A method for the protection of spruce stands againstIps typographus by the use of barriers of pheromone traps in north-eastern Slovakia

A method and layout of various systems of barriers of pheromone traps is described. The rationale of the method is based on the stress of spruce and the chemical communication ofIps typographus. Various systems of pheromone trap barriers were used according to the required level of protection. The method was used in two areas affected by air pollution and bark beetle outbreak. The first area was in an unnatural spruce monoculture region while the second was in a National Park. The described method led to a significant reduction of bark beetle attacks on trees along forest edges and subsequently to the stopping of movement of the zone of attacked trees due to bark beetle damage. In the case of forest stands with no reduced canopy closure, the reduction of attacks led to a dramatic decline of bark beetle outbreak. On the other hand, this method was not able to reduce the level of bark beetle attack in the interior of forest stands with a decreased level of canopy closure. This method, as part of differentiated pest management measures in one forest district, was successful without any other protection measures in the condition of natural reserves in a spruce vegetation zone.     

Bark beetle (Coleoptera, Scolytidae) outbreak and system of IPM measures in an area affected by intensive forest decline connected with honey fungus (Armillaria sp.)

The character of a bark beetle outbreak, planning system, and implementation of IPM measures in a forest affected by intensive decline connected with honey fungus (Armillaria sp.) is described. It is possible to distinguish two levels of outbreak in the study area. The first level is characterized by spruce mortality connected with yellowing of spruce and presence of plant pathogens, mostly Armillaria sp. Forest stands have disperse infestations of bark beetles. Identification of infested trees and salvage cutting in time are problematic. In case of late processing of infested trees, the second level of outbreak could become manifest. The populations of bark beetle increase. Beetles could attack relatively healthy trees. The classical outbreak with forest edges and spot infestations starts. The identification of infested trees is easier. The application of pheromone trap barriers is effective. Thus, the second level of outbreak could be easily managed. The planning of IPM measures is concerned with localization of various pheromone trap systems in particular forest stands. It is based on field survey, data acquisition, estimation of swarming bark beetle population, and information of pheromone system effectiveness.     

Bark beetle (Coleoptera, Scolytidae) outbreak and system of IPM measures in an area affected by intensive forest decline connected with honey fungus (Armillaria sp.)

The character of a bark beetle outbreak, planning system, and implementation of IPM measures in a forest affected by intensive decline connected with honey fungus (Armillaria sp.) is described. It is possible to distinguish two levels of outbreak in the study area. The first level is characterized by spruce mortality connected with yellowing of spruce and presence of plant pathogens, mostly Armillaria sp. Forest stands have disperse infestations of bark beetles. Identification of infested trees and salvage cutting in time are problematic. In case of late processing of infested trees, the second level of outbreak could become manifest. The populations of bark beetle increase. Beetles could attack relatively healthy trees. The classical outbreak with forest edges and spot infestations starts. The identification of infested trees is easier. The application of pheromone trap barriers is effective. Thus, the second level of outbreak could be easily managed. The planning of IPM measures is concerned with localization of various pheromone trap systems in particular forest stands. It is based on field survey, data acquisition, estimation of swarming bark beetle population, and information of pheromone system effectiveness.     

A two-year study of parasitoid entomofauna associated with spruce bark beetles (Coleoptera: Curculionidae) in the altimontane belt of Slovenia (Pohorje)

Parasitoids are known to be an important factor in the population density regulation of bark beetles. In our study of the parasitoid complex of spruce bark beetles in 2011 and 2012, we collected bark samples from trees infested with I. typographus from spruce stands in the altimontane belt of Slovenia. The samples were taken at different altitudes: 450, 700 and 1230 m above sea level. A total of 9 bark beetle species and 12 parasitoid species was found. Ips typographus was most abundant, with 93% of all species of scolytids. The parasitoid species that were found belonged mainly to the Pteromalidae and Braconidae families. By far the most abundant and frequent species was Roptrocerus xylophagorum, which represented 84% of all parasitoids and was present in all study samples. Differences in species composition, parasitoid species diversity, species abundance and parasitism rate were confirmed between locations and also between both years of our study.     

