Survival of Salmonella Typhimurium in pesticide solutions used in fresh produce production in Northwestern Mexico

Intensive agriculture is closely associated with the use of pesticides for pest control. These pesticides are often diluted in non-potable water before field application, which may pose microbiological risks to consumers of raw fresh produce. This study aimed to experimentally evaluate the survival and growth of Salmonella Typhimurium in commonly used and recently introduced pesticide solutions. Four commercial insecticidal formulations were evaluated at high, medium, and low concentrations, as recommended by the manufacturers. Each was diluted with sterile distilled water and inoculated with S. Typhimurium at an initial concentration of 107 CFU mL−1. Bacterial survival was assessed after 1, 60 and 1440 min of exposure. The average survival percentages of S. Typhimurium were 98.13% in solutions containing the active ingredient (a.i.) afidopyropen, 96.69% for thiamethoxam and lambda-cyhalothrin, and 90.88% for pymetrozine. Chlorpyrifos completely inhibited S. Typhimurium after 60 min of exposure at all tested dilutions. Neither pesticide concentration nor exposure time had a statistically significant effect (p > 0.05) on bacterial survival. These findings indicate that S. Typhimurium can persist in pesticide solutions, potentially posing a health risk to consumers.