Search

This review gathers the majority of foregoing information about the red mason bee (Osmia bicornis, syn. rufa) (Apoidea: Megachilidae) and elaborates on the following issues: taxonomy and morphology...

Ectotherms usually require a narrow range of thermal conditions for development; thus, parental selection of oviposition sites is crucial. In a field experiment, we investigated female solitary red mason bee (Osmia bicornis) preferences for potential nest site temperatures and their effects on offspring development. The results showed that bees detected and avoided nest sites with high temperatures (28°C) and often chose cooler (24°C) or ambient temperatures (average 18–20°C). This is a protective behaviour because offspring survival decreases with increasing nest temperature, mostly due to mortality at the egg stage. Elevated temperatures also led to weight loss in adult bees. However, hot nest temperatures appeared to deter adults or kill parasite larvae, as the highest numbers of parasites were observed in unheated nests. We concluded that choosing the proper temperature for nests is an important element in bee life strategies, especially in warming environments.

Wild bees are of immense value playing a vital ecosystem role because of the pollination services they provide to natural and agricultural ecosystems (Aleixoa et al., 2014). They forage on flowers ...

The research enabled the optimal parameters of reed stalks Phragmites australis (Cav.) Trin. ex Steud, to be determined and then be used for rearing red mason bees (Osmia rufa L.). During research conducted in 2015 and 2016, 3,293 reed stalks were occupied by red mason bees, and 19,461 nest cells were counted in the stalks, of which there were 16,222 non-parasitized larvae. The mean weight of one cocoon was 0.085 g. The mean length of the reed stalk occupied by the red mason bee was 169.45 mm, its mean diameter was 6.11 mm and the mean number of cells in the reed was 5.47. The mean length of the first cell, the vestibulum, was 38.38 mm. The mean degree of parasitism was 0.16. The length of the reed stalk positively correlated with the number of cells in the reed nest (r=0.543), vestibulum length (r=0.392) and cocoon mass (r=0.362) The diameter of the reed positively correlated with the mass of the cocoon (r=0.536), the number of cells in the reed (r=0.406) and vestibulum length (r=0.254). Correlation between degree of parasitatism and length, and diameter of the reed was insignificant. Reed stalks with a length of 150 to 200 mm and a diameter of 5–7 mm are recommended for the choice of red mason bee nesting material.

Many bee species are dietary specialists and restrict their pollen foraging to a subset of the available flowers. However, the reasons for specialization-and the reasons certain plant taxa support numerous specialists-are often unclear. Many bees specialize on the plant family Asteraceae, despite evidence its pollen is a poor food for non-specialists. Here, we studied six mason bee (Osmia) species, including three Asteraceae specialists, to test whether observed pollen-usage patterns reflect larval nutritional requirements, to investigate what aspects of Asteraceae pollen make it unsuitable for non-specialists, and to understand how Asteraceae specialists tolerate their seemingly low-quality diet. We reared larval bees on host and nonhost pollen and found that Asteraceae specialists could develop on nonhost provisions, but that other bees could not survive on Asteraceae provisions. These effects did not seem related to nutritional deficiencies, since Asteraceae provisions were not amino acid deficient, and we found no consistent differences in digestive efficiency among pollen types. However, Asteraceae specialists completed more foraging flights per larva, generally collected relatively larger provisions, and produced more frass (waste) than the other species, suggesting quantitative compensation for low food quality. Toxins, deficiencies in unmeasured nutrients, or aspects of pollen grain structure might explain poor survival of non-specialists on Asteraceae provisions. Our results suggest that floral host selection by specialist bees is not related to optimizing larval nutrition. We recommend further investigation of host-selection behaviour in adult bees and of pollen digestion in larvae to better understand the evolution of bee-flower associations.

