Ris Menoel R. Modina*
Acetylcholinesterase (AChE) activities were determined as affected by exposure to sublethal doses of fenobucarb (BPMC) on Nile tilapia. Fish were exposed for different periods, namely: 0, 7, 14, 21, and 28 days. AChE activities of brain and muscle tissues were measured spectrophotometrically. The sublethal doses of the insecticide did not induce treatment-related poisoning but were enough to significantly induce effects on the hepatosomatic index. The concentration used was also enough to significantly induce AChE inhibition on brain and muscle. AChE inhibitions were significantly different between unexposed and exposed fish in both brain (KW=14.02, P<0.05) and muscle (KW=6.87, P<0.05) tissues. The inhibition on brain AChE was highest on the 14 day-exposed fish. The inhibition on muscle AChE was highest on the 21-day-exposed fish which could be due to the direct exposure of muscle tissues to toxicants. The sensitivity of the relative liver weights and AChE activity of Nile tilapia could therefore be used as potential bioindicator of carbamate insecticide contaminated waters.
Keywords: fenobucarb (BPMC), acetylcholinesterase (AChE) inhibition, bioindicator, Nile tilapia, Oreochromis niloticus Linn.