Gnathotrichus materiarius Fitch (Col., Scolytidae) in Pheromonfallen vonIps cembrae (Heer) (Col., Scolytidae), ein neuer Fundort für NW-Deutschland

Several individuals of the ambrosia beetleGnathotrichus materiarius Fitch were captured by Pheromone traps ofIps cembrae within stands ofLarix kaempferi andPinus sylvestris in the forest district of Lingen (Emsland). So this bark beetle introduced from North America (“Eastern Pine Wood Stainer”) should be settled in NW Germany.     

Types of bark beetle (Coleoptera: Scolytidae) infestation in spruce forest stands affected by air pollution, bark beetle outbreak and honey fungus (Armillaria mellea)

583 spruce stands in an area affected by air pollution and bark beetle outbreak in Eastern Slovakia were studied in 1996. According to bark beetle infestation of dominant and codominant trees, stands were classified into following types of spruce stand decline:Ips typographus-A,Ips typographus-B,Polygraphus poligraphus, I. typographus/P. poligraphus—A,I. typographus/P. poligraphus—B. The presence of attacked trees in forest edges, bark beetle spots and forest interior was the key important factor for the classification. Data from forest inventory and forest management evidence together with data on types of spruce stands decline were used in further analyses. Results shows that the distribution of forest stands classified into different types or uninfested stands is related mainly to host size and site quality. The percentage of spruce, exposition of stands and stand density showed significant effects. The mechanisms of spreading of studied bark beetle outbreak could be explained by direct effects of stress of trees caused by an abrupt increase of level of solar irradiation and by weakening of trees by the honey fungus.     

Effectiveness of different types of pheromone traps used against Ips typographus (L.) (Col., Scolytidae) in Sweden

No effects of different surface textures on cylinder traps were found, except for traps with a very smooth surface which caught fewer beetles. The addition of a large exterior funnel, collecting beetles falling down on the outside of the cylinders, resulted in a doubling of trap catches. Two types of barrier traps, which turn with the wind, are described. The best of these traps had a catch efficiency approaching that of the most efficient cylinder traps.     

Seasonal variation in the light reactions ofBastophagus piniperda (Col., Scolytidae) at different temperatures

Ohne Zusammenfassung     

Variations in sex ratio during an outbreak ofIps typographus (Col., Scolytidae) in Southern Bavaria

Extensive areas of spruce forest were affected by an outbreak of the Scolytid beetleIps typographus all over Southern Bavaria between 1990 and '95. During this gradation young beetles were collected from bark samples and examined with regard to the male to female sex ratio. It turned out that there is a significant interaction between gradation phase and sex ratio. An increase of population density was accompanied by an increasing portion of female beetles, up to 72%. A decrease of the females to an equal index of 5050 indicated the breakdown of mass propagation. This experiences could be used as an indicator of gradation phase and thus to create a new method of monitoring gradations of spruce bark beetle. The regulation mechanisms responsible for this deviation from a genetically plausible index of 11 can take influence as at the time of fertilisation as at embryonal or postembryonal development of the beetles. Parthenogenetic reproduction was not found inI. typographus.

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Veränderungen des Geschlechterverhältnisses beiIps typographus während einer Massenvermehrung in Südbayern

Zusammenfassung Im Rahmen einer Massenvermehrung des Buchdruckers in Südbayern (Raum München) zwischen 1990 und '95 wurden Jungkäfer aus Rindenproben im Hinblick auf die Geschlechterverteilung untersucht. Es zeigte sich eine Korrelation zwischen Gradationsphase und Sexualindex. Der Anstieg der Populationsdichte äußerte sich in einem erhöhten Weibchenanteil von bis zu 72%. Ein Rückgang des Weibchenüberhanges bis zum ausgeglichenen Geschlechterverhältnis von 5050 kennzeichnete den Zusammenbruch der Massenvermehrung. Es läßt sich also aus dem Sexualindex eine Prognose über die Dichteentwicklung einer Buchdruckerpopulation ableiten.Die Steuermechanismen, die für die Abweichung vom genetisch plausiblen Index 11 verantwortlich sind, können am Befruchtungsvorgang sowie an der embryonalen oder postembryonalen Entwicklung der Käfer ansetzen. Es konnten keine Hinweise auf eine parthenogenetische Vermehrung vonI. typographus gefunden werden.

