Bee phenology is predicted by climatic variation and functional traits.

Climate change is shifting the environmental cues that determine the phenology of interacting species. Plant-pollinator systems may be susceptible to temporal mismatch if bees and flowering plants differ in their phenological responses to warming temperatures. While the cues that trigger flowering are well-understood, little is known about what determines bee phenology. Using generalised additive models, we analyzed time-series data representing 67 bee species collected over 9 years in the Colorado Rocky Mountains to perform the first community-wide quantification of the drivers of bee phenology. Bee emergence was sensitive to climatic variation, advancing with earlier snowmelt timing, whereas later phenophases were best explained by functional traits including overwintering stage and nest location. Comparison of these findings to a long-term flower study showed that bee phenology is less sensitive than flower phenology to climatic variation, indicating potential for reduced synchrony of flowers and pollinators under climate change.

Non-bee insects are important contributors to global crop pollination.

Wild and managed bees are well documented as effective pollinators of global crops of economic importance. However, the contributions by pollinators other than bees have been little explored despite their potential to contribute to crop production and stability in the face of environmental change. Non-bee pollinators include flies, beetles, moths, butterflies, wasps, ants, birds, and bats, among others. Here we focus on non-bee insects and synthesize 39 field studies from five continents that directly measured the crop pollination services provided by non-bees, honey bees, and other bees to compare the relative contributions of these taxa. Non-bees performed 25-50% of the total number of flower visits. Although non-bees were less effective pollinators than bees per flower visit, they made more visits; thus these two factors compensated for each other, resulting in pollination services rendered by non-bees that were similar to those provided by bees. In the subset of studies that measured fruit set, fruit set increased with non-bee insect visits independently of bee visitation rates, indicating that non-bee insects provide a unique benefit that is not provided by bees. We also show that non-bee insects are not as reliant as bees on the presence of remnant natural or seminatural habitat in the surrounding landscape. These results strongly suggest that non-bee insect pollinators play a significant role in global crop production and respond differently than bees to landscape structure, probably making their crop pollination services more robust to changes in land use. Non-bee insects provide a valuable service and provide potential insurance against bee population declines.

A review of the Stelidium group of Stelis Panzer, 1806 (Hymenoptera: Megachilidae) with two new species from western North America.

The Stelidium group is readily distinguished from all other members of the subgenus Stelis Panzer, 1806 by the combination of small body size ( 6 mm), pale maculations on the head adjacent to the inner margins of the compound eyes and laterally on the vertex in both sexes, and females with sternum 6 extended beyond tergum 6, the former with the dorsal lip trowel-shaped with the apex broadly rounded or subtruncate to more narrowly pointed. This monophyletic clade, which is endemic to North America, currently consists of members previously placed into two species groups: the permaculata group containing S. anasazi Parker & Griswold, 2013, S. ashmeadiellae Timberlake, 1941, S. permaculata Cockerell, 1898, and S. robertsoni Timberlake, 1941, and the palmarum group containing S. broemelingi Parker & Griswold, 2013, S. elongativentris Parker, 1987, and S. palmarum Timberlake, 1941; two additional species, S. herberti (Cockerell, 1916) from Mexico, and S. nyssonoides (Brues, 1903) from Texas, United States, have not been definitively placed in either species group. Two new species are herein described, one from southcentral British Columbia, Canada, the other from New Mexico, United States. A preliminary molecular phylogeny places both new species in the permaculata species group. In addition, S. herberti is also placed within the permaculata species group based on morphological similarity, sharing the multi-spotted maculation pattern on the terga. Based on molecular affinity, S. broemelingi also belongs to the permaculata species group. Because no type specimen for S. nyssonoides is seemingly available for examination, it is hereby considered nomen dubium until the specimen is found and its taxonomic status clarified in relation to the more recently described species in the permaculata species group. A key to females and diagnoses are provided for all known taxa.

Teratognathini Silveira, the priority family-group name for Ancyloscelidini Engel and Michener (Hymenoptera: Apoidea: Apidae: Eucerinae).

The genus Ancyloscelis Latreille, 1829 (Hymenoptera: Apidae), a taxon restricted to the Neotropics and southern Nearctic (Michener 1942, 2000, 2007; Schaller and Roig-Alsina 2021; Melo 2022), has been difficult to place precisely within the higher classification of bees (Roig-Alsina and Michener 1993; Aguiar et al. 2019; Freitas et al. 2020), and even the genus name has a confusing history (see Michener 1942). Michener (1944) placed it together with Exomalopsis Spinola, 1853 within the Exomalopsini Vachal, 1909, and Michener and Moure (1957) later expanded this tribe to include ten additional genera, with Ancyloscelis the sole member of one of the five distinct sections they recognized (reviewed by Silveira 1993). Later, Jesus S. Moure (cited in Roig-Alsina and Michener 1993) suggested that the placement of Ancyloscelis should be within Emphorini Robertson, 1904, a position supported in that work. However, Roig-Alsina and Michener (1993) concluded that it differed enough from other members to recognize two subtribes, proposing Ancyloscelina Roig-Alsina and Michener, 1993 containing only the type genus, with the remaining Emphorini recognized at that time (i.e., Diadasia Patton, 1879, Diadasina Moure, 1950, Melitoma Lepeletier and Serville, 1828, and Ptilothrix Smith, 1853) placed in subtribe Emphorina Robertson, 1904. Michener (2000, 2007) and others (Silveira et al. 2002, Rodrguez and Roig-Alsina 2004) continued to recognize Ancyloscelis within Emphorini, but subtribal classifications were not used in those works.

