Peter H W Biedermann

University of Freiburg | Albert-Ludwigs-Universität Freiburg · Forest Entomology and Protection

Fitness-determining interactions with microbes — in particular fungi — have often been considered a by-product of social evolution in insects. Here, we take the view that both beneficial and harmful microbial consortia are major drivers of social behaviours in many insect systems — ranging from aggregation to eusociality. We propose evolutionary fe...

Tree-killing bark beetles are the most economically important insects in conifer forests worldwide. However, despite >200 years of research, the drivers of population eruptions and crashes are still not fully understood and the existing knowledge is thus insufficient to face the challenges posed by the Anthropocene. We critically analyze potential...

The evolution of a mutualism requires reciprocal interactions whereby one species provides a service that the other species cannot perform or performs less efficiently. Services exchanged in insect–fungus mutualisms include nutrition, protection, and dispersal. In ectosymbioses, which are the focus of this review, fungi can be consumed by insects o...

Contributors explore common elements in the evolutionary histories of both human and insect agriculture resulting from convergent evolution. During the past 12,000 years, agriculture originated in humans as many as twenty-three times, and during the past 65 million years, agriculture also originated in nonhuman animals at least twenty times and in...

Fungal cultivation is a defining feature for advanced agriculture in fungus-farming ants and termites. In a third supposedly fungus-farming group, wood-colonizing ambrosia beetles, an experimental proof for the effectiveness of beetle activity for selective promotion of their food fungi over others is lacking and farming has only been assumed based...

Animal societies have nestmate-recognition to protect against social cheaters and parasites. In most social insect societies individuals recognize and exclude any non-nestmate. There, the roles of cuticular hydrocarbons as recognition cues are well documented. Some ambrosia beetles live in cooperatively breeding societies, within nests that are alm...

By-product mutualisms are ubiquitous yet seldom considered in models of mutualism. Most models represent conditional mutualisms that shift between mutualism and antagonism in response to shifts in costs and benefits resulting from changes in environmental quality. However, in by-product mutualisms, benefits arise as a part of normal life processes...

Bark beetles (Curculionidae: Scolytinae) spend most of their life in tissues of host plants, with several species representing economically relevant pests. Their behaviour is largely guided by complex olfactory cues. The compound verbenone was discovered early in the history of bark beetle pheromone research and is now sometimes referred to as a ‘u...

Some fungus-farming ambrosia beetles rely on multiple nutritional cultivars (Ascomycota: Ophiostomatales and/or yeasts) that seem to change in relative abundance over time. The succession of these fungi could benefit beetle hosts by optimal consumption of the substrate and extended longevity of the nest. However, abundances of fungal cultivars and...

Many wood-boring insects use aggregation pheromones during mass colonization of host trees. Bark beetles (Curculionidae: Scolytinae) are a model system, but much less is known about the role of semiochemicals during host selection by ambrosia beetles. As an ecological clade within the bark beetles, ambrosia beetles are obligately dependent on funga...

By-product mutualisms are ubiquitous yet seldom considered in models of mutualism. Most models represent conditional mutualisms that shift between mutualism and antagonism in response to shifts in costs and benefits resulting from changes in environmental quality. However, in by-product mutualisms, benefits arise as a part of normal life processes...

In 2022, two independent insect surveys in canton Ticino (southern Switzerland) revealed the widespread occurrence of the invasive ambrosia beetle Anisandrus maiche from southern to central-upper Ticino. This species is native to east Asia and has previously been found as a non-native invasive species in the United States, Canada, western Russia, U...

Fungus farming insects encounter multiple microbial threats in their cultivar gardens. They can affect both the nutritional cultivar and the insect’s health. In this study, we explored the potential of ambrosia beetles and their larvae to detect the presence of antagonistic or entomopathogenic fungi. The ability to recognize a threat offers individ...

Animal societies have nestmate-recognition to protect against social cheaters and parasites. In most social insect societies individuals recognize and exclude any non-nestmate. There, the roles of cuticular hydrocarbons as recognition cues are well documented. Some ambrosia beetles live in cooperatively breeding societies, within nests that are alm...

Intensification of land use by humans has led to a homogenization of landscapes and decreasing resilience of ecosystems globally due to a loss of biodiversity, including the majority of forests. Biodiversity-ecosystem functioning (BEF) research has provided compelling evidence for a positive effect of biodiversity on ecosystem functions and service...

Fungus farming insects encounter multiple microbial threats in their cultivar gardens. They can affect both the nutritional cultivar and the insect`s health. In this study, we explored the potential of ambrosia beetles and their larvae to detect the presence of ubiquitous weed or entomopathogenic fungi. The ability to recognize a threat offers indi...

