Siberian silkmoth in the Republic of Tyva, the history of studies

Siberian silkmoth (eggar) Dendrolimus sibiricus Tsch., (1908) is one of the most dangerous forest pests in the Republic of Tyva. Outbreaks of this phytophage in the republic occur frequently and cause significant damage to forests. Studies in Tyva were initiated by A. I. Cherepanov, N. G. Kolomiets, N. F. Reimers and others in the 50–70s of the XX century. They described the phenology of the Siberian silkmoth, the biological and ecological aspects of its life activity. In this paper we tried to summarize all the accumulated knowledge of the Siberian silkmoth in Tyva. The chronology of the Siberian silkmoth outbreaks was restored using the collected and analyzed data. We demonstrate that outbreaks of the Siberian silkmoth in the Republic of Tyva are most frequently observed in the forests of Shagonarsky, Chadansky and Turan forestry districts. On the whole, five outbreaks were registered: in 1954–1966, 1969–1975, 1979–1985, 1997–2000, and in 2009–2011. Duration of the outbreaks was 13–7–7–4–3 years and the intervals without outbreaks were 2–1–2–1 years. The fragmented character of the obtained data on outbreaks shows the need for their verification by dendrochronological methods. Valid analysis of data is possible with the use of control tree species not susceptible to the Siberian moth damage and some parameters of the annual rings, for example, optical density of the wood.