Environmental effects on transmission of Discocotyle sagittata (Monogenea): egg production and development.

Egg production by the freshwater gill monogenean Discocotyle sagittata infecting rainbow trout (Oncorhynchus mykiss) was monitored at 5, 13 and 18 degrees C; eggs were incubated at 6, 10, 13, 15, 16, 18, 22 and 26 degrees C and the hatching times determined. Mean per capita output at 13 degrees C ranged from 0.8 eggs/worm/day (e/w/d) to 18.

Larval survival characteristics and behaviour of the gill monogenean Discocotyle sagittata.

The survival characteristics of Discocotyle sagittata larvae are both age- and temperature-dependent. In laboratory studies at constant temperatures of 6, 10, 13, 18 and 22 degrees C, oncomiracidia had a maximum life-span of 96 h at 6 degrees C, declining with increasing temperature to 26 h at 22 degrees C. Larval swimming activity was also age dependent, and continued for a large proportion of survival time.

Cholinergic, serotoninergic and peptidergic components of the nervous system of Discocotyle sagittata (Monogenea:Polyopisthocotylea).

Cholinergic, serotoninergic (5-HT) and peptidergic neuronal pathways have been demonstrated in both central and peripheral nervous systems of adult Discocotyle sagittata, using enzyme histochemistry and indirect immunocytochemistry in conjunction with confocal scanning laser microscopy. Antisera to 2 native flatworm neuropeptides, neuropeptide F and the FMRFamide-related peptide (FaRP), GNFFRFamide, were employed to detect peptide immunoreactivity. The CNS is composed of paired cerebral ganglia and connecting dorsal commissure, together with several paired longitudinal nerve cords.