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Mymaridae

Main diagnostic characters

1. Head with a transverse, membranous suture (sometimes called a trabecula or carina) below anterior ocellus and also along inner eye margins (100%), rarely with additonal sutures behind ocelli.
2. Scutellum normally divided transversely into an anterior and posterior part (98%)
3. Hind wing petiolate, the membrane of the disc not extending to the base of the wing (99%)
4. Minute to moderate-sized insects, length varying from 0.35-1.8mm
5. Antennal toruli situated far apart, much closer to eye margin than to each other and situated quite high on the head, about midway between mouth margin and vertex (95%)

Included taxa

The family currently includes 103 genera and 1424 species. No generally accepted subfamily classification has been proposed.

Australomymar sp. Chaetomymar sp.
(Australomymar sp.) (Chaetomymar sp.)

Biology

All species of Mymaridae are internal, solitary or gregarious parasitoids of the eggs of other insects. Available records suggest they parasitize eggs in concealed situations such as those embedded in plant tissue, placed under scales bracts or in soil (Huber, 1986). Species do not seem to be particularly host specific, and mymarid species within one genus may parasitize eggs of insects belonging to several families. The most common hosts (to which 45% of the total records refer) are the eggs of auchenorrhynchous Homoptera, but eggs of other Hemiptera (especially Coccoidea, and less frequently Tingidae and Miridae) together with those of Coleoptera (especially Curculionidae and Dytiscidae) and Psocoptera are commonly parasitized. There are occasional records of species parasitizing other hosts, but many of these require confirmation.

gen. indet., New Zealand Cybomymar fasciifrons
(gen. indet., New Zealand) (Cybomymar fasciifrons)

Oviposition normally takes place before the host egg has undergone much development, and after oviposition further development of the host usually ceases. The egg is elongate-oval with a short pedicel at one end (Jackson, 1961). The number of larval instars is difficult to ascertain, but from two to four have been recorded (Balduf, 1928; Bakkendorf, 1934; Sahad, 1982). The first instar larva is generally either sacciform or mymariform. The second larval instar of some species with a sacciform first instar larva is very distinctive and is known as a histriobdellid. It is cylindrical and divided into six segments, the first and last segments being the largest, and often bearing paired fleshy processes (Jackson, 1961). The second instar larva of other species is often without segmentation and lacking spines or setae. There does not appear to be a functional tracheal system or spiracles in any larval instar. Pupation takes place within the host egg-shell. Overwintering is normally as a mature larva in the host egg.

Mymar sp. Polynema sp.
(Mymar sp.) (Polynema sp.)


Several mymarids (eg Caraphractus cinctus) parasitize the submerged eggs of aquatic insects (eg Dytiscidae) and to do this they are capable of swimming underwater, using their wings as paddles (Matheson & Crosby, 1912; Jackson, 1966). Females need not exit from the water immediately after emergence, and mating may also take place underwater. Individuals are capable of remaining underwater for 15 consecutive days (Rimsky-Korsakov, 1933). The mymarid may exit from the water by climbing the stem of a plant that breaks the surface.
Several species have been used successfully in biological control programmes, the most notable being Anaphes nitens to control Gonipterus scutellatus (Coleoptera: Curculionidae), a serious pest of eucalyptus in southern Europe, South Africa, New Zealand and South America.

Polynema sp. Scleromyma breve
(Polynema sp.) (Scleromymar breve)
Steganogaster silvicola
(Steganogaster silvicola)

Identification

Annecke, & Doutt, 1961 (World genera); Peck, Boucek & Hoffer, 1964 (Central European genera); Schauff, 1984 (Holarctic genera); Debauche, 1948 (Belgian species); Hincks, 1950, 1952, 1959, 1960a, b (British species of some genera); Matthews, 1986 (British Gonatocerus species); Noyes & Valentine, (New Zealand genera); Yoshimoto, 1990 (New World genera).

References

Annecke, D.P.; Doutt, R.L. 1961a. The genera of the Mymaridae. Hymenoptera: Chalcidoidea. Entomology Memoir of the Department of Agriculture of the Union of South Africa 5:1-71.

