Contamination of the waters and fishery resources of Lake Nokoué by pyrethroid molecules

The use of pesticides in agricultural activities near water bodies and fishing practices with the use of impregnated mosquito nets contaminate fishery resources. This is the case of Lake Nokoué in the Municipality of Sô-Ava, which for decades has become a receptacle for chemical pollutants such as pyrethroids. This observation prompted the present research which aims to determine the level of contamination of the waters and fishery resources of Lake Nokoué by pyrethroid molecules. The method used consisted of surveying the farmers working on the shores of Lake Nokoué, the different types of pesticides they use in the fight against pests on their crops. Then, the pyrethroid molecules (deltamethrin and cypermethrin) were looked for in water and fish samples taken, by the QuEChERS technique (Quick, Easy, Cheap, Efficient, Rugged an Safe) at the Laboratory of the 'International Institute of Tropical Agriculture (station) of Benin. At the end of the work, 13 types of pesticides were identified, of which only 26.31% are approved by the Sahelian Pesticides Committee (CSP). A wide range of unapproved pesticides representing 73.68% is also used in the study environment. Laboratory analyzes revealed the presence of the desired active ingredients at concentrations that greatly exceed the WHO standard in all water and fish samples. Non-repeat two-way proc ANOVA analysis of variance and the Student Newman Keuls test revealed that the concentrations of cypermethrin in the samples exceeded those of deltametrin.