Pathogenesis of Helicosporidium sp. (Chlorophyta: Trebouxiophyceae) in susceptible noctuid larvae

Host age and pathogen dosage impact cyst morphogenesis in the invertebrate pathogenic alga Helicosporidium sp. (Chlorophyta: Trebouxiophyceae)

“…A low frequency of cyst production may occur in larval stages as early as 7 days post-treatment. This observation is consistent with the results of Bläske-Lietze and Boucias (2005), who observed cyst morphogenesis in third-instar-treated S. exigua ten days post-treatment. However, the majority of infected larvae, regardless of their age at exposure, produced cysts nine to thirteen days post-treatment, when treated larvae reached the prepupal stage.…”

“…The results of our study suggest that the SjHe may be more infective than CsHe among noctuid hosts, and this idea is supported by the results of Bläske and Boucias (2005), who observed 100% infection among third instar S. exigua treated with 10 5 SjHe cysts. Larval age affected the dosage responses of infection and mortality.…”

“…New cyst suspensions were generated bi-monthly by injection of late instar H. zea larvae with Helicosporidium vegetative cells and by subsequent purification of cysts from homogenates of infected pupae. Dehiscence assays as described in Bläske-Lietze and Boucias (2005) were conducted on each suspension prior to each assay to confirm cyst viability.…”

“…(Chlorophyta; Trebouxiophyceae) (Tartar et al, 2002), possesses a unique life history consisting of cyst, filamentous, and vegetative cell stages (Bläske-Lietze et al, 2006;Boucias et al, 2001). This achlorophytic alga is able to infect species in different invertebrate Orders (Bläske and Boucias, 2004;Bläske-Lietze and Boucias, 2005;Conklin et al, 2005). Cysts, the infectious stage, have been detected in aquatic (micro-) habitats such as moist soil, pond water, and tree sap (Avery and Undeen, 1987b;Kim and Avery, 1986;Yaman and Radek, 2005).…”

“…Although cyst dehiscence, filament rupture, and vegetative growth phases have been documented under both in vivo and in vitro conditions (Bläske and Boucias, 2004;Bläske-Lietze and Boucias, 2005;Bläske-Lietze et al, 2006;Boucias et al, 2001;Conklin et al, 2005;Lindegren and Hoffmann, 1976;Purrini, 1984;Weiser, 1970), at present little is understood about cyst morphogenesis. Cyst formation occurs in vivo in only a portion of stationary-phase vegetative cells, and has yet to be induced in vitro (Boucias et al, 2001).…”