Bakkendorf, O. 1934. Biological investigations on some Danish hymenopterous egg-parasites, especially in homopterous and heteropterous eggs, with taxonomic remarks and descriptions of new species. Ent. Meddel. 19:1-96.

Balduf, W.V. 1928. Observations on the buffalo tree-hopper Ceresa bubalus Fabr. (Membracidae, Homoptera) and the bionomics of an egg parasite, Polynema striaticorne Girault (Mymaridae, Hymenoptera). Annals of the Entomological Society of America 21(3):419-435.

Debauche, H.R. 1948. Étude sur les Mymarommidae et les Mymaridae de la Belgique (Hym., Chalcidoidea). Mem. Mus. Hist. Nat. Belg. 108:248pp.

Hincks, W.D. 1950. Notes on some British Mymaridae (Hym.). Trans. Soc. Brit. Ent. 10:167-207.

Hincks, W.D. 1952. The British species of the genus Ooctonus Haliday, with a note on some recent work on the fairy flies (Hym., Mymaridae). Trans. Soc. Brit. Ent. 11(7):153-163.

Hincks, W.D. 1959. The British species of the genus Alaptus Haliday in Walker (Hym., Chalc., Mymaridae). Trans. Soc. Brit. Ent. 13(8):137-148.

Hincks, W.D. 1960a. Some additions to the British Mymaridae (Hym., Chalcidoidea). Entomologist's Monthly Magazine 95:210-216.

Hincks, W.D. 1960b. A new British species of the genus Alaptus Haliday (Hym., Mymaridae). Entomologist 93:170-172.

Huber, J.T. 1986. Systematics, biology, and hosts of the Mymaridae and Mymarommatidae (Insecta: Hymenoptera): 1758-1984. Entomography 4:185-243.

Jackson, D.J. 1961. Observations on the biology of Caraphractus cinctus Walker (Hymenoptera: Mymaridae), a parasitoid of the eggs of Dytsicidae (Coleoptera). 2. Immature stages and seasonal history with .a review of mymarid larvae. Parasitology 51:269-294.

Jackson, D.J. 1966. Observations on the biology of Caraphractus cinctus Walker (Hymenoptera: Mymaridae), a parasitoid of the eggs of Dytiscidae (Coleoptera). Transactions of the Royal Entomological Society of London 118(2):23-49.

Matheson, R. & Crosby, C.R. 1912. Aquatic Hymenoptera in America. Annals of the Entomological Society of America 5:65-71.

Matthews, M.J. 1986. The British species of Gonatocerus Nees (Hymenoptera: Mymaridae), egg parasitoids of Homoptera. Systematic Entomology 11:213-229.

Noyes, J.S. & Valentine, E.W. 1989. Mymaridae (Insecta: Hymenoptera) - introduction and review of genera. Fauna of New Zealand 17:1-95.

Peck, O., Boucek, Z. & Hoffer, A. 1964. Keys to the Chalcidoidea of Czechoslovakia (Insecta: Hymenoptera). Memoirs of the Entomological Society of Canada No 34:170pp, 289 figs.

Rimsky-Korsakov, M.N. 1933. Methoden zur Untersuchungen von Waserhymenopteren. Hanb. biol. ArbMeth. 9:227-258.

Sahad, K.A. 1982. Biology and morphology of Gonatocerus sp. (Hymenoptera, Mymaridae), an egg parsasitoid of the green rice leafhopper, Nephotettix cincticeps Uhler (Homoptera, Deltocephalidae). .II. Morphology. Kontyû 50(3):467-476.

Schauff, M.E. 1984. The Holarctic genera of Mymaridae (Hymenoptera: Chalcidoidea). Memoirs of the Entomological Society of Washington 12:1-67.

Yoshimoto, C.M. 1990. A review of the genera of New World Mymaridae (Hymenoptera: Chalcidoidea). Flora & Fauna Handbook 7:1-166. Sandhill Crane Press Inc., Gainsville, Florida.

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Last updated 07-Jun-2004 Dr B R Pitkin