Outbreaks of Lymantria dispar (L.) in Tyva, Research History

The gypsy moth Lymantria dispar (L., 1758) is a widespread and damaging forest pest in the Republic of Tyva. Outbreaks of the phytophage lead to chronic weakening of trees and reduction in their growth and seed germination capacity. From 1950 to 2004, studies of gypsy moth in Tyva were carried out by researchers taking part in forest health surveys headed by such scientists as O. A. Kataev, V. P. Grechkin, G. I. Golutvin, V. A. Sevastyanyuk, N. I. Berdnikov, V. V. Popov, A. A. Liberman, and others. The researchers have described the phenology of the gypsy moth and its regional morphological and bioecological features. The present work attempts, based on the generalization of the accumulated data on gypsy moth in Tyva, to restore the chronology of pest outbreaks, show their spatial coverage, and propose approaches to their reconstruction over a longer period in the Republic of Tyva. The results of the study showed that in Tyva, four outbreaks of gypsy moth, which occurred in 1950, 1969–1983, 1993–2004, and 2018, were detected. Outbreaks were of a protracted nature and simultaneously covered up to 80 % of forest districts (in some years, the area affected by the pest reached half a million hectares or more). The most intense outbreaks were observed in the central part of the Republic, in the warm conditions of larch and birch forests – in the Kaa-Khem, Tandinsky, Tes-Khem, and Shagonarsky forest districts