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habitus illustration: female of Encyrtidae

Female of Encyrtidae

This family rivals the Pteromalidae and Eulophidae for most number of species and genera (although many of the genera are monotypic). The Encyrtidae is one of the more useful families in biological control. If the Aphelinidae are considered as a subfamily of Encyrtidae (Riek 1970, Gordh 1979), then the family would be considered the most important one in biocontrol. However, there is some question as to the status of the aphelinids, which have been placed as Eulophidae, as Encyrtidae, and as a distinct family. There is always the possibility that some aphelinids belong with the Encyrtidae and others with the Eulophidae. For the purposes of this handbook we treat the aphelinids as a distinct family. Somewhat the same problem arises with the Signiphoridae which was placed as a subfamily of Encyrtidae (Gordh 1979) but which we also treat as a family. The encyrtids hold the distinction of being among the most morphologically diverse groups of chalcidoids, and this may account for some of the excessive splitting at the generic level. They possess an incredible array of variations in structure of antennae, heads, and just about every other part of the body.

The Encyrtidae have been classified by Tryapitsyn (1973, 1974) who recognizes 2 subfamilies as follows:

Tetracneminae: Worldwide this subfamily is divided into 12 tribes and 11 subtribes with 66 genera and about 400 species. In the Nearctic we have 6 tribes, 20 genera, and 46 species, plus 5 species in 5 unplaced genera.

Encyrtinae: Worldwide this subfamily has 36 tribes and 30 subtribes with over 170 genera and about 1600 species. Additionally there are over 200 unplaced genera (mostly Australian) and untold numbers of undescribed species. In the Nearctic, where 21 new genera were just described (Noyes and Woolley 1994) we have 20 tribes, about 90 genera, and 300 species, plus 72 species in 33 unplaced genera.
Although Tryapitsyn recognized and characterized 48 tribes of encyrtids, he did not give a key to them so it is somewhat difficult to assign a new genus to a tribe. Tryapitsyn published a key to Palearctic genera (1971) and more recently (1989) revised the entire family for the region. Tryapitsyn and Gordh (1978a, b) gave keys to Nearctic genera of Encyrtidae and a new key has just been published by Noyes, Woolley, and Zolnerowich (in Gibson, et al. 1997). Noyes and Woolley (1994) added a substantial number of new genera and revised the placement of many species in North America. The genera of Neotropical Encyrtidae have been reviewed by Noyes (1980) who discusses 153 genera and gives a key to them, and the Indo-Australian genera were recently revised by Noyes and Hayat (1984). Most recently, Noyes (1988) revised the encyrtid fauna of New Zealand. The Oriental mealybug parasitoids of the tribe Anagryrini were extensively treated in a book by Noyes and Hayat (1994). In these keys neither subfamilies nor tribes are keyed and the presumption is that although technically good characters are present for higher categories, they are too difficult to see and use for practical purposes. Genera of the Encyrtidae seem to have close affinities with bees where it has been said (by some) that it is best to identify a bee to genus and then place it in its correct family!

STATISTICS: Number of world species: about 3300 (over 400 Nearctic); number of world genera: over 450 (172 Nearctic).

BIOLOGY: Members of the Encyrtidae may be found on almost any host imaginable. A majority of the species are parasitic upon Homoptera in the families Coccidae, Diaspididae, and Pseudococcidae. Other species attack Coleoptera (eggs or larvae of 10-15 families), Diptera (eggs or larvae of 10 families), Lepidoptera (eggs or larvae of 15 or 20 families), and Hymenoptera (larvae, or hyperparasites of other chalcidoids, in about 10 families), Neuroptera (eggs or larvae of 5 families), Orthoptera (eggs of 3 families), Heteroptera (eggs, or nymphs and adults of 4 or more families), and Arachnida (nymphs of Ixodidae, eggs of Araneina). Tachikawa (1978) gave a world list of encyrtid genera and the host families with which they are associated. Noyes (1990b) summarized the biology and taxonomy of encyrtid genera known to attack armored scales.

DISTINGUISHING CHARACTERS: Encyrtids may be confused with eupelmids and tanaostigmatids based upon the shared, bulging mesopleuron. Generally encyrtids are most easily recognized by the nearly transverse axillae which meet medially and the positioning of the cerci anterior to the tip of the abdomen. In most species, the very short marginal vein is another reliable character. On occasion, some encyrtids may be confused with those aphelinids which have a somewhat convex mesopleuron. However, members of that family have widely separated and complete notauli and do not have the triangular axillae or the advanced cerci.

COLLECTING: Encyrtidae are often reared from branches containing populations of scales or mealybugs. These branches may be held in a plastic or cardboard box, in ice cream cartons, or petri dishes. General sweeping will yield encyrtids almost anywhere. Occasionally rearing larvae of Diptera (e.g. Calliphoridae, Sarcophagidae, Tachinidae, Syrphidae), Coleoptera (e.g. Coccinellidae, Nitidulidae), and Lepidoptera (e.g. Gelechiidae, Pyralidae) will produce encyrtids, as will eggs of Lepidoptera, Heteroptera (e.g. Pentatomidae, Reduviidae), Orthoptera (e.g. Tettigoniidae), Blattaria, and Diptera (e.g. Asilidae). Also, encyrtids may emerge from nymphal and adult Heteroptera (e.g. Coreidae, Pentatomidae, Scutelleridae).

DISTRIBUTION: Encyrtidae are widespread and common throughout the world.

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