma Ratzeburg. The early stages of the embryo separate into several to many clusters of cells most of which grow up into normal larvae, so that a single laid egg of the parasite gives rise to many individuals of the species."

"The parasitic species are often grouped according to the stage of the host attacked and according to the taxonomic groups to which the hosts belong. In economic entomology it is of particular importance as to whether the parasite attacks only one host species (monophagy), several host species (oligophagy) or many host species (polyphagy). It is also of the first importance to define the relationship of a parasite to its host species, particularly those which are pests. A parasite may be defined as primary, secondary or even of the third or fourth grade. The primary parasite attacks only a phytophagous or otherwise non-parasitic species. It may be stable in this habit: an obligate primary parasite. Some of the originally primary parasites may occasionally be able to complete development on a host already attacked by another primary parasite, destroying the latter in the process. In most cases this possibility of facultative secondary parasitism excludes such as species from use in biological control. Only rarely, if the secondary parasitic habit (hyperparasitism) does not prevail, both the primary and the facultatively secondary parasite may be used to enhance the restrictive effect on a pest species. For instance Aprostocetus (formerly under Tetrastichus) sokolowskii (Kurdjumov) is used against Plutella xylostella (L.), although it also destroys, but not preferentially, another primary parasite of Plutella, Apanteles plutellae Kurdjumov (Greathead, 1986: 307). Some chalcids are obligate hyperparasites, such as certain species of Brachymeria attacking tachinids and sarcophagids in pupae of Lepidoptera."

"The eggs are laid on (ectoparasites) or into the host (egg-parasites and various endoparasites). Well known exceptions are found in Perilampinae and Eucharitidae. Their eggs are laid mostly far from the actual host and the first-instar larva is of the planidium-type; it has no legs but the side margins of the tergites are produced ventrally and enable the larva to move. In many perilampids the planidium actively searches for the host and then attaches itself on it (e.g. Monacon) or bores into it and there waits till a primary endoparasite (braconid, ichneumonid or tachinid) eventually attacks the same host. The perilampid then gets into the body of the larva of this primary parasite (some Perilampus). In eucharitids the eggs are laid on leaves or in buds of plants in large numbers, because many larvae do not reach a suitable host. This is always an ant species. The planidium attaches itself on an ant which carries it into the nest and there the larva has to find an ant larva, but delays feeding till the host reaches sufficient size."

"The attacked host is often immediately prevented from further growth and feeding, but in other cases the parasitic chalcid larva coexists with the feeding host for a considerable time. First Haselbarth (1979), and then Askew & Shaw (1986) have drawn attention to this important difference. Haselbarth termed the former parasites 'idiophytic' and the latter 'koinophytic,' whilst Askew & Shaw called them, perhaps more conveniently, idiobionts and koinobionts. The idiobionts include particularly the parasitic species attacking non-feeding stages of hosts, such as eggs and pupae, and they terminate the life of the host before it reaches the feeding stage. Host larvae and adults subjected to permanent paralysis by the attack of a parasite are also victims of the idiobiont strategy. On the other hand koinobionts are in particular larval and egg-larval parasite, less often among those attacking adult hosts. The koinobiont larva feeds first slowly on the host, allowing it to grow (and continue to be injurious to its host-plant, though the host's food consumption is often reduced). Its host may reach the stage of a mature larva or prepupa or even pupa, though often of reduced growth, before the parasite kills it."

