Hundreds of people from the professional and lay public ask this question today and every day. These tiny animals responsible for the number of dry forests are endowed with an interesting form of communication. During evolution, they brought communication almost to perfection and became a prime example of an insect, for the eventual extermination of which baits "with the smell of pheromones" are used. Experts from the Faculty of Forestry and Wood Sciences, CULS have set a practical goal – to compare the effectiveness of two types of ECOLURE pheromone evaporators used in forest protection to reduce the number of European spruce bark beetle.
The overgrowth of the spruce bark beetle (Ips typographus) is a well-known phenomenon affecting spruce forests throughout Eurasia. Population gradations are often associated with catastrophic events such as wind calamities, such as Hurricane Kyrill, which in January 2007 also affected the territory of our republic. Spruce stands affected by these disturbances represent a suitable environment for bark beetles with plenty of food opportunities. In these habitats, they do not have to lead a dramatic duel with the defence mechanisms of healthy trees, which produce enough resin toxic for bark beetles.
It did not get its name "bark beetle" by accident. The name reflects the way of his life, which he largely spends buried under the bark, where he not only digs corridors and chambers, but also produces the already mentioned aggregation pheromones. It is these pheromones that mediate communication within the species even over considerable distances – thanks to them, partners are attracted or the raid on the weakened tree is synchronized. Today, we already have considerable knowledge about these biologically active substances, which can be used in the production of pheromone evaporators. These contain three main components of the spruce bark beetle pheromone, of which cisverbenol is key. There are several types of these evaporators available on the market, differing in the type of packaging or guaranteed efficiency.
In this study, a common (ECOLURE CLASSIC) and an all-season (ECOLURE MEGA) pheromone evaporator were compared. Twenty pairs of pheromone traps were located in spruce commercial forests near Písek. The experiment began on May 1 and lasted about 133 days. This period represents the extended efficiency of the all-season evaporator, which should be 18-20 weeks. While only one package was used from this evaporator, the conventional one, which should serve the purpose for 5 to 6 weeks, was replaced three times. Traps were inspected every 10 days until 10 September.
After one season, all 40 pheromone traps numbered a total of 179,477 individuals, of which 32% were caught in traps filled with a seasonal evaporator and 68% in traps containing a common evaporator. At first glance, it is clear that a conventional evaporator performed significantly better. The results also showed that two generations of bark beetles occurred during the year – the first in the spring around May 20 and the second in the summer around July 12. This two-generation cycle is typical for the conditions of forests in the middle altitudes, in higher localities one generation per year occurs, the cause is lower temperatures and therefore a shorter season. In the initial phase of the experiment, the differences in the number of captured individuals were not so significant, but after only 10 days the all-season evaporator began to lose its effectiveness relatively quickly, and after the second swarm in summer the efficiency was almost negligible.
It can be stated unequivocally that a conventional evaporator has proved to be more effective in comparison with an all-season evaporator. Here, the question arises as to whether it makes any sense to use all-season evaporators to control spruce bark beetle. In this context, it is important to realize that not all areas are easily accessible. Difficult terrain sometimes severely impairs accessibility, and it is not always possible to inspect traps every week. Therefore, a seasonal evaporator can be a suitable option for these locations, but it should be replaced in less than 50 days. The results of this study provide knowledge that can be applied after considering all factors, including ecological, in ordinary forestry practice. When choosing a suitable agent, we could be easily disoriented by the promise of a prolonged effect. The facts presented in this article can open our eyes during a decision what type of ECOLURE to fill the traps in our forest, in which we want to kill the spruce bark beetle more effectively.
Nakládal, O., Šenfeld, P., Franjević, M., Uhlíková, H. (2013): Comparison of all season and standard type of Ecolure® Dispenser efficacy in trap catches of European spruce bark beetle (Ips typographus (L.)). Šumarski list, 7–8: 395–401.
doc. Ing. Oto Nakládal, Ph.D. (* 1980)
In 2003, he started his career at the Faculty of Forestry and Wood Technology of the Czech University of Life Sciences in Prague as a student of Forest Engineering, then continued his doctoral studies there and in 2012 received an associate professor degree on the same field. He remains faithful to his alma mater to the present day and at the current Department of Forest Protection and Entomology he works as an associate professor and mainly teaches entomology. As part of his research, he deals with the issue of insect taxonomy; from a purely forestry point of view, his area of ??interest includes mostly bark beetles and nun moths.
Prepared by: Martina Feriancová