Behavior of Honey Bees (Apis mellifera L.) Exposed to Tebuconazole Under Laboratory Conditions

Honey bees are constantly exposed to various environmental threats, among which pesticide pollution, including fungicides, is one of the most serious. The bees were 3 days old when they received the experimental solution. This study aimed to evaluate the behavior and mortality of honey bee workers exposed to a commercial formulation of the fungicide tebuconazole (Tebu® EW, a.i. 25.8%; HELM, Hamburg, Germany). The experiment was conducted under laboratory conditions and lasted 7 days for all experimental groups. The fungicide solution was prepared by adding 6.25 mL of Tebu® EW per 1 L of water, corresponding to 156.25 mg of tebuconazole (active ingredient) in the prepared solution of sugar syrup. The solution was served in 5 mL dispensers (=group feeding) placed in the cages. This concentration was used for the acute-exposure group (24 h). After 24 h bees were supplied with untreated sugar syrup for the remainder of the experiment. For the chronic-exposure group (168 h), the solution was a 1000-fold dilution of the acute solution, containing 0.15625 mg tebuconazole, dissolved in sugar syrup, provided continuously for 7 days with daily replacement. After 7 days, bee behavior was recorded using a camera and analyzed with Noldus Observer XT software (12.5: Windows 7 64-bit (SP1) version) Five basic honey bee behaviors were examined: walking, flight, self-grooming, contact between individuals and stillness. The results showed statistically significant differences between the experimental groups and the control group (α = 0.05) in the duration of walking, contact between individuals and self-grooming, and the frequency of walking and flight. This was particularly evident for self-grooming; the longer the group was exposed to tebuconazole, the less time the bees spent on this behavior (the acute group spent 47% less time self-grooming and the chronic group spent 88.8% less time self-grooming compared to the control group). Meanwhile, the frequency of walking and flying increased significantly with increasing exposure. No significant differences were observed in the survival between the groups. Based on these findings, it can be concluded that the fungicide containing tebuconazole significantly affects the behavior of honey bee workers.