A potential driver of pollinator declines that has been hypothesized but seldom documented is the introduction of exotic pollinator species. International trade often involves movement of many insect pollinators, especially bees, beyond their natural range. For agricultural purposes or by inadvertent cargo shipment, bee species successfully establishing in new ranges could compete with native bees for food and nesting resources. In the Mid-Atlantic United States, two Asian species of mason bee (Osmia taurus and O. cornifrons) have become recently established. Using pan-trap records from the Mid-Atlantic US, we examined catch abundance of two exotic and six native Osmia species over the span of fifteen years (2003–2017) to estimate abundance changes. All native species showed substantial annual declines, resulting in cumulative catch losses ranging 76–91% since 2003. Exotic species fared much better, with O. cornifrons stable and O. taurus increasing by 800% since 2003. We characterize the areas of niche overlap that may lead to competition between native and exotic species of Osmia, and we discuss how disease spillover and enemy release in this system may result in the patterns we document.

A new cadinane-type sesquiterpene named cornifronone is isolated from the body surface of a mason bee ( Osmia cornifrons)–derived Streptomyces sp. OC1611-8A. Its structure is identified by high-resolution electrospray ionization mass spectrometry data and nuclear magnetic resonance spectroscopic analysis. The absolute configuration of cornifronone was determined by electronic circular dichroism spectra calculations. Cornifronone inhibits hexokinase activity with a mean IC50 of 124.3 μM.

Threats to bee pollinators such as land use change, high pesticide risk and reduced floral diet diversity are usually assessed independently, even though they often co-occur to impact bees in agroecosystems. We established populations of the non-native mason bee Osmia cornifrons at 17 NY apple orchards varying in proportion of surrounding agriculture and measured floral diet diversity and pesticide risk levels in the pollen provisions they produced. We used path analysis to test the direct and indirect effects of different habitats, diet diversity and pesticide risk on emergent female offspring number and weight. High proportions of agricultural habitat surrounding bee nests indirectly reduced the number of female offspring produced, by reducing floral diet diversity in pollen. When the proportion of agriculture surrounding bee nests was high, bees collected increased proportions of Rosaceae in their pollen provisions, which marginally (0.05 < p < 0.1) increased fungicide risk levels in pollen. This, in turn, marginally reduced female offspring weight. In contrast, female offspring weight increased as proportions surrounding open habitat (wildflowers, grassland and pasture) increased, but this effect was not influenced by proportion Rosaceae or fungicide risk levels in pollen. Synthesis and applications. Threats to bee health such as land use change, pesticide exposure and changes in pollen diet composition are often studied in isolation. However, our results suggest that these threats can simultaneously influence one another to impact bee populations in the agroecosystems where we rely on them for pollination. By replacing surrounding agricultural habitats with more natural habitats, such as grasslands and pastures, we can increase floral diet diversity and reduce pesticide exposure in bee-collected pollen, resulting in healthier mason bee populations in apple orchards.

