Parasitoids of Ips typographus (Col., Scolytidae), their frequency and composition in uncontrolled and controlled infested spruce forest in Bavaria

Abstract

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.

Reproductive performance and natural antagonists of univoltine population of Ips typographus (Coleoptera, Curculionidae, Scolytinae) at epidemic level: a study from Šumava Mountains, Central Europe

“…The parasitism rate most often varies in the range of 5-55 % (Mills 1986, Eck 1990, Wermelinger 2002, Feicht 2004), but it can be even higher (Weslien 1992, Markovic, Stojanovic 2003. Parasitism rate in this study is near the lower limit of the published data outbreak Reproductive performance and natural antagonists of univoltine population of Ips typographus (Coleoptera, Curculionidae, Scolytinae) at epidemic level: a study from Šumava Mountains, Central Europe 159…”

“…It is a common endoparasitoid in the adults (Eck 1990), but the rate of parasitism is low, i.e. 0-9.5 % (Feicht 2004). The data in this instance fall entirely within the expected range, even though it concerns only larvae of the first instar, where the species affiliation is clear.…”

“…Also Thanasimus formicarius (Linnaeus, 1758) (Coleoptera) is able to reduce the offspring generation of I. typographus by as much as 18 % (Mills 1985). In the final larval stages and in the pupal stage, parasitoids predominate (Krüger, Mills 1990, Feicht 2004. It is highly likely that at the endemic level predation effectively reduces the beetle density and its population growth.…”

“…There are no works evaluating reproductive success in univoltine population of I. typographus in mountain conditions in Central Europe at an epidemic level, except for the studies of parasitism from the Bavarian side of the Šumava Mountains (Kalina 2000, Feicht 2004). There also are no studies dealing with the levels of parasitism, pathogen infections and nematode parasitism among maternal beetles and/or on parasitism of the offspring generation of the beetle.…”

The Evaluation of the Bark Beetles Populations on Spruce Logging Debris

“…The samples were added in PE tubes (eclectors). The PE tubes have on top plastic mesh for ventilation and on base a large funnel with a pot which contained ethanol 70% (Feicht 2004(Feicht , 2006. PE tubes were hung on the shadow of the building from Ic Ponor and controlled until the end of September.…”