Parasitoids of<Emphasis Type="Italic"> Ips typographus</Emphasis> (Col., Scolytidae), their frequency and composition in uncontrolled and controlled infested spruce forest in Bavaria

In the Bavarian Forest national park, the spruce bark beetle Ips typographus (Col., Scolytidae) has caused an uncontrolled mass propagation for more than 10 years. To find out if the population of parasitoid species, which can develop in an uncontrolled natural forest, is able to restrict spruce bark beetle gradation, we investigated the parasitoid fauna, their abundance and frequency in the central part of the park (no control), in the protection area and the enlargement area of the park and in a productive forest where the spruce bark beetle is strictly controlled. In 2002 and 2003, the species Coeloides bostrichorum, Roptrocerus xylophagorum/mirus, Rhopalicus tutela, Tomicobia seitneri and Dendrosoter eupterus were identified. C. bostrichorum was the most numerous species before Roptrocerus sp. and Rh. tutela. T. seitneri and D. eupterus were not as numerous. The order of frequency differed. Roptrocerus sp. was the most frequent parasitoid wasp in both years, and Rh. tutela and even T. seitneri were more frequent than C. bostrichorum. C. bostrichorum and Rh. tutela were found to be protandrous, whereas Roptrocerus sp. males and females had different sequences of appearance in different forest types. The average percentages of parasitism increased with time of exposure and was highest in the second generation. We found astonishingly high parasitization rates at sites where attacked trees are regularly removed.