Vertical stratification and microhabitat selection by the Great Capricorn Beetle (Cerambyx cerdo) (Coleoptera: Cerambycidae) in open-grown, veteran oaks

Abstract

Abstract. The great capricorn beetle or Cerambyx longicorn (Cerambyx cerdo, Linnaeus, 1758) is an internationally protected umbrella species representing the highly diverse and endangered fauna associated with senescent oaks. For the conservation and monitoring of populations of C. cerdo it is important to have a good knowledge of its microhabitat requirements. We investigated determinants and patterns of C. cerdo distribution within individual old, open-grown oaks. Trees inhabited by this species were climbed, and the number of exit holes and environmental variables recorded at two sites in the Czech Republic. Distribution of exit holes in relation to height above the ground, trunk shading by branches, orientation in terms of the four cardinal directions, diameter, surface and volume of inhabited tree parts were investigated. This study revealed that the number of exit holes in the trunks of large open-grown oaks was positively associated with the diameter of the trunk and openness and negatively with height above the ground, and the effects of diameter and openness changed with height. The number of exit holes in the surface of a trunk was also associated with the cardinal orientation of the surface. Approximately half of both C. cerdo populations studied developed less than 4 m and approximately a third less than 2 m above the ground. This indicates that most C. cerdo develop near the ground. Active management that prevents canopy closure is thus crucial for the survival of C. cerdo and searching for exit holes is an effective method of detecting sites inhabited by this species.

Imeretian oak and a great capricorn beetle – the problem of relations on the territory of Ajameti Managed Reserve (Republic of Georgia)

“…The physiological condition of the tree plays a decisive role in the settlement of great capricorn beetle (Rudnev 1957;Albert et al 2012). Our research also showed that the determining criterion for settlement of great capricorn beetle is the sanitary condition of trees, and the more weakened trees are more suitable for settlement and development of C. cerdo.…”

“…The presence of a significant number of older trees damaged by root rot and other factors is a prerequisite for long-term existence of mass reproduction of C. cerdo. Albert et al (2012) indicates the strong relationship between the diameter of tree and the number of fly holes on the tree. Also, this study revealed that the number of exit holes in the trunks of large, open-grown oaks was positively associated with the diameter of the trunk and openness and negatively with height above the ground, and the effects of diameter and openness changed with height (Albert et al 2012).…”

“…Albert et al (2012) indicates the strong relationship between the diameter of tree and the number of fly holes on the tree. Also, this study revealed that the number of exit holes in the trunks of large, open-grown oaks was positively associated with the diameter of the trunk and openness and negatively with height above the ground, and the effects of diameter and openness changed with height (Albert et al 2012). In the oak forests of Ajameti Managed Reserve, the fly exit holes of great capricorn beetle were often concentrated in the lower part the tree trunk (up to 1.5-2 m), but one tree with processions and fly exit holes of C. cerdo at a height of 4.5 m with broken thick branch was also found during the survey.…”

“…At the beginning, the first year larvae feed itself in the thickness of bark only on alive but weakened tree, then they move under the bark deep into the wood where they make feeding road in length from 40-60 to 100 cm even next years (Lozovoy 1958b;Sama 2002). The distribution of C. cerdo in a landscape and amongst trees are described very well (Buse et al 2007(Buse et al , 2008b) and the distribution of C. cerdo exit holes in old open-grown oaks in relation the height above the ground, shading, cardinal orientation and diameter of the parts of the trunk inhabited were studied by Albert et al (2012). Rudnev (1957), who studied the development of C. cerdo in the forests of Ukraine, Abkhazia and Georgia, considered that great capricorn beetle is only populated on live but weakened trees and stumps of fresh oaks.…”

“…According to the data of Samedov (1963), in Azerbaijan, C. cerdo often appears in orchards and deciduous forests. Miroshnikov (2009) and Albert et al (2012) indicate a wide range of forage species of C. cerdo. The settlements of great capricorn beetle were found only on two species of oaks in Ajameti -Imeretian oak and Iberian oak.…”