Uptake, translocation, and degradation of spirotetramat in tomato (Lycopersicon esculentum Miller): Impact of the mixed-application with pymetrozine

Fate characteristics and risk quantification of cyflumetofen from tomato cultivation to processing based on large-scale applications

Elucidating the fate characteristics of cyflumetofen and its main metabolite 2-TFMBA in tomato from cultivation to processing is crucial for safeguarding the environment and humans from hazardous effects. Cyflumetofen and 2-TFMBA could exist stably in tomato matrices for at least 343 days under frozen and dark conditions according to UHPLC-MS/MS, with a limit of quantitation of 0.001 mg/kg and retention time within 2.12 min. The occurrence, dissipation, and concentration variation of cyflumetofen were reflected by original depositions of 0.02-0.44 mg/kg, half-lives of 1.7-7.2 days, and terminal magnitudes of 0.005-0.30 mg/kg, respectively, with various influencing factors, e.g., climate conditions and tomato cultivars. Additionally, 13.5-59.3% of cyflumetofen was metabolized to 2-TFMBA, showing significant toxicological effects ranging from cultivation to processing. When the concentration decreased by 0.06 mg/kg, cyflumetofen was effectively removed by peeling, while washing was the recommended method for removing 2-TFMBA with a processing factor of 0.70. The comparative dietary risks of sum cyflumetofen were assessed for all life cycle populations using deterministic and probabilistic models. The risk quotients decreased to 1.3-4.8 times during the preparation of home canning tomato paste. Despite the low exposure risk, the potential health hazards of sum cyflumetofen should be considered, given its ubiquity and cumulative effects.

Bidirectional Uptake, Transfer, and Transport of Dextran-Based Nanoparticles in Plants for Multidimensional Enhancement of Pesticide Utilization

The development of effective multifunctional nano-delivery approaches for pesticide absorption remains a challenge. Here, a dextran-based pesticide delivery system (MBD) is constructed to deliver tebuconazole for multidimensionally enhancing its effective utilization on tomato plants. Spherical MBD nanoparticles are obtained through two-step esterification of dextran, followed by tebuconazole loading using the Michael addition reaction. Confocal laser scanning microscopy shows that fluorescein isothiocyanate-labeled MBD nanoparticles can be bidirectionally transported in tomato plants and a modified quick, easy, cheap, effective, rugged, and safe-HPLC approach demonstrates the capacity to carry tebuconazole to plant tissues after 24 h of root uptake and foliar spray, respectively. Additionally, MBD nanoparticles could increase the retention of tebuconazole on tomato leaves by up to nearly 2.1 times compared with the tebuconazole technical material by measuring the tebuconazole content retained on the leaves. In vitro antifungal and pot experiments show that MBD nanoparticles improve the inhibitory effect of tebuconazole against botrytis cinerea by 58.4% and the protection against tomato gray molds by 74.9% compared with commercial suspensions. Furthermore, the MBD nanoparticles do not affect the healthy growth of tomato plants. These results underline the potential for the delivery system to provide a strategy for multidimensional enhancement of pesticide efficacy.

Uptake and Biotransformation of Spirotetramat and Pymetrozine in Lettuce (Lactuca sativa L. var. ramosa Hort.)

Here, we investigated the uptake, transport, and subcellular distribution of the pesticides pymetrozine and spirotetramat, and spirotetramat metabolites B-enol, B-glu, B-mono, and B-keto, under hydroponic conditions. Spirotetramat and pymetrozine exhibited high bioconcentrations in lettuce roots, with both having root concentration factor (RCF) values >1 after exposure for 24 h. The translocation of pymetrozine from roots to shoots was higher than that of spirotetramat. Pymetrozine is absorbed in roots mainly via the symplastic pathway and is primarily stored in the soluble fraction of lettuce root and shoot cells. The cell wall and soluble fractions were the major enrichment sites of spirotetramat and its metabolites in root cells. Spirotetramat and B-enol were mainly enriched in the soluble fractions of lettuce shoot cells, whereas B-keto and B-glu accumulated in cell walls and organelles, respectively. Both symplastic and apoplastic pathways were involved in spirotetramat absorption. Pymetrozine and spirotetramat uptake by lettuce roots was passive, with no aquaporin-mediated dissimilation or diffusion. The findings of this study enhance our understanding of the transfer of pymetrozine, spirotetramat, and spirotetramat metabolites from the environment to lettuce, and their subsequent bioaccumulation. This study describes a novel approach for the efficient management of lettuce pest control using spirotetramat and pymetrozine. At the same time, it is of great significance to evaluate the food safety and environmental risks of spirotetramat and its metabolites.

Uptake, Translocation, and Subcellular Distribution of Oxathiapiprolin and Famoxadone in Tomato Plants (Lycopersicon esculentum Miller)

The uptake, translocation, and subcellular distribution of oxathiapiprolin and famoxadone in tomato plants were investigated using hydroponic experiments. Oxathiapiprolin and famoxadone mainly accumulated in the tomato roots with limited translocation capacity from the roots to the upper part. The root absorption and inhibitor results noted the dominance of the apoplastic and symplastic pathways in the oxathiapiprolin and famoxadone uptake by the tomato roots, respectively. Furthermore, the uptake process for the two fungicides followed passive and aquaporin-dependent transport. Insoluble cell components (cell organelles and walls) were the dominant storage compartments for oxathiapiprolin and famoxadone. In the protoplast, oxathiapiprolin in the soluble fraction had a higher proportion than that of famoxadone. Finally, the uptake and distribution of the two fungicides by the tomato plants was accurately predicted using a partition-limited model. Thus, this study provides an in-depth understanding of the transfer of oxathiapiprolin and famoxadone from the environment to tomato plants.