Osmia rufa as a polylectic insect is used in the pollination of numerous plants. The usefulness of this insect for plant breeders is considerably limited because of the short flight periods of the insects in the natural environment. In order to break this limitation, the wintering period of the insects in cocoons is elongated. The temperature is maintained at 4°C up to the time of plant blooming. This treatment does shortens the lifetime of the insects which may be the result of oxidative stress. Such results led to the examination of the selected components of antioxidative system. These components are: total antioxidative status, content of glutathione and activity of peroxidase and glutathione S-transferase in O. rufa emerged in spring, according to their biological clock, and emerged in summer - after elongated diapause. It was observed that diapause elongation unprofitably influenced the antioxidative system of a bee. A statistically significant decrease in total antioxidative status, and activity of both antioixidative enzymes - peroxidase and glutathione S-transferase, was noted. The changes in the glutathione level in turn, were insignificant. In our opinion, the lower efficiency of antioxidative systems of the red mason bee emerged in summer, may limit their response ability to endo- and exogenous factors influencing oxidative stress. The results of our study are the first publication concerning an antioxidative system in mason bees.
