Estimation of median lethal dose of commercial formulations of some type II pyrethroids

The present study aims to investigate the median lethal dose (ld50) of three commercially formulated type ii pyrethroids,namely fenvalerate (hafen),deltamethrin (decis) and cypermethrin (cybil) against female albino rats. acclimatised experimental animals were divided into three sets and respective doses of pyrethroids under investigation were administrated orally to them. survival and mortality number was observed following 96 hours of intoxication. ld50 was calculated statistically by log-dose/probit regression line method from the numerical data obtained and came out to be 1532.5,656.2 and 618.2 mg/kg b.wt. for hafen,decis and cybil respectively. structural changes in type ii pyrethroid vide supra have been considered responsible for the differences in ld50. © 2017 jordan journal of biological sciences.