Sci Total Environ. 2025 Sep 17;1001:180509. doi: 10.1016/j.scitotenv.2025.180509. Online ahead of print.
ABSTRACT
Pollinators are critical contributors to the natural world as well as to humans. However, their population numbers have been rapidly declining, in part due to pesticide exposure. Using the systemic pesticide thiamethoxam and the ornamental species Bloomify™ rose lantana (Lantana strigocamara R. W. Sanders ‘UF-1011-2’), this study investigated the influence of application method (drench vs. spray), rate (control, low, medium, high), bud stage timing (pre-bud, immature, mature), and pruning (non-pruned or pruned) on the contamination of nectar in container-grown plants. A subset of plants was later transplanted into landscape conditions to determine how long it takes for the pesticides levels in nectar to drop to non-detectable levels. Results showed significant effects of application timing, rate, and method on the concentration of thiamethoxam (and its metabolite clothianidin) in nectar. While spray applied thiamethoxam was not observed at quantifiable concentrations in nectar, drench-applied thiamethoxam surpassed published LC50’s for several bee species. Overall, as the application times approached flower bud maturity and as higher application rates were used, concentrations of thiamethoxam and clothianidin in nectar increased. Additionally, the practice of pruning or non-pruning drenched plants did not affect thiamethoxam or clothianidin concentrations found in nectar. When container-treated plants were transferred to landscape plots, pesticide concentrations in nectar were nominal after 10 days and close to non-detectable after 29 days. These results provide insight into the development of nursery guidelines to help limit pesticide risk to pollinators before plants go to market.
PMID:40966811 | DOI:10.1016/j.scitotenv.2025.180509
