The results of manipulated experiments with inoculation of Ips typographus (L., 1758) to spruce trees under various levels of water stress

Abstract

Manipulated experiments with males of Ips typographus (L., 1758) were conducted in spruce stands in north-western Slovakia. Some of trees were stressed by a lack of water caused by preparation of roofs under canopy. Inoculation experiments with bark beetles were conducted on such trees. According to results, the differences in attack rates between differently positioned trees on slope were not statistically significant (P = 0.389 for bottom and middle and P = 0.924 for bottom and top, and P = 0.530 for middle and top trees, t-test). Also the differences in attacks rate and the speed of entry holes preparation between more stressed and less-stressed trees were not statistically significant (P = 0.321, t-test). Thus the results of inoculation confirmed that low level of water stress does not lead necessarily to higher attack rate and (neither) faster speed of entry holes preparation. The obtained results are discussed.