(P19-004-24) Evaluation of Pesticide Residues Contamination in Onion Bulb (Allium cepa L.) Related to Cultural Practices in Kalassane and Nguéthioro Areas of Northern Senegal

Objectives: The research was conducted to verify if cultivation practices had an impact on pesticide contamination of onion bulbs. The aim was to evaluate the pesticide residues of onion bulbs produced at the Kalassane and Nguethioro sites related to the cultural practices.

Methods: The plant material comes from experiment divided into split-plot design with three replicates using “violet of Galmi” variety. The cultivation methods are related to farmer's cultivation practices and to optimized method based on the recommendations of the SAED technical data sheet. In addition, pesticide residue extraction was carried out in accordance with the modified QuEchERS method and onion extracts are read using Gas Chromatograph (Yapo and al., 2021). Welch's test is used as a statistical treatment to assess the results.

Results: The results reveal heavy contamination of onion bulbs at both sites by pesticides such as aldrine, bifenthrine and lindane, with values exceeding MRLs. In Kalassane, onion bulbs from the farmer’s method have a higher residue (0.16 ± 0.01mg/kg for aldrine; 1.1 ± 0.01mg/kg for bifenthrine; 0.1± 0.01mg/kg for lindane) than those from the optimized practice (0.10 ± 0.01mg/kg for aldrine; 0.88 ± 0.01mg/kg for bifenthrine; 0.09 ± 0.01mg/kg for lindane). However, a comparison of the optimized methods for the two sites shows that onion bulbs from Nguéthioro have higher pesticide residues (0.79 ± 0.01mg/kg for aldrine; 1.3 ± 0.01mg/kg for bifenthrine; 0.09 ± 0.01mg/kg for lindane) than those from Kalassane. The Welch test shows a significant difference only for aldrine and bifenthrine between the two sites.

Conclusions: Chemical analyses carried out according to different cultural practices made it possible to detect and quantify certain pesticide residues at values above the MRLs. The consumption of onions at these levels of contamination because of the toxicity of pesticides exposes to many health risks. This work sketches out a frame of reference for the development of a decision-making tool that is essential for better pesticide management.

Funding Sources: This work was funded by the WAGRINNOVA project as part of the LEAP-Agri Initiative.