Effect of thymol, trans-anethole, and diallyl disulfide on honey bee survival and antioxidant system

Honeybees play a key role in food safety, but various pests such as Varroa have been threatened the health of colonies. To control this mite, the application of pesticides is inevitable, but the consequence of pesticide usages is associated with increased incidences of Varroa resistance. Hence, the researchers point out the botanicals. Despite the effectiveness of botanicals in combating Varroa, their side effects on colony health are key topics. In the present study, the biological effects of thymol, trans-anethole, and diallyl disulfide were investigated on honeybees. The results showed that the lethal concentrations of 50% of thymol, trans-anethole, and diallyl disulfide were 16.46, 55.22, and 37.30 mg ml-1, respectively. The effects of LC15, LC30, and LC50 of these compounds on the activities of honeybee antioxidant enzymes (catalase, superoxide dismutase, and glutathione S-transferase) and the lipid peroxidation showed that the activities of these enzymes in thymol, and trans-anethole treatments significantly increased compared to the control, while in diallyl disulfide treatment, the activity of these enzymes decreased. The results also showed that the amount of malondialdehyde was significantly reduced in all treatments. Survival study showed that all concentrations of thymol, trans-anethole, and diallyl disulfide caused 100% mortalities of the honeybee at four, six, and three days post-treatment, respectively. The results showed that the lethal concentrations of thymol, trans-anethole, and diallyl disulfide could induce oxidative stress and influence the survival of the honeybees. Therefore, it is recommended that these compounds could be used with caution to control Varroa in apiaries