"Among the Australasian groups dealt with here egg-parasites are known among Eurytomidae, Torymidae, Pteromalidae, Eupelmidae, Tetracampidae and Eulophidae. Several species of Axanthosoma and Eurytoma develop in eggs of Cicadidae and Gryllidae. The torymid species of Podagrionini attack mantid oothecae, those of Chrysochalcissa and Rhynchoticida eggs of several families of Heteroptera, e.g. Pentatomidae. The large family Pteromalidae includes relatively few egg-parasites. In the region they are found in cockroach eggs under bark (Agamerion), but most such pteromalids attack heteropterous and lepidopterous eggs similarly exposed in groups on plant leaves (Klabonosa, Acroclisoides, Agiommatus, Acroclisissa), whereas Neopolycystus species and several tetracampids develop in chrysomelid eggs. Some extralimital pteromalids attack eggs of Orthoptera, of Curculionidae, more rarely of other insects. Eupelmids of Anastatus and several related genera, also some Eupelmus, are parasitic (or predatory) on eggs of Heteroptera, Lepidoptera, less often (Eupelmus and allies) of the cicadas, grasshoppers, crickets or mantids. The eulophid Arachnoobius develops in egg sacs of certain spiders."

"Most regional species are probably larval and egg-larval parasites. The latter are known among some attackers of leaf-miners and in the genus Entedon, Eulophidae. They are typical koinobionts. The pupal parasites attack either prepupae or pupae and some tend to hyperparasitism, as there is probably not much differences between food provided by the body of a lepidopterous larva and the body of a braconid eating that lepidopteron."

"The pupal parasites are very common among Chalcididae, some eurytomid genera close to Eurytoma, some Monodontomerinae (Torymidae), and especially a number of genera of Pteromlinae. In Eulophidae, a similar role is played by some Tetrastichus."

World patterns of distribution

Faunistic Elements of Australasian Chalcids.-- Bou…ek (1988) noted that "The composition of the fauna largely depends on the geological history of the region. Most chalcids are not primarily associated with plants, but the group seems to have evolved parallel to the angiosperms since their rapid differentiation in the middle Cretaceous. Therefore the regional history of the Australasian biota, from the Gondwanaland to the present, with the subsequent displacement of the landmasses, reviewed by Barlow (1981) for the botanists, provides much useful information for us."

"Many groups of the regional fauna are much better known than chalcids and their species have been classified into several groups, mainly according to their supposed origin and their present distribution. A short review has been provided e.g. by Mackerras (1970). In chalcids such grouping has to await a revision of species, and more information, especially also from other parts of the world. In spite of the unreliability of conclusions based on the generic classification it seems that in chalcids the grouping is quite similar to the results obtained in much better known groups."

"There are altogether about 550 genera available for assessment, but about 10 of them come from outside the limits of the area. Of the circa 540 Australasian ones, 167 were found only in Australia, 14 only in New Zealand, 19 only in New Guinea or the Solomon Islands. The Australian endemic ones include 93 pteromalid genera, 34 eulophid ones, 13 torymid, 9 eucharitid, 8 eurytomid genera and only a few in other families. Most of the solely New Zealand genera belong to Eulophidae (7) and Pteromalidae (6), in New Guinea to Pteromalidae (10), Agaonidae (14) and Eulophidae (4). The difference between New Guinea and Australia is emphasized by the distinct Oriental element in the New Guinean fauna. Gressitt (1982) concluded that the New Guinea fauna appears to be mainly Oriental, with a relatively weak Australian element. Although the southern lowlands of New Guinea are a part of the Australian plate of Gondwanian origin and separated from Australia only by the shallow Torres Strait, the southern influence is weaker than might be expected. The actual barrier between the Australian elements and the Oriental ones in the southern edge of the rain-forest. Further east the Oriental elements become poorer and intermixed with the endemic forms. New Caledonia seems to have also some additional Australian elements. In chalcids the available data seem to confirm those findings. Several Australian elements were found only around Port Moresby, in the dry-savannah conditions, only odd rain-forest species, close to the Australian ones, in the Highlands."

"The New Zealand fauna of Chalcidoidea is much poorer than that of other parts of Australasia. it includes several ancestral elements such as the Rotoitidae (Rotoita) and the pteromalid genera Zeala, Errolia and Fusiterga. The remaining 10 endemic genera are probably descendants of related forms which arrived at various times from Australia, probably carried by the strong westerly winds. Several more genera are found both in Australia and New Zealand, but in different species. Progenies of some such successful arrivals speciated extensively in new habitats. Judging from the unusually wide variation of some New Zealand species the process of rapid speciation is still going on in present times. Apart from these Australasian elements there is also a high percentage of species introduced by man from the northern hemisphere, in particular from Europe."

