Ecological segregation of bark beetles (Coleoptera, Scolytidae) of spruce^1,2

Abstract

In two stands of spruce in northern Germany colonization patterns of seven species of bark beetles were examined under field conditions. It can be shown that all species are segregated from each other by means of only a few factors. Those are stand‐specific microclimate, cover of logs with soil, bark thickness, and body size of beetles. Particularly the relation between body height and minimal bark thickness is pointed out. The lower limit of thickness of bark which can be colonized by Ips typographus (L.) is 2.5 mm. Zusammenfassung Öml;kologische Segregation bei Borkenkäfern (Col., Scolytidae) der Fichte Die Besiedlungsmuster von 7 Borkenkäferarten an der Fichte wurden an 2 Standorten in Norddeutschland unter Freilandbedingungen untersucht. Es wird gezeigt, daß wenige Faktoren allein ausreichen, die Segregation aller Arten voneinander nachzuweisen. Es handelt sich hierbei um das standortspezifische Mikroklima, Erdbedeckung der Stämme, Rindendicke und Körper‐größe der Käfer. Der Beziehung zwischen Körperhöhe und minimaler Rindendicke kommt besondere Bedeutung zu. Die Untergrenze der von Ips typographus (L.) besiedelbaren Rinde liegt bei 2,5 mm Dicke.

Reproduction abilities of Ips typographus (L.) (Coleoptera: Curculionidae, Scolytinae) in the stands damaged by the wind in 2013 in the Kościeliska Valley (Tatra National Park)

“…Reduced larvae survival could -in turn -result from less favourable development conditions in the breeding material of lower quality. The bark thickness did not affect the reproduction; however, most of the analysed gallery systems were established in optimal conditions concerning this parameter (Grünwald 1986). …”

Ecological segregation of bark beetle (Coleoptera, Curculionidae, Scolytinae) infested Scots pine

“…The assessment of biotic interactions among the individuals in the bark beetle populations was based on the equations used in similar studies related to the ecology of bark beetles (Paine et al 1981;Gru¨nwald 1986;Schlyter and Anderbrant 1993;Amezaga and Rodrı´guez 1998).…”

“…The methods adopted in earlier studies using bark thickness as a factor related to niche segregation in bark beetles were not fully effective (Gru¨nwald 1986;Amezaga and Rodrı´guez 1998). This occurred because various parts of individual trees may have different levels of suitability as food for bark beetles depending on the system and intensity of the entire complex of environmental factors affecting food resources (phloem, cambium, wood).…”

“…and Ips typographus (L.), I. typographus and Orthotomicus suturalis (Gyll.) as well as C. pusillus and O. suturalis (Gru¨nwald 1986). The original sampling method presented here based on a uniform partitioning of food resources is fully effective.…”

“…(Karst.) (Gru¨nwald 1986) or in pine species such as P. sylvestris (Amezaga and Rodrı´guez 1998;Borkowski 2013), Pinus radiata (D. Don) (Amezaga and Rodrı´guez 1998), Pinus resinosa Ait. (Ayres et al 2001) and Pinus taeda (L.) (Paine et al 1981).…”