Document Type: Research Paper
Peninsular Aquaculture Division of Central Institute of Fresh water Aquaculture, Hesaraghatta Lake Post, Bangalore-560089, Karnataka, India.
The efficacy of neem against Lernaea cyprinacea was studied. Two types of neem seed powder, viz; (1) dried and powdered neem seeds and (2) solvent extracted neem seed powder prepared by treating dried seed powder with petroleum ether were used in the present study. Different types of extracts were prepared by separately solubilising both types of neem powder in (i) 1% NaCl solution and (ii) water at two temperatures (28 oC and 90oC). These extracts were tested at varying concentrations (10, 25, 50 and 100µg/ml) against Lernaea. Results indicated that neem seed powder treated with solvent and further solubilized with hot water (90 oC) at a concentration of 100µg/ml was effective in preventing the hatching of L.cyprinacea eggs and their further development. Nauplii and copepodid-I stages were also exposed to above mentioned neem seed extracts at a concentration of 100µg/ml. Nauplii became inactive within 2 hrs and copepodids died after 43 minutes exposure to solvent treated neem powder extracted with hot water. Fishes survived for an average period of 5 hrs and 30 min in all types of neem seed extracts except the one extracted with water at 28oC (both solvent treated and untreated neem seed powde