Migration of the Northern Boundary of the Siberian Silk Moth

Climate changes have induced the northward migration of outbreaks of the Siberian silk moth (Dendrolimus sibiricus Tschetv.), one of the most dangerous pests in the taiga. The initial outbreak of the Siberian silk moth began in 2014 in Siberian pine.fir stands within the Yenisei Plain on the southwestern flat slopes at elevations up to 200 m above sea level. Further, the outbreak extended to the parts of the forest with higher humidity, the northern slopes, and Yenisei Ridge at low and middle elevations. The northern limit of the outbreak zone shifted to 50 km (to 60°26′ N) northward from the historical boundary of formerly observed outbreaks. The outbreak was incited by an increase in aridity, the sum of positive temperatures (t > +10°C), and a decrease in soil moisture. It extended to an area of 800000 ha. Stand mortality was accompanied by the activation of secondary pests, including aggressive bark beetle species Polygraphus proximus. The outbreak under study is part of the panzonal outbreak that occurred in 2014–2017 on the territory of Siberia in Krasnoyarsk krai and Tomsk, Kemerovo, and Irkutsk oblasts. The increase in warming, aridity, and vegetative period provides opportunities for the Siberian silk moth to migrate to the northern dark-conifer taiga.