Articles containing the keyword 'kaarnakuoriaiset'

Ips acuminatus Gyll. (Coleoptera, Scolytidae) is a bark beetle that causes deep bluing in thin-barked Scots pine (Pinus sylvestris L.) pulpwood. It has been shown that this decreases pulp yield. The purpose of this study was to map the southern border of the distribution of Ips acuminatus in Finland. It was found that there have been changes in the distribution of this species during the last three decades. Ips acuminatus has now disappeared from southern Finland. On the basis of the sample plots (134 cutting areas) the southern border of this pest lies on the line running through the towns Vaasa–Seinäjoki–Äänekoski–Jyväskylä–Pieksämäki–Savonlinna–Punkaharju. A certain degree of localisation was observed in the occurrence of I. acuminatus in its distribution area, for instance, differences in its occurrence frequency in cutting areas and even in log and cutting residue piles in the sample cutting area.

It is considered that the most important reasons for these changes in distribution are the increase in logging and changes in the location of cutting sites, and resulting competition for breeding material for the increased population of bark beetles. Furthermore, the long-distance transport of unpeeled logs from the north across the present southern borders may, in the future, contribute to local changes in the southern distribution of Ips acuminatus.

The PDF includes a summary in English.

• Puukko, E-mail: kp@mm.unknown

The dying-off of more trees in an over-aged Norway spruce (Picea abies (L.) H. Karst.) stand caused by Ips-bark beetles was reduced by a pheromone preparation, ipslure. 20 preparations placed in trapping bolts captured more than 13,700 specimens of Ips typographus L. and Ips duplicatus Sahlb., which alone corresponded to a saving of five old trees in this valuable exhibition and seed collection stand. Attractance of ipslure to the following predators of bark beetles was also examined; Thanasimus formicarius, T. rufipes, Epuracea bickhardti, Rhizophagus ferrugineus, Pityophagus ferrugineus.

The PDF includes a summary in English.

• Selander, E-mail: js@mm.unknown
• Nuorteva, E-mail: mn@mm.unknown

The aim of the study was to determine which kinds of insects had infected the Norway spruce (Picea abies (L.) H. Karst.) in different stands killed by flooding caused by beavers (Castor canadensis Kuhl), and if there was any danger that they would subsequently cause damage in the surrounding forests. The effect of tree diameter and certain stand characteristics on the fauna of dead trees are discussed. The occurrence of different insect combinations and qualifications for their coexistence were studied.

Pityogenes chalcographus L., Trypodendron lineatum O., Hylurgops palliatus Gyll. and Dryocetes autographus Ratz. occurred most abundantly. 20 phloem or wood boring species were observed in 5 regular succession types. Secondary species occurred in a virgin stand while Ips typographus L. was found at the edge of a felling area. Owing to the flooding, species preferring moist conditions were abundant. In this case damages had not spread to the surrounding forests which, however, might be possible under certain conditions.

The PDF includes a summary in English.

• Saarenmaa, E-mail: hs@mm.unknown

The paper studied the effect of felling time and conditions in the forest depot of timber to damages caused by spruce ambrosia beetle (Trypodendron lineatum Oliv.) to coniferous timber with bark, both experimentally and observing forest depots in Finland. Effects of fellings was studied by studying the abundance of the beetles in logging residue.

The results show that the spruce ambrosia beetles favour timber felled during the late autumn and winter, stored in a shaded place in the forest. In addition, new spruce stumps maintain and increase the beetle population. Fellings in the forest will increase population during the next year and cause damages in forest depot of timber nearby, because the insect breeds in the stumps. The experiments showed that it is possible to diminish the damages caused by the beetle to timber with bark by spraying with insecticides, and timing the fellings and transport of timber so that there is no timber in the forest in the spring during the time when the insect swarms.

The PDF includes a summary in German.

• Löyttyniemi, E-mail: kl@mm.unknown

Degree of decomposition of logging residue, and decay in stumps have been used in forest inventories to estimate the time of the felling. In this paper, a method was developed to use insects breeding in the logging residue to determine how long ago the felling took place. The method is based on the arrival and rate of development of the different species of bark beetles that breed in the logging residue.

The most suitable insect species to be used in the purpose of timing the age of logging residue were defined, and their occurrence in different tree species and fellings performed at different times of the year were described. The species can be easily identified by gallery systems characteristic to the species.

It is concluded that the method does not suit for broadleaved species, because there is no common insects suitable for this purpose. Also, the time of swarming of the insects depends on the weather conditions in the spring, which makes it difficult to give definite dateshe progress of the spring has to be taken into account when the occurrence of the insects is used in the determination of the time of the felling. In addition, local conditions, such as shading, affect drying of the branches, and can influence the occurrence of the insects. For Scots pine and Norway spruce the age of the logging residue can be determined precisely only at most two years back.

• Nuorteva, E-mail: mn@mm.unknown

Bark beetle populations live usually in a balance in natural forests, and outbreaks occur seldom. The populations have been found to increase in managed forests. Fellings affect the structure of the forests, which influence the living conditions of the insects, and produce material for reproduction. In this study the occurrence of bark beetles was studied in a forest area in Etelä-Häme in Southern Finland using line plot survey.

The forests in the area were Norway spruce (Picea abies L. Karst.) dominated. Over third of the 140 sample plots studied were in forests which had never been cut or it was over ten years to the last logging. Bark beetles of 26 different species were found in 66 of the sample plots. The most common species was six-toothed spruce bark beetle (Pityogenes chalcographus L.), which was due to the abundance of growth material suitable for the species in the area. New species in the area were common double-eyed spruce bark beetle (Polygraphus polygraphus L.), Pityophthorus micrographus L., and Dryocetes-beetle (either Dryocetes autographus or D. hectographus). The fellings increased the occurrence of beetles. The amount and quality of logging residue affected the abundance of the insects.

The PDF includes a summary in German.

• Nuorteva, E-mail: mn@mm.unknown

The aim of the study was to investigate the abundance of bark beetle species and their damage in Finland. The bark beetle populations were studied in several areas in Finland, both in sites with known beetle damage and without. Two-meter wide lines were measured in the sample plots, where all trees were studied for bark beetle damage in the stem and the crown of the trees. The abundance of bark beetle species and the beetle damages in 25 study areas, and 52 different species are discussed in detail.

Divided by their lifestyle, the most important groups of bark beetles are the pine shoot beetles (Tomicus sp.), beetles reproducing in Scots pine (Pinus sylvestris L.) stems and branches under the bark, beetles reproducing in Norway spruce (Picea abies (L.) H. Karst.) stems and branches under the bark, beetles living in the other coniferous trees, beetles reproducing in roots, beetles reproducing under the Betula sp. bark, beetles reproducing in other deciduous trees and beetles reproducing inside of the stems. Of individual species, Blastophagus piniperda (now Tomicus piniperda) and B. minor cause worst damage to pine and Ips typographus (L.) and Pityogenes chalcographus (L.) to spruce. Serious damage is caused also by Xyloterus lineatus to coniferous trees, Polygraphus polygraphus and P. subopacus to Norway spruce and Scolytus Ratzburgi to Betula sp.

• Saalas, E-mail: us@mm.unknown