Comparative acute toxicity of two phytosanitary molecules, lambda-cyhalothrin and acetamiprid, on Nile Tilapia (Oreochromis Niloticus) juveniles.

This study aimed to compare the toxicity for fish of two active ingredients (lambda-cyhalothrin-20 g L-1, a pyrethroid, and acetamiprid-15 g L-1, a neonicotinoid) which are components of a commercial insecticide (Acer 35 EC) used in cotton crop in many West African countries. The juveniles of Oreochromis niloticus (4.01 ± 0.34 g, mean body weight) were exposed for 96 h to increasing concentrations of active ingredients (lambda-cyhalothrin and acetamiprid) or a mixture similar to Acer 35 EC (composed by 20 g of chemical compound lambda-cyhalothrin and 15 g of acetamiprid dissolved in 1 L of acetone). The experiments were carried out under controlled conditions in aquaria according to OECD Guidelines. During the experiments, the behavioral responses (loss of balance, color change, hyperactivity, etc.) that usually precede death were observed in exposed fish. Mortalities were recorded in each aquarium and the LC50-96h of each chemical was determined. The LC50-96h obtained were respectively 0.1268, 0.0029, 182.9 and 0.5685 ppm for Acer 35 EC, lambda-cyhalothrin, acetamiprid and mixture. All insecticides used in this study had profound impact on Nile tilapia behavior which may confirm the neurotoxicity of each single active compound as well as of their mixture.

Occurrence of Acetamiprid Residues in Water Reservoirs in the Cotton Basin of Northern Benin.

An Ultra performance liquid chromatography (UPLC) coupled to UV detection method was developed to determine acetamiprid residues in water reservoirs of northern Benin, close to cotton fields. The quantification limit of this method was 0.2 µg L-1 acetamiprid in water, its precision ranged between 8% and 22%, and its trueness between 99% and 117% (for concentrations ranging from 0.2 to 5.0 µg L-1). Acetamiprid residues were determined in water samples collected in four reservoirs from northern Benin during the phytosanitary treatment period of cotton. The minimum and maximum concentrations of acetamiprid residues in water were 0.2 and 7.7 µg L-1, respectively. These levels do not represent any risk for human consumption of this water, but indicate a regular use of acetamiprid, possibly together with other pesticides which could be more harmful for both humans and aquatic species.