In the present dissertation the possibilities of aggregation of antagonists of bark beetles using allochthonous kairomones were to be analysed. The focus of the analysis was the species of European red-bellied clerids (Thanasimus spp.) in forests of Scots pine (Pinus sylvestris) and common spruce (Picea abies). Differences in trap efficiency have been analysed using the normal THEYSOHN® - slit trap and those with closed lids filled with a catching liquid. It transpired that significantly more target organisms have been locked in with the closed trap system than with the customary model. As potential attractants for European red-bellied clerids (Thanasimus spp.) standard attractants such as Pheroprax®, Sexowit®, Cembräwit®, Acuwit®, Tomowit® as well as Chalcoprax® have been tested. Furthermore the aggregate effect of individual semiochemicals, which form part of the above attractants, have been analysed in relation to European red-bellied clerids and bark beetles which appeared in the habitat. The effect of an increase of the emission rate of the attractant onto the target organisms was also part of the analysis. In addition to trials with attractants in THEYSOHN®-slit traps trials with attractants on stems of pine wood and spruce wood have also been conducted and analysed. This was to clarify whether one could aggregate that many antagonists of bark beetles that the stem does not at all or gets less populated with bark beetles. In the course of this analysis it has been attempted to identify further antagonists of bark beetles that could be aggregated with attractants. It was determined that there are important differences in levels of aggregation between the species of Thanasimus formicarius, Thanasimus rufipes and Thanasimus pectoralis with respect to the substances tested. Thanasimus formicarius has been observed in spring and early summer in pine and spruce forests. The concentration of activity of this species was higher in pine forests than in spruce forests. With respect to the tested attractants Thanasimus formicarius showed a stronger preference for Ipsdienol and Ipsenol as for (S)-cis-Verbenol in each case in connection with 2-3-2-Methylbutenol. It is also possible to replace 2-3-2-Methylbutenol with other substances. The substances of Sexowit® and Acuwit® ((+)-Ipsdienol, (-)-Ipsenol, α- and β-Pinen, 2-Phenylethanol or rather Ethanol) also seem to have a strong attraction for the Thanasimus formicarius. Thanasimus rufipes and Thanasimus pectoralis mainly appeared from early summer into the late summer and were respectively recorded in the traps. Both species, in comparison to the Thanasimus formicarius, showed a much stronger preference to (S)-cis- Verbenol, respectively attractant mixtures which contained (S)-cis-Verbenol. Thanasimus rufipes has mainly been detected in pine forests and Thanasimus pectoralis in spruce forests. In pine forests Pheroprax® could be confirmed as an effective allochthonous kairomone. In spruce forests, until the completion of this analysis, no definitive attractant could be identified which aggregats European red-bellied clerids (Thanasimus spp.) on the object to be protected without attracting bark beetles (namely Ips typographus).

Spruce bark beetle (Ips typographus (Linnaeus, 1758)) is our most serious pests, frequently invading spruce stands. The most important predators of I. typographus are two species from genus Thanasimus - Thanasimus formicarius (Linnaeus, 1758) and Thanasimus femoralis (Zetterstedt, 1828). Monitoring of these three species were carried out from April to August, using pheromone traps type Theyson with pheromone lures designed for their capture. New pheromone lure attracting beetles of genus Thanasimus has been tested. It was used a total of six traps that were placed at three locations. Two traps were always placed at one location, one with pheromone lure Pheroprax attracting spruce bark beetles and the second one with pheromone lure called Thanasiwit attracting beetles of the genus Thanasimus. All traps were checked once a week. A total of 10 291 of spruce bark beetles were captured, 25 specimens of T. formicarius and 7 individuals of T. femoralis. Spruce bark beetle flight activity had two generations and one sister brood. The first catches were recorded on 26 April 2015 and the end of the flight activity was recorded on 26 July 2015. The species T. formicarius flight activity was from 12 April 2015 to 2 August 2015 and during this period two generations were recorded. For T. femoralis flight activity was from 17 April 2015 until 9 August 2015, during this period we also recorded two generations, which took place before and after the flight activity of I. typographus. Laboratory work was conducted after the end of captures. From every of sample twenty individuals were dissected and then inspected using a light microscope to presence of pathogens. The most frequently identified pathogen of spruce bark beetles were nematodes, but only in one case nematods were identified in T. formicarius. Other pathogens were found only in the spruce bark beetles and they included microsporidia Chytridiopsis typographi, neogregarine Mattesia schwenkei and nematodes of the genus Contortylechus sp.