Patterns of bark beetle occurrence in Norway spruce stands of national parks in Tatra Mts. in Poland and Slovakia

This paper presents the results of a research project concerning bark beetle populations in Norway spruce stands managed under a nature protection regime in national parks in Tatra Mountains in Poland and Slovakia. The preliminary data on bark beetle occurrence and related selected stand characteristics are presented. The dynamics of a bark beetle outbreak that occurred from 1994–97 in the stands localized on both sides of the state border and in various nature protection regimes is analyzed retrospectively. The data concerning the tree/stand characteristics, i.e. DBH and increment of trees are discussed in relation to its potential role in the mechanism for the spread of bark beetle populations. The patterns of the spatial distribution of trees attacked during the research period (1999–2001) are described.     

Patterns of bark beetle occurrence in Norway spruce stands of national parks in Tatra Mts. in Poland and Slovakia

This paper presents the results of a research project concerning bark beetle populations in Norway spruce stands managed under a nature protection regime in national parks in Tatra Mountains in Poland and Slovakia. The preliminary data on bark beetle occurrence and related selected stand characteristics are presented. The dynamics of a bark beetle outbreak that occurred from 1994–97 in the stands localized on both sides of the state border and in various nature protection regimes is analyzed retrospectively. The data concerning the tree/stand characteristics, i.e. DBH and increment of trees are discussed in relation to its potential role in the mechanism for the spread of bark beetle populations. The patterns of the spatial distribution of trees attacked during the research period (1999–2001) are described.     

Occurrence of pathogens in associated living bark beetles (Col., Scolytidae) from different spruce stands in Austria

Pathogen occurrence was studied in 16099 adult specimens of 10 different bark beetle species, which live associated on Norway spruce (Picea abies (L.) Karst.). Beetles (mainly Ips typographus L. and Pityogenes chalcographus L.) were collected from 6 different localities in Austria (4 secondary spruce stands and 2 natural forest type stands, 9 sampling plots in total) in elevations between 400m and 1600m. Various viral, protozoan, and fungal pathogens could be diagnosed with a light microscope in the examined beetles. Numerous pathogen species were known from former studies, some pathogens were totally new or could be found in a new host species beside their type host. The most dominant pathogen species were Protozoa, Gregarina cf. typographi, Malamoeba cf. scolyti, and Chytridiopsis cf. typographi. Over the whole investigation period, the highest pathogen diversity with eight pathogen species was found in I. typographus. Differences were observed in the pathogen complex of each beetle species from the different collection sites and in different years of investigation. Several species showed an overlapping in their host range and infected various bark beetle species. Furthermore, pathogen occurrence and prevalence differed in bark beetles from 4 different sampling plots in an area (one locality) within a distance of a few kilometres.     

Differences in bark beetle (<Emphasis Type="Italic">Ips typographus</Emphasis> and <Emphasis Type="Italic">Pityogenes chalcographus)</Emphasis> abundance in a strict spruce reserve and the surrounding spruce forests of Serbia

Frequent windthrow in the strict reserves of spruce in the Kopaonik National Park provides much material favorable for the development of Ips typographus (L.) and Pityogenes chalcographus (L.) (Coleoptera, Scolytidae). Therefore it was assumed that the abundance of these bark beetles in the reserves was high and that they dispersed to the surrounding spruce forests. To verify this opinion, their population levels were monitored in the strict reserve Jankove Bare and the adjoining spruce forests over the period 2006–2008. I. typographus parasitoids were identified and the parasitism percent was determined in spruce forests around the reserves. Throughout the monitoring period, the abundance of I. typographus and P. chalcographus was found to be lower in the reserve than in the surrounding spruce forests. Five species of I. typographus parasitoids and a low parasitization percent were identified in spruce forests surrounding the reserve.     

Winter mortality in sub-corticolous populations of Ips typographus (Coleoptera, Scolytidae) and its parasitoids in the south-eastern Alps

A study concerning the winter mortality of a sub-corticolous population of Ips typographus and its parasitoids has been carried out in the south-eastern Alps (Italy) during the winter 1997/98. Three attacked spruce trees were sampled three times (November, February and April) by collecting infested bark disks (1dm² each). All insects that emerged from the bark or died in the samples before emergence were counted. The mean number of living Ips typographus occurring under the bark decreases by 49% from November to April. Winter mortality mainly affects larval stages and young adults. The same trend was observed for the parasitoids Coeloides bostrychorum (48.5%) and Roptrocerus xylophagorum (47.5%).     

