Microcalorimetric and respirometric investigation of the effect of temperature on the antivarroa action of the natural bee product-propolis

The antivarroa action of propolis and its synergism with temperature was investigated calorimetrically and respirometerically, using female Varroa destructor mites from adult workers, worker- and drone broods. The treatment of Varroa mites with 4% propolis affected their metabolic activity, with the influence directly related to the temperature of treatment. The changes in heat production and oxygen consumption rates, as a function of temperature, showed similar patterns before as well as after treatment with 4% propolis. The mites collected from worker- and drone broods reacted similarly to propolis treatment at different temperatures. In contrast, the mites from adult workers, phoretic mites, responded differently: the treatment with 4% propolis at 40 °C resulted in 100% mortality of mites from adult workers but only reduced the heat production rate of mites from worker- and drone broods by 68 and 60%, respectively. Exposure of mites to 45 °C agitates them as witnessed by the elevated heat production rates (23.5±2.5 μW/mg compared to that at 35 °C with 14.4±1.0 μW/mg). After treatment with propolis at 45 °C all mites died regardless of their origin indicating that the simultaneous use of varroacides and high temperature treatment for a short period of time could be more effective rather than the prolonged use of either method.