Cascade form of process at arising of an aggressive biotype of the winter pine shoot moth(Rhyacionia buolianaschiff., Lepid. Tortr.)

Abstract

Creation of the big trophical niches of the winter pine shoot moth (Rhyacionia buoliana Schiff.) on susceptible trees of Pinus silvestris L. provoked the mass outbreak of the pest in the south areas in Ukraine. In its turn, high density of the pest induced processes of the aggressivity's growth of population. In so doing the wide range of adaptive zones represented by groups of the pines with different resistance is favourable for formation of aggressive biotypes. The spreading of the pest from weakened to more resistant groups on the pines is similar to the process of “drift”. This problem will be considered more detaily in the second part of this article.