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With one figure and one table

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These examinations were financially supported by the Bavarian Ministry of Food, Agriculture and Forestry.

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Dedicated to Prof. Dr.W. Schwenke for 75th birthday 22. 3. 1996.     

Racemat und Enantiomere von Ipsdienol zur Anlockung vonIps amitinus (Eich.) (Col., Scolytidae)

Zusammenfassung Enddarmextrakte des Kleinen Buchdruckers (Ips amitinus) ergaben, daß die Männchen während der Aggregationsphase hauptsächlich (+)-Ipsdienol und Amitinol produzieren.Cis-Verbenol,trans-Verbenol, Myrtenol, Verbenon und (–)-Ipsenol werden nur in geringen Mengen freigesetzt. Das von den Weibchen produzierte 2-Methyl-3-buten-2-ol, das beim Großen Buchdrucker als Landestimulus dient, scheint ablenkend zu wirken.Freilanduntersuchungen mit den Enantiomeren von Ipsdienol, gemischt mit Amitinol, zeigten, daß die Mischung von (+)-Ipsdienol mit Amitinol für beide Geschlechter attraktiv ist. Das Racemat/Amitinol-Gemisch zeigt eine geringe Lockwirksamkeit, während die Kombination von (–)-Ipsdienol/Amitinol gar nicht attraktiv ist.

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Racemate and enantiomeres of Ipsdienol for attractingIps amitinus (Eichh.) (Col., Scolytidae)

Hindgut extracts ofIps amitinus revealed that males of this polygamous bark beetle produce mainly (+)-Ips-dienol and Amitinol in the attraction phase.Cis- andtrans-Verbenol, Myrtenol, Verbenon and (–)Ipsenol are produced only in minor amounts. 2-Methyl-3-buten-2-ol is produced by females and seems to be inhibitive.Field experiments with different enantiomeric mixtures of Ipsdienol and Amitinol showed that the mixture (+)-Ipsdienol and Amitinol is attractive for both males and females. The mixture of racemic Ipsdienol and Amitinol seems to be less attractive; (–)-Ipsdienol and Amitinol is not attractive at all.

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Mit 1 Abbildung     

Der Buchdrucker (Ips typographus L.) (Col., Scolytidae) und seine Problematik in der Tschechischen Republik

The Czech Republic is passing the third outbreakperiod ofIps typographus since 1880. The first and second outbreaks (1870–1876 and 1945–1954) were a consequence of falling of masses of trees caused by storm. The data ofIps duplicatus during the first outbreak mentioned in later papers are a mistake, reality it has beenIps amitinus.The third outbreak from 1980 until now has not one but several from man dependent and not dependent causes. There are: Falling of trees, by repeating windstorms damage of trees by pollutions of SO₂ and their pollutants, the increasing temperatures during the last period of 30 years and the development of higher numbers of generations of the beetle. The successes in using pheromones in control ofIps typographus were overestimated. Also the changes in the ownership of forest stands were of importance. Ips duplicatus occured in North Moravia having been migrated across Northpoland to the east Czech Republic.In the Nationalpark of umava (on the other side to the Nationalpark of Bavaria) in some reservations no measures againstIps typographus as in Bavaria were made. Here new control measures must be taken against this pest.     

Zur Kenntnis des „Kleinen Buchdruckers”, Ips amitinus (Eichh.) (Col., Scolytidae)

On the knowledge of Ips amitinus (Eichh.) The authors compile some quantitative data on the Smaller Spruce Bark BeetleIps amitinus, comparing it withIps typographus. In addition to well known values, differences were measured in diameter of entrance holes, distance between the egg niches, and size of the larvae's head capsules. Very small differences, between the two species, were found in offspring production depending upon gallery density, and in egg mortality.     

