Åke Lindelöw

Attraction of scolytids and associated beetles by different absolute amounts and proportions of α-pinene and ethanol.

The attraction of bark and ambrosia beetles as well as associated beetles to α-pinene and ethanol was studied in field experiments with flight barrier traps. α-Pinene and ethanol were released individually and as combinations in approximately 1∶1 or 1∶10 ratios and at four different release rates. Ethanol attractedTomicus piniperda (L.),Hylurgops palliatus (Gyll.),Trypodendron lineatum (Oliv.),Hylastes cunicularius Er.,H. brunneus Er.,H. opacus Er., andAnisandrus dispar (F.) (Scolytidae);Glischrochilus quadripunctatus (L.) andEpuraea spp. (Nitidulidae);Thanasimus formicarius (L.) (Cleridae); andRhizophagus depressus (F.) (Rhizophagidae). α-Pinene attracted all these species with the exception ofT. lineatum, H. cunicularius, andA. dispar. Combinations of a-pinene and ethanol resulted in synergistically increased attraction of all species with the exception ofH. opacus andA. dispar. A. dispar, the only hardwood-associated species in the study, was repelled by α-pinene. Both the release rates and the ratio at which the two substances were released influenced the response of the beetles. The differences in response between the beetle species seem to reflect dissimilarities in the release of the two substances among the various types of breeding material to which the species are adapted.

Attacks on living spruce trees by the bark beetle Ips typographus (Col. Scolytidae) following a storm-felling: a comparison between stands with and without removal of wind-felled trees

Abstract 1 To maintain biodiversity in forests more wind‐felled trees must be left where they fall. However, there is concern among forest owners that this may result in higher tree mortality caused by the spruce bark beetle, Ips typographus (L.) (Col.: Scolytidae).

Attacks by Ips typographus and Pityogenes chalcographus on windthrown spruces (Picea abies) during the two years following a storm felling.

Attacks by Ips typographus and Pityogenes chalcographus during the first 2 yrs after a storm were studied on 1848 windthrown spruces (Picea abies) in southern Sweden. In the first and second summer, 29% and 24%, respectively, of the spruces were attacked by I. typographus, while 21% and 44%, respectively, were attacked by P. chalcographus. High stumps were attacked less frequently than tops, broken trees and windfelled trees with root contact. In both years, trunks in gaps were preferred over those in stands. The proportion of windthrown trees attacked by I. typographus increased with stem diameter, whereas the opposite was true for P. chalcographus. Positive interspecific associations between the species were found on the lower, middle and upper third parts of the trees in the first summer and on the lower part in the second summer. The results are discussed with regard to forest protection and nature conservation.

Ecological effects and management aspects of an exotic tree species: the case of lodgepole pine in Sweden.

The North American tree Pinus contorta var, latifolia was experimentally introduced in Sweden already in the 1920s, and has been used in Swedish forestry on a large scale since the 1970s. These pla ...

Attacks by bark- and wood-boring Coleoptera on mechanically created high stumps of Norway spruce in the two years following cutting

Abstract Attacks of bark- and wood-boring beetles on mechanically created high stumps of Norway spruce, Picea abies L. (Karst.), were studied in the provinces of Dalarna (Grangarde area) and Uppland (Fageron) in central Sweden. The experiment included a total of 362 stumps in the Grangarde area as well as 48 stumps and 18 logs at Fageron. Most inspections were conducted in the first and second autumns following the cuttings made to create the stumps. All stumps were attacked by at least one species during the two-year period, and for almost all of them (95%) the initial attacks occurred in the first summer. The most frequently encountered species on the stumps were the scolytids Ips typographus (L.), Pityogenes chalcographus (L.), Hylurgops palliatus (Gyll.), Orthotomicus spp., Trypodendron lineatum (Oliv.), Dryocoetes sp. and Polygraphus poligraphus (L.), and the cerambycids Tetropium spp. and Monochamus sutor (L.). Both the time of cutting and stump diameter influenced beetle colonisation. I. typographus was not found in autumn-cut stumps, while Orthotomicus spp. was found more frequently in autumn-cut stumps than in spring-cut stumps. There was a positive relationship between I. typographus occupancy and stump diameter, while negative relationships were found between stump diameter and H. palliatus and T. lineatum occupancy. Most stumps (ca. 80%) were attacked by more than one bark- and wood-boring species in the first summer. The proportion of stumps attacked was significantly higher than the proportion of logs attacked for P. poligraphus, T. lineatum and Tetropium spp., whereas the opposite was true for I. typographus. The percentage of bark area utilised by I. typographus was significantly higher in logs than in stumps.

RESPONSE ON THE GROUND OF BARK BEETLE AND WEEVIL SPECIES COLONIZING CONIFER STUMPS AND ROOTS TO TERPENES AND ETHANOL

Responses of threeHylastes species,Dryocoetes autographus, and twoHylobius species to terpenes and ethanol were studied in field experiments on clear-cut forest sites in Sweden using baited ground traps.α-Pinene alone did not attract any of the six species. A terpene blend (spruce turpentine consisting mainly ofα-pinene,β-pinene, and 3-carene) attractedHylastes cunicularius, H. brunneus, andHylobius abietis in some experiments, but not in others. The attractiveness of ethanol also varied; the only species consistently attracted wasH. abietis. Baits containing both terpenes and ethanol, particularly the combination of spruce turpentine and ethanol, were attractive to all species exceptHylobius pinastri. InH. abietis, the terpene plus ethanol/ ethanol catch ratios increased during early summer. Seasonal differences in catch levels were observed inH. cunicularius andH. abietis. The addition ofα-pinene reduced the attractiveness of the combination of spruce turpentine and ethanol toH. cunicularius, H. opacus, andD. autographus. The differences in response to the volatiles between species are probably related to differences in reproductive behavior and host preferences.