In the present dissertation the possibilities of aggregation of antagonists of bark beetles using allochthonous kairomones were to be analysed. The focus of the analysis was the species of European red-bellied clerids (Thanasimus spp.) in forests of Scots pine (Pinus sylvestris) and common spruce (Picea abies). Differences in trap efficiency have been analysed using the normal THEYSOHN® - slit trap and those with closed lids filled with a catching liquid. It transpired that significantly more target organisms have been locked in with the closed trap system than with the customary model. As potential attractants for European red-bellied clerids (Thanasimus spp.) standard attractants such as Pheroprax®, Sexowit®, Cembräwit®, Acuwit®, Tomowit® as well as Chalcoprax® have been tested. Furthermore the aggregate effect of individual semiochemicals, which form part of the above attractants, have been analysed in relation to European red-bellied clerids and bark beetles which appeared in the habitat. The effect of an increase of the emission rate of the attractant onto the target organisms was also part of the analysis. In addition to trials with attractants in THEYSOHN®-slit traps trials with attractants on stems of pine wood and spruce wood have also been conducted and analysed. This was to clarify whether one could aggregate that many antagonists of bark beetles that the stem does not at all or gets less populated with bark beetles. In the course of this analysis it has been attempted to identify further antagonists of bark beetles that could be aggregated with attractants. It was determined that there are important differences in levels of aggregation between the species of Thanasimus formicarius, Thanasimus rufipes and Thanasimus pectoralis with respect to the substances tested. Thanasimus formicarius has been observed in spring and early summer in pine and spruce forests. The concentration of activity of this species was higher in pine forests than in spruce forests. With respect to the tested attractants Thanasimus formicarius showed a stronger preference for Ipsdienol and Ipsenol as for (S)-cis-Verbenol in each case in connection with 2-3-2-Methylbutenol. It is also possible to replace 2-3-2-Methylbutenol with other substances. The substances of Sexowit® and Acuwit® ((+)-Ipsdienol, (-)-Ipsenol, α- and β-Pinen, 2-Phenylethanol or rather Ethanol) also seem to have a strong attraction for the Thanasimus formicarius. Thanasimus rufipes and Thanasimus pectoralis mainly appeared from early summer into the late summer and were respectively recorded in the traps. Both species, in comparison to the Thanasimus formicarius, showed a much stronger preference to (S)-cis- Verbenol, respectively attractant mixtures which contained (S)-cis-Verbenol. Thanasimus rufipes has mainly been detected in pine forests and Thanasimus pectoralis in spruce forests. In pine forests Pheroprax® could be confirmed as an effective allochthonous kairomone. In spruce forests, until the completion of this analysis, no definitive attractant could be identified which aggregats European red-bellied clerids (Thanasimus spp.) on the object to be protected without attracting bark beetles (namely Ips typographus).