老秃顶子国家级自然保护区小蠹虫发生危害调查

在老秃顶子国家级自然保护区共采到小蠹虫29种,隶属4亚科15属,其中红松根小蠹Hy-lastes plumbeusBlandford、东北四眼小蠹Polygraphus sachalinensisEggers、中穴星坑小蠹Pityo-genes chalcographasLinnaeus、落叶松八齿小蠹IpssubelongatusMotschuleky、六齿小蠹I.acuminatusGyllenhal等为优势种,主要危害衰弱木、濒死木、枯萎木及风倒雪压木等,少数种类如纵坑切梢小蠹Tomicus piniperda Linnaeus、黄须球小蠹Sphaerotrypes coimbatorensisStebblng等危害健康树木。不同海拔高度及不同类型的林分中,小蠹虫的种类存在明显差异。及时清除、集中处理风倒木是控制虫源,减轻危害的重要措施。     

Zur Wirkung von Verbenon auf den Buchdrucker,Ips typographus L. (Col., Scolytidae)

Zusammenfassung Eine Verdunstungsrate von 93 mg/Baum/Tag aus 24 Polyethylen-Dispensern von je 50 cm Länge und mit 10 ml Verbenon gefüllt, verhinderte nicht den Befall der verbenonbehandelten lebenden Fichten durch Buchdrucker, obwohl pheropraxbeköderte Schlitzfallen in nur 6 m Entfernung (d. i. die Hälfte des praxisüblichen Sicherheitsabstandes) standen. Im Gegenteil, alle 6 verbenonbehandelten Fichten wurden besiedelt, 5 von ihnen innerhalb von 2 Tagen nach Applikation der Verbenondispenser, wogegen nur 2 der ebenfalls in 6 m Entfernung stehenden unbehandelten Kontrollfichten ganz schwach (1 bzw. 2. Einbohrungen) nach 10 Tagen befallen wurden. An den Verbenonfichten reichte die Zone der Einbohrlöcher (4–38 je Baum) nicht wesentlich über 3 m hinaus, d. i. etwa die obere Grenze der Verbenon-Zone, die 0,5m über dem Boden beganri. Die Käfer hatten sich dicht neben und sogar unter den Dispensern eingebohrt. Diese Befunde deuten an, daß Verbenon in Kombination mit flüchtigen Wirtsbauminhaltsstoffen eine gewisse Attraktivität für Buchdrucker besitzt.In zusätzlichen Experimenten (Rotation mit Schlitzfallen) konnte sichergestellt werden, daß die hier verwendete Verbenoncharge die übliche antiaggregative Eigenschaft hat (die mit diesem Verbenon beköderten Fallen erbrachten nur 2% des Fanges der ausschließlich mit Pheroprax^R beköderten Vergleichsfallen). Schlitzfallen mit Pheroprax^R plus Verbenon können aber auch sehr viel mehr Buchdrucker fangen, nämlich wenn sie inmitten einer Anzahl von in der Nähe befindlichen, nur mit Pheroprax^R beköderten Fallen stehen (40–60% von deren Fängen, z. B. innerhalb einer kreuzförmigen Anordnung mit Abständen von 2 m zwischen den Fallen).Offenbar besteht kein Zusammenhang zwischen dem o. g. Mangel an Reppellentwirkung des an der lebenden Fichte applizierten Verbenons und der Photoisomerisation bzw. der Umwandlung des Verbenon zu Chrysanthenon: Nach kontrollierter Lichtexposition (in voller Sonne und bei einer zweiten Variante innerhalb einer schwarzen Schlitzfalle) reduzierte das lichtexponierte Verbenon in mit zusätzlichem Pheroprax^R beköderten Schlitzfallen die Fänge um 95–98%, unabhängig davon, ob die Expositionszeit 1 Stunde oder 1 Monat betragen hatte. Vermutlich war nur ein Teil der Verbenonmenge umgewandelt und der Rest reichte zur Abschreckung. Lediglich eine Variante mit frischem, nicht lichtexponiertem Verbenon bewirkte eine signifikante, wenn auch sehr schwache Steigerung der Fangreduktion auf 98,8%, was darauf hindeutet, daß von der ursprünglichen, repellenten Wirkung doch ein wenig durch Photoisomerisation verlorengegangen ist.

