BARK BEETLE MONITORING IN AUSTRIA 2005/ CRITICAL EVALUATION. Hannes Krehan

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1 BARK BEETLE MONITORING IN AUSTRIA 2005/ CRITICAL EVALUATION Hannes Krehan BFW: Federal Research and Training Centre for Forests, Natural Hazards and Landscape Department of Forest Protection Unit of Entomology Seckendorff-Gudent-Weg 8, A-1131 Vienna ( hannes.krehan@bfw.gv.at) Abstract The Austrian bark beetle monitoring was initiated 2004, one year after the bark beetle gradation started to reach new record dimensions due to wind throw and summer draught. In 2006 the capture rates of 183 pheromone traps were presented in the web ( many of them in combination with online-results of temperature measurements of climate stations nearby the pheromone traps. The interpretation of the results of the trap captures should be done very carefully and always in consideration of possible influencing factors. Keywords: bark beetle, monitoring, pheromone trap, gradation, web-presentation, Ips typographus, Pityogenes chalcographus, Ips cembrae 1. Introduction The recent outbreak of bark beetles in coniferous stands after a disastrous storm in November 2002 in some parts of the Alps and a very strong draught period during the summer of 2003 were the main reasons for initiating a bark beetle monitoring in Austria. It is presented in the web and therefore can be used by all interested people for getting current information e.g. about the flight activity of the beetles. The application is available in the web since It is the result of good cooperation between the forest protection offices of many federal states, the chamber of agriculture and forestry and the BFW. Primary intension: More information for foresters and forest companies about the actual bark beetle situation in the districts Base for planning of control activities on time Figure 1: Amount of felled timber in Mio m³ (Efm) due to bark beetle attack (right scale and blue line) and storm- or snow damages (left scale and green bars) IUFRO Working Party Proceedings of the Workshop 2006, Gmunden/Austria 26

2 2. Materials and methods On the web page of the BFW and the domain-link the results (captures) of 185 pheromone traps are presented in graphs. It is also possible to compare the capture rates of the previous year(s) with current data. In Burgenland, Niederösterreich and Salzburg the bark beetle captures are associated with data of climate stations. Evaluation, identification and separation of the beetles, cleaning of the traps and online data input via home- or office computer is done every week by skilled foresters of the forest office or the chamber. As pheromone traps Theysohn slot traps, single or as triple trap system, baited with Ipsowit or Pheroprax ampoule for the spruce bark beetle Ips typographus, Chalcowit or Chalcoprax ampoule for the Small Spruce bark beetle (Pityogenes chalcographus), Cembräwit for the larch bark beetle (Ips cembrae), Sexowit for Ips sexdentatus and Accuwit for Ips accuminatus were used. The data of the climate stations (temperature) are automatically updated with the help of a special application program. Temperature data collected and processed as half-hour mean values have been allocated and summed up to three different temperature ranges in order to illustrate favourable weather conditions for bark beetle flight: 16,5 C to 30 C (ideal), below 16,5 C (too cold) and above 30 C (too hot). Krehan & Steyrer (2006) Figure 2: Map of the sites of pheromone traps (orange spots) and pheromone traps in combination with climate stations (cyan). IUFRO Working Party Proceedings of the Workshop 2006, Gmunden/Austria 27

3 Figure. 3: Bark beetle capture rate of a single trap in comparison with temperature sums 3. Results 3.1 Monitoring 2005 The first peak of swarming of Ips typographus and I. cembrae was observed in the first week of May (also in alpine regions). In most cases P. chalcographus started later. Mostly 2 generations (+ sister breeding generations) could be evaluated, in higher altitudes only one generation. Also remarkable was the low flight activity of the beetles in autumn. IUFRO Working Party Proceedings of the Workshop 2006, Gmunden/Austria 28

