environmental science & technology,2024，
abstract
plant guttation is an important source of water/nutrients for many beneficial insects, while the presence of pesticides in guttation has been considered as a new exposure route for nontarget insects. this study aimed to elucidate how 15 diverse pesticides are translocated from growth media to guttation by maize plants through a hydroponic experiment. all pesticides were effectively translocated from the growth solution to maize guttation and reached a steady state within 5 days. the strong positive correlation (r2 = 0.43–0.84) between the concentrations of pesticides in guttation and in xylem sap demonstrated that xylem sap was a major source of pesticides in guttation. the relationship between the bioaccumulation of pesticides in guttation (bcfguttation) and the chemical kow was split into two distinct patterns: for pesticides with log kow > 3, we identified a good negative linear correlation between log bcfguttation and log kow (r2 = 0.71); however, for pesticides with log kow < 3, all data fall close to a horizontal line of bcfguttation ≅ 1, indicating that hydrophilic pesticides can easily pass through the plants from rhizosphere solution to leaf guttation and reach saturation status. besides, after feeding with pesticide-contaminated guttation, the mortality of honeybees was significantly impacted, even at very low levels (e.g., ∑600 μg/l with a mortality of 93%). our results provide essential information for predicting the contamination of plant guttation with pesticides and associated ecological risks.
environmental science & technology，if=11.4