"In Australia, apart from the endemic forms two elements seem to be outstanding: the Palaeotropical one and the Asio-Australian one. The latter is due to the spreading of the Oriental elements eastwards. Altogether 51 genera are Asio-Australian ones, including Eulophidae (10), Pteromalidae (15), Agaonidae (10), Chalcididae (6), Eucharitidae (5), Torymidae (2) and Eupelmidae (2)."

"The Palaeotropical forms are sometimes called Lemurian, as they usually include Madagascar in their distribution, covering land masses around the Indian ocean. However, the Chalcidoidea in most of these areas are only poorly known. Included in the following numbers are a few genera which are found not only in Africa but also in the Mediterranean region and that suggests that not all components may belong to the same element. There are at least 79 genera of a Palaeotropical distribution, belonging to the following families: Pteromalidae (26), Eulophidae (17), Agaonidae (10), Chalcididae (7), Torymidae (6), fewer in Perilampidae (3), Eurytomidae, Cucharitidae, Eupelmidae and Tetracampidae (each 2). Compared with that there are at least 90 more or less cosmopolitan genera and at least 13 circumtropical ones in Australia. Most of the latter include parasites secondarily distributed with some widespread hosts, especially pests of rice, sorghum and other crops. For instance Eupelmus australiensis, associated with midges on sorghum and rice, probably came originally from southern Asia, but its valid name was given to it in Australia, it was named popa in Florida and has several other synonyms including one from the Ukraine (USSR)."

A more meaningful pattern than that given by numbers of genera is provided by the distribution of certain old chalcidoid groups, partly phytophagous, partly parasites of wood-boring beetles."

"The pteromalid Melanosomellini (formerly Brachyscelidiphagini) include about 30 genera of which 26 are found in Australasia. Of these 23 are known from Australia only, 2 reach Africa, 1 Southeast Asia. A similar distribution, yet more restricted, is found in Coelocybinae, with altogether 15 genera. Of these one is South American, associated with Nothofagus, 13 occur in Australia, 2 in New Zealand (1 in common with Australia). The two groups are closely associated with plants, as their members are, as far as is known, gall-causers or otherwise phytophagous, some possibly develop in inquilines in galls of other insects. They could be of Gondwanian origin."

"Another such ancestral group is the pteromalid subfamily Colotrechninae the species of which, as far as known, are also associated with galls. From 15 genera 12 are found in the region and only one of them, Colotrechnus, is distributed also in other major regions, whilst 2 genera are endemic to New Zealand and 6 to Australia (and 3 to South America)."

"Australasia, especially Australia, has a rich coccoid fauna (e.g. mealy bugs; Williams, 1985). One group of their enemies belongs to Eunotinae (Pteromalidae) and therefore it is not surprising that eunotines, in particular the tribe Moranilini, has most of its members in the region."

"Moranilini include altogether 16 genera of which 9 are found only in Australia, 2 only in New Zealand, 1 only in New Guinea (plus 1 in common with Australia). Of the Australian ones Ophelosia reaches parts of Southeast Asia. Two eunotine genera are largely circumtropical, but probably of Australian origin (Moranila, Cephaleta)."

"Another solely Australian genus, the primitive pteromalid Keirana, was reared from a primitive coccoid of the family Margarodidae (Callipappus)."

"In Eulophidae the forms with a greater number of antennal segments are regarded as most ancestral. Kerya, with 12 antennal segments, and Anselmellini (3 genera) with 11 segments are known from Australia, and of the latter group only Anselmella is more widely distributed, as far as India and Fiji. Another such genus with many antennal segments is Platytetracampe. This and Kerya are known so far from single specimens. No related forms are known from elsewhere and if they are not represented in South America it may mean that the latter continent split off from the Gondwanian land mass before eulophids came into existence."