Insects on lodgepole pine in Sweden — current knowledge and potential risks

Abstract Eighty species of forest insects have thus far been recorded feeding on lodgepole pine in the Nordic countries (61 in Sweden). The list includes species that have Scots pine as their main host and which feed on needles, flowers, cones, and shoots, as well as species boring in the phloem and xylem of dead or dying Norway spruce. Contrary to our expectations, most of the insect species that have colonised lodgepole pine in Sweden can be considered specialists (with regard to host plant range and feeding mode) rather than generalists. We suggest that the current dominance of specialised insect herbivores is related to the similarity in chemistry and morphology between lodgepole and Scots pine. Only a few of the species considered to be pests have caused considerable damage in lodgepole pine stands in the Nordic countries. The most severe damage has been caused by the needle feeders Neodiprion sertifer and Anthonomus phyllocola. Hylobius abietis, the most harmful forest insect species in Scandinavia, attacks lodgepole pine seedlings to about the same degree as it attacks Scots pine and Norway spruce and causes similar levels of mortality. Other pest species reported to have caused considerable damage to lodgepole pine are Pissodes validirostris (cones) and Rhyacionia bouliana (shoots). No insect species native to North America and living on lodgepole pine have yet to become established in the Nordic countries since the introduction of this exotic tree species. The risk of large-scale damage in Sweden is discussed in relation to the distribution and management of lodgepole pine.

Adapting forest health assessments to changing perspectives on threats—a case example from Sweden

A revised Swedish forest health assessment system is presented. The assessment system is composed of several interacting components which target information needs for strategic and operational decision making and accommodate a continuously expanding knowledge base. The main motivation for separating information for strategic and operational decision making is that major damage outbreaks are often scattered throughout the landscape. Generally, large-scale inventories (such as national forest inventories) cannot provide adequate information for mitigation measures. In addition to broad monitoring programs that provide time-series information on known damaging agents and their effects, there is also a need for local and regional inventories adapted to specific damage events. While information for decision making is the major focus of the health assessment system, the system also contributes to expanding the knowledge base of forest conditions. For example, the integrated monitoring programs provide a better understanding of ecological processes linked to forest health. The new health assessment system should be able to respond to the need for quick and reliable information and thus will be an important part of the future monitoring of Swedish forests.

Seasonal flight patterns of Ips typographus in southern Sweden and thermal sums required for emergence

The spruce bark beetle Ips typographus is the major tree‐killing bark beetle in Eurasia. To increase knowledge about its seasonal flight patterns and about the thermal sums required for emergence, a study was conducted in southern Sweden from 2006 to 2010. Seasonal flight patterns were recorded by pheromone traps and development was recorded by felling trees three times during each season. Flight began, on average, on 27 April [after 47 degree‐days (dd) > 5 °C]. More than 50% of flight activity occurred after mid‐June, and this continued to mid‐August. Re‐emergence of parental beetles after they had produced the first brood started, on average, on 24 May (after 122 dd). Continued flight and oviposition demonstrated that sister broods were frequent. A higher proportion of parental beetles re‐emerged from trees colonized in May (95%) than in July (20%). Beetles that colonized trees late had to accumulate a higher thermal sum before re‐emerging (400 dd). Filial beetles began to emerge, on average, on 29 June (after 437 dd) and started to fly in early July, giving rise to at least a partial second generation in each year. A higher proportion of filial beetles had emerged from trees colonized in May (75%) than in July (15%). Knowledge of these region‐specific flight patterns and the associated thermal sums required for emergence will facilitate efficient pest management by enabling timely removal of fallen and standing weakened host trees. The obtained data will also be useful for improving models that predict the population dynamics in a warmer climate.

Response of Ips typographus (Scolytidae: Coleoptera) and other bark- and wood-boring beetles to a flash-flood event

On 30–31 August 1997, a thunderstorm accompanied by heavy rain caused flood erosion on the forest-covered slopes of Mt Fulufjäll in central Sweden. Large numbers of mature Norway spruce trees [Picea abies (L.) Karst.] were uprooted and deposited along streams in the area. Attacks by bark-and wood-boring beetles in lying spruces were recorded along three flooded and three unflooded streams in the three years following this flooding event. The bark beetles Ips typographus (L.), Pityogenes chalcographus (L.), Orthotomicus sp. and the cerambycid Monochamus sp. were found to be much more abundant along flooded than unflooded streams. In contrast, the bark beetle Hylurgops glabratus (Zett.) showed the opposite pattern. Mortality among standing trees peaked in the second year following the flooding event. A considerable proportion of this additional tree mortality could be attributed to attacks by I. typographus. In contrast, no trees killed by this species were found along the three unflooded streams.