[1]Department of Forest Regeneration and Establishment Latvian State Forest Research Institute "Silava " Salaspils L V-2169 Latvia;
[2]Department of Forest Products Processing Latvian State Forest Research Institute "Silava " Salaspils L V-2169 Latvia;
[3]Department of Entomology Latvian State Forest Research Institute "Silava" Salaspils LV-2169 Latvia;
[4]Rector of Daugavpils University 13 Vienibas Street Daugavpils LV-5401 Latvia;