The effect of gamma irradiation on piophila casei (Linnae)

In a study on insects infesting sun-dried salted mackerell, samples were collected from six markets in South Jakarta. It was found that piophila casei was the only insect infesting the sun-dried salted mackerell. The eggs, larvae and pupae of the flies were generally found in the head cavity and in the stomach of the fish. For the determination of disinfestation dose, the larvae and the pupae were irradiated by gamma rays. It was found that the larvae was more sensitive to irradiation than the pupae. The LD99 of pupae was 0.366 kGy. Various combinations of salting and drying processes have been done for the preservation of mackerell. It could be concluded that the growth of piophila casei was influenced more by water content than by salt content. Other aspects such as the occurence of mold and yeast, have to be considered in the preservation of fish. It was also found that ten and twenty hours salting time and thirty hours drying are the best treatments. Piophila casei did not infest on the surface of fish. (author)