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The Role of Bark Beetles in Silver Fir Decline and Possible Use of Pheromone Traps for the Monitoring

Milan Pernek orcid.org/0000-0001-8200-6913 ; Hrvatski šumarski institut Jastrebarsko
Nikola Lacković ; Hrvatski šumarski institut Jastrebarsko

Sažetak

Silver fir is the most important coniferous species in Croatian forestry, but in the same time the most threatened whose strong decline occurs periodically.Recent decline in Croatia was registered in the year 2003, especially in Lika and Gorski Kotar, with strong attack of fir bark beetles.This beetle gradation is connected with the three known Pityokteines species in Croatia: P. curvidens, P. spinidensandP. vorontzowi.The aim of this work was to determine what impact bark beetles have on the decline of Silver fir.For this purpose pheromone traps were placed in Litoric (Gorski Kotarmiddle Croatia), for monitoring through the vegetation periods from 2004to 2010. In addition, in 2007the effectiveness of different trap systems was tested. The commonly used Theysohn trap with dry container was modified through locking the container so liquid that was previously put in it couldn’t efflux. A pheromone mixture named Curviwit ® was used which is used for individuals baiting of fir bark beetle species Pityokteines curvidens.
The results during the seven year monitoring period show clearly visible connection between fir bark beetles and fir decline (Figure 1). The largest catches in pheromone traps were measured between 2005 and 2007,when the most injured trees were felled in the forests.Most catches, about 94 %, throughout the year of monitoring occur in April and May (Figure 2 and 3), which concludes that traps should be placed only in those months. The test results of dry versus wet traps show that more important catch is achieved by modifying Theysohn traps to wet traps (Figure 4).
On the basis of calculating the abundance of bark beetles ofP. spinidens andP. curvidensin the trunk (Table 1) and the use of maximum mortality rates of 70 %, from previous studies biological potential of these insects was simulated.One infected 90 year old fir tree is directly threatening 50-60 trees in the next years.This result demonstrates the enormous potential of the silver fir bark beetle species. Because of the need to reduce the population of bark beetles, use of pheromone traps for monitoring should be considered as one action for effective preventive and sanitary measures in protection of forests.

Ključne riječi

Pityokteines spinidens; P. curvidens; P. vorontzowi; Abies alba; pheromone traps

Hrčak ID:

72319

URI

https://hrcak.srce.hr/72319

Datum izdavanja:

14.10.2011.

Podaci na drugim jezicima: hrvatski

Posjeta: 2.872 *