Impact of temperature, salinity and light on hatching of eggs of Anisakis simplex (Nematoda, Anisakidae), isolated by a new method, and some remarks on survival of larvae

A new efficient method of isolating large number of eggs from anisakid worms is described. The method involves blending the worms in an electric mixer and isolating the eggs by centrifugation. Eggs were used to study factors affecting egg hatching and survival of emerged larvae of Anisakis simplex. The hatching time (range 3–21 days) varied inversely with temperature (5-21 0q, but did not differ significantly with salinity (0–28 psu). The final proportions of eggs which hatched, increased with salinity. This proportion was highest at 13 °C and lowest at 21°C; larvae which emerged in fresh water died within a few hours irrespective of temperature. The mean survival time of larvae was in the range of 92-131 days. The survival time increased with salinity but decreased with temperature. Light exposure (at 13°C) was found to reduce significantly the time needed for the hatching of eggs. The results support the hypothesis that A. simplex is adapted to off-shore pelagic marine environments.