Articles containing the keyword 'insect damages'
Category : Article
Shoot losses due to maturation feeding by pine shoot beetles (Tomicus piniperda (L.) and T. minor (Hart.), Col., Scolytidae) and subsequent growth losses were studied in Scots pine (Pinus sylvestris L.) stands growing at different distances from a timber yard, where pine timber was stored during the years 1982–84. In autumn 1985, pine trees were felled at 20, 40, 80, 500 and 1,500 m distance from the timber yard, five trees in each distance class. Trees were analysed for beetle attack, needle biomass and growth. In autumn 1988, increment cores were taken from 20 trees in each distance class.
In 1985, different damage estimates showed that beetle damage was more than 10-fold in the crowns of pine trees growing close to the timber yard as compared to less damaged trees in greater distance. Crude needle biomass estimates indicated that the trees attacked most had lost more than half of the total foliage. Following three years of attack, basal area growth decreased for 2–3 years and recovered during the subsequent 3 years, the total period of loss thus being 5–6 years. The loss in volume growth during 1983–85 was ca. 70, 40, 20 and 10% at 20, 40, 80 and 500 m distance from the beetle source, respectively, compared to the stand at 1,500. Growth losses did not occur until the number of beetle-attacks, ”pegs”, exceeded ca. 200 per tree. The highest observed growth losses occurred in trees with more than 1,000 pegs per tree.
The PDF includes an abstract in Finnish
-
Långström,
E-mail:
bl@mm.unknown
- Hellqvist, E-mail: ch@mm.unknown
This review discusses whether forests are affected by biotic damages due to present or future environmental disturbances, and do environmental threats, such as air pollution and climatic change, weaken the condition of forest in a way that makes them vulnerable to damages by fungi and insect. The defence mechanisms of trees and factors affecting the development of an outbreak are described. Finally, the ways that air pollution and climatic change may affect biotic damages are discussed.
-
Annila,
E-mail:
ea@mm.unknown
Paratization of Petrova resinella L. in the gall stage was studied in the surrounding of Harjavalta, south-western Finland, in relation to industrial air pollution. Of the studied 283 galls, 28% produced a moth, 52% of the larvae/pupae were paratisized, and 20% were empty or contained a dead larva. The proportion of paratisized galls did not depend on the distance from emission sources of industrial air pollutants.
The PDF includes an abstract in Finnish.
-
Heliövaara,
E-mail:
kh@mm.unknown
- Väisänen, E-mail: rv@mm.unknown
The relationship between industrial air pollutants and the occurrence of galls of Petrova resinella (Lepidoptera, Torticiadae) was studied around the industrialized town of Harjavalta in Western Finland. There were 44 sampling sites set out at logarithmic distances along five transects (NW, W, SW, SE) froma a distive source of emissions. Each site consisted of three circular sample plots (30 m2) in young Scots pine (Pinus sylvestris L.) stands. The number of galls, including cankers from several years earlier, was highest in the vicinity of the factory complex on each transect. The highest number of two-year-old galls containing living larvae was usually recorded at the ends of the transects several kilometres from the factories. However, the significance of the differences both between zones and transects was rather low. Correlations between the deposition of heavy metals (Cd, Cu, Ni, Pb, Zn), used as an indication of the general level of air pollution, and the total number of galls, were positive and generally highly significant. It is concluded that P. resinella has benefitted from air pollution although perhaps to less extent than some sap-sucking species.
The PDF includes an abstract in Finnish.
-
Heliövaara,
E-mail:
kh@mm.unknown
Flight periods of insects breeding on birch (Betula sp.) timber were observed by means of window flight traps baited with freshly cut birch logs in five locations in Finland from 1972 to 1976. Only few species were caught during the study. In general, these species were on the wing during midsummer, although flight periods of some of them were relatively long. Scolytus ratzeburgi Jans. caused harmful staining of wood within a month from attack, but the damage by the wood-boring pests remained negligible throughout the first storage summer.
The PDF includes a summary in Finnish.
-
Löyttyniemi,
E-mail:
kl@mm.unknown
The effect of nitrogen fertilization and two insecticides on the occurrence of the plant pine bark bug, Aradus cinnamomeus Panzer, was investigated in a young Scots pine (Pinus sylvestris L.) stand in Southern Finland. Three years after the treatment the bug density was lowest in the trees treated with lindane or dimethoate. However, in spite of the increasing height growth of the trees, they did not grow significantly faster than the control trees. Nitrogen fertilization increased both bug density and the height growth of the trees. Thus, the value of nitrogen fertilization against Aradus cinnamomeus remains obscure.
