Interactions between photoperiodism and temperature with respect to the control of dormancy in the adult stage of Pterostichus oblongopunctatus F. (Col., Carabidae) : II. The development of the reproduction potential during the winter months in the field.

The short day effect in gonad maturation (previtellogenesis in the females) of the short day/long day beetle Pterostichus oblongopunctatus depends on an extremely narrow range of temperature (about 10-15°C). This effect was first found in the laboratory. Experiments with beetles captured from the field have demonstrated that they, too, show this dependence. When the short day effects of autumn had acted on the beetles at temperatures around the favourable span, they became fully mature and produced the normal quantity of offspring when brought into the laboratory at long day. These short day maturation effects were diminished in beetles captured during the colder part of the winter from the field; such beetles showed only a small reproduction rate if brought into the long day conditions of the laboratory. Beetles caught during short day at about 10°C in spring again showed the normal reproduction rate in the favourable laboratory conditions. From this, the conclusion is drawn that the short day maturation effect of autumn is diminished in nature by the cold of winter and can be restituted by short day at spring temperatures in a similar manner as was formerly shown by climate simulation experiments in the laboratory (Thiele, 1975).