REDUCTION OF THE TOXICITY OF FENITROTHION TO PRAWNS BY PIPERONYL BUTOXIDE

The effectiveness of piperonyl butoxide (PB) in reducing the mortality of striped prawn and kuruma prawn during exposure to fenitrothion (FS ) was examined. The 24-h LC50 values of PB for striped and kuruma praw ns were 3.5 and 1.6 ppm at 25-degrees-C, respectively. Therefore, PB-t reatment for both prawns was conducted at 0.25 ppm, corresponding to o ne-tenth of the mean of both 24-h LC50 values. The PB-pretreatment bef ore FS-exposure and also the addition of PB to FS-water were effective in decreasing the FS-toxicity to both prawns. The most effective redu ction of the toxicity to the prawns was obtained by continuous PB-trea tment before and during FS-exposure, resulting in extensions of 50% su rvival time by 4-6 times in striped prawn and 10-16 times in kuruma pr awn, compared with the respective control groups non-treated with PB.