The dynamics of the spread of pine sawfly in the forests of the Bryansk region

On the basis of forest pathology survey of pine plantations of the Bryansk region for the period of 2011-2014, the nature of the centers of the European pine sawfly is studied and the reasons for their change are established. Works are made in the definition of the number of larvae per one tree in the growth phase of the outbreak, cocoons, male adults, and the sanitary conditions of pine forests on 5 plots in pest outbreaks are evaluated. The area of distribution of foci ranged from 896.6 to 8176.8 ha depending on the year of survey and prevailed in maturing pine plantations. There was a wide range of defoliation of trees - from mild to complete. Average condition category of plots in pine plantations, partially restored after damage was 1.84-2.42. The average number of sawfly larvae per tree has reached an average of 308 pieces. Previously unknown method for selecting the place of their cocoon - a thicker crust of fodder trees is discovered. Relatively low density of sawfly cocoons in the forest litter - 1-17 pcs/m2 is set. At the regional level for the first time, to assess the intensity of the flight of the European pine sawfly and prognosis of foci used pheromone traps were used. The number of males caught in traps varied over wide limits. Mixed results when comparing the two observation periods in 2013 and 2014 are got and the dependence of flight on the weather conditions at that time is shown. Broad ecological plasticity of this species in its ability to form foci in various conditions is confirmed.