Polyphagy is a very common trait among insects. In this study, we focus on a generalist bark-beetle predator, Thanasimus formicarius (L.) (Coleoptera, Cleridae), which feeds on many scolytids in spruce, pine and broad-leaf stands. It is known to respond to the pheromones of many scolytids, among which the most harmful spruce bark beetle in Europe, Ips typographus (L.). The adults attack scolytid adults and oviposit on attacked trees where their larvae feed upon immature stages of the prey. However, a bottom-up process limits Thanasimus formicarius’ impact on spruce bark beetles, because in most cases the bark of spruce is too thin for sheltering pupal niches and mature larvae have to leave the trees. On pine however, pupation is quite successful and reproductive success is high. The present work estimates the advantages (complementary prey during gaps among the phenology of pine bark beetles or due to the population fluctuations of most scolytids) and constraints (landing on unsuitable host trees for the predator’s reproduction) for T. formicarius to have a wide range of prey. Passive barrier-trappings showed that the presence and abundance of scolytid species vary strongly from year to year. So, polyphagy in T. formicarius appears as a response to fluctuating prey supplies. This way of foraging may lead T. formicarius towards stands not always favourable for its development (for example, spruces). At the tree level, funnels and pitfall-traps caught high numbers of third-instar T. formicarius larvae walking on the bark surface of standing spruces infested by Ips typographus (respectively 365 and 70 L3s). After feeding into the whole infested part of the trunk, these larvae are obliged to migrate outside of the galleries to favourable pupation site (e.g. the base of the trees where the bark is thicker), or even to leave the trees and search for an acceptable pupation substrate in the litter. At the landscape level, different trapping experiments showed a correlation between catches of T. formicarius and the proportion of pines around each trap. Consequently, in a metapopulation landscape pattern, pines would act as “sources” of predators, whilst spruces are “sinks”. Indeed, Thanasimus formicarius are trapped in higher numbers in mixed stands comprising pines. This observation is also corroborated in a four-year trapping experiment in the North-East of France, following the storms of December 1999. The predator/prey ratios (T. formicarius/I. typographus) were higher in stands comprising pines than in stands without pines. The first step of a method to estimate Ips typographus infestation trends thanks to the predator/prey ratios was also developed.

Bark beetles are major pests of pine forests in North America that can inflict considerable damage and cause severe economic loss. The checkered beetle Thanasimus dubius Fabricius (Coleoptera: Cleridae), an abundant predator in the Eastern USA and Canada, has been suggested to influence the dynamics of several bark beetles, including the economically important southern pine beetle (SPB), Dendroctonus frontalis Zimmermann (Coleoptera: Curculionidae). Because of the importance of T. dubius in pine forests, I studied several aspects of T. dubius biology including both its chemical and dispersal ecology. I first present an experiment that was conducted to improve the rearing system of T. dubius so that sufficient numbers of predators could be produced more efficiently for both behavioral and ecological studies. Improvements to the rearing method potentially could be achieved by adding a preservative to increase the shelf-life of the diet used to feed larval T. dubius thereby allowing feeding intervals to be extended. To evaluate this, I added sorbic acid, a preservative, to the larval diet at three different concentrations (0, 0.1 and 0.2%) and for two different intervals between feedings (2-3 vs. 5 days). Additionally, I measured potential deleterious effects of this preservative on predator performance (i.e., female fecundity). I then assessed the effect of this predator on SPB survival by releasing newly hatched T. dubius larvae at several densities (0, 50 100, and 200) on pine logs infested by SPB. I also studied the chemotactic response of this predator toward various volatiles such as prey pheromones or tree volatiles in a wind tunnel. I developed a method that associated upwind flight behavior and antennal behavior to quantify the relative attractiveness of each tested source of chemical. I then conducted three experiments to investigate the ability of individual T. dubius to respond to different prey olfactory signals (bark beetle pheromones) and assess their potential for learning. First, I examined individual predator preferences toward three major prey pheromones (ipsenol, ipsdienol, and frontalin) in a study that combined a mark-release-recapture experiment with a field choice test. I also measured the responses of individual wild T. dubius in a wind tunnel, which allowed the testing of a wider range of semiochemicals (frontalin, ipsenol, ipsdienol, sulcatol, and α-pinene). A final wind tunnel experiment tested the ability of naive predators to learn two prey pheromones, frontalin and ipsenol, that were presented alone or associated with a reward. In the last chapter, I quantified the dispersal of this predator and its behavior along an edge separating a pine forest from a non-suitable habitat. I analyzed T. dubius distribution and movement in the field relative to its bark beetle prey Ips grandicollis Eichhoff (Coleoptera: Curculionidae) and to the root feeder Dendroctonus valens LeConte (Coleoptera: Curculionidae). These three insects are associated with the phenomenon of red pine decline in the Great