Development of the Myzozoan Aquatic Parasite Perkinsus marinus as A Versatile Experimental Genetic Model Organism.

The phylum Perkinsozoa is an aquatic parasite lineage that has devastating effects on commercial and natural mollusc populations, and also comprises parasites of algae, fish and amphibians. They are related to dinoflagellates and apicomplexans and thus offer excellent genetic models for both parasitological and evolutionary studies. Genetic transformation was previously achieved for Perkinsus spp.

Development of the anal vesicle, salivary glands and gut in the egg-larval parasitoid Chelonus inanitus: tools to take up nutrients and to manipulate the host?

Larvae of endoparasitoids undergo extensive morphological changes and often have special features to allow their development inside the host. We present the first detailed study on the development of the anal vesicle and the gut. The analyses reveal that the anal vesicle is first seen on the dorsal side of the abdomen as an internal structure covered by a membrane.

Stage-dependent strategies of host invasion in the egg-larval parasitoid Chelonus inanitus.

Chelonus inanitus (Braconidae) is a solitary egg-larval parasitoid which lays its eggs into eggs of Spodoptera littoralis (Noctuidae); the parasitoid larva then develops in the haemocoel of the host larva. Host embryonic development lasts approx. 3.

Overview of parasitism associated effects on host haemocytes in larval parasitoids and comparison with effects of the egg-larval parasitoid Chelonus inanitus on its host Spodoptera littoralis.

In the first part we review the effects of larval endoparasitoids and their polydnavirus and venom on the immune system of their hosts. In all systems investigated, haemocyte spreading and encapsulation activity was reduced; in some cases effects on total (THC) or differential (DHC) haemocyte count as well as modification of haemocyte morphology and ultrastructure were also documented. In many cases polydnavirus (and venom) were shown to play a major role in abrogation of the host's immune reaction.

Ovary development and polydnavirus morphogenesis in the parasitic wasp Chelonus inanitus. II. Ultrastructural analysis of calyx cell development, virion formation and release.

Polydnaviruses are unique symbiotic viruses that are formed only in calyx cells in the ovary of parasitic wasps in the families Braconidae and Ichneumonidae; accordingly, two genera, Bracovirus and Ichnovirus are recognized. We have presented a detailed ultrastructural analysis of ovary and calyx cell differentiation and virion morphogenesis, together with the first data on virion release in a bracovirus. Differentiation of the ovary into germarium/vitellarium and the calyx region begins immediately after pupation.