Research on the red mason bee, Osmia bicornis (L., 1758) (Hymenoptera: Megachilidae), which is an important pollinator particularly for stone fruits, in Turkey is limited to the last decade. After the first report in sweet cherry orchards of Afyonkarahisar, this study aimed to determine the presence and the density of the red mason bee and to collect data on its nesting biology between 2014 and 2016 in the mixed orchards of Ankara and Çankırı Provinces. Although the red mason bee was detected in almost all orchards sampled using the Malaise trap, the nesting activity was recorded in only four orchards in 2014 and 2015. Reeds with an inner diameter of 6-9 mm and a length of 15-25 cm were used as the artificial trap-nests. It was determined that the percentage of the nesting success varies between 6 and 48%. The cocoons that originated from the nests were placed in the incubator to stimulate diapause. Then, the temperature of the incubator was gradually increased to complete the life cycle of the species with starting the bud stage of stone fruits in early spring. Consequently, the emergence rates of the adults from the 135 cocoons collected in 2014 were 36 to 95%. It was not recorded the adult emergence from any of the 143 cocoons obtained from the dissections of the nests in 2015. The sex ratios, both between orchards and from 2014 to 2015 in the same orchard ranged between 1:1.5-1:4 (♀:♂). The results are discussed based on stress conditions such as weather, limited pollen and nectar sources and insecticide application., Özellikle sert çekirdekli meyvelerin önemli bir polinatörü olan Kırmızı duvarcı arısı, Osmia bicornis (L., 1758) (Hymenoptera: Megachilidae) ile ilgili araştırmalar, Türkiye’de son on yıl ile sınırlıdır. Afyonkarahisar’daki kiraz bahçelerinde ilk çalişmanın ardından 2014 ile 2016 yılları arasında Ankara ve Çankırı illerindeki karışık meyve bahçelerinde yürütülen bu çalışma, Kırmızı duvarcı arısının varlığını ve yoğunluğunu belirlemek ile yuvalanma biyolojisi hakkında veri elde etmeyi amaçlamıştır. Kırmızı duvarcı arısı, Malaise tuzak kullanılarak örneklenen hemen tüm bahçelerde belirlenmiş olmasına rağmen, yapay yuvalanma 2014 ve 2015 yıllarında sadece dört bahçede kaydedilmiştir. İç çapı 6-9 mm, uzunluğu 15-25 cm olan kamışlar yapay tuzak yuva olarak kullanılmışlardır. Yuvalanma başarısının %6 ile 48 arasında değiştiği belirlenmiştir. Yuvalardan elde edilen kokonlar diapozu başlatması için inkübatöre yerleştirilmiştir. Daha sonra inkübatörün sıcaklığı, erken ilkbaharda sert çekirdekli meyvelerin tomurcuk kabarması döneminin başlaması ile türün yaşam döngüsünü tamamlaması için kademeli olarak arttırılmıştır. Sonuç olarak, 2014 yılında toplanan 135 kokondan ergin çıkışı oranı %36 ile 95 olmuştur. 2015 yılına ait yuvaların diseksiyonundan elde edilen 143 kokonun hiç birinde ergin çıkışı kaydedilmemiştir. Eşey oranları hem tüm bahçeler arasında hem de aynı bahçenin 2014 ve 2105 yıllarında 1:1.5 ile 1:4 (♀:♂) arasında çeşitlilik göstermiştir. Sonuçlar, iklim, sınırlı polen ve nektar kaynakları ile insektisit uygulaması gibi stres koşullarına dayandırılarak tartışılmıştır.

In recent years, insect husbandry has seen an increased in- terest in order to supply in the production of raw materials, food or as biological/environmental control. Unfortunately, large insect rearings are susceptible to pathogens, pests and parasitoids which can spread rapidly due to the confined nature of a rearing system. Thus, it is of interest to quickly and efficiently monitor the spread of such manifesta- tions and the overall population size. Medical imaging techniques could be used for this purpose, as large volumes can be scanned non-invasively. Due to its 3D acquisition nature, computed tomography seems to be the most suitable for this task. This study presents an automated, computed tomography-based, counting method for bee rearings that performs com- parable/similar to identifying all Osmia cornuta cocoons manually. The proposed methodology achieves this in an average of 7 minutes per sam- ple, compared to 90 minutes per sample for the manual count over a total of 12 samples collected around lake Zurich in 2020. Such an automated bee population evaluation tool is a valuable in combating environmental influences on bee, and potentially other insect, rearings.

Insect pollinators provide crucial ecosystem services yet face increasing environmental pressures. The challenges posed by novel and reemerging pathogens on bee health means we need to improve our understanding of the immune system, an important barrier to infections and disease. Despite its importance, for certain ecologically important species, such as solitary bees, our understanding of the genomic basis and molecular mechanisms underlying immune potential, and how intrinsic and extrinsic factors may influence immune gene expression is lacking. Here, to improve our understanding of the genomic architecture underlying immunity of a key solitary bee pollinator, we characterised putative immune genes of the red mason bee, Osmia bicornis. In addition, we used publicly available RNA-seq datasets to determine how sexes differ in immune gene expression and splicing but also how pesticide exposure may affect immune gene expression in females. Through comparative genomics, we reveal an evolutionary conserved set of more than 500 putative immune-related genes. We found genome-wide patterns of sex-biased gene expression, including immune genes involved in antiviral-defence. Interestingly, the expression of certain immune genes were also affected by exposure to common neonicotinoids, particularly genes related to haemocyte proliferation. Collectively, our study provides important insights into the gene repertoire, regulation and expression differences in the sexes of O. bicornis, as well as providing additional support for how neonicotinoids can affect immune gene expression, which may affect the capacity of solitary bees to respond to pathogenic threats.