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Effects of verbenone on the spruce bark beetleIps typographus L. (Col., Scolytidae)

Release of antiaggregation pheromone, verbenone, at 93 mg/tree/day from 24 polyethylene dispensers (earch 50 cm long, filled with 10 ml verbenone) per living spruce (Picea abies) did not prevent attacks by spruce bark beetle (Ips typographus) despite aggregation pheromone dispensers (Pheroprax^R) have been placed much below security distance only 6m apart of the verbenone-treated spruce in order to trigger a lot of beetles to both the treated and untreated spruces. In opposite, all of the 6 verbenone-treated spruces were colonized by spruce bark beetles, 5 of them within 2 days after treatment whereas only 2 of the nearby neighbouring untreated spruces have been slightly (1 resp. 2 boring holes) attacked 10 days atter treatment. On the verbenone-spruces, the boring holes (4–38 per tree) did not much exceed 3 m of height, i. e. the upper border of the verbenone-treated zone beginning 0.5 m above ground. Attacks of spruce bark beetles occured close to and even under the verbenone dispenser. These findings obviously reveal some attractiveness of verbenonen in combination with host tree odors. The charge of verbenone used in this experiment had proved to be well antiaggregative in additional trials with rotating slot traps: traps baited with Pheroprax^R and verbenone in polyethylene bags caught only 2% of those baited exclusively with the spruce bark beetle pheromone Pheroprax^R.But slot traps containing both Pheroprax^R and verbenone can also catch much moretypographus when positioned among a number of Pheroprax-baited traps close by (40–60% of their catches, e. g. within a cross of traps with distances of 2m between traps). The lack of any repellent activity of verbenone released in large amounts from dispensers on living trees obviously does not depend on photoisomerization of verbenone, converted to chrysanthenone: After having been exposed either to full sunlight or to sunlight within the shelter of a black slot trap, verbenone released from a dispenser within a slot trap baited with Pheroprax^R reduced the response ofIps typographus at the (in trap trials) well known level of about 95–98%, regardless of the duration of the preceding light exposure within the scope of 1 hour to 1 month. Presumably, only a small part of verbenone has been converted to chrysanthenon and the remaining part was still antiaggregative. Merely absolutely unexposed verbenone showed significant higher reduction of spruce bark beetles (98.8%) than the light exposure treatments did. This may indicate a very slight loss of bioactivity of verbenone by photoisomerization.

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Mit 3 Tabellen     

Beetles (Coleoptera) caught with pheromones of Gnathotrichus retusus and G. sulcatus (Col., Scolytidae) in southern Finland

The ambrosia beetle Gnathotrichus materiarius, which originally came from North America, was discovered in southern Finland in 1996. In 1997, using Norwegian drainpipe traps baited with pheromones of Gnathotrichus retusus and G. sulcatus, we collected beetles in the region where the first specimen had been caught in order to determine whether this potential pest species had become established in the area. Samples from a total of 16 traps included 79 species of beetles and 719 individuals, but no specimens of G. materiarius. The most abundant species in the samples were the ambrosia beetles Xyleborus dispar and Trypodendron lineatum. Several predators and other associates of bark beetles were also captured. The majority of the beetles caught were saproxylic species.     

Über Borkenkäfer (Col., Scolytidae) in Zweigen der Zirbe (Pinus cembra) in Südtirol

In dead twigs ofPinus cembra taken from two localities above 2000 m in South Tyrol in 1984Pityogenes bistridentatus, three species ofPityophthorus (henscheli, knoteki, pityographus) and one species ofIps (amitinus) were found. Informations are given on taxonomy, host preference and bionomy of these bark beetles.     

