The first record of an outbreak of the larch bud moth, Zeiraphera diniana Gn (Lep, Tortricidae) on an evergreen conifer host (Pinus pumila [Pall] Regel) in North-Eastern Asia

An outbreak of the larch bud moth (Zeiraphera diniana Guenee) occurred from 1988 to 1993 on Pinus pumila [(Pall.) Regel] on Kamchatka Peninsula while the sympatric Larix gmelinii [(Rupr.) Litv.] remained unattacked. This first major outbreak of Z. diniana ever observed and reported on an evergreen host in Siberia and North Fast Asia is discussed in the larger context of its population dynamics throughout the Palaearctic. The complex interactions between site-, host plant- and insect-characteristics in conjunction with climatic release allows us to explain this unique event in a conventional manner: the eggs survive the extremely cold winter temperatures on dwarf pines underneath the snow the slow developing light colour morph, which is adapted to the phenology of evergreens, benefits from the mesoclimate close to the ground it was temporarily favoured by the significantly warmer spring and summer seasons during the outbreak 1988-1991. The occurrence of the pine-feeding Z. diniana in North East Asia supports the hypothesis that the host-associated genetic divergence might have evolved sympatrically.