Lakes area. Thus, understanding the relative pattern of movements of these three beetles could provide considerable knowledge on the spatial and temporal progression of red pine decline by, for instance, assessing the connection between existing pockets. I estimated the dispersal quantiles for this predator relative to its bark beetle prey and determined whether dispersal behavior was relatively homogeneous (one kind of disperser) or heterogeneous (two kinds). In a second part, I sampled the abundance of T. dubius, I. grandicollis, and D. valens along transects set between a matrix area constituted by a clearing and a habitat zone composed of red pine forest. I further developed a diffusion model, including a constant k (corresponds to the ratio of densities along the edge), that permits characterization of beetle behavior around the boundary. Studies developed in the present dissertation, therefore, investigated several aspects of T. dubius ecology: predation on SPB, ability to respond to an olfactory signal, and dispersal traits. I first showed that augmentation with larval T. dubius can successfully reduce the SPB ratio of increase in infested pine logs. I also developed a system of rearing T. dubius that was more efficient and could allow larger numbers of predators to be produced. Sorbic acid did not reduce adult lifetime or size but did affect female fecundity (20 - 40% reduction). Increasing feeding time interval to 5 days (instead of 2-3 days) improved the efficiency of the system, even when sorbic acid was not added in the diet. Wind tunnel experiments present a methodology that could enable future quantification of the relative attractiveness of various semiochemical treatments. I identified a particular antennal behavior, which I called "stand up antennal" that was typically produced when the insect was attracted to a semiochemical. The choice tests in the field and the wind tunnel experiment using wild adults both showed that T. dubius individuals are generalists that are flexible in their response to a broad range of semiochemical signals (frontalin, ipsenol, ipsdienol, sulcatol, and α-pinene). I demonstrate that naive predators are more attracted toward ipsenol after having experienced conditioning with this kairomone via a reward. Finally, experiments on dispersal and edge behavior revealed that T. dubius and one of its common prey, the bark beetle I. grandicollis, exhibit a different pattern of movement within red pine stands and surrounding habitats. First, adult T. dubius can disperse substantially further (50% dispersed beyond 1.54 km) than I. grandicollis adults (50% dispersed beyond 0.13 km). Second, T. dubius was highly affected by the presence of an edge, showing a step-like pattern with very predators caught in unsuitable areas. Conversely, the behavior of I. grandicollis was less limited by such a boundary. As with T. dubius, the root colonizer D. valens showed a strong edge behavior that was characterized by avoiding matrix zones.

Arthropod predators are able to influence the population dynamics of forest insects such as bark beetles. Two common predators of bark beetles are Temnochila virescens (F.) (Coleoptera: Trogositidae) and Thanasimus dubius (F.) (Coleoptera: Cleridae). Studies on T. virescens ecology have been few and not quantitative. Also, in recent years there has been increased focus on multiple-predator effects on the population dynamics of a single prey species, which better describes a natural system. Therefore, a series of three studies was conducted to provide a general overview of T. virescens ecology and its potential use for biological control. The first study examined the functional response of T. virescens toward its Ips prey. The second evaluated the impacts of intraguild competition between T. virescens and T. dubius adults on predation of a mutual prey species, I. grandicollis. The third determined if there were differences in pheromone preference among individual T. virescens adults. To evaluate the functional response, T. virescens and Ips grandicollis (Eichhoff) adults were combined in varying densities. Ips grandicollis survival was assessed by examining the number of prey eaten in relation to predator and prey densities. I found that a type II functional response model incorporating interference provided a good fit for the data. The interference was strong enough that a ratio-dependent model fit the data just as well as the full model. The effect of competition between T. dubius and T. virescens adults on I. grandicollis survival was determined by placing varying numbers of each predator with a set prey number. I found a significant interaction between densities of the two predators, which indicates possible emergent predator effects. The combined effect of the predators was risk reducing for prey, likely because of intraguild predation. The predator T. dubius alone was more efficient at reducing the number of prey adults successfully entering the log. This study indicates the importance of low density releases of these predators for augmentative biological control, to reduce the effects of intraspecific competition. To determine if there were differences in pheromone preference among individual T. virescens adults, a mark-release-recapture experiment was combined in the field to provide a choice test between ipsenol and ipsdienol pheromones. Temnochila virescens adults that were initially captured on ipsenol were more frequently recaptured with this pheromone, while those first captured on ipsdienol were recaptured on both pheromones. This suggests populations of T. virescens are composed of specialists attracted only to ipsenol and generalists attracted to both ipsdienol and ipsenol pheromones.