In the Eastern United States, two mason bee species from Asia have become recently established. The Japanese horn-faced bee, Osmia cornifrons Radoszkowski 1887, was intentionally introduced from Japan by the United States Department of Agriculture (USDA) in the 1970’s for crop pollination services. In 2002, another mason bee from Asia, Osmia taurus Smith 1873, was first documented in the United States, without record of its being intentionally imported. My dissertation first documents trends of native Osmia species decline with the concurrent increase of non-native Osmia taurus (Chapter 1) from 2003-2017. In Chapter 2, I investigate the occurrence of fungi originally described in Japan (genus Ascosphaera) now expanding their host range to native Osmia species in Virginia. In Chapter 3, I evaluate the differential climatic distributions of O. taurus and O. cornifrons in Virginia that offer clues for why O. taurus has such a marked regional increase since 2003 compared to unchanging levels of O. cornifrons. Lastly, in Chapter 4, I sought to evaluate the conservation utility of “bee hotels” for native springtime Osmia. I document how bee hotels in anthropogenically disturbed landscapes offer disparate outcomes for native and non-native Osmia species. In particular, non-native Osmia are attacked by parasitic wasps less frequently than native Osmia inside these nesting structures even though non-native Osmia are found most frequently inside bee hotels. Bee hotels may facilitate a demographic release of the invasive O. taurus, and these negative outcomes for native Osmia in bee hotels call into question the conservation utility of bee hotels in the Virginia springtime season.

Agricultural landscapes have changed substantially in recent decades, shifting from the dominance of small fields (S) with diverse cropping systems toward large-scale monoculture (L), where landscape heterogeneity disappears. In this study, artificial nests of the red mason bee, Osmia bicornis, were placed in S and L landscape types on the perimeter of oilseed rape fields representing different oilseed rape coverages (ORC, % land cover). The local landscape structure around each nest was characterised within a 100, 200, 500, and 1000 m radius using ORC and 14 landscape characteristics, which were then reduced by non-metric multidimensional scaling (nMDS) to two axes: nMDS1 characterised the dataset primarily according to land fragmentation and the main crop, whereas nMDS2 captured the prevalence of more natural areas in the landscape. Pollen diversity and insecticide risk levels in the pollen provisions collected by the bees were analysed, and their dependence on the landscape structure was tested. Thereafter, the effects of pollen diversity, insecticide risk, and landscape structure on the life-history traits of bees and their sensitivity to topically applied Dursban 480 EC were determined. Pollen taxa richness in a single nest ranged from 3 to 12, and 34 pesticides were detected in the pollen at concentrations of up to 320 ng/g for desmedipham. The O. bicornis foraging range was relatively large, indicating that the landscape structure within a radius of ~1000 m around the nest is important for this species. Pollen diversity in the studied areas was of minor importance for bee performance, but the ORC or landscape structure significantly affected the life-history traits of the bees. Contamination of pollen with insecticides affected the bees by decreasing the mass of newly emerged adults but their sensitivity to Dursban 480 EC was not related to environmental variables.

The mason bee, Osmia pedicornis Cockerell, 1919, which is importantly used as the pollinator, particularly for apples in Korea. We sequenced the mitochondrial genome (mitogenome) of O. pedicornis a...

Impacts of neonicotinoid-containing pesticides on pollinators have been heavily debated in recent years. While bees in the field get rarely exposed to lethal concentrations of neonicotinoids applied as seed coating, sublethal levels found in pollen and nectar may affect bee population development. We assessed a realistic and a worst-case scenario of clothianidin exposure to mason bees (Osmia bicornis) and bumblebees (Bombus terrestris) by conducting a small-scale field and semi-field experiment at sites planted with winter oilseed rape. Flight activity, mortality and population development (brood, colony strength and weight) of bumblebees and number of mason bee brood cells were assessed at three locations. We also analysed clothianidin residues in bee-collected pollen and nectar. We detected clothianidin at low concentrations in nectar and pollen; residues in pollen were higher than in nectar but did not exceed a maximum field concentration of 2.7 µg/kg for bumblebees and 4.7 µg/kg for mason bees. Exposure did not result in significant negative impacts on bumblebee colony development and potential reproductive success of mason bees in either semi-field or field setup. During exposure bumblebees in semi-field treatment tunnels were flying less actively than in control tunnels. Bumblebee colonies in treatment tunnels weighed more than control colonies at the end of the experiment. Our findings suggest that field-realistic exposure to oilseed rape grown from clothianidin-treated seeds (10 g clothianidin/kg seeds) poses little risks to mason bees, bumblebees and their population development. However, an impairment of flower visitation under a worst-case scenario may have implications for pollination services and crop production.

Background Solitary bees, such as the red mason bee (Osmia bicornis), provide important ecosystem services including pollination. In the face of global declines of pollinator abundance, such haplodiploid Hymenopterans have a compounded extinction risk due to the potential for limited genetic diversity. In order to assess the genetic diversity of Osmia bicornis populations, we developed microsatellite markers and characterised them in two populations. Methods and results Microsatellite sequences were mined from the recently published Osmia bicornis genome, which was assembled from DNA extracted from a single male bee originating from the United Kingdom. Sequences were identified that contained dinucleotide, trinucleotide, and tetranucleotide repeat regions. Seventeen polymorphic microsatellite markers were designed and tested, sixteen of which were developed into four multiplex PCR sets to facilitate cheap, fast and efficient genotyping and were characterised in unrelated females from Germany (n = 19) and England (n = 14). Conclusions The microsatellite markers are highly informative, with a combined exclusion probability of 0.997 (first parent), which will enable studies of genetic structure and diversity to inform conservation efforts in this bee.

Solitary bees provide essential pollination services for many arable crops, but are prone to global decline. Agricultural intensification, which is connected with pesticide usage, is among major threats to bees and, thus, to the food security and ecosystem stability. As it may not be possible to cease pesticide usage currently because of the growing demand for food, it is crucial to understand the pesticide toxicities to bees for better protection of pollinator populations. The majority of studies have focused on social bees, and those on solitary bees studied effects of adult exposure, whereas these bees are also likely to be exposed as larvae via the consumption of contaminated pollen. Here, the effects of three commonly used insecticide-based plant protection products on the development of the solitary bee, Osmia bicornis (red mason bee), were studied by exposing larvae to insecticide-contaminated multifloral pollen. The tested insecticides were: Dursban480EC, containing the organophosphate chlorpyrifos (CHP), Sherpa100EC, containing the pyrethroid cypermethrin (CYP), and Mospilan20SP with the neonicotinoid acetamiprid (ACT). When compared to the control larvae fed with uncontaminated-pollen, both CHP and CYP significantly reduced the O. bicornis larval survival and their body mass at all tested concentrations. In contrast, ACT did not affect either larval survival or body mass, but the length of larval stage to cocoon formation was significantly shortened compared to controls. None of studied insecticides affected the mass of cocooned individuals. However, at least 80% of individuals exposed to any of the tested insecticides died before reaching the adult stage, whereas 43% of the controls emerged successfully after overwintering. Although no clear monotonic dose-response relationships were found, our study showed that at least some insecticide formulations affect the development of O. bicornis even at concentrations actually found in pollen in the field, indicating an urgent need for revising current pesticide usage recommendations.

We assessed impacts of direct acute contact with imidacloprid-treated soil on nesting behavior and mortality of the blue orchard mason bee (Osmia lignaria Say), which is a native solitary cavity-nesting species that collects mud for nest partitions. Laboratory-reared O. lignaria females were exposed to three concentrations of imidacloprid (0, 50, 390 and 780 ppb), in wet (30% moisture) soil for 20 min and released in large flight cages, where impacts on nesting activity and nest cell production were evaluated. Mortality was tested in another experiment using exposure at the same concentrations with two differing soil moisture levels (20% and 40%). Nesting activity was reduced by 42% for females exposed at 390 ppb and by 66% for females exposed at 780 ppb. Females treated at 780 ppb produced 40% fewer nest cells per day. Sex ratios of F1 generation were skewed toward male in the 50 ppb treatment group with 50% fewer females. The number of cells and pre-pupae per nest, as well as the weight of pre-pupal cocoons did not vary among exposure levels. There were no mortality effects at 20% soil moisture for any level of imidacloprid, but at 40%, mortality of females was >50% at all levels of imidacloprid. These results suggest that acute exposure to imidacloprid residue in soil can have negative impacts on soil-interacting bees, and the effects may be relative to the degree of soil moisture.

Solitary bees are subject to a variety of pressures that cause severe population declines. Currently, habitat loss, temperature shifts, agrochemical exposure, and new parasites are identified as major threats. However, knowledge about detrimental bacteria is scarce, although they may disturb natural microbiomes, disturb nest environments, or harm the larvae directly. To address this gap, we investigated 12 Osmia bicornis nests with deceased larvae and 31 nests with healthy larvae from the same localities in a 16S ribosomal RNA (rRNA) gene metabarcoding study. We sampled larvae, pollen provisions, and nest material and then contrasted bacterial community composition and diversity in healthy and deceased nests. Microbiomes of pollen provisions and larvae showed similarities for healthy larvae, whilst this was not the case for deceased individuals. We identified three bacterial taxa assigned to Paenibacillus sp. (closely related to P. pabuli/amylolyticus/xylanexedens), Sporosarcina sp., and Bacillus sp. as indicative for bacterial communities of deceased larvae, as well as Lactobacillus for corresponding pollen provisions. Furthermore, we performed a provisioning experiment, where we fed larvae with untreated and sterilized pollens, as well as sterilized pollens inoculated with a Bacillus sp. isolate from a deceased larva. Untreated larval microbiomes were consistent with that of the pollen provided. Sterilized pollen alone did not lead to acute mortality, while no microbiome was recoverable from the larvae. In the inoculation treatment, we observed that larval microbiomes were dominated by the seeded bacterium, which resulted in enhanced mortality. These results support that larval microbiomes are strongly determined by the pollen provisions. Further, they underline the need for further investigation of the impact of detrimental bacterial acquired via pollens and potential buffering by a diverse pollen provision microbiome in solitary bees.

Most of the studies on learning in bees have focused on the foraging context; we know little about the preferences and cognitive processes in nest-site selection, especially in solitary bees. The majority of the bee species are solitary and in contrast to eusocial bees, solitary bees’ cognition and social information use have remained largely unstudied. Solitary cavity-nesting mason bees (Osmia spp.) are an ideal system to study interspecific information use in nest choice in the wild as many species share similar nesting requirements. Here, we show that the blue mason bee (O. caerulescens) and the orange-vented mason bee (O. leaiana) examine hallmarks of parasitization of the nests of red mason bees (O. bicornis) before deciding where to establish their own nests. They were also presented with contextual cues (geometric symbols) that could be linked to parasitization by observational learning. Subjects subsequently had the choice of nesting in a nest site marked by the symbol that matched, or did not match, the one seen at the parasitized or healthy nest. We show that the bees copied and rejected the symbol of the examined nest manipulated to exhibit successful and unsuccessful nesting, respectively. We conclude that solitary bees use interspecific information in their nest-site selection. In contrast with current theories of species coexistence, niche overlap between species may dynamically change depending on the observed success of surrounding individuals.

Solitary bees are frequently exposed to pesticides, which are considered as one of the main stress factors that may lead to population declines. A strong immune defence is vital for the fitness of bees. However, the immune system can be weakened by environmental factors that may render bees more vulnerable to parasites and pathogens. Here we demonstrate for the first time that field-realistic concentrations of the commonly used neonicotinoid insecticide thiacloprid can severely affect the immunocompetence of Osmia bicornis. In detail, males exposed to thiacloprid solutions of 200 and 555 µg/kg showed a reduction in hemocyte density. Moreover, functional aspects of the immune defence - the antimicrobial activity of the hemolymph - were impaired in males. In females, however, only a concentration of 555 µg/kg elicited similar immunosuppressive effects. Although males are smaller than females, they consumed more food solution. This leads to a 2.77 times higher exposure in males, probably explaining the different concentration thresholds observed between the sexes. In contrast to honeybees, dietary exposure to thiacloprid did not affect melanisation or wound healing in O. bicornis. Our results demonstrate that neonicotinoid insecticides can negatively affect the immunocompetence of O. bicornis, possibly leading to an impaired disease resistance capacity.

Research into vibrational communication is becoming increasingly important as we discover more species using vibrational signals in different types of behavior. Males of the solitary red mason bee, Osmia bicornis, are known to use vibrations in female choice, where the females not only evaluate a male’s fitness through their vibrational signal but also use them to distinguish between males of different origins. This was shown conclusively via bioassays, in which females from Germany rejected English males unless they were imbued with an artificial German signal and vice versa. However, an investigation into which parameters of the signal might differ between species and populations has been lacking so far. We therefore recorded O. bicornis as well as O. cornuta males from Germany, England, and Denmark using a laser vibrometer and analyzed the recordings using the software Spike to measure frequency, modulation range, and average pulse duration in each signal. Our results clearly showed significant differences in the signal between O. bicornis and O. cornuta males in all three parameters measured. O. bicornis populations from Germany and Denmark surprisingly also differed significantly in frequency and modulation range, with England lying in between the two. We believe that the females probably use another signal parameter that we have not evaluated yet to make their mate choice. This leaves us with the question of why the observed signal parameters differ between Germany and Denmark. From our knowledge about the system to date, we believe that we are looking at the first steps of speciation in this system and further study could help us with new insights into evolutionary processes in the future.

The mason bee Osmia (Helicosmia) latreillei Spinola is one of the dominant species of bees throughout Egypt, and can be found commonly in the Suez Canal Region. The species visits numerous plant species of the family Asteraceae and is considered the most important pollinator of certain crops such as sunflower. This species and some other solitary cavity nesting bees are threatened by fragmentation of their nesting habitats. Several attempts were made to establish and propagate O. latreillei, and success was achieved for re-nesting it in various artificial materials such as wood and polystyrene with rolled paper straws. These artificial nests were established at the conservation area of the Bee Research Centre, Suez Canal University, in order to study the nesting behavior and biology of O. latreillei under artificial conditions and to document their natural enemies. Biologically, there was no significance difference between the life cycle of O. latreillei under natural and artificial nesting conditions. This solitary bee was univoltine, individuals active only during Spring, and attacked by diverse enemies, with Stelis (Stelis) murina Perez and chrysidid wasps considered the two most major pests of this wild bee species.

