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Leucospidae

Main diagnostic characters

1. Hind leg with femur characteristically swollen with one or more teeth on its inner margin and with tibia markedly curved (100%)
2. Prepectus very narrow, not clearly visible (100%)
3. Tegula elongate and narrow, at least 2X as long as broad (100%)
4. Generally very large and robust, about 4-17mm in length (100%)
5. Forewings, at rest, longitudinally folded (100%)

Included taxa

The family currently includes 4 genera and 134 species. No subfamily classification has been proposed.

Leucospis sp.

Leucospis sp.

Biology

Leucospids develop as parasitoids of aculeate Hymenoptera. Their hosts are mainly solitary bees, less frequently solitary wasps, eg. Vespidae and Sphecidae nesting in a similar way to bees. Occasionally parasitic bees have also been recorded as hosts and are probably attacked by the leucospid when occupying the cell of a soiltary bee after killing its original owner.

Uniparental reproduction is rare but is known in European populations of Leucospis gigas (Berland, 1934a) and is suspected in other species (Bytinski-Salz, 1963).

Oviposition was first described by Jurine (1807) and later by Westwood (1835), Fabre (1886), Bischoff (1927), Clausen (1940) and Habu (1962). The egg is laid through the protective wall of the cell of the host, ie through the hard, dry mud, wood or other material, in a special way enabled by the unique structure of the female gaster. The ovipositor is spiralled back into the basal part of the gaster while the gaster is bent down beyond the first tergite. The space for the ovipositor is provided by the unusual extension of the median membranous part of the second tergite (and a part of the third) which bulges out, while the tip of the hypopygium is turned down and forward into a vertical position to guide the apex of the ovipositor.

The eggs are relatively large (3mm in length in Leucospis gigas), whitish, curved and tapering to one end (Fabre, 1886; Parker, 1924; Habu, 1962). They are deposited externally on the host larva or nearby. The first instar larva does not take any food at first but searches the host cell for competitors; in all cases only one parasitoid larva survives and develops as an ectoparasitoid sucking the body fluids of the host larva. The mature larva of Leucospis gigas has been described by Parker (1924) and of L. hopei by Janvier (1933).

The development from the deposited egg to emergence of the adult depends largely on temperature and takes about three weeks under optimal conditions in Leucospis japonica (Habu, 1962) and five weeks in L. affinis and L. hopei (Clausen, 1940; Janvier, 1933).

The adults have well adapted protractile mouthparts to lick nectar from shallow and medium-deep blossoms, and may be encountered either on such flowers or near the nesting sites of their hosts.

Identification

Boucek, 1974 (World genera and species).

References

Berland, L. 1934b. Un cas probable de parthénogenèse géographique chez Leucospis gigas (Hyménoptère). Bull. Soc. Zool. Fr. 59:172-175.

Bischoff, H. 1927. Biologie der Hymenopteren :598pp. Berlin

Boucek, Z. 1974. A revision of the Leucospidae (Hymenoptera: Chalcidoidea) of the world. Bulletin of the British Museum (Natural History) (Entomology) Supplement 23:241pp.

Bytinski-Salz, H. 1963. Geographical variation and sex-ratio in Leucospis gigas (Hymenoptera, Chalcidoidea). Acta Entomologica Musei Nationalis Pragae 35:527-530.

Clausen, C.P. 1940. Entomophagous Insects :688pp. McGraw Hill, New York; London.

Fabre, J.H. 1886. Souvenirs entomologiques (Troisième Série) études sur l'instinct et les moeurs des insectes. (Troisième Edition) :433pp. Libraire Ch. Delagrave, Paris.

Habu, A. 1962. Chalcididae, Leucospidae and Podagrionidae (Insecta: Hymenoptera). Fauna Japonica x+232pp, 19 pls. Biogeographical Society of Japan, Tokyo.

Janvier, H. 1933. Etude biologique de quelques Hyménoptères du Chili. Annls. Sci. nat. Zool. (10) 16:209-356.

Jurine, L. 1807. Nouvelle méthode de classer les Hyménoptères et les Diptères 1:320+4pp, 14 plates.

Parker, H.L. 1924. Recherches sur les formes postembryonaires de chalcidiens. Annales de la Société Entomologique de France 93:261-379.

Westwood, J.O. 1835. On Leucospis, a genus of hymenopterous insects. Entomological Magazine 2:212-218.

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Last updated 05-Sep-2003 Dr B R Pitkin