The effects of mechanical fuel reduction treatments on the activity of bark beetles (Coleoptera: Scolytidae) infesting ponderosa pine

Selective logging, fire suppression, forest succession and climatic changes have resulted in high fire hazards over large areas of the western USA. Federal and state hazardous fuel reduction programs have increased accordingly to reduce the risk, extent and severity of these events, particularly in the wildland–urban interface. In this study, we examined the effects of mechanical fuel reduction treatments on the activity of bark beetles in ponderosa pine, Pinus ponderosa Dougl ex. Laws., forests located in Arizona and California, USA. Treatments were applied in both late spring (April–May) and late summer (August–September) and included: (1) thinned biomass chipped and randomly dispersed within each 0.4 ha plot; (2) thinned biomass chipped, randomly dispersed within each plot and raked 2 m from the base of residual trees; (3) thinned biomass lopped-and-scattered (thinned trees cut into 1–2 m lengths) within each plot; (4) an untreated control. The mean percentage of residual trees attacked by bark beetles ranged from 2.0% (untreated control) to 30.2% (plots thinned in spring with all biomass chipped). A three-fold increase in the percentage of trees attacked by bark beetles was observed in chipped versus lopped-and-scattered plots. Bark beetle colonization of residual trees was higher during spring treatments, which corresponded with peak adult beetle flight periods as measured by funnel trap captures. Raking chips away from the base of residual trees did not significantly affect attack rates. Several bark beetle species were present including the roundheaded pine beetle, Dendroctonus adjunctus Blandford (AZ), western pine beetle, D. brevicomis LeConte (AZ and CA), mountain pine beetle, D. ponderosae Hopkins (CA), red turpentine beetle, D. valens LeConte (AZ and CA), Arizona fivespined ips, Ips lecontei Swaine (AZ), California fivespined ips, I. paraconfusus Lanier (CA) and pine engraver, I. pini (Say) (AZ). Dendroctonus valens was the most common bark beetle infesting residual trees. A significant correlation was found between the number of trees chipped per plot and the percentage of residual trees with D. valens attacks. A significantly higher percentage of residual trees was attacked by D. brevicomis in plots that were chipped in spring compared to the untreated control. In lopped-and-scattered treatments, engraver beetles produced substantial broods in logging debris, but few attacks were observed on standing trees. At present, no significant difference in tree mortality exists among treatments. A few trees appeared to have died solely from D. valens attacks, as no other scolytids were observed in the upper bole. In a laboratory study conducted to provide an explanation for the bark beetle responses observed in this study, monoterpene elution rates from chip piles declined sharply over time, but were relatively constant in lopped-and-piled treatments. The quantities of β-pinene, 3-carene, -pinene and myrcene eluting from chips exceeded those from lopped-and-piled slash during each of 15 sample periods. These laboratory results may, in part, explain the bark beetle response observed in chipping treatments. The implications of these results to sustainable forest management are discussed.     

疑山郭公虫对纵坑切梢小蠹捕食作用研究

研究了疑山郭公虫对纵坑切梢小蠹成虫捕食量及对纵坑切梢小蠹繁殖过程和繁殖率的影响.在室温为22～24 ℃条件下,繁殖期疑山郭公虫平均每天可捕食纵坑切梢小蠹成虫0.61±0.043头.在实验室内,先将纵坑切梢小蠹引入云南松新鲜木段,7 d后再引入疑山郭公虫成虫.结果表明:疑山郭公虫成虫对纵坑切梢小蠹成虫的产卵过程形成干扰,从而导致后者繁殖率下降.疑山郭公虫幼虫可以捕食木段内纵坑切梢小蠹幼期各虫态,捕食率为8.3%.在野外,将疑山郭公虫成虫放到受到纵坑切梢小蠹危害的树干上,再用尼龙网将其包裹起来.研究结果表明,疑山郭公虫对树干内纵坑切梢小蠹幼期(幼虫和蛹)的捕食率大体为10.6%.疑山郭公虫对繁殖期纵坑切梢小蠹的影响主要包括捕食繁殖期纵坑切梢小蠹成虫、干扰纵坑切梢小蠹繁殖过程以及捕食纵坑切梢小蠹幼虫等.研究初步认为,疑山郭公虫对纵坑切梢小蠹种群增长具有明显控制作用.     

