Abstract:To demonstrate the process of occurrence of mass attack by Platypus quercivorus on living trees and the process of tree death after mass attack, the beetles landing on tree trunks of Quercus crispula and Q. serrata were collected with adhesive paper traps, and the number of entry holes bored by the beetles into the trunks were counted in Kyoto, Japan. Within one week after the first collection of the beetle, both the number of beetles collected and the number of entry holes bored by them suddenly reached a peak simultaneously and then decreased quickly. On the killed tree, it took three weeks from the first collection of the beetle to discoloration of all leaves. To reproduce the mass attack artificially, male beetles were introduced to two trees that had never suffered boring attacks until mid-August. As a result, many beetles landed on these trees and a large number of entry holes were bored. Moreover, almost all leaves of one of these trees had become discolored by 27 days after introduction of the beetles, and the tree had died by the following spring. These results suggest that the first entry holes bored by male beetles triggered the mass attack.
111 119. An overabundance of Sika deer Cervus nippon at Mt. Ôdaigahara, in west-central Japan has necessitated the introduction of exclusion fences to protect forest decline from excessive feeding damage. However, the effect of these exclusion fences on the biodiversity of arthropods within the protected areas has not been investigated. In this study we examined the relationships between the volume of dwarf bamboo Sasa nipponica , the major forage for the deer, on associated with browsing by deer and the structure of ground beetle assemblage. Both inside and outside of the exclusion fences, pitfall traps were setup in plots that had been assigned treatments of either no treatment control or artificial clipping of dwarf bamboo. Ground sticky traps were also set up in each plot to sample the abundance of small animals as the diet of ground beetles. Bamboo volume did not reltate to abundance, species richness, or diversity of the ground beetle assemblage. The abundance of the most dominant beetle species, Leptocarabus kumagaii, increased positively in response to both bamboo volume and the abundance of Orthopterans. The second most dominant species, Pterostichus fujitai, did not relate to bamboo volume, but decreased in abundance in relative to the propotions of open canopy. The third most species, Pterostichus microcephalus, decreased in abundance relative to bamboo volume, but increased positively in response to the abundance of Collembolans, Dipterans, and Hymenopterans. These results suggested that reduction of bamboo volume by browsing of deer did not affect the diversity of ground beetle aseemblage but affected its structure.
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