Ips typographus (L.) and Pityogenes chalcographus (L.) (Coleoptera: Curculionidae) are two common bark beetle species on Norway spruce in Eurasia. Multiple biotic and abiotic factors affect the life cycles of these two beetles, shaping their ecology and evolution. In this article, we provide a comprehensive and comparative summary of selected life-...

Fungal cultivation is a defining feature for advanced agriculture in attine ants and fungus-farming termites. In a third supposedly fungus-farming group, wood-colonizing ambrosia beetles (Curculionidae: Scolytinae and Platypodinae), an experimental proof for the effectiveness of beetle activity for selective promotion of their food fungi over other...

The invention of agriculture is a revolutionary moment in the history of humankind that allowed a transition to sedentarism, the creation of urban settlements, and a titanic population explosion. We owe to such technology the complexity of our society, but humans are not the only farmers. Groups of highly social insects were growing fungal crops te...

The fungus-farming ambrosia beetle Xylosandrus germanus (Blandford) uses a pouch-like structure (i.e., mycangium) to transport spores of its nutritional fungal mutualist. Our current study sought to identify reference genes necessary for future transcriptome analyses aimed at characterizing gene expression within the mycangium. Complementary DNA wa...

Plant volatiles play a major role in plant-insect interactions as defense compounds or attractants for insect herbivores. Recent studies have shown that endophytic fungi are also able to produce volatiles and this raises the question of whether these fungal vol-atiles influence plant-insect interactions. Here, we qualitatively investigated the vola...

We provide an overview of both traditional and innovative control tools for management of three Xylosandrus ambrosia beetles (Coleoptera: Curculionidae: Scolytinae), invasive species with a history of damage in forests, nurseries, orchards and urban areas. Xylosandrus compactus , X. crassiusculus and X. germanus are native to Asia, and currently es...

Fungus-farming within galleries in the xylem of trees has evolved independently in at least twelve lineages of weevils (Curculionidae: Scolytinae, Platypodinae) and one lineage of ship-timber beetles (Lymexylidae). Jointly these are termed ambrosia beetles because they actively cultivate nutritional "ambrosia fungi" as their main source of food. Th...

Bark beetles (sensu lato) colonize woody tissues like phloem or xylem and are associated with a broad range of microorganisms. Specific fungi in the ascomycete orders Hypocreales, Microascales and Ophistomatales as well as the basidiomycete Russulales have been found to be of high importance for successful tree colonization and reproduction in many...

Fungus-farming is known from attine ants, macrotermites, and ambrosia beetles (Scolytinae, Platypodinae). Farming ant and termite societies are superorganismal and grow fungal cultivars in monocultures. Social organization of ambrosia beetle groups and their farming systems are poorly studied, because of their enigmatic life within tunnel systems i...

Symbiotic microbes help a myriad of insects acquire nutrients. Recent work suggests that insects also frequently associate with actinobacterial symbionts that produce molecules to help defend against parasites and predators. Here we explore a potential association between Actinobacteria and two species of fungus-farming ambrosia beetles, Xyleborinu...

Ambrosia beetles farm their own food fungi within tunnel systems in wood and are among the three insect lineages performing agriculture (the others are fungus-farming ants and termites). In ambrosia beetles, primary ambrosia fungus cultivars have been regarded essential, whereas other microbes have been more or less ignored. Our KEGG analyses sugge...

Ambrosia beetles farm fungal cultivars (ambrosia fungi) and carry propagules of the fungal mutualists in storage organs called mycangia, which occur in various body parts and vary greatly in size and complexity. The evolution of ambrosia fungi is closely tied to the evolution and development of the mycangia that carry them. The understudied ambrosi...

With about 400,000 species, beetles (Coleoptera) are the largest order of animals, making up almost 40% of described insect species and 25% of all known animal species. Beetles are present in virtually all habitable terrestrial environments. They can live well both on land and in fresh water and use a great variety of food sources from detritus to...

There is some confusion in the scientific literature concerning terms involving insect-fungus symbioses, including associations vs. interactions, mycetangia vs. mycangia, symbiote vs. symbiont, and symbiosis vs. mutualism. We present a rationale that demonstrates the difference between an association and an interaction, and why the correct term for...

Social immunity—the collective behavioural defences against pathogens—is considered a crucial evolutionary force for the maintenance of insect societies. It has been described and investigated primarily in eusocial insects, but its role in the evolutionary trajectory from parental care to eusociality is little understood. Here, we report on the exi...

Pilz-züchtende Ambrosia-Käfer (Coleoptera: Scolytinae) sind durch ihre Symbiose mit mutualistischen Pilzen gekennzeichnet, welche ihnen als essentielle Nahrungsquelle dienen. Die Käfer kultivieren aktiv einen oder mehrere ihrer Nahrungspilze (Ambrosia-Pilze) in ihren Tunnelsystemen, die sie im Xylem toter oder stark geschwächter Bäume anlegen. Die...

