Impact of Tebuconazole Fungicide on Drone Semen Quality

Tebuconazole (TEB) is a widely used fungicide of the triazole group, especially in fruit tree cultivation. It has adverse effects on the reproductive system by disrupting cellular and hormonal mechanisms in most species. Lots of studies are proven the presence of TEB’s residues on fruit trees. However, no study has been found on its effect on the reproductive parameters of drones. Honey bees are considered at risk in terms of reproductive systems since they most probably transport this chemical to the colony through nectar and pollen. Therefore, it was aimed to investigate to potential toxic effects of TEB on drone semen quality, a crucial element in reproductive system of honey bee in dose and time dependent manner. Honey bee semen in five different tubes, each containing 1.0 – 1.5 x 108/ml spermatozoa, were exposed to 0, 1, 10, 100, and 1000 µM of TEB, respectively for 24 h. Afterward, semen were analyzed for motility (MOT), plasma membrane integrity (PMI), and mitochondrial membrane potential (MMP) at 0 and 24 hours. The findings of this study revealed that highest concentration of TEB (1000 µM) significantly reduced (p≤0.05) MOT and PMI of semen compared to other concentrations even at 0 h. Following 24 h incubation, MOT, PMI and MMP values of groups exposed to 1000 µM TEB significantly lower (p≤0.05) than other groups. On the other hand, lower concentrations of TEB between 0-100 µM did not significantly change any parameters evaluated in this study at both 0 and 24 h (p>0.05). In conclusion, although it is only observed at the highest dose of TEB, our results showed that TEB has a detrimental effect on drone semen. Furthermore, it would be useful to conduct more comprehensive studies supported by in vitro and in vivo research in the future.