The effects of fungicides on pollinators remain relatively understudied despite their widespread use and high likelihood of environmental exposure. We assessed the effects of a single exposure to the commercial formulation Tebucur® 250 EW (containing tebuconazole as the active ingredient) on learning and memory in Bombus terrestris workers. Using the Free-Moving Proboscis Extension Response (FMPER) paradigm, bees were exposed to two concentrations: 9.4 µg of tebuconazole per mL (group T 1/100) and 94 ng of tebuconazole per mL (group T/10,000) of tebuconazole through either pure sucrose (Method 1) or Tebucur® 250 EW-supplemented sucrose (Method 2) during conditioning. No significant differences between groups were detected during the learning phase (all p > 0.05). In contrast, significant differences emerged during the memory test at the earliest time point (5 min). In Method 1, bees exposed to the higher concentration (treatment group T 1/100) showed significantly lower performance compared to the control group (p < 0.05). In Method 2, the lowest performance was observed in the group exposed to the lower concentration (treatment group T 1/10,000; p < 0.01). No significant differences were detected at later time points (10 and 30 min). These results indicate that a single exposure to Tebucur® 250 EW (active ingredient: tebuconazole, 250 g/L) can affect short-term memory in bumblebees without impairing initial learning performance. Although the observed effects were subtle and time-limited, they may have important implications for foraging efficiency and pollination under natural conditions.
Murawska et al. (Wed,) studied this question.