Effect Of Pirimiphos-Methyl On Esterase Activities In Oreochromis Niloticus In Morogoro, Tanzania

ABSTRACT

This study was conducted to investigate the effect of Actellic Super (pirimiphos-methyl) in Oreochromis niloticus (Nile tilapia) in Mvomero District, Morogoro, Tanzania. Field surveys using questionnaire interviews were used to collect sociological data from households that own fish ponds. The response of Acetylcholinesterase (AChE) and Pseudocholinesterase (BuChE/PChE) activities in O. niloticus as a result of Organophosphates (OPs) and carbaryl waterborne exposure was determined in plasma and brain samples of fish using Ellman’s method and 5,5’-dithiobis-2-nitrobenzoic acid (DTNB) chromophore. . The in vivo dose-effect relationships were assessed using pirimiphos-methyl at 0.04, 0.08 and 0.16 µM. The majority, 56% (n=25) of respondents with the age above 51 years practiced fish farming. Males 64.0% (n=25) were more than females. Sixty eight percent of all respondents (n=25) had primary education. Oreochromis niloticus was the most kept fish species because of its good and lucrative market. Moreover, 24 percent (n=25) of respondents used pirimiphos-methyl. Concentrations that inhibited 50% (IC50) of AChE activities in brain in in vitro exposures were 0.004, 0.005 and 1.307 mM and in BuChE exposure were 0.743, 0.007 and 0.031 mM for carbaryl, pirimiphos-methyl, and profenofos respectively. Also, concentrations that inhibited 50% (IC50) of AChE and BuChE activities in plasma in in vitro exposure were 1.801, 0.031 and 0.630 mM for carbaryl, profenofos and pirimiphos-methyl and 0.045, 0.153 and 0.091 mM for carbaryl, pirimiphos-methyl and profenofos respectively. Following in-vivo exposure of fish to pirimiphos-methyl at concentrations of 0.16µM a significant inhibition of AChE (53%), PChE (90%) activities in plasma and AChE (50%), PChE (75%) in brain was observed respectively. The investigation from this work revealed that inhibition of AChE and BuChE activity in O. niloticus is a useful biomarker for assessing aquatic environmental pollutants by anticholinesterases.