Impact of irrigation on the gallery parameters of spruce bark beetle (Ips typographus L., Coleoptera: Curculionidae, Scolytinae)

In the spruce stand situated in Central Slovakia, a manipulation experiment was performed aimed at attracting spruce bark beetle (Ips typographus) to living and healthy spruce trees using pheromone dispensers. The goal of the experiment was to show that the galleries of the Ips typographus in the irrigated spruce trees differed in the parameters from the galleries in drought-stressed trees. Significant differences were revealed mainly in those gallery parameters that occur after the excavation of a nuptial chamber, or after the mating of parental beetles. The revealed differences prove that drought in combination with extreme temperatures significantly reduces defence reactions of spruce against the attack of Ips typographus. Water deficit together with high temperatures significantly postpone and retard the activation of defence reactions of spruce on one side, and accelerates the regeneration and the development of Ips typographus on the other side.