Bark-Beetle Parasitoids Population Surveys Following Storm Damage in Spruce Stands in the Vosges Region (France)

This paper presents the results of a long-term study designed to follow the population dynamics of hymenopteran parasitoids associated with Ips typographus L. (Coleoptera: Scolytidae) in northeastern France (Alsace and Vosges) in spruce stands devastated by the December 1999 storms. Population densities were estimated by periodic samplings in the pre-emerging insect populations developing under the bark of attacked trees. Data were collected between July 2000 and October 2001. I. typographus population density (per m²) increased respectively by 28%, 105%, and 212% in one year in the three sites surveyed. Six hymenopteran ectoparasitoids were found: Coeloides bostrichorum Giraud and Dendrosoter middendorffi Ratzeburg (Hymenoptera: Braconidae); Rhopalicus tutela (Walker), Roptrocerus xylophagorum (Ratzeburg), Roptrocerus mirus (Walker) and Dinotiscus eupterus (Walker) (Hymenoptera: Pteromalidae). After two years, the parasitoid populations increased in terms of average density but parasitism rates remained at a relatively low level, ranging from 0% to 40%, with 60% of the trees having a parasitism rate below 5%. Data outlined the recurrent coexistence of competing parasitoid species.     

Pathogenicity of four blue-stain fungi associated with aggressive and nonaggressive bark beetles

ABSTRACT The pathogenicity of two isolates of each of four bark beetle-associated blue-stain fungi was evaluated after mass inoculation of about 40-year-old Norway spruce trees (Picea abies). Trees were inoculated with a different isolate of each fungus in 1995 and 1996 at a density of 400 inoculations per m(2) in a 1.2-m-wide band on the lower bole (about 270 inoculations per tree). Trees were felled 15 weeks after inoculation. In 1995, Ceratocystis polonica was the only fungus that had stained the sapwood (56.3% of cross-sectional sapwood area). It induced five times longer phloem necroses, 21 times more dead cambium, and 11 times more dead phloem than any other fungus. In 1996, C. polonica induced less extensive host symptoms and an unidentified Ambrosiella sp. induced comparable symptoms to C. polonica in the phloem and cambium. No trees showed any foliar symptoms 15 weeks after inoculation, but six out of eight trees inoculated with C. polonica in 1995 had only 0 to 25% functional sapwood and probably would have died if felling had been delayed. This study confirms that C. polonica, an associate of the aggressive bark beetle Ips typographus, is pathogenic to Norway spruce. The pathogenicity of the Ambrosiella sp., which is associated with a nonaggressive bark beetle, seems moderate and varies between isolates. The two remaining fungi included in this study (Ophiostoma piceae and a dark fungus with sterile mycelium), which are associated with nonaggressive bark beetles, were nonpathogenic in both experiments. These results are consistent with the hypothesis that aggressive bark beetle species vector virulent fungi that may help them kill trees, but the results also show that some nonaggressive bark beetles may vector phytopathogenic fungi.     

Parameters Relevant for Modelling the Potential Development of <Emphasis Type="Italic">Ips typographus</Emphasis> (Coleoptera: Scolytidae)

A model that contributes to assessing the risk of bark beetle mass outbreaks was established. By means of modelling air and cambial temperature for any location, an investigation area is evaluated with respect to its thermal conditions for the development of Ips typographus (Coleoptera: Scolytidae). Besides topo-climatic relations of a study area, modelling the potentials of bark beetle development implies profound information on eco-physiology. Thermal requirements for development, type of voltinism, and spring swarming behaviour of two examined beetle populations are discussed in terms of the definition of input parameters for modelling.     

