Efficacy of trifluralin for control aquatic fungi, its residue, and median lethal concentration to banana shrimp

Trifuralin is one of 215 candidate aquatic fungicides screened for their efficacy against pathogenic fungi. The effective candidate fungicides will be replacement the usage of malachite green, a potential carcinogen. Today, trifluralin was widely used in marine and freshwater hatcheries, especially for shrimps, crabs and ornamental fishes larvae. However, its efficacy for controlling aquatic fungi, its residue and median lethal concentration (LC50) to hose aquatic larvae has been virtually uninvestigated. This study aims to test the efficacy of trifluralin 48 percent W/V-EC for control marine fungi by adding to nursing water, its residue and LC50 to banana shrimp (Penaeus merguiensis ).Efficacy for control fungi were performed by nursing larval shrimp from zoea to post larvae(P15) in the experiment tanks and adding trifluralin to the each tral at 0.5 and 1 ppm. Every other day. It was found that both concentrations can control the aquatic fungi and that the survival rate of PL 5 were significantly higher than the control group. After treated with trifluralin at 0.5 and 1 ppm. For 24 and 48 h. respectively, no trifluralin was detected in the seawater. The residue in muscle of shrimp detected at 48 h. was found at the average of 0.155 and 1.197 ppb, respectively. Although, at 96 h. no trifluralin was detected in the shrimp muscle. Rang finding test was performed using larval shrimp of the stages mysis , postlarvae 5,10,20and 30. The samples were exposed to 30 ppt seawater containing trifluralin at 0.5-30 ppm for 96 h. After exposure, it was found that larval shrimp were killed in trifluralin 1-30 ppm but no mortality was observed in 0.5 ppm. The results of full scale test showed LC50 of the mysis,PL5, pL10, PL20 and PL30 at 2.96 ppm ,.35 ppm ,7.97 ppm,9.98 ppm and 13.13 ppm at 24 h. respectively. There studies revealed clearly that an appropriated method and dozes on using trifluralin effective for control the risk of aquatic fungi occurring in seawater. The effluence from hatchery should be stock in the treated pond at last 3 days before release to the natural resources.