Fecundity of Neodiprion sertifer (Hymenoptera, Diprionidae) related to cyclic outbreaks:: invariance effects

In pine plantations of the Khoperskii Reserve (Voronezh region), the population of European pine sawfly is capable to preserve its structure. According to the data of the long-term monitoring (1969-2004), the population is in the status of mobile equilibrium represented by waves of cyclic outbreaks. The fecundity of a sawfly individual is 30-120 eggs. The cleavage of descendants according to the duration of their diapause and negative relations in the system of interacting organisms equalize the population fecundity. The fecundity correlates weakly with the sawfly population density: its mean value is about 70 eggs. During the population waves, it amounts to 56-88 eggs. The system exhibits both features of variability and constancy.