The overall aim is to understand the mechanisms of conifer tree-bark beetle interactions on the tree level. One hypothesis is that drought stress predisposes the tree to bark beetle attack.
We aim to understand the connections of genetics, tree health (physiology), susceptibility, and resistance to bark beetle, including the chemical messengers involved such as attractants and anti-attractants. Rapid detection of tress under stress or beetle attack is a more direct applied goal.
Detection of Trees under Stress
This research is based on the observation that the stressed trees seems to be more likely to be attacked. Experimental plots are 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 (Pictures above, photo S. Netherer). The trees condition and vulnerability for bark beetle attack will be measured by several approaches.
Susceptibility of stressed Norway spruces to bark beetle attack
Hypotheses: Changes in physiological and biochemical characteristics in spruces as consequences of sudden stress by predispose trees to bark beetle attack
First, we use the physiological approaches to quantify the physiological stress of trees compared to the susceptibility to bark beetle attack. Among others, the sap flow measurement is the most important physiological instrument as it reveals the cooling abilities of the tree. Normally, the water consumption is 15 - 65 l/day depending on stem diameter. With prolonged period of drought, the tallest tree has the same transpiration as smaller trees with suppressed crown (ca 5 l/day). The hypothesis we are working on is the higher level of drought stress in trees with bigger diameter compared to smaller ones. If the smaller trees could restrict the transpiration 3X under drought, the large trees would have to lower the transpiration > 10X. The tallest trees in the forest of the same age may then be the first targets for bark beetle.
Figure 1. Sap flow meter EMS81 with isolation: The instrument for sap flow measurement is based on thermodynamic method and the insulation layer should cover the instrument to prevent the heat from outside. Photo: I. Tomaskova
Figure 2. EMS81 without isolation: This instrument take a 10minutes measurements of stem diameter and water movement within the xylem. The dendrometer is very sensitive to stem volume changes so the shrinkage, swelling and real growth of the stem is being recorded. Sensors below the dendrometer records the water amount per 1 cm of the stem perimeter. Photo: I. Tomaskova
Figure 3. Meteo station consist of anemometer, global radiance sensor, sensor for air temperature and relative humidity, precipitation gauge and sensors for soil humidity in two depths. Photo: S. Netherer
Figure 4. Receiver and sender is the equipment enabling wireless data transfer to internet portal. Data are stored for 5 years here. Pair of spare batteries are inside of the metal box in case of insufficient energy from solar panels. Photo: S. Netherer
FIgure 5. Solar energy runs all physiological equipment. The energy is stored in batteries. Photo: S. Netherer
- Acute stress on fresh forest edge as the initial locality of bark beetle infestation
- Drought effect on defence ability of Norway spruces against bark beetle’s attack/Roofing experiment/5 roofs
5 roofs were established in the University Forest Enterprise in Kostelec n/Cernymi lesy
Aerial scanning + physiological and microclimatic data recording +
Data collection: Biochemistry in needles and phloem: Non structural carbohydrates,
Phenolics, Monoterpene from phloem, Prolin, Inducing of defense chemistry by Methyl jasmonate treatment, Bioassay with live beetles/ non-choice in Eppendorf tubes, sandwiche
Chemical Indicators, Anti-attractants, and Semiochemical Signals
Screening in ODOROSPHERE of Ips typographus for active compounds attractants /repellents -in host trees , - non-host trees , - symbiotic fungi, -beetles itself
With methods of -analytical chemistry GCMS, -electrophysiology based on connecting of insect antenna as biodetector. Possible use in Integrated Pest Management.
Figure GCxGC-MSTOF B): Post-run analysis. More info on lab in operation see https://extemit.fld.czu.cz/en/r-12327-vizual/modern-chemical-ecology-laboratories-are-fully-in-operation.html
We test the field activity of the new lab-active potential anti-attractants, compounds which reduce attraction or host-acceptance in I. typographus. Anti-attractants are emitted by fungi or by the non-host angiosperm tree. Anti-attractants may come also from the resistance compounds of the attacked host tree or from 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. 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.
1. Anti-attractants (repellent) mixture to protect spruce against Ips typographus with new compound (+)-trans-4-thujanol
Protection of young tree forest fragments and forest edge in mature Norwas spruce forest
Anti-attract bait:
2.The smell of symbiotic ophiostomatid fungi Endoconidiophora polonica, Grosmannia penicillata, Leptographium europhioides.increase attraction of Ips typographus to its pheromone
These fungi released a broad spectrum of volatile organic compounds with predominant fusel alcohols and acetates. The synergistic effect of this smell to attraction o I. typographus to pheromone is studied.
3. Establishment of rapid attacked tree detection/diagnosis by sniffer dogs
Snifferdog BeBe indicating an early attack on a mature tree. Blue-red arrow) GPS dog collar with antenna.
We aim to establish the method of rapid attacked tree detection by snifferdog-handler pairs 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.
Genetic dissection of complex resilience traits in Norway spruce -Genotyping by Sequencing
Hypotheses. We expect significant difference among and within the 3 ecotypes of Norway spruce under water stress (used as a precursor to resistance
