The overall aim is to understand the mechanism of conifer tree-bark beetle interactions on the tree level.
Detection of Trees under Stress as Likely First Targets
This research is based on the observation that the stressed trees are more attractive for the bark beetle attack. Experimental plots will be established in spruce forest with low, endemic bark beetle population where trees will be exposed to sun or drought stress. Inoculation bioassay with bark beetles will be performed there. In addition, the observational plots established in spruce forest with high, epidemic bark beetle population will observe natural bark beetle populations attacking naturally stressed but physiologically monitored spruces. The trees condition and its vulnerability for bark beetle attack will be measured by the several methodical approaches.
Prediction of tree stress by physiology, dendroecology, genetics and chemical methods
Physiological methods (measuring of water flow in xylem by sap flow meters and dendrometers, measuring of leaf area by plant canopy analyzer, and measuring the plant water status by pressure chamber) will be used for detection of the stressed trees in the experimental and observation stands.
The other approach will the usage of dendroecological techniques which will show the past annual tree growth based on the tree rings in combination with isotope signal in the tree rings.
Furthermore the volatile compounds as the possible bark beetle primary attractant will be collected and identified by the gas chromatography methods. The experimental trees will be genetically characterized. We aim to understand the connections of tree health (physiology) characteristics to tree susceptibility and resistance to bark beetle attack.
Early warning by remote sensing of change of spruce needle reflectance connected with drought stress measured by aerial hyperspectral scanner
From (Näsi et al., 2015)
Remote sensing methods will be used for detection of the stressed trees in the experimental and observation stands. Our working hypothesis is that the changes in needle physiology and lower cooling abilities of stressed trees prior and after bark beetle attack affects needle reflectance. We will mount the spectral scanners to the drones which will help to make an overview of the countryside. The knowledge about connection of tree physiology and tree reflectance can be used for detection and mapping of trees susceptible to bark beetles, tree resistance to bark beetle attack and early attack detection. An additional hypothesis is that the expansion of bark beetle infestations depends on spatial distribution of susceptible and resistant trees and on mechanism of spreading – including stand light conditions.
Real-time detection by thermal emission under different crown and stand geometry
Thermal scanning will be used for detection of the stressed trees in the experimental and observation stands. Drought stressed trees emit more volatiles due to higher temperature of bark or needle and it can hypothetically serve as first targets of beetle attack. An important factor connected with temperature changes on bark and needles is sun insulation in connection to crown geometry. Therefore the real-time detection of stressed trees with poor cooling properties by medium-range thermal imaging or connected with tree crown geometry will be scanned. The surface temperature will be mapped either by the aerial - terrestrial laser scanner or image based structure, where the architecture can be evaluated.
Chemical Indicators, Anti-attractants, and Semiochemical Signals
The second point of view at the conifer tree-bark beetle interactions on the tree level focusing mainly on chemical compounds with the communication function for bark beetles.
Field activity of new physiology active semiochemicals and blend function
We will test the field activity of the new lab-active potential anti-attractants, the compounds which repel I. typographus. Anti-attractants are emitted by fungi or by the non-host angiosperm tree. As the antiatractants can serve also the resistance compounds of the attacked host tree or switching pheromone of the attacking beetles. In our experiments will be paid special attention to the new combinations of anti-attractants of different activity mode, which can change the range-of-action of non-host volatiles-dispensers (used later in level L). We will test the activity of the new anti-attractants by trapping I. typographus in and around its pheromone traps and we will study the protection of the single tree by anti-attractants.
Establishment of rapid attacked tree detection / diagnosis by sniffer dogs
We aim to establish the method of rapid attacked tree detection by sniffer dogs for prompt removal of attacked trees. The structure of this research item is different from all the others in that it has a large element of demonstration. We expect a full success and acceptance of the method by Czech dog trainers and foresters, probably followed by founding of fully commercial small service companies.
Jakus R, Zajíčkova L, Cudlín P, Blaženec M, Turčani M, Ježík M, Lieutier F, Schlyter F (2011) Landscape-scale Ips typographus attack dynamics: from monitoring plots to GIS-based disturbance models. iForest-Biogeosciences and Forestry 4: 256. doi:
Näsi R, Honkavaara E, Lyytikäinen-Saarenmaa P, Blomqvist M, Litkey P, Hakala T, Viljanen N, Kantola T, Tanhuanpää T, Holopainen M (2015) Using UAV-based photogrammetry and hyperspectral imaging for mapping bark beetle damage at tree-level. Remote Sensing 7: 15467-15493. doi: