Andreas Müller

ETH Zurich | ETH Zürich · Institute of Agricultural Sciences

Chlidoplitis and Megahoplitis are closely related Palaearctic subgenera of the osmiine bee genus Hoplitis (Megachilidae) containing nine and two species, respectively. Analysis of female pollen loads and field observations suggest that all spe- cies are pollen specialists. Whereas the H. (Chlidoplitis) species are probably all narrowly oligolectic...

Within the genus Osmia, the three subgenera Osmia, Monosmia, and Orientosmia form a closely-related group of predominantly pollen generalist (‘polylectic’) mason bees. Despite the great scientific and economic interest in several species of this clade, which are promoted commercially for orchard pollination, their phylogenetic relationships remain...

Bees are extraordinarily diverse with respect to host plant choice and adaptation. Recent findings suggest that bee host range might be largely governed by evolutionary constraints related to pollen digestion or flower recognition and handling. In the present study, we applied phylogenetic inference to investigate whether such constraints underlie...

1.Generalist herbivorous insects, which feed on plant tissue that is nutritionally heterogeneous or varies in its content of secondary metabolites, often benefit from dietary mixing through more balanced nutrient intake or reduced exposure to harmful secondary metabolites. Pollen is similarly heterogeneous as other plant tissue in its content of pr...

Knowledge about the quantitative pollen requirements of solitary bees is crucial for the preservation of endangered bee species and the understanding of the evolution of bee–flower relationships. We estimate the number of flowers required to rear a single larva for 41 European bee species (i) by comparing the pollen content of brood cells with the...

The European mining bee species Andrena lathyri (Andrenidae) is a narrow specialist of flowers of Lathyrus and Vicia (Fabaceae), from which both females and males gain nectar by primary nectar robbing. Both sexes are equipped with a unique proboscis, which is much longer and more strongly angled than in most other Andrena bees including the most cl...

Two nests of Celonites jousseaumei are described in detail from the Antiatlas in Morocco. The nests consisted of two or three linearly arranged earthen brood cells that were attached to the almost vertical surface of medium sized stones. The brood cell provisions consisted exclusively of Heliotropium pollen (Boraginaceae). Species affiliation of de...

Osmia (Allosmia) and O. (Neosmia) are two closely related Palaearctic osmiine bee subgenera (Megachilidae, Megachilinae, Osmiini) comprising eleven and ten species, respectively. Analysis of female pollen loads revealed that the representatives of O. (Allosmia) and O. (Neosmia) are pollen generalists collecting pollen on up to 13 and 17 plant famil...

The examination of undetermined material of Moroccan bees of the tribe Osmiini (Megachilidae) and several excursions to Morocco in the past fifteen years revealed the existence of numerous undescribed osmiine bee species, indicating that the Moroccan osmiine bee diversity is distinctly higher than the 148 species listed in a recent compilation. In...

Maintaining the diversity of wild bees is a priority for preserving ecosystem function and promoting stability and productivity of agroecosystems. However, wild bee communities face many threats and beekeeping could be one of them, because honey bees may have a strong potential to outcompete wild pollinators when placed at high densities. Yet, we s...

The study of wild bees has markedly increased in recent years due to their importance as pollinators of crops and wild plants, and this interest has been accentuated by increasing evidence of global declines in their abundance and species richness. Though best studied in Europe and North America, knowledge on the current state of wild bees is scarc...

Disturbance sounds to deter antagonists are widespread among insects but have never been recorded for the larvae of bees. Here, we report on the production of disturbance sounds by the postdefecating larva ("prepupa") of the Palaearctic osmiine bee Hoplitis (Alcidamea) tridentata, which constructs linear series of brood cells in excavated burrows i...

One of the most important non-Apis groups of bees for agriculture is the mason bee subgenus Osmia Panzer (Osmia), or Osmia s.s. (Hymenoptera: Megachili-dae). Out of the 29 known species, four have been developed as managed pollinators of orchards. In addition, the group is important as a source of non-native pollinators, given that several species...

Morocco is a well known hot-spot of biodiversity in the Mediterranean basin. While some taxa like vascular plants are relatively well recorded, important groups of pollinators like bees are still understudied. This article presents an updated checklist of the bee species of Morocco and includes a summary of global and regional distribution of each...

Osmia (Melanosmia) uncinata Gerstäcker is a Palaearctic megachilid bee distributed from temperate and northern Europe eastwards to the Russian Far East. The discovery of over 80 nests in Switzerland, southern Germany and Scotland enabled for the first time a closer investigation of its nesting biology and prompted the assessment of the species' phe...

Osmia (Hemiosmia), O. (Tergosmia) and O. (Erythrosmia) are three related Palaearctic osmiine bee subgenera (Megachilidae, Megachilinae, Osmiini) comprising eight, seven and four species, respectively. Analysis of female pollen loads and field observations revealed that the species of both O. (Hemiosmia) and O. (Tergosmia) have a distinct or even ex...

Most temperate wild bees overwinter in the larval or imaginal stage inside their nests after the entire larval food provisions have been consumed. Here, we report on the finding that Colletes hederae (Colletidae), a late-flying European bee species active in September and October, passes the winter as half-grown larva inside the brood cell that sti...

Osmia andrenoides Spinola, 1808 is a rare bee that nests in empty snail shells. To clarify aspects of its breeding biology, a dry rocky slope in the Domleschg (Grisons, Switzerland) was searched for nests of O. andrenoides in the fall of 2018. All 19 nests discovered were invariably hidden in (semi-)shady places under rock outcroppings or under lar...

Osmia (Melanosmia) nigriventris (Zetterstedt) is a predominantly boreoalpine megachilid bee species, whose biology is poorly known due to its pronounced rarity all over Central Europe. The discovery of 19 nests in the Grisons and Valais (Switzerland) allowed for the investigation of its nesting biology and prompted the assessment of the species' ho...

In addition to a previously published study about Siberian osmiine bees, we here further report records of 19 rarely collected and little known species. Twenty-seven species of osmiine bees are currently known from Siberia. Hoplitis beijin-gensis Wu, 1987, H. kaszabi Tkalců, 2000, and H. inconspicua Tkalců, 1995 are recorded for the first time for...

We revise the Alpine bee taxa related to Andrenabicolor (Fabricius, 1775), including A.montana Warncke, 1973 and A.allosa Warncke, 1975, the status of which has remained contentious. Phylogenetic analyses of one mitochondrial gene and one nuclear gene, as well as morphological examination reveal the presence of four Alpine species in this complex,...

Hoplitis robusta (Nylander) is a rare and poorly known osmiine bee species occurring in the subalpine zone of the Alps. The discovery of two nests of H. robusta in a thin branch of a dead fallen spruce on a sunny clearing of a subalpine spruce forest allowed the investigation of the nest architecture, the analysis of the larval diet and the assessm...

The pollen host selection by 19 bee species, which have their main Central European distribution in the Alps, was assessed by microscopical analysis of the scopal contents of about 900 females from museum and private collections. The results of the pollen analyses were complemented by a literature survey as well as by field observations. The examin...

Wainia , a species-poor genus of osmiine bees, contains two Palaearctic species, whose biologies are unknown. In the present publication, we describe the nesting site and nest architecture of W.sexsignata and analyse the pollen host spectra of W.sexsignata and W.eremoplana by microscopical analysis of larval faeces and female scopal contents. W.sex...

Agricultural intensification leads to large-scale loss of habitats offering food and nesting sites for bees. This has resulted in a severe decline of wild bee diversity and abundance during the past decades. There is an urgent need for cost-effective conservation measures to mitigate this decline. We analysed the impact of five different high-quali...

Hoplosmia, a subgenus of the osmiine bee genus Osmia (Megachilidae), comprises 21 species restricted to the Palaearctic region. Analysis of female pollen loads and field observations indicate that probably all O. (Hoplosmia) species are specialized on Asteraceae except for one pollen generalist species, which exhibits a preference for the pollen of...

Females of Quartinia major Kohl were observed to visit flowers of Pulicaria mauritanica Batt., Cladanthus arabicus (L.) Cass. and Asteriscus graveolens (Forssk.) Less., (all Asteroideae Asteraceae) at two localities in southern Morocco. Pollen in the provisions of two brood cells was more than 99% Aster-type (Asteroideae), indicating broad oligolec...

This volume of Fauna Helvetica provides identification keys and distribution maps of the Swiss bee species of the genera Apis and Bombus.

Haetosmia is a species-poor genus of osmiine bees (Megachilidae) containing six species, which inhabit deserts and semideserts from the Canary Islands to Central Asia. Formerly considered to be restricted to the southern Palaearctic region, the genus is shown here to occur also in the northern Afrotropical region. The females of all six Haetosmia s...

The osmiine bee species Hoplitis mucida is considered to consist of two subspecies with H. mucida mucida (Dours, 1873) ranging from northwestern Africa to Israel and Jordan and H. mucida stecki (Frey-Gessner, 1908) occurring in southwestern Europe and Sicily. The discovery of nests of H. mucida in Morocco and Tunisia revealed striking differences i...

Chelostomopsis represents a subgenus of the osmiine bee genus Protosmia (Megachilidae) containing three Palaearctic and one Nearctic species. Analysis of female pollen loads and literature data indicate that all Chelostomopsis species are broad pollen generalists exploiting the flowers of numerous plant families, such as Fabaceae, Asteraceae, Lamia...

Osmia pilicornis is distributed from western temperate Europe to western Siberia, where it exclusively occurs in open-structured, mesophilous and mainly deciduous woodland below 1000 m a.s.l. In Central Europe, its peak activity ranges from the last third of March to the first third of June. Due to its rarity and its low population densities over m...

Quartinia canariensis was recorded from three semidesertic sand habitats in Fuerteventura. All localities were sparsely covered by halophytic vegetation and characterized by large patches of flowering plants of Frankenia laevis (Frankeniaceae). Males and females were exclusively observed to visit flowers of Frankenia laevis. During flower visits th...

Formicapis and Tkalcua are related subgenera of the osmiine bee genus Hoplitis (Megachilidae) containing four and three species, respectively. H. (Formicapis) species inhabit open forests and windfalls mainly in the boreal zone with one spe- cies distributed across the Holarctic and three species occurring in eastern Asia. H. (Tkalcua) species live...

Hoplitis (Hoplitis) galichicae spec. nov., a new European osmiine bee species belonging to the Hoplitis adunca species group (Osmiini) is described and diagnosed. It is currently known only from the Galichica mountain range in southwestern Macedonia. Analysis of pollen contained in the metasomal scopae revealed that all females of the type series c...

Although Hoplitis tuberculata is a rather common bee species in the upper montane and subalpine zone of the Alps, its biology is only fragmentarily known. In the present publication, both nest architecture and pollen host spectrum are described. H. tuberculata nests in insect borings in dead wood, where one to several brood cells are built in a lin...

Gyrodromella represents a subgenus of the osmiine bee genus Chelostoma (Megachilidae) containing eight species, which are confined to the Palaearctic region. Analysis of female pollen loads, field observations and literature data suggest that all C. (Gyrodromella) species are oligolectic harvesting pollen exclusively on flowers of Campanula and pos...

Platosmia, a subgenus of the osmiine bee genus Hoplitis (Megachilidae), contains ten species, which are confined to de- sertic and semidesertic areas of the Palaearctic region. Analysis of female pollen loads and field observations indicate that several H. (Platosmia) species are strictly oligolectic on Reseda (Resedaceae) and possibly Hedysareae (...

Celonites fischeri was recorded from ten localities in various open, disturbed habitats in North-West Cy- prus. The species is probably narrowly oligolectic exploiting exclusively flowers of Echium (Boraginaceae) as the sole pollen and nectar source. Females perform a pollen collecting strategy hitherto unknown in pollen wasps; they ingest pollen f...

Herein we describe the nests (including structure, closure, orientation, and depth of cells) of the bee Haetosmia vechti Peters found nesting in Rehovot, Israel. The nesting biology of H. vechti mirrors the ancestral nesting biology within the Osmia group of the Osmiini. Nests in sandy soil consist of an excavated burrow, ending below in a small cl...

Empirical evidence suggests that pollen chemistry plays an important role in shaping the pollen host spectra of many bee species. Although the underlying mechanisms are poorly understood, pollen diets of several plant taxa have experimentally been found to impede larval development of unspecialized bees. The pollen of all plant taxa, for which such...

Hoplitis bees of the Palaearctic subgenus Stenosmia (Megachilidae) inhabit deserts and semideserts between southern Spain and eastern Asia. They nest in excavated burrows in the soil and collect pollen from plant taxa that typically grow in desert areas, such as Frankenia (Frankeniaceae), Peganum (Nitrariaceae), Tamarix (Tamaricaceae) or Zygophyllu...

Hofferia and Stenoheriades are closely related, species-poor genera of the osmiine bees (Megachilidae). Analysis of fe- male pollen loads and field observations indicate that species of both genera have a strong affinity to Asteraceae as pollen hosts. Both genera use insect burrows in dead wood as nesting site, and Hofferia schmiedeknechti was foun...

This volume of Fauna Helvetica provides identification keys and distribution maps of the Swiss bee species of the genera Colletes, Dufourea, Hylaeus, Nomia, Nomioides, Rhophitoides, Rophites, Sphecodes and Systropha.

1. Pollen host choice in bees is in many cases highly conserved, which might partly be due to physiological limitations of bee larvae to digest non-host pollen. These limitations need to be overcome in order to incorporate new pollen hosts; however, the mechanisms underlying such host expansion are poorly understood. 2. In this study, we examined i...

The construction of nests to rear offspring is restricted to vertebrates and few insect taxa, such as termites, wasps, and bees. Among bees, species of the family Megachilidae are characterized by a particularly high diversity in nest construction behaviour. Many megachilid bees nest in excavated burrows in the ground, others place their brood cell...

The genus Hoplitis (Megachilidae: Osmiini) comprises about 360 described species and occurs on all continents except Australia, South America, and Antarctica. Using five genes, we inferred the phylogeny of Hoplitis including 23 out of the 27 currently recognized subgenera, applying both Bayesian and maximum likelihood methods. Compared to the curre...

The genus Fragaria (Rosaceae) contains 24 plant species, including hybrid species such as the octoploid garden strawberry (F. × ananassa). Natural hybridization between Fragaria species has repeatedly been reported, and the potential future cultivation of genetically modified strawberries has made the study of hybridization potential between F. × a...

Bees of the tribe Osmiini (Megachilidae) are represented by about 230 described species in Europe. In this publication, 15 new European osmiine bee species are described and diagnosed: Hoplitis (Alcidamea) occidentalis spec. nov., Hoplitis (Anthocopa) peniculifera spec. nov., Hoplitis (Hoplitis) hilbera spec. nov., Hoplitis (Hoplitis) lithodorae sp...

Growing evidence suggests that the freely accessible pollen of some plants is chemically protected against pollen-feeding flower visitors. For example, a diet of pollen from buttercup plants (Ranunculus) recently was shown to have a deleterious effect on developing larvae of several bee species not specialized on Ranunculus. Numerous Ranunculus spe...

In the present publication, a new bee species of the genus Osmia is described: Osmia (Orientosmia) maxschwarzi sp. n. The new species occurs from western Turkey to central Iran, possesses very long mouthparts, which are as long as the whole body, and has a strong or even exclusive preference for Fabaceae as pollen hosts. The reexamination of the th...

Conservation of wild bees: translating research into practice.The present study intends to translate the results of the extensive scientific literature on bee conservation into a catalogue of practical measures to enhance a diverse and individual rich bee fauna and to conserve endangered species.

1. Given the enormous quantitative pollen requirements of bees and their high efficiency in pollen removal, flowers should balance the need to attract bees for pollination on the one hand and to restrict pollen loss to bees on the other hand. Although various morphological flower traits have been identified that reduce excessive pollen losses to be...

To investigate whether landscape structures act as insurmountable barriers for foraging bees, we conducted mark-recapture studies with two pollen-specialist solitary species. Foraging options of the bees were confined to host plant stands across different landscape structures. Differences in altitude of more than 130 m were overcome and forests cov...

Data about the bionomics of the pollen wasp Ceramius palaestinensis (Giordani Soika, 1957) are presented for the first time. Ceramius palaestinensis is characterized by the following ethological elements: (i) the nest is excavated in non-friable soil; (ii) the burrow is surmounted by a turret from earth extracted from within the burrow; (iii) the n...

Herein we describe the nests (including construction, closure, orientation, and depth of cells) of the bee Osmia (Ozbekosmia) avosetta Warncke found nesting near Antalya, Turkey, and Sepidan, Iran. Cells are unusual in that they are lined by two layers of colorful flower petals that sandwich a thin middle layer of mud. Analyses of pollen taken from...

To preserve populations of endangered bee species, sound knowledge of their maximum foraging distance between nest and host plants is crucial. Previous investigations predicted maximum foraging distances of 100–200m for small bee species and up to 1100m for very large species based on mainly indirect methods. The present study applied a new and dir...

1. Solitary bees are central place foragers returning to their nests several times a day with pollen and nectar to provision their brood cells. They are especially susceptible to landscape changes that lead to an increased spatial separation of suitable nesting sites and flower rich host plant stands. While knowledge of bee foraging ranges is curre...

This volume of Fauna Helvetica provides identification keys and distribution maps of the Swiss bee species of the genera Andrena, Melitturga, Panurginus and Panurgus.

The Mediterranean orchid Anacamptis papilionacea, despite showing a typical food-deceptive floral display, has also been reported to frequently attract male pollinators, suggesting a potentiality for sexual attraction. In a survey from a southern Italian popu-lation of A. papilionacea and their hybrids with Anacamptis morio, we collected 37 pollina...

To assess the pollen hosts of 60 western palaearctic bee species of the genus Colletes (Colletidae), we microscopically analysed 1336 pollen loads of collected females. Twenty-six species (43.3%) were found to be specialized at the level of plant family, subfamily or genus. Thirty-four species (56.7%) proved to be pollen generalists to varying degr...

To trace the evolution of host-plant choice in bees of the genus Chelostoma (Megachilidae), we assessed the host plants of 35 Palearctic, North American and Indomalayan species by microscopically analyzing the pollen loads of 634 females and reconstructed their phylogenetic history based on four genes and a morphological dataset, applying both pars...

This taxonomic catalogue covers all family-, genus- and species-group names of the Palaearctic bees of the tribe Osmiini as published by the end of 2006. As the taxonomy of the Palaearctic Osmiini is currently in a poor state, the primary goal of this catalogue is to provide a complete coverage of the widely dispersed and often not easily accessibl...

To investigate the effect of larval pollen diet on floral choice in a specialized bee species, we compared the floral preferences of individuals of Heriades truncorum (Megachilidae) reared on host pollen with those of individuals reared on two different types of non-host pollen. Females were allowed to nest in cages where both host and non-host flo...

The Osmiini (Megachilidae) constitute a taxonomically and biologically diverse tribe of bees. To resolve their generic and suprageneric relationships, we inferred a phylogeny based on three nuclear genes (Elongation factor 1-alpha, LW-rhodopsin and CAD) applying both parsimony and Bayesian methods. Our phylogeny, which includes 95 osmiine species r...

Bees require large amounts of pollen for their own reproduction. While several morphological flower traits are known to have evolved to protect plants against excessive pollen harvesting by bees, little is known on how selection to minimize pollen loss acts on the chemical composition of pollen. In this study, we traced the larval development of fo...

The females of six closely related European Tetraloniella species are equipped with a specialized pilosity on the abdominal sternites 3-5 composed of numerous hairs robust at their base and wavily twisted in their apical portion. This sternal pilosity is used to efficiently remove pollen from the flower heads of Inula and Pulicaria (Asteraceae), re...

This volume of Fauna Helvetica provides identification keys and distribution maps of the Swiss bee species of the genera Ammobates, Ammobatoides, Anthophora, Biastes, Ceratina, Dasypoda, Epeoloides, Epeolus, Eucera, Macropis, Melecta, Melitta, Nomada, Pasites, Tetralonia, Thyreus and Xylocopa.

Hoplitis pici (Friese, 1899) is a rare species of bee occurring in southeast Europe, Turkey and the Near East. The females are equipped with conspicuous hooked bristles on the galeae of the proboscis. Microscopical analysis of both pollen contained in the abdominal scopa and sticking to the bodies of females indicates a distinct preference of H. pi...