J. HYM. RES. Vol. 15(2), 2006, pp. 232-250 The Biology and Morphology of Entedon sylvestris (Hymenoptera: Eulophidae), a Larval Endoparasitoid of Ceutorhynchus sisymbrii (Coleoptera: Curculionidae) Alex V. Gumovsky Schmalhausen Institute of Zoology, 15 Bogdan Khmelnitsky St., 01601 Kiev-30, Ukraine; email:
[email protected] Abstract. — The biology and morphology of preimaginal stages of Entedon sylvestris Szelenyi (Hymenoptera: Eulophidae), are described in detail for the first time. Entedon sylvestris is a larval endoparasitoid of the seed-feeding larvae of the weevil Ceutorhynchus sisymbrii Dieckmann on the small tumbleweed mustard, Sisymbrium loeselii L. (Brassicaceae). In the Ukraine, females of £. sylvestris begin ovipositing in late May and continue to lay eggs until the beginning of July. Females of E. sylvestris parasitize weevil larvae of various instars. The parasitoid larva remains within the body of the host weevil larva until the emergence of the latter from the dried host-plant pods. The morphology of each of the three larval instars is described in detail. The moult of the parasitoid larva into the final instar, as well as pupation, takes place underground. Adults of E. sylvestris must therefore penetrate a soil layer to emerge the following spring. Key words. — Entedoninae, larval endoparasitoids, parasitoid-host relationships, preimaginal morphology, Sisymbrium loeselii Parasitic wasps of the genus Entedon Dalman (Eulophidae, Entedoninae) are endoparasitoids of immature stages of beetles. Curculionidae (including Scolyti-nae), Brentidae (including Apioninae), An-obiidae, Chrysomelidae (including Bruchi-nae), Buprestidae, Cerambycidae, Mordel-lidae, and Nitidulidae are recorded as hosts (Boucek and Askew 1968, Graham 1971, Askew and Kopelke 1989, Rasplus 1991). Entedon ergias Walker has been imported from Europe into North America for the biological control of the smaller European elm bark beetle, Scolytus multi-striatus (Marsham) (Peck 1963). For some species, parasitism rates and/or general descriptions of the larval morphology are given (Ferriere 1939, Erdos 1944, Abedin and Quayum 1972, Tiwari 1976). However, these descriptions lack many morphologi-cal details, especially for the first instar larvae. Beaver (1966) and Fisher (1970) gave the most complete bioassays and reported egg-larval parasitism for Entedon ergias Walker, E. rumicis Graham, E. phar-nns Walker. Askew (1991) and Gumovsky (1997) provided some information on per-centage parasitism, the biology of the final instar larva and pupation procedure of E. cioni Thomson, E. cionobius Thomson and E. zanara Walker. In general, despite some thorough re-views (Parker 1924, Parker and Thomson 1925) and occasional detailed descriptions (e.g., Darling 1992, 1995) of the larvae of Chalcidoidea, our knowledge of morphol-ogy of preimaginal stages of chalcid wasps is incomplete. Most discussions on larval morphology and biology concern ectopar-asitoids, whereas endoparasitoid larvae traditionally attract less attention, mainly due to the difficulties with their prepara-tion and identification. The larvae of Eulophidae were classified by Parker (1924) in group II (the ectoparasitoid forms) and V (egg endoparasitoids), dif-fering mostly in having spiracles (group II) or being apneustic (group V). Later, when
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