Lagenidium thermophilum isolated from eggs and larvae of black tiger shrimp Penaeus monodon in Thailand

Abstract

A fungal infection was found in eggs and larvae of black tiger shrimp Penaeus monodon at a hatchery in Chachensao Province, Thailand in August 2000. Fungi were isolated from eggs and larvae with fungal infection, and studied on the morphological and biological characteristics. When it was transferred from PYGS broth to artificial seawater, discharge tubes developed from the mycelia, and a vesicle for zoospore formation was produced at the top of each discharge tube. The characteristic feature of an asexual reproduction of the fungus was that zoospores swam away in seawater after the vesicle separated from the discharge tube. Based on these morphological characteristics, the fungus was identified as Lagenidium thermophilum. Some biological characteristics of the selected isolate NJM 0031 were compared with the other species in the genus Lagenidium isolated from some crustaceans. As a result, the isolate NJM 0031 showed similar characteristics to those of L. thermophilum ATCC 200318 isolated from mangrove crab Scylla serrata. The isolate was demonstrated to be pathogenic to larvae of black tiger shrimp by artificial infection. This is the first report of L. thermophilum infection in black tiger shrimp in Thailand. © 2006 The Japanese Society of Fish Pathology.