Overview of development of an anti-attractant based technology for spruce protection against Ips typographus: From past failures to future success

We describe a series of experiments on the protection of Norway spruce (Picea abies (L.) Karst.) logs and standing trees against Ips typographus L. (Coleoptera: Scolytidae). The tested protective materials were applied 1) at point sources and 2) area-covering using zeolite-based dispensers. We performed 11 terrestrial and one aerial application (using a helicopter) between 1992 and 2001. We gradually replaced polyethylene-bag verbenone dispensers by composite dispensers releasing verbenone and non-host volatiles (NHV: green leaf volatiles, trans-conophthorin, and C8-alcohols). Many experiments did not give statistically significant results, due to the low number of true replicates and the spatial heterogeneity of beetle attacks. The protection of horizontal objects like logs or lying trees with anti-attractants was not always successful. In the future, positive results can be expected with an area covering spray applied by zeolite dispensers containing mixtures of verbenone and NHV. A similar approach could probably be used in aerial spraying of anti-attractants.We have succeeded in our attempt to protect zones of standing spruce trees from I. typographus attacks. We used dispensers with a combination of verbenone and a full blend of NHV compounds. The protection is not complete, but in both 2000 and 2001, the treatment significantly decreased the probability of the insect attack on trees by 60–80%.     

Monitoring of Bark and Wood-Boring Beetles in France after the December 1999 Storms

After the December 1999 storms, two networks were set up over 2 years (2000 and 2001) to assess the scale and type of insect colonisation on storm damaged trees and to interpret these events for the future. The Level 1 network, was a large-scale survey that covered the entire storm area and provided qualitative observations on its 898 plots in which every major tree species was assessed. The Level 2 network, was a regional survey set up only in two regions: the 'Landes' region and the Northeast of France. The observations were intensive and quantitative, devoted only to maritime pine in the 'Landes' region and to Norway spruce in the Northeast of France. The Level 1 network indicated that less than 40% of the storm damaged trees were colonised by bark beetles in September 2000. No attacks were observed on standing trees in 2000 but many occurred during 2001 in spruce and maritime pine stands. The Level 2 network in the Vosges mountains showed a late colonisation in October and November 2000. The emerging population of Ips typographus on attacked trees reached 25 000–30 000 insects/m³. This huge population combined with the low rate of parasitism in 2001 leads to the expectation of increasing damage in spruce stands next year.     

Attraction of Ips typographus (Coleoptera: Curculionidae) beetles by lure-baited insecticide-treated tripod trap logs and trap trees

The numbers of Ips typographus beetles captured by lure-baited insecticide-treated tripod trap logs (TRIPODs) versus classic trap trees (TRAP TREEs) were compared in a spruce forest in northeastern Czech Republic in the year 2012. During the time of I. typographus flight activity (22 April–24 August), TRAP TREEs were periodically deployed and replaced, while TRIPODs were deployed at the start of flight activity, and lure and insecticide were periodically refreshed. The numbers of I. typographus beetles captured was significantly greater on TRAP TREEs than on TRIPODs during the first sampling period (22 April–25 May) but did not differ between the two kinds of traps in the subsequent sampling periods (26 May–29 June, 30 June–27 July, or 28 July–24 August). More females than males were captured by both kinds of trap. Similarly, more beetles were captured in the spring (April–June) than in the summer (July–August) by both trap models. The main advantages of TRIPODs compared to the TRAP TREEs are twofold: first, that pheromone lures will make any spruce timber attractive to I. typographus; and second, that logs need not be decontaminated at a particular time and, consequently, they require significantly less surveillance.     

Pathogens of bark beetles (Coleoptera: Curculionidae) in Bulgarian forests

The occurrence and prevalence of bark beetle pathogens in forest stands in Bulgaria were investigated in 944 specimens belonging to 21 bark beetle species. Protozoa, microsporidia, fungi and nematodes occurred in 19 of all investigated species. The infections were found in the gut (nematodes, gregarines, microsporidia), gonads (microsporidia) and hemolymph (nematodes) of the infected insects. Protozoan species (Gregarina typographi, Gregarina spp.) were detected in eight bark beetle species. Morphometric data about G. typographi and Gregarina spp. are presented. The prevalence of the gregarines varied between 1.4% and 64.2%. Microsporidia of the genera Nosema and Chytridiopsis were revealed in three bark beetle species. The prevalence of microsporidia ranged between 1.5% and 11.8%. This is the first report of a microsporidium in Taphrorychus villifrons and of gregarines in T. villifrons, Pityogenes bistridentatus, P. conjunctus, and Orthotomicus erosus. The fungus Beauveria bassiana was found in 3.4% of Hylurgops palliatus specimens. Nematodes (in gut and haemolymph) were revealed in 19 bark beetle species and their prevalence varied between 10% and 98.5%.     