Polyphagy is a very common trait among insects. In this study, we focus on a generalist bark-beetle predator, Thanasimus formicarius (L.) (Coleoptera, Cleridae), which feeds on many scolytids in spruce, pine and broad-leaf stands. It is known to respond to the pheromones of many scolytids, among which the most harmful spruce bark beetle in Europe, Ips typographus (L.). The adults attack scolytid adults and oviposit on attacked trees where their larvae feed upon immature stages of the prey. <p>However, a bottom-up process limits Thanasimus formicarius’ impact on spruce bark beetles, because in most cases the bark of spruce is too thin for sheltering pupal niches and mature larvae have to leave the trees. On pine however, pupation is quite successful and reproductive success is high. <p><p>The present work estimates the advantages (complementary prey during gaps among the phenology of pine bark beetles or due to the population fluctuations of most scolytids) and constraints (landing on unsuitable host trees for the predator’s reproduction) for T. formicarius to have a wide range of prey. <p><p>Passive barrier-trappings showed that the presence and abundance of scolytid species vary strongly from year to year. So, polyphagy in T. formicarius appears as a response to fluctuating prey supplies. <p><p>This way of foraging may lead T. formicarius towards stands not always favourable for its development (for example, spruces). <p>At the tree level, funnels and pitfall-traps caught high numbers of third-instar T. formicarius larvae walking on the bark surface of standing spruces infested by Ips typographus (respectively 365 and 70 L3s). After feeding into the whole infested part of the trunk, these larvae are obliged to migrate outside of the galleries to favourable pupation site (e.g. the base of the trees where the bark is thicker), or even to leave the trees and search for an acceptable pupation substrate in the litter. <p><p>At the landscape level, different trapping experiments showed a correlation between catches of T. formicarius and the proportion of pines around each trap. Consequently, in a metapopulation landscape pattern, pines would act as “sources” of predators, whilst spruces are “sinks”. Indeed, Thanasimus formicarius are trapped in higher numbers in mixed stands comprising pines. This observation is also corroborated in a four-year trapping experiment in the North-East of France, following the storms of December 1999. The predator/prey ratios (T. formicarius/I. typographus) were higher in stands comprising pines than in stands without pines. The first step of a method to estimate Ips typographus infestation trends thanks to the predator/prey ratios was also developed. <p> / Doctorat en sciences, Spécialisation biologie animale / info:eu-repo/semantics/nonPublished

Naturnahe Verfahren im Management bast- und holzbesiedelnder Insekten basieren auf der Ausnutzung olfaktorischer Reaktionen dieser Insekten und teilweise auch derer Antagonisten auf Semiochemikalien käferbürtigen und baumbürtigen Ursprungs. Verfahren, die im Rahmen der Forschungsarbeit verfolgt wurden, waren zum überwiegenden Teil das Wirkungsprinzip Allochthoner Kairomone sowie Abwehrverfahren bei denen Nichts-Wirtsbaum-Volatile zum Einsatz kommen. Als biologischer Detektor von zu identifizierenden Semiochemikalien aus Laubwaldhabitaten wurde der Ameisenbuntkäfer Thanasimus formicarius verwendet. Von T. formicarius ist eine stark generalistische Lebensweise bekannt, die zur Annahme verleitet, dass dieser auch als Prädator an diversen Laubholz besiedelnden Borkenkäferarten auftritt. Entsprechend wurden als Beuteobjekte in Laubwaldhabitaten die Arten Trypodendron domesticum, Trypodendron signatum, Leperisinus varius und Scolytus intricatus vermutet und schwerpunktartig untersucht. Mittels GC-MS/EAD-Analysen konnte nachgewiesen