Frequency, species composition and efficiency of Ips typographus (Col., Scolytidae) parasitoids in infested spruce forests in the National Park “Bavarian Forest” over three consecutive years

During the summers of three consecutive years (2002, 2003 and 2004) the parasitoid fauna of the spruce bark beetle Ips typographus was investigated in the national park “Bavarian Forest”. In the central part of this forest no human influence in the population dynamics is allowed, whereas, in the surrounding no bark beetle attacks are accepted and all infested wood is removed consequently. Species frequency and species composition did not differ much in 2002 and 2003, when Coeloides bostrichorum and Roptrocerus sp. was most numerous. But in 2004 species composition changed with the increase of R. tutela and the decrease of C. bostrichorum. We found that C. bostrichorum reached very high numbers of individuals, but its frequency did not exceed 31% during 3 years while the pteromalid wasps were not so numerous, but had very high frequencies. For Roptrocerus, we found 55, 82 and 85% and for R. tutela 41, 67 and 85% frequency. In 2004, mean parasitization was higher (8.5) as in 2003 (5.8%). The highest parasitization in one sample was 92.2% in 2002 caused by C. bostrichorum, 73.5% in 2003 caused by C. bostrichorum and R. tutela and 59.8% in 2004 caused by R. tutela and Roptrocerus. Our hypothesis that the influence of parasitoids on the population dynamics of I. typographus is greater in natural forests than in normal treated forests could not be corroborated.     

Protozoen als Krankheitserreger bei einigen Borkenkäferarten (Col., Scolytidae) im Königssee-Gebiet,Oberbayern

Up to now 16 species of Protozoa are known as pathogens of bark beetles. A list containing informations on the hosts, authors, size of spores and other characteristics of these 16 species is given. In 1976 and 1977 studies were made in the Alps near Berchtesgaden (Königssee) to clear up the Protozoan diseases of 8 bark beetle species:Ips typographus, I. amitinus, Dryocoetes autographus, Pityogenes chalcographus, Hylurgops palliatus, H. glabratus, Xyloterus lineatus andHylastes cunicularius. During this time the bark beetles showed normal density. Four species:Ips typographus, Dryocoetes autographus, Hylurgops palliatus andH. glabratus, were infected by altogether 5 species of Protozoa (Sporozoa):Gregarina typographi, Menzbieria cf.chalcographi, Mattesia schwenkei, Nosema cf.typographi andMalamoeba cf.locustae. Nearer informations on morphology, distribution0 and systematics of the five pathogens are given.     

Intraspezifische Differenzierung in der Epidemiologie und Ökologie vonPityogenes chalcographus L. (Col., Scolytidae) unter dem Aspekt der interpopularen Bastardierung

Four regionally different strains and six F₁ interpopular crosses ofPityogenes chalcographus were used for infestation and starvation experiments. In the infestation experiment beetles were placed for three days on vital Norway spruce and the amount of nuptial chambers were recorded. During the viability experiment the insects were kept under a daily varying temperature for 16h at 20°C and for 8h at 10°C. The rel. humidity was set at 93%, 77% and 57%. The infestation potential differs in the susceptibility of host trees and within the populations. Especially the F₁ crosses provide an enhanced attack and potential of injury which are to be considered a case of heterosis. Because of the irregular host-tree preference in some populations it is assumed that there is a highly specific interaction in feeding stimulation. The effect of heterosis is also present in starvation experiments, but it seems to be only restricted to an optimal survival range. It is emphasized that genetic factors play a remarkable role in the interactions between bark beetles and host trees as well as in population dynamics.