Zur Weiterentwicklung eines halbsynthetischen N?hrmediums fürIps typographus L.

Zusammenfassung  Das halbsynthetische N?hrmedium vonSimsek undFührer (1993) sowieSimsek (1995) wurde in bezug auf Handhabung und Inhaltsstoffe weiterentwickelt. Es eignet sich sehr gut als Ern?hrungssubstrat für Larven, Puppen und adulte K?fer. Ganze Generationszyklen lassen sich jedoch noch nicht reproduzierbar darauf züchten.

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Further development of a semiartificial diet forIps typographus L.

The semiartificial diet for the bark beetleIps typographus L. ofSimsek andFührer (1993) andSimsek (1995) was further developed in its handling and composition of the vitamin solution. The biological availability of the vitamins of the vitamin b-group was investigated. The diet is useful as rearing medium for larvae, pupae and adult beetles. But it is not possible by now to grow reproducibly a whole generation cycle on this diet.

     

Distribution of the double-spined spruce bark beetle <Emphasis Type="BoldItalic">Ips duplicatus</Emphasis> in the Czech Republic: spreading in 1997–2009

Ips duplicatus (Coleoptera: Curculionidae) was reported in the Euro-Siberian taiga from Sweden to Sakhalin and in the Alps at the beginning of the 20th Century. It has been recorded in spruce stands in the north-eastern part of the Czech Republic since the beginning of the 1970s; monitoring of I. duplicatus was conducted in the Czech Republic in 9 years between 1997 and 2009. Beetles of the overwintering generation were captured in Theysohn pheromone traps baited with a lure of ipsdienol and E-myrcenol, and after 2005 in ID Ecolure lures. Surprisingly, I. duplicatus was found throughout the Czech Republic already in 1997. In 2002, there was a nationwide decrease in their numbers. Particularly since 2005, there has been a spread from the main center of occurrence in the eastern areas to the south and west into the central part of Bohemia where, until that time, its population densities had been lower and had not caused economically significant damage. Moreover, it was observed that in the north-eastern parts of the Czech Republic up to 80% of spruce trees from sanitary felling had been infested by this pest in recent years. The recorded amount of spruce trees infested by I. duplicatus is correlated significantly with the amount of spruce trees recorded as damaged by Ips typographus, Ips amitinus and Pityogenes chalcographus infestation as well as with the numbers of individuals of I. duplicatus captured during the aforementioned monitoring.     

The elm bark beetle Scolytus kirschi and its control in Israel1

Scolytus kirschi, a bark beetle new to Israel, was found in 1983 near Lake Kinneret affecting and killing young elm trees under stress. The main cause of the stress was water deficiency. Phytosanitation, seasonal irrigation and exposure of trap logs all slowed down the spread of the beetle and prevented further damage.     

Xylem sap flow of Norway spruce after inoculation with the blue-stain fungus Ceratocystis polonica

In a field experiment, the sap flow of Norway spruce ( Picea abies ) was measured in response to inoculation with Ceratocystis polonica , a virulent fungal associate of the spruce bark beetle Ips typographus. Four vigorous, mature Norway spruce trees were mass-inoculated with C. polonica at a density of four inoculations per dm² within a 120-cm-wide band on the lower bole. Two other trees were inoculated with sterile agar and served as controls. Sap flow of the six trees was measured by the thermal dissipation method from three weeks prior to inoculation until five months after inoculation. In three trees that had been inoculated with the fungus, sap flow density decreased dramatically within the first weeks after inoculation until no sap flow was measurable 4–6 weeks after inoculation. No marked changes in sap flow density were recorded in the fourth tree that had been inoculated with C. polonica , and this tree survived the inoculation. Inoculation with sterile agar did not have any apparent influence on the sap flow of the control trees. The results confirm the ability of C. polonica to kill mature Norway spruce trees. Sap flow measurements by the thermal dissipation method provided a direct and nondestructive method for monitoring the effects of fungal infection on sapwood functionality. Its application for further studies on vascular wilt and vascular stain diseases of trees is therefore recommended.