werden, dass T. formicarius Substanzen aus den Habitaten in Wäldern von Rot-Buche, Gemeiner Esche und Eiche wahrnehmen kann. Für einen Teil der von T. formicarius wahrgenommenen Substanzen wurden Dosis-Antwort-Kurven aufgenommen, um Erkenntnisse über die Wahrnehmungsschwelle bei T. formicarius zu erhalten und eine mögliche Bedeutungen der Substanzen in der olfaktorischen Orientierung im Laubwaldhabitat abzuleiten. Die Ergebnisse verdeutlichten, dass T. formicarius neben käferbürtigen Substanzen auch eine Vielzahl von pflanzenbürtigen Volatilen wahrnehmen kann. Dabei wurden für einige dieser Substanzen sehr geringe Wahrnehmungsschwellen festgestellt, was eine besondere Bedeutung der Substanzen in der olfaktorischen Orientierung von T. formicarius vermuten lässt. Substanzen, von welchen eine signifikante Wahrnehmung von T. formicarius erfasst werden konnte, wurden in Olfaktometerexperimenten auf verhaltensmodifizierende Wirkungen beim Ameisenbuntkäfer untersucht. Die in Laborexperimenten auf Wahrnehmung von T. formicarius getesteten Substanzen wurden letztlich in Fallenfangexperimente und Fangholzexperimente eingebunden. Ein Anflug von T. formicarius auf die in den Laborexperimenten erprobten Substanzen, konnte in Fallenfangexperimenten im Freiland, bei der Verwendung der zu erprobenden Substanzen als Einzelsubstanzen, kaum beobachtet werden. Auch die Kombination der Einzelsubstanzen zu Mixturen erzeugte keine nennenswerten Attraktivitäten auf T. formicarius und andere Prädatoren im Freiland. Dennoch schienen die Substanzen aufgrund ihrer teilweise repellenten Wirkung auf bast- und holzbesiedelnde Insekten geeignet, um zumindest in naturnahen Managementverfahren eingesetzt zu werden. Den Ergebnissen der Fallenfang- und Fangholzexperimente entsprechend können die aus dem Nadelwaldhabitat stammenden Pheromondispenser Sexowit® und Chalcogran als Allochthone Kairomone im Laubwaldhabitat empfohlen werden. Darüber hinaus scheint eine Applikation von exo-Brevicomin und endo-Brevicomin als Allochthone Kairomone im Nadelwaldhabitat denkbar, muss jedoch noch am Fangholz geprüft werden. Aus den Fallenfangexperimenten konnten zudem Substanzen abgeleitet werden, welche sich im Monitoring von bast- und holzbesiedelnden Insekten aus Laub- und Nadelwaldhabitaten eignen. / Nature-based methods in the regulation of bark and wood boring insects are based upon the use of olfactory responses of these insects and also partly of their antagonists to semiochemicals that originate from bark and wood boring insects or their host plants. Methods used during this research were the Allochthonous Kairomones principle and defense methods with non-host volatiles. Thanasimus formicarius was used as biological detector for identifying semiochemicals from deciduous forest habitats. T. formicarius is known to be a highly generalist predator, which led to the assumption that T. formicarius may occur as predator of various bark and wood boring insects living on deciduous tree species. Accordingly, Trypodendron domesticum, Trypodendron signatum, Leperisinus varius and Scolytus intricatus were assumed to be prey species in deciduous forest habitats and hence focused on in this study. A GC-MS/EAD analysis demonstrated that T. formicarius is able to perceive substances from the habitats of European beech, common ash and oak. For some of the perceived substances dose-response-curves were recorded to obtain knowledge about the perception threshold of T. formicarius and to derive the potential importance of the substances in the olfactory orientation in deciduous forest habitats. The results show that T. formicarius is able to recognize a variety of plant-derived volatiles as well as substances from bark and wood boring insects. For some of these substances very low perception thresholds were determined, suggesting a particular importance of these