efficacy of neem seed extracts on developmental stages of lernaea cyprinacea

The efficacy of neem (azadiracta indica) against lernaea cyprinacea was studied. two types of neem seeds powder, viz; (1) dried and powdered neem seeds and (2) solvent extracted neem seeds powder prepared by treating dried seeds powder with petroleum ether were used in the present study. these experiments were carried out in the month of august 2014. different types of extracts were prepared by separately solubilising both types of neem` seeds 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 100 micro;g ml1) against lernaea. results indicated that neem seeds powder treated with solvent and further solubilized with hot water (90 oc) at a concentration of 100 micro;g ml1 was effective in preventing the hatching of l.cyprinacea eggs and their further development. nauplii and copepodidi stages were also exposed to above mentioned neem seed extracts at a concentration of 100 micro;g ml1. nauplii became inactive within 2 hrs and copepodids died after 43 minutes exposure to solvent treated neem`s powder extracted with hot water. fishes (labeo fimbriatus) survived for an average period of 5 and 30 min in all types of neem seeds extracts except the one extracted with water at 28oc (both solvent treated and untreated neem`s seeds powder).