The effect of parasitization by Trichogramma australicum on Helicoverpa armigera host eggs and embryos

Histological investigations of the pathology of Helicoverpa armigera (Hübner) eggs after attack by the egg parasitoid, Trichogramma australicum (Girault), indicate that the developing embryo is immediately killed by envenomation. Soon afterward the histological staining characteristics of parasitize...

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Bibliographic Details
Published in:Journal of invertebrate pathology 2004, Vol.85 (1), p.1-8
Main Authors: Jarjees, Ekhlass A, Merritt, David J
Format: Article
Language:English
Subjects:
Animals
Artificial diet
Biological and medical sciences
Biological control
Control
Diet
Egg parasitoids
Embryo, Nonmammalian - parasitology
Embryo, Nonmammalian - pathology
Female
Fundamental and applied biological sciences. Psychology
Helicoverpa armigera
Host
Hymenoptera - physiology
Insecta
Invertebrates
Mass-rearing
Moths - parasitology
Noctuidae
Ovum - parasitology
Ovum - pathology
Pathology
Phytopathology. Animal pests. Plant and forest protection
Protozoa. Invertebrates
Trichogramma australicum
Trichogrammatidae
Venom
Venoms - toxicity
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Summary:Histological investigations of the pathology of Helicoverpa armigera (Hübner) eggs after attack by the egg parasitoid, Trichogramma australicum (Girault), indicate that the developing embryo is immediately killed by envenomation. Soon afterward the histological staining characteristics of parasitized host embryos change and the embryonic germ band dissociates into a mass of individual rounded cells. Hosts attacked by females sterilized by γ-irradiation showed the same pathological effects as normally parasitized hosts, indicating that host degeneration is due to female venom rather than factors derived from the parasitoid embryo or larva. Cell death also occurred in older host embryos although tissue breakdown was delayed. These findings have allowed us to determine not just that the host dies but what happens to the cells and tissues, i.e., their physical appearance, the time course of their degeneration, and that the process is retarded in older hosts. These processes can possibly be emulated in artificial diets.
ISSN:0022-2011
1096-0805
DOI:10.1016/j.jip.2003.12.001