Declines of pollinator health and their populations continue to be commercial and ecological concerns. Agricultural practices, such as the use of agrochemicals, are among factors attributed to honey bee (Apis mellifera L. (Hymenoptera: Apidae)) population losses and are also known to have negative effects on populations of managed non-Apis pollinators. Although pesticide registration routinely requires evaluation of impacts on honey bees, studies of this social species may not reveal important pesticide exposure routes where managed, solitary bees are commonly used. Studies of solitary bees offer additional bee models that are practical from the aspect of availability, known rearing protocols, and the ability to assess effects at the individual level without confounding factors associated with colony living. In addition to understanding bees, it is further important to understand how pesticide characteristics determine their environmental whereabouts and persistence. Considering our research expertise in advancing the management of solitary bees for crop pollination, this forum focuses on routes of pesticide exposure experienced by cavity-nesting bees, incorporating the relative importance of environmental contamination due to pesticide chemical behaviors. Exposure routes described are larval ingestion, adult ingestion, contact, and transovarial transmission. Published research reports of effects of several pesticides on solitary bees are reviewed to exemplify each exposure route. We highlight how certain pesticide risks are particularly important under circumstances related to the cavity nesters.

There has been increasing interest in the effects of neonicotinoid insecticides on wild bees. In solitary bee species the direct link between each individual female and reproductive success offers the opportunity to evaluate effects on individuals. The present study investigated effects of exposure to winter oilseed rape grown from thiamethoxam-treated seed on reproductive behavior and output of solitary red mason bees (Osmia bicornis) released in 6 pairs of fields over a 2-yr period and confined to tunnels in a single year. After adjustment to the number of females released, there was significantly lower production of cells and cocoons/female in tunnels than in open field conditions. This difference may be because of the lack of alternative forage within the tunnels. Under open field conditions, palynology of the pollen provisions within the nests demonstrated a maximum average of 31% oilseed rape pollen at any site, with Quercus (oak) contributing up to 86% of the pollen. There were no significant effects from exposure to oilseed rape grown from thiamethoxam-treated seed from nest establishment through cell production to emergence under tunnel or field conditions. Environ Toxicol Chem 2018;37:1071-1083. © 2017 SETAC.

1. Habitat loss and fragmentation potentially affect the performance of bees that forage nectar and pollen of plants in their habitats. In forest landscapes, silvicultural conifer plantations often have reduced and fragmented natural broadleaf forests, which seem to provide more floral resources for bees than do the plantations. 2. This study evaluated the effects of forest characteristics (i.e. elevation, area, edge length, and tree size of natural forests) on pollen diets (plant taxa assemblages of pollen grains in provisions) and total provision mass in oviposited chambers in nests made by a standardised number of Osmia cornifrons bees at 14 sites in a forestry area in central Japan. 3. From April to May, the numbers of nests and chambers per nest increased, and the provision mass per chamber decreased. Main pollen sources were Prunus at higher elevations in April and Wisteria at lower elevations in May, foraging on which increased the numbers of nests and chambers per nest. The provision mass per chamber was smaller at higher elevations in more fragmented natural forests. Decreases in the area of natural forests within the foraging range (400‐m radii) of O. cornifrons increased the utilisation of Rubus pollen and decreased the total provision mass. 4. These findings suggest that the loss and fragmentation of natural broadleaf forests change pollen diets and reduce the provision mass of mason bees, which may reduce the number and size of their offspring.

We have surveyed the current status of insect pollinator use for horticultural crops in 2016. The use rate and farmnumber of insect pollinators for 26 horticultural crops were 25.8% and 55,208, respectively. The colony number of insectpollinators used in this survey was 479,777, which include 344,690 for honeybees, 119,104 for bumblebees, 2,415 formason bees, 1,317 for flies, and 2,415 for the combination of bumblebees, honeybees, and mason bees. The use rateof insect pollinators was 59.4% for 11 vegetable crops and the colony number of insect pollinators used for 11 vegetablecrops was 449,287. The colony number of insect pollinators used for 15 fruit tree crops was 30,290, which include honeybees(66.3%), bumblebees (20.2%), mason bees (8.0%), flies (1.6%), and the combination (3.9%) of bumblebees, honeybees,and mason bees. Together, farms of 98% showed positive effect for the use of insect pollinators and most of farms (97.0%)planed for the continuous use of insect pollinators