Improving the Monitoring System Towards Early Detection and Prediction of the Siberian Moth Outbreaks in Eastern Siberia

: The Siberian moth, Dendrolimus sibiricus Tschetverikov ( Lepidoptera: Lasiocampidae ) is a dangerous pest of the taiga forest in Siberia. The present research is aimed to improve the monitoring system towards early detection and prediction of the Siberian moth outbreaks in dark-conifer-ous taiga in the mountainous region of Krasnoyarsk Krai (Eastern Siberia). The study determined the habitats preferred by the Siberian moth considering the relief, the type of forest and forest inventory characteristics. For that, we analyzed data obtained with the remote sensing and those collected in nature in 2018-2019 through surveying the plots damaged by the pest.

We aim to improve the monitoring system towards early detection and prediction of the Siberian moth outbreaks in dark-coniferous taiga in the mountainous region of Krasnoyarsk Krai (Eastern Siberia).The first step is to determine the habitats with the optimal conditions for the pest development and foci occurrence.
For that, we analyzed data obtained with the remote sensing and those collected in nature in 2018-2019 through surveying the plots damaged by the pest.To define the habitats with the optimal conditions, we took into account the relief, the type of forest and forest inventory characteristics.Figure 1 demonstrates the study area in September 9, 2019.
There were six forest types in the damaged area: Bergenia, Reedgrass/Tall Grasses, Bilberry, Mossy, Sedges/Herb-rich, and Next-to-the-stream.Figure 2 shows the spatial distribution of forest types within the study area.
The study area is located in mid-mountain relief.Most of forest types are located on neutrally-insolated slopes (Figure 3).The analysis did not reveal a significant correlation between insolation on slopes and forest type in areas defoliated by the Siberian moth neither at the onset nor during an outbreak.
Figure 4 shows indicators for quantifying the Siberian moth larvae abundance according to the field study where forest type and tree species were took into account.At the time of survey (September, 2019) larvae of the third and forth instars dominated in the age structure of the population.We found no larvae being ill or infested with parasites.
The most preferred habitats of D. sibiricus, where its foci most often occur, are mossy insolated forest plots, followed by grassy forest plots.The plots situated in the terrain depressions, next to the streams, as well as grassy-bog forests are avoided by the pest.We showed that population density of the pest depends on the forest structure.
We indicated that larvae population size increased when Pinus sibirica and Abies sibirica dominated in the stand structure.The revealed pattern in pests' distribution is determined by the Siberian moth preferred host-trees (Figure 5).
The indicators for larvae abundance were higher in mid-density forest stands (a relative density of 0.5-0.7).The Siberian moth population density was low in stands with a relative density of 0.4 and 0.9 (Figure 6).
As a result, we differentiated forest stands by the degree of their resistance to the insect attacks.The obtained results can be used for improving the pest monitoring and the prediction of its outbreaks.Institutional Review Board Statement: Not applicable.
Informed Consent Statement: Not applicable.

Conflicts of Interest:
The authors declare no conflict of interest.The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.

Figure 1 .
Figure 1.Study area of dark-coniferous taiga damaged by the Siberian moth (Eastern Siberia, Krasnoyarsk Krai, South Siberia Mountain Forest Zone, Altay-Sayan Mountain Taiga Province.Red shows the areas of forest stands damaged by the pest (defoliation of 50% or more) on a 09.09.2019.

Figure 2 .
Figure 2. Spatial distribution of forest types within the damaged dark-coniferous stands.

Figure 3 .
Figure 3. Stands distribution by forest types depending on solar radiation on sloping surfaces.

Figure 5 .Figure 6 .Funding:
Figure 5.Correlation between the Siberian moth abundance and the proportion of dark-coniferous species (Pinus sibirica and Abies sibirica) in the stand species composition.