substances in the olfactory orientation of T. formicarius. Substances that were found to be significantly perceived by T. formicarius were further examined in olfactometer experiments in order to test for behavior-modifying effects. Substances that were tested for perception by T. formicarius in the laboratory experiments were finally included in trapping experiments and trap log experiments. When used as single compounds, low numbers of T. formicarius were attracted to substances used in trapping experiments. Also the combination of single substances to mixtures produced no significant attractions of T. formicarius and other predators in trapping experiments. However, some of the substances seemed to be appropriate for using in nature-based management methods because of repellent effects to bark and wood boring insects. According to the results of trapping and trap log experiments, pheromone dispensers such as Sexowit® and chalcogran from coniferous forest habitats can be recommended as Allochthonous Kairomones in deciduous forest habitats. In addition, an application of exo- and endo-brevicomin as Allochthonous Kairomones in coniferous forest habitats seems possible, but still has to be tested with trap log experiments. In addition within these experiments substances were detected that can be used in the monitoring of bark and wood boring insects in coniferous and deciduous forest habitats.

Naturnahe Verfahren im Management bast- und holzbesiedelnder Insekten basieren auf der Ausnutzung olfaktorischer Reaktionen dieser Insekten und teilweise auch derer Antagonisten auf Semiochemikalien käferbürtigen und baumbürtigen Ursprungs. Verfahren, die im Rahmen der Forschungsarbeit verfolgt wurden, waren zum überwiegenden Teil das Wirkungsprinzip Allochthoner Kairomone sowie Abwehrverfahren bei denen Nichts-Wirtsbaum-Volatile zum Einsatz kommen. Als biologischer Detektor von zu identifizierenden Semiochemikalien aus Laubwaldhabitaten wurde der Ameisenbuntkäfer Thanasimus formicarius verwendet. Von T. formicarius ist eine stark generalistische Lebensweise bekannt, die zur Annahme verleitet, dass dieser auch als Prädator an diversen Laubholz besiedelnden Borkenkäferarten auftritt. Entsprechend wurden als Beuteobjekte in Laubwaldhabitaten die Arten Trypodendron domesticum, Trypodendron signatum, Leperisinus varius und Scolytus intricatus vermutet und schwerpunktartig untersucht. Mittels GC-MS/EAD-Analysen konnte nachgewiesen werden, dass T. formicarius Substanzen aus den Habitaten in Wäldern von Rot-Buche, Gemeiner Esche und Eiche wahrnehmen kann. Für einen Teil der von T. formicarius wahrgenommenen Substanzen wurden Dosis-Antwort-Kurven aufgenommen, um Erkenntnisse über die Wahrnehmungsschwelle bei T. formicarius zu erhalten und eine mögliche Bedeutungen der Substanzen in der olfaktorischen Orientierung im Laubwaldhabitat abzuleiten. Die Ergebnisse verdeutlichten, dass T. formicarius neben käferbürtigen Substanzen auch eine Vielzahl von pflanzenbürtigen Volatilen wahrnehmen kann. Dabei wurden für einige dieser Substanzen sehr geringe Wahrnehmungsschwellen festgestellt, was eine besondere Bedeutung der Substanzen in der olfaktorischen Orientierung von T. formicarius vermuten lässt. Substanzen, von welchen eine signifikante Wahrnehmung von T. formicarius erfasst werden konnte, wurden in Olfaktometerexperimenten auf verhaltensmodifizierende Wirkungen beim Ameisenbuntkäfer untersucht. Die in Laborexperimenten auf Wahrnehmung von T. formicarius getesteten Substanzen wurden letztlich in Fallenfangexperimente und Fangholzexperimente eingebunden. Ein Anflug von T. formicarius auf die in den Laborexperimenten erprobten Substanzen, konnte in Fallenfangexperimenten im Freiland, bei der Verwendung der zu erprobenden Substanzen als Einzelsubstanzen, kaum beobachtet werden. Auch die Kombination der Einzelsubstanzen zu Mixturen