Parasites of window-pane oyster (Placuna placenta Linnaeus, 1758) from Trapiche, Oton in west central Philippines

Abstract

Parasitology of edible and commercially valuable window-pane oysters (Placuna placenta L.) using gross macroscopic examination and histology was conducted. To screen for the presence of parasites, wild oysters were collected monthly from January 2008 to December 2008 from Trapiche, Oton in west central Philippines. Thirty live adult oysters with shell length (SL) of 52-89 mm were hand-picked monthly. Gross observation showed the presence of pea crabs (Pinnotheres sp.) in the mantle cavity of the oysters. The overall prevalence and intensity of P. placenta with pea crabs were 4.44% and 1, respectively. Histological examination revealed the occurrence of Tylocephalum sp. (prevalence and intensity of the parasites were 1.66 % and 0.5, respectively) in connective tissues around the digestive gland. Tylocephalum sp. was found surrounded by hemocytic infiltration. Ciliates (Ancistroma sp.) were also observed in the gills with overall prevalence of 38.83% and intensity of 7.51. Larval stages of trematodes of Bucephalus sp. (prevalence, 18.83%; intensity of 1.5) were found in the connective tissues of the female gonad. The study presents a documentation of parasites of P. placenta in the Philippines.