Effects of Flupyradifurone (Butenolide) on some physiological, behavioral, and colony development characteristics in bumblebees (Bombus terrestris L.)

Bumblebees (Bombus spp.) play a vital role in maintaining the sustainability of both natural and agricultural ecosystems. Their conservation is critical for plant biodiversity, food security, and ecosystem health. This study investigates the effects of Flupyradifurone (FPF), an active ingredient marketed as an eco-friendly insecticide (Sivanto, Bayer), on the physiology, behavior, and colony development of Bombus terrestris. Five experimental groups were established based on the recommended field application dose of FPF: control, FPF 1/100, FPF 1/10, FPF 1/1, and FPF 2/1. Bee survival and mortality rates were evaluated using the microcolony method over a 28-day period. The shortest lifespan and highest mortality were observed in the FPF 2/1 group. While FPF affected worker and queen production as well as the timing of first male emergence, it had no significant impact on competition point, first gyne emergence time, or reproductive strategies. Memory and learning tests revealed no adverse effects, and nest-finding behavior remained unaffected by FPF exposure. However, neuropil irregularities were detected in brain tissue across all dosage groups, with the most severe disruptions occurring in the FPF 2/1 group. Furthermore, it has been determined that as exposure to FPF increases, the number of hemocytes decreases. Overall, FPF did not demonstrate devastating effects on B. terrestris, nor did it impair their pollination performance. However, the physiological disruptions observed at higher concentrations warrant further investigation to ensure long-term safety in bumblebee populations.