erzeugte keine nennenswerten Attraktivitäten auf T. formicarius und andere Prädatoren im Freiland. Dennoch schienen die Substanzen aufgrund ihrer teilweise repellenten Wirkung auf bast- und holzbesiedelnde Insekten geeignet, um zumindest in naturnahen Managementverfahren eingesetzt zu werden. Den Ergebnissen der Fallenfang- und Fangholzexperimente entsprechend können die aus dem Nadelwaldhabitat stammenden Pheromondispenser Sexowit® und Chalcogran als Allochthone Kairomone im Laubwaldhabitat empfohlen werden. Darüber hinaus scheint eine Applikation von exo-Brevicomin und endo-Brevicomin als Allochthone Kairomone im Nadelwaldhabitat denkbar, muss jedoch noch am Fangholz geprüft werden. Aus den Fallenfangexperimenten konnten zudem Substanzen abgeleitet werden, welche sich im Monitoring von bast- und holzbesiedelnden Insekten aus Laub- und Nadelwaldhabitaten eignen. / Nature-based methods in the regulation of bark and wood boring insects are based upon the use of olfactory responses of these insects and also partly of their antagonists to semiochemicals that originate from bark and wood boring insects or their host plants. Methods used during this research were the Allochthonous Kairomones principle and defense methods with non-host volatiles. Thanasimus formicarius was used as biological detector for identifying semiochemicals from deciduous forest habitats. T. formicarius is known to be a highly generalist predator, which led to the assumption that T. formicarius may occur as predator of various bark and wood boring insects living on deciduous tree species. Accordingly, Trypodendron domesticum, Trypodendron signatum, Leperisinus varius and Scolytus intricatus were assumed to be prey species in deciduous forest habitats and hence focused on in this study. A GC-MS/EAD analysis demonstrated that T. formicarius is able to perceive substances from the habitats of European beech, common ash and oak. For some of the perceived substances dose-response-curves were recorded to obtain knowledge about the perception threshold of T. formicarius and to derive the potential importance of the substances in the olfactory orientation in deciduous forest habitats. The results show that T. formicarius is able to recognize a variety of plant-derived volatiles as well as substances from bark and wood boring insects. For some of these substances very low perception thresholds were determined, suggesting a particular importance of these substances in the olfactory orientation of T. formicarius. Substances that were found to be significantly perceived by T. formicarius were further examined in olfactometer experiments in order to test for behavior-modifying effects. Substances that were tested for perception by T. formicarius in the laboratory experiments were finally included in trapping experiments and trap log experiments. When used as single compounds, low numbers of T. formicarius were attracted to substances used in trapping experiments. Also the combination of single substances to mixtures produced no significant attractions of T. formicarius and other predators in trapping experiments. However, some of the substances seemed to be appropriate for using in nature-based management methods because of repellent effects to bark and wood boring insects. According to the results of trapping and trap log experiments, pheromone dispensers such as Sexowit® and chalcogran from coniferous forest habitats can be recommended as Allochthonous Kairomones in deciduous forest habitats. In addition, an application of exo- and endo-brevicomin as Allochthonous Kairomones in coniferous forest habitats seems possible, but still has to be tested with trap log experiments. In addition within these experiments substances were detected that can be used in the monitoring of bark and wood boring insects in coniferous and deciduous forest habitats.