Development of Trichogramma cacoeciae Marchal (Hymenoptera : Trichogrammatidae): time table and evidence for a single larval instar

Reproduction and Immature Development of Egg Parasitoids

“…(Saakian-Baranova 1990, T. pintoi (Saakian-Baranova 1990), T. semblidis (Aurivillius) (Saakian-Baranova 1990), T. minutum (Manweiler 1986), T. platneri Nagarkatti (Saakian-Baranova 1990), T. brassicae Bezdenko (Wu et al 2000), T. maidis (Hawlitzky and Boulay 1982) and four in T. brevicapillum Pinto and Platner (Pak and Oatman 1982). Trichogramma australicum Girault, T. brassicae and T. cacoeciae were reported to have three larval instars (Brenière 1965, Saakian-Baranova 1990, but later studies reported only one instar (Volkoff et al 1995, Dahlan and Gordh 1996, 1997, Jarjees et al 1998, Wu et al 2000, Jarjees and Merritt 2002. Recent studies suggest that only one larval instar is present in Trichogramma based on the fact that the shape and size of the first (and only) larval instar change considerably during larval development because of important ingestion of food early in its development (see later).…”

“…Between these two envelopes, free cells with large nuclei can be observed (Volkoff et al 1995). Soon after, the late-stage embryo, still surrounded by the embryonic exuvia, shows vigorous movements of its anterior section (Jarjees et al 1998) that eventually ruptures the chorion.…”

“…The embryo is then released within the host egg together with the cells that were observed between the chorion and the embryonic exuvia. At this stage no feeding takes place and this stage has been termed a "free living embryo" (Volkoff et al 1995, Cônsoli et al 1999. A similar stage enclosed in its serosal membrane has also been described from Scelionidae.…”

“…The mandibles gradually appear and are pushed against the embryonic exuvia. At the end of that stage the embryonic exuvia is broken by the mandibles at its anterior end and the larva emerges (Volkoff et al 1995). The embryonic membrane remains attached to the posterior end of the larva.…”

Trichogramma in Brazil: feasibility of use after twenty years of research

“…In recent years, the findings that Trichogramma has only a single instar (Volkoff et al 1995, Dahlan & Gordh, 1996 and the influence of symbionts, especially Wolbachia, on the sex ratio of Trichogramma (Stouthamer et. al.…”