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25.1.1 Bacterial disease
It affects zoea, mysis and post larvae. It may choke the gills affecting respiration. Luminous bacterial disease. It is caused by Vibrio harveyi / V. alginolyticus. Infected larvae exhibit contimuous greenish luminescence when observed on total darkness. Vibriosis- It affects haemolymph and mid gut gland. Fungal disease Mysis stages are most vulnerable to fungal attacks. The common fungae that attack the shrimp larvae are Lagenidium. Viral disease: They appear mainly during post larval and juvenile stages. This may cause high mortality in post larvae. Beculovirus group affect mid gut and hepatopancreas whereas parvovirus group (IHHNV) affect epidermal, hypodermis & mesoderm. Larval fouling – Large scale infectation of Zoothamnium, Vorticella etc on the gills, eyes of larvae lead to hypoxia and death. Though they are not directly pathogenic, they can cause mortality in larvae. |
Last modified: Saturday, 24 December 2011, 8:18 AM