4 100% 90% 80% 70% 60% 50% Kupferstecher Buchdrucker 40% 30% 20% 10% 0% Figure 4: Comparison of flight activity between Pityogenes chalcographus (cyan bars) and Ips typographus (violet bars) in percentage of the maximum mean capture rate per week in the year 2005 in Austria Due to the extraordinary bark beetle outbreak in some alpine districts in Salzburg and Styria, the numbers of collected beetles was extremely high. As in Fig. 5 demonstrated almost beetles were caught in one triple-trap system already in the first week of May. Figure 5: Capture rate of a triple-trap system for Ips typographus installed in Salzburg in 1200m altitude in the Year 2005 IUFRO Working Party Proceedings of the Workshop 2006, Gmunden/Austria 29

5 A further worth mentioning fact is the high population density of the small Spruce bark beetle Pityogenes chalcographus in alpine forest stands (Fig.6). Figure 6: Capture rate of a triple-trap system for Pityogenes chalcographus installed in Salzburg in 1440m altitude in the Year 2005 The figures listed in Tab. 1 should demonstrate the bark beetle situation in different federal districts of Austria. But it is advised against jumping to conclusions, because the capture rate of bark beetle pheromone traps is influenced by several additional factors. Federal district Pityogenes chalcographus Ips typographus No. of traps Burgenland (triple trap system) Kärnten (Single trap) Niederösterreich (Single trap) Oberösterreich (Single trap) Salzburg (triple trap system) Steiermark (triple trap system) Table 1: Average capture rate of the pheromone traps included to the monitoring system in 2005 IUFRO Working Party Proceedings of the Workshop 2006, Gmunden/Austria 30

6 3.2 Monitoring 2006 Comparison to 2005 In spite of a long lasting snow cover the swarming of the beetles did not start much later than in The capture rate is also comparable to the year before. In some cases the numbers of collected beetles of the second swarming generation was higher than those of the first. The warm weather period during late summer and autumn did not increase the attraction of the pheromone traps in that time. The capture rate was rather low in Figure 7: Comparison of capture rates of a triple-trap system for Ips typographus installed in Salzburg, Flachgau in 490m altitude of the years 2005 and 2006 IUFRO Working Party Proceedings of the Workshop 2006, Gmunden/Austria 31

7 Figure 8 and 9: Comparison of capture rates of a triple-trap system for Ips typographus installed in Lungau in 1525m altitude and in Burgenland, Güssing (245m) of the years 2005 and IUFRO Working Party Proceedings of the Workshop 2006, Gmunden/Austria 32

8 Figure 10: Comparison of capture rates of a triple-trap system for Ips typographus installed in Styria, Judenburg (935m) of the years 2005 and Discussion and conclusion One of the benefits of bark beetle monitoring is its topicality and availability via Internet. Forest owners, forest managers or advisors will get a good overview of the risk of bark beetle infestation in their region, allowing them to assess the situation individually in combination with weather conditions. In addition, up-to-date information including prediction by experts will be published on the BFW homepage. Increased attention and enhanced forest protection measures (keyword: forest sanitation) at the right moment may reduce the volumes of damaged timber. Krehan & Steyrer (2006) Three years after creating the monitoring system several problems still exist or had not been considered to remain unsolved for such a long time, when the monitoring was established. Online-climate data (temperature) are not available from all sites where trap have been placed. Regularly failure rate (loss) of data = white column in the graph because of problems with data transmission. Counting (evaluation) of the beetles in the traps happens only once a week. Some regions are not represented. In some cases permanent high flight activity was observed and therefore permanent potential danger of new attacks against trees would be possible. This forces a continuous observation of dangerous areas, but this is not possible to be fulfilled in practice. Specific site conditions may influence the catch rate more than e.g. temperature or precipitation. These influencing factors (competition of lying or standing trees) should be reduced to a minimum. IUFRO Working Party Proceedings of the Workshop 2006, Gmunden/Austria 33

9 5. References KREHAN H. & STEYRER G. 2006: Bark-Beetle Monitoring in Austria: An example of a well functioning early warning system for forest practice. _EN IUFRO Working Party Proceedings of the Workshop 2006, Gmunden/Austria 34