Lethal and sublethal effects of flupyradifurone and cyantraniliprole on two neotropical stingless bee species

Stingless bees are important pollinators in tropical regions, but their survival and behavior have been impacted by various factors, including exposure to insecticides. Here, we evaluated the lethal and sublethal effects of commercial formulations of two widely used insecticides, flupyradifurone (FPF formulation), and cyantraniliprole (CY formulation), on Melipona beecheii and Nannotrigona perilampoides. The study involved oral exposure of bees to insecticides, calculation of the lethal concentration (LC₅₀) and the lethal time (LT₅₀), and evaluation of walking and flight take-off activities. The LC₅₀ values showed that the largest bee, M. beecheii, was more sensitive than N. perilampoides to both insecticides and that the FPF formulation had faster lethal effects in both species (N. perilampoides, 9.6 h; M. beecheii, 5 h) compared to the effects of the CY formulation (N. perilampoides, 17 h; M. beecheii, 24.7 h). Sublethal concentrations (LC_50/10 and LC_50/100) of both insecticides affected walking and flight take-off activities. After 6-24 h of exposure, both FPF and CY formulations significantly reduced the mean walking speed of N. perilampoides (0.962-1.402 cm/s) and M. beecheii (2.026-2.589 cm/s) compared to the control groups (N. perilampoides: 1.648-1.941 cm/s; M. beecheii: 2.759-3.471 cm/s). Additionally, the FPF and the CY formulation impaired individual flight take-off in both species. This study provides the first comprehensive evaluation of the lethal and sublethal effects of flupyradifurone and cyantraniliprole on M. beecheii and N. perilampoides, offering valuable information for future research on insecticide toxicity in stingless bees.