Spore characteristics of wood-inhabiting fungi suggest that wind is their predominant dispersal vector. However, since they are restricted to ephemeral habitats, colonizing new patches should benefit from dispersal by animals with similar habitat preferences because the directed, resource-searching movement of animals increases the likelihood of re...

Symbiotic microbes help a myriad of insects acquire nutrients. Recent work suggests that insects also frequently associate with actinobacterial symbionts that produce molecules to help defend against parasites and predators. Here we explore a potential association between Actinobacteria and two species of fungus-farming ambrosia beetles, Xyleborinu...

Bark beetles are ubiquitously associated with fungi and together have the potential to substantially affect forest ecosystems. Beetle-fungus interactions are poorly understood for most species, which is of paramount importance to better understand the ecology of bark beetles. The ambrosia beetle genus Trypodendron is characterized by boring tunnels...

Ambrosia fungi are a polyphyletic group from currently seven ascomycete and basidiomycete lineages that independently evolved an obligate farming mutualism with wood-boring weevils. One long known, but understudied association is the mutualism between the scolytine beetle genus Trypodendron (Curculionidae: Xyloterini) and the Microascales fungal ge...

Fungi can provide insects with nutrients and essential elements, detoxify plant defenses in recently dead wood, and protect or, in contrast, attack and digest insects. Insects can affect fungi through feeding or propagule dispersal. Fungal grazing may induce changes in fungal chemistry, morphology, and growth. Insect-fungus interactions in dead woo...

Significance Ambrosia beetles are among the true fungus-farming insects and cultivate fungal gardens on which the larvae and adults feed. After invading new habitats, some species destructively attack living or weakened trees growing in managed and unmanaged settings. Ambrosia beetles adapted to weakened trees tunnel into stem tissues containing et...

Ambrosia beetles farm ascomycetous fungi in tunnels within wood. These ambrosia fungi are regarded asexual, although population genetic proof is missing. Here we explored the intraspecific genetic diversity of Ambrosiella grosmanniae and Ambrosiella hartigii (Ascomycota: Microascales), the mutualists of the beetles Xylosandrus germanus and Anisandr...

Bark beetles (Curculionidae: Scolytinae) are one of the most species-rich herbivorous insect groups with many shifts in ecology and host-plant use, which may be mediated by their bacterial and fungal symbionts. While symbionts are well studied in economically important, tree-killing species, little is known about parasitic species whose broods deve...

The genus Ambrosiella accommodates species of Ceratocystidaceae (Microascales) that are obligate, mutualistic symbionts of ambrosia beetles, but the genus appears to be polyphyletic and more diverse than previously recognized. In addition to Ambrosiella xylebori, Ambrosiella hartigii, Ambrosiella beaveri, and Ambrosiella roeperi, three new species...

We review the morphology, larval feeding habits, reproductive behavior, and social behavior of Scolytinae and Platypodinae. Their morphology and behavior are adaptations to a lifestyle centered on tunneling in wood. Tunnels are easily defended, and dead wood is a relatively long-lasting resource that can support large populations but that is unpred...

Covering: through 2014Many organisms team up with microbes for defense against predators, parasites, parasitoids, or pathogens. Here we review the described protective symbioses between animals (including marine invertebrates, nematodes, insects, and vertebrates) and bacteria, fungi, and dinoflagellates. We focus on associations where the microbial...

Unlabelled: The ability to cultivate food is an innovation that has produced some of the most successful ecological strategies on the planet. Although most well recognized in humans, where agriculture represents a defining feature of civilization, species of ants, beetles, and termites have also independently evolved symbioses with fungi that they...

Most insects are associated with mutualistic microorganisms that can confer novel traits and thereby play important roles for the ecology and evolution of host organisms. Although many insects ensure that their offspring are endowed with the beneficial symbionts by transmitting them vertically from parent to offspring, others rely on environmental...

Zusammenfassung: Die Bedeutung der Blockierung des Eingangstunnels beim Kleinen Holzbohrer Xyleborinus saxesenii Ratzeburg (Coleoptera; Scolytinae) Die Evolution von Kooperation und Altruismus im Tierreich lässt sich in vielen Systemen durch Hamiltons Theorie der Verwandtenselektion (1964) erklären. Sie besagt, dass Helfer indirekt die eigene Fitne...

Insect fungus gardens consist of a community of interacting microbes that can have either beneficial or detrimental effects to the farmers. In contrast to fungus-farming ants and termites, the fungal communities of ambrosia beetles and the effects of particular fungal species on the farmers are largely unknown. Here we used a laboratory rearing tec...

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