SITES_bård 160701-4

The European spruce bark beetle (Ips typographus), an increasing problem in southern Sweden

Photo 1: European spruce bark beetle infested trees from 2018. Photographer: Martin Ahlström. Photo 1: European spruce bark beetle infested trees from 2018. Photographer: Martin Ahlström.

The dry and hot summer of 2018 caused draught in many areas in southern Sweden and as a consequence the population of the European spruce bark beetle (Ips typographus) increased. The combination of warm and dry weather during a long period resulted in two successful regenerations of bark beetles. The situation i Götaland and especially in eastern Götaland is critical and the development of 2019 is closely monitored. In Asa, around 40 outbreak sites are identified. The early spring suits the bark beetles and this year’s swarming has already started. Control measures such as, pheromone traps, pheromones on standing trees to focus bark beetle infestation and closely monitoring of infested areas from 2018, are used. The most important active measure is to harvest newly infested trees. The weather conditions however, determine the magnitude of the outbreak. To hope for the best, is to hope for a cold and rainy summer.

Photo 2: Male of Spruce Bark beetle entering the bark. Photographer: Göran Birgersson. Photo 2: Male of Spruce Bark beetle entering the bark. Photographer: Göran Birgersson.

Research
Professor Göran Birgersson and PhD student Maria Sousa both from Chemical Ecology, SLU Alnarp are monitoring the European spruce bark beetle outbreak in Asa. Their main focus is one of the most important bark beetle predators, long legged flies from the genera, Medetera. Larvae of the Medetera locate and attack the bark beetle larvae under the bark.

Photo 3: Female of Medetera. Photographer: Göran Birgersson. Photo 3: Female of Medetera. Photographer: Göran Birgersson.

One of the areas that Göran and Maria studies is also part of a pilot drone monitoring study. Previous studies have shown promising results concerning detection of early bark beetle infestations in near the infrared band. Since the most important active measure is to harvest infested trees before the beetles leave the tree, drone monitoring has a potential of reducing the manual cost of detecting damaged trees. Also, if the multispectral images can show an earlier detection than manual efforts, it can save valuable time and increase efficiency.

Photo 4: Larvae of Medetera, note the black ”jaws” with which they attack the bark beetle larvae. Photographer:  Göran Birgersson. Photo 4: Larvae of Medetera, note the black ”jaws” with which they attack the bark beetle larvae. Photographer: Göran Birgersson.

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