The PDF includes a summary in Finnish.
-
Heliövaara,
E-mail:
kh@mm.unknown
- Annila, E-mail: ea@mm.unknown
- Terho, E-mail: et@mm.unknown
The resistance of Finnish softwood timbers to Macrotermitinae termites was tentatively tested under tropical conditions in Zambia using a field microtest method. Picea abies (L.) H. Karst. and Larix sibirica L. sapwood and heartwood, as well as Pinus sylvestris L. sapwood, and the sapwood of the locally grown Pinus kesiya, exhibited no natural termite resistance. On the other hand, Juniperus communis heartwood appeared to be virtually immune and the heartwood of P. Sylvestris had some resistance. There were also some differences in the resistance of the heartwood of the different P. Sylvestris individuals tested, which was correlated with the width of the annual rings in the wood samples. The termite species involved were Microtermes sp. and Odontotermes sp. The possibilities of using different types of Finnish softwood timber in the regions in the tropics where there is a risk of termite damage is discussed.
The PDF includes a summary in Finnish.
-
Löyttyniemi,
E-mail:
kl@mm.unknown
Relationships between densities of pine bark bug, Aradus cinnamomeus Panzer and the height growth of young Scots pine (Pinus sylvestris L.) were studied in several habitats, including a highly infested area in Southern Finland. The slower the growth of the pines was, the greater was the height up to which bugs were found. On the average, maximum bug density was noted at a height corresponding to a fifth of the height of the tree. In stands restocked by natural generation, the greatest bug densities were noted in pines about three metres high and over twenty years old. Bug densities in trees whose height growth had been decelerating for five years were twice those in trees whose growth was accelerating. A significant negative correlation was found between the bug density and the last-year height increment.
The PDF includes a summary in Finnish.
-
Heliövaara,
E-mail:
kh@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 development of Scots pine (Pinus sylvestris L.) seedlings and damage caused by Hylobius abietis L. (Coleoptera, Curculionidae) were studied during a three-year period. Olfactory responses of H. abietis was studied in laboratory with several volatile oils isolated from different kinds of P. sylvestris seedlings. Resistance of seedlings against H. Abietis was evaluated in terms of their monoterpene composition. Three aspects of resistance (preference, antibiosis and tolerance) were evaluated separately. Seedling chemotype was found to be associated with these aspects of host resistance on only minor scale. Discussion was attached to a further search for host resistance arising from other properties and constituents of oleoresin. Height growth of the seedlings recovering from weevil damage was 86–91% compared to healthy seedlings.
The PDF includes a summary in English.
-
Selander,
E-mail:
js@mm.unknown
- Kalo, E-mail: pk@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
Hybrid aspen (Populus tremula L. x Populus tremuloides Michx.) has been grown in Finland for about 20 years, and the area of the stands is currently about 400 ha. Growing is planned to be greatly expanded to grow raw material for match industry. The aim of this investigation was to study susceptibility of hybrid aspen to insect damages. Insect damages in hybrid aspen, growing in Southern Finland, were examined in 15 stands in 1972. Saperda species were observed to be the most numerous and harmful insect species. Saperda carcharias L. occurred in 26% and Saperda populnea L. in 36% off trees inspected. Mass occurrence of Chionaspis salicis L. was observed in some sample areas.
-
Löyttyniemi,
E-mail:
kl@mm.unknown
The aim of the study was to find out more about pine weevil (Hylobious abietis L.) injuries in Scots pine (Pinus sylvestris L.) seedling stands and their control by means of DDT. For this purpose, inventories were made of seedling stands established earlier. Control experiments were made on burnt areas by planting seedlings dipped in a DDT emulsion.
The results of the inventories show that injuries caused by pine weevils can, in certain circumstances, especially in seedling stands established by planting, cause the complete failure in artificial regeneration. The extent and quality of the injuries vary greatly according to planting method, treatment of the cutting area, age of the seedling stand, environmental factors, and weather conditions. The most extensive injuries occur in regeneration areas of old Norway spruce stands burnt after clear cutting and planted with Scots pine seedlings. Injuries are greater in seedling stands established by planting, especially after broadcast burning, than in seedling stands originating either from artificial or natural seeding. The quality of the patch for sowing or planting has a considerable effect on the quantity and character of the injuries: in a patch from which organic matter has been removed, injuries do not appear or they are slighter. Seedlings can be protected effectively and economically by dipping their tops up to the root collar, in a DDT emulsion before planting.
The PDF includes a summary in English.
-
Nenonen,
E-mail:
mn@mm.unknown
- Jukola, E-mail: jj@mm.unknown