"Among the parasites of xylophagous (wood-boring) beetles most significant as primitive chalcids (and biogeographical indicators) seem to be some pteromalid groups, especially Cleonyminae, apart from odd genera of several other subfamilies (Leptofoeninae, Nefoeninae) or families (Chalcididae, Eupelmidae). Cleonyminae presently include some 30 genera and are found in all continents. However, no less than 24 are represented in Australasia and from these 13 are found only in Australia, 3 others in Australia and New Guinea, and 5 are of wider, mostly Palaeotropical distribution. Only two genera of the last group are found in New Zealand. The genus Epistenia is well represented in the Neotropical region, in Australasia Parepistenia is its closest relative. Of all genera of this subfamily only these 2 suggest a possible transantarctic relationship, i.e. a probable Gondwanian origin."

"Only Pteromalidae seem to include groups old enough to be in existence before the split-up of the Gondwanaland, whilst the most primitive Eulophidae (Anselmellini and Kerya) are not known to have close relatives in other southern landmasses."

"It may be concluded that although a number of Australasian genera of chalcids belong to the so-called southern element, even in the most ancestral groups there is little positive evidence for a Gondwanian origin."

Origins/Relationships of Chalcidoidea.

Bou…ek (1988) commented that "The phylogeny of the superfamily has not been thoroughly studied; it has received some attention only in the last two decades. It cannot rely on fossil records, because the small and often only weakly sclerotised bodies of these wasps do not preserve well. Therefore only the resin inclusions offer some help, but they are at most about 90 million years old (mya), and they exhibit samples of certain groups which were at that time already fairly specialised. The oldest ones, from Cretaceous Canadian amber (Yoshimoto, 1975) and from Siberian deposits of about the same age, include only Mymaridae, Tetracampidae, Trichogrammatidae and the questionably chalcidoid Mymarommatidae. Most of these forms (if not all) are probably egg-parasites. The groups which we regard as most ancestral, such as some Chalcididae, Eurytomidae, Pteromalidae and perhaps Torymidae, all with relatively heavier bodies than the former groups, appear among fossils only from the Tertiary, about 60 mya."

"Another approach to studies of ancestral links is by an analysis of the morphology of the extant forms. This has received major impetus from the recent widespread application of cladistic methods. However, this method has not yet been fully exploited, mainly because the chalcidoid groups are taxonomically still rather poorly known. The main problem is to decide which of the character states are derived (apomorphic) and which are ancestral (plesiomorphic). For instance it is still uncertain how to rate phytophagy in relation to entomophagy. Another problem arises from apparent losses of synapomorphic features in some more specialised members of a presumably monophyletic group or in the same linear. Unless the groundplant characters of a group can be reliably identified it is not possible to construct a credible phylogenetic tree. In this respect much work is being done at present, but only in few and rather small groups, while the bulk of chalcidoids has as yet received little attention."

"The first concentrated attempt to find synapomorphies for Chalcidoidea was made by Königsmann (1978). He agreed with the previous views according to which the superfamily may be a sister group of Cynipoidea. This has been confirmed rather than refuted by more recent work, although some doubts remain. Much attention has been paid to the peculiar Mymarommatidae. The group was transferred to Serphitidae (mainly fossil) of Proctotrupoidea by Kozlov & Rasnitsyn (1979), and to Diaprioidea by Rasnitzin (1980), but regarded as closer to Chalcidoidea, although probably best as a separate superfamily, by Gibson (1986a). In the present paper it is keyed out but not dealt with."

"Within Chalcidoidea only Mymaridae were singled out as probably a sister group of the complex of all remaining families (Gibson, 1986a), based on synapomorphies which, however, may be merely specialised features of egg-parasites. Otherwise only the complex of Eupelmidae-Encyrtidae- Tanaostigmatidae has been studied in some depth (Gibson, 1985, 1986b), particularly the thorax morphology including the musculature, and the possible relationship of Chrysolampinae- Perilampinae-Eucharitidae, based on larval morphology (Heraty & Darling, 1984)."

"In view of this situation a more conservative view is presented here as to the relationships and limits of the families. First, because it has not been a priority for this work; second, because it needs much more study to be sure how to interpret some results which, generally, offer very tenuous reasons for changes."

Classification.

Commenting on classification, Bou…ek (1988) stated that "During the whole study the main aim has been practical identification of the genera. The higher classification could not be given satisfactory attention, and this applies also to the family limits. Some changes have been made, however, e.g. in uniting the true fig-wasps under Agaonidae. The author is aware of some recent criticism of the classification, and of the variety of views concerning the family status of certain groups. For instance Riek's (1970) classification differs greatly from the system presented here, and in the American Catalog (1979) Burks and Gordh present a classification which differs both from that used here and that given by Riek. These differences affect the family status of Leucospidae, Agaonidae, Ormyridae, Perilampidae, Eucharitidae, Eupelmidae, Tanaostigmatidae, Aphelinidae, Elasmidae, Signiphoridae (= Thysanidae), Tetracampidae and Mymarommatidae. The last one is probably an extraneous group (Gibson, 1986a; Mymarommatoidea) or, despite all (rather tenuous) arguments, may be related to Mymaridae. All the above-mentioned groups are retained here as families. In some cases there is little dispute, in most cases there are different views but so far no justification has been put forward for major revision of the family classification and until the reasons for changes of family limits are discussed the status quo is preferred. One outstanding case is retaining Elasmidae as a family distinct from Aphelinidae, although the single genus Elasmus Westwood shows great similarity to e.g. Euryischia Riley (Aphelinidae, Eriaporinae). The similarity is so extensive that it is difficult to accept its explanation by convergency, it seems rather to reflect some close relationship, which would require placing Aphelinidae under Elasmidae (the latter name has priority)."

"The particular problems are mentioned under the family taxa in question. The only major change is introduced here under Agaonidae. There the present study has shown that the non-pollinating fig-wasps can be derived from a common ancestor, but it does not seem possible to find for them sister groups among Torymidae and Pteromalidae as thought before."

"In recent discussions also the monophyly of Pteromalidae has been questioned. Here again, as in Agaonidae, the relationship of all included subfamilies has been confirmed, although the family may be paraphyletic, if other groups, such as Perilampidae and Eupelmidae which branched off from the early pteromalid stem, are included. In the present Pteromalidae there seems to be no group distinct enough to merit the status of a separate family. The placement of the Perilampidae remains questionable. Riek (1970) placed them under Pteromalidae but without giving any reasons. The Perilampidae are regarded as an apomorphic sister-group of Chrysolampinae and the latter were placed in Pteromalidae by Peck (1951) and by Graham (1969). The possibility of a lineage Chrysolampinae- Perilampinae-Eucharitinae was discussed on the basis of primary larval morphology by Heraty & Darling (1984), and found to be in agreement with the previously held views (Bou…ek, 1956b) based on adult morphology. This view is partly questioned here, however, because Eucharitidae show too many plesiomorphic features to be accepted as an apomorphic sister-group of Chrysolampinae and Perilampinae (last two here as Perilampidae). There is no easy solution to this problem and therefore a conservative approach has again been adopted. Probably a less controversial subject is the weighting of various categories, from subfamily down to genus or subgenus. Many groups are here raised to subfamily status. On the other hand a number of earlier suprageneric taxa are here not recognised."

"Some zoologists regard the genus as an arbitrary category and this is true to a degree. Therefore, to get some idea bout the grade of relationship of various groups of species, in many cases manuscript keys were prepared to species. In this way it is hoped that a consistent approach to genus-level taxa has been achieved avoiding the necessity for eventual lumping of alien species into one genus or unnecessary splitting of genera. Further research based on richer material than so far available will introduce the necessary corrections."

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