DNA barcoding reveals diversity of Hymenoptera and the dominance of parasitoids in a sub-arctic environment.

BACKGROUND: Insect diversity typically declines with increasing latitude, but previous studies have shown conflicting latitude-richness gradients for some hymenopteran parasitoids. However, historical estimates of insect diversity and species richness can be difficult to confirm or compare, because they may be based upon dissimilar methods. As a proxy for species identification, we used DNA barcoding to identify molecular operational taxonomic units (MOTUs) for 7870 Hymenoptera specimens collected near Churchill, Manitoba, from 2004 through 2010. RESULTS: We resolved 1630 MOTUs for this collection, of which 75% (1228) were ichneumonoids (Ichneumonidae + Braconidae) and 91% (1484) were parasitoids. We estimate the total number of Hymenoptera MOTUs in this region at 2624-2840. CONCLUSIONS: The diversity of parasitoids in this sub-Arctic environment implies a high diversity of potential host species throughout the same range. We discuss these results in the contexts of resolving interspecific interactions that may include cryptic species, and developing reproducible methods to estimate and compare species richness across sites and between surveys, especially when morphological specialists are not available to identify every specimen.

Bombus (Pyrobombus) johanseni Sladen, 1919, a valid North American bumble bee species, with a new synonymy and comparisons to other "red-banded" bumble bee species in North America (Hymenoptera, Apidae, Bombini).

The bumble bee (Hymenoptera, Apidae, Bombini, Bombus Latreille) fauna of the Nearctic and Palearctic regions are considered well known, with a few species occurring in both regions (i.e., with a Holarctic distribution), but much of the Arctic, especially in North America, remains undersampled or unsurveyed. Several bumble bee taxa have been described from northern North America, these considered either valid species or placed into synonymy with other taxa. However, some of these synonymies were made under the assumption of variable hair colour only, without detailed examination of other morphological characters (e.g., male genitalia, hidden sterna), and without the aid of molecular data. Recently, Bombus interacti Martinet, Brasero & Rasmont, 2019 was described from Alaska where it is considered endemic; based on both morphological and molecular data, it was considered a taxon distinct from B. lapponicus (Fabricius, 1793). Bombus interacti was also considered distinct from B. gelidus Cresson, 1878, a taxon from Alaska surmised to be a melanistic form of B. lapponicus sylvicola Kirby, 1837, the North American subspecies (Martinet et al. 2019). Unfortunately, Martinet et al. (2019) did not have DNA barcode sequences (COI) for females of B. interacti, but molecular data for a melanistic female specimen matching the DNA barcode sequence of the holotype of B. interacti have been available in the Barcodes of Life Data System (BOLD) since 2011. Since then, additional specimens have been obtained from across northern North America. Also unfortunate was that B. sylvicola var. johanseni Sladen, 1919, another melanistic taxon described from far northern Canada, was not considered. Bombus johanseni is here recognized as a distinct taxon from B. lapponicus sylvicola Kirby, 1837 (sensuMartinet et al. 2019) in the Nearctic region, showing the closest affinity to B. glacialis Friese, 1902 of the Old World. As the holotype male of B. interacti is genetically identical to material identified here as B. johanseni, it is placed into synonymy. Thus, we consider B. johanseni a widespread species occurring across arctic and subarctic North America in which most females are dark, with rarer pale forms (i.e., "interacti") occurring in and seemingly restricted to Alaska. In addition to B. johanseni showing molecular affinities to B. glacialis of the Old World, both taxa also inhabit similar habitats in the arctic areas of both Nearctic and Palearctic, respectively. It is also likely that many of the specimens identified as B. lapponicus sylvicola from far northern Canada and Alaska might actually be B. johanseni, so that should be considered for future studies of taxonomy, distribution, and conservation assessment of North American bumble bees.

First records of the Common Eastern Bumble Bee, Bombus impatiens Cresson (Hymenoptera: Apidae, Apinae, Bombini) from the Prairies Ecozone in Canada.

BACKGROUND: In Canada, the Common Eastern Bumble Bee (Bombus impatiens Cresson) is native to southern Ontario and Quebec, but since being developed as a managed commercial pollinator, it has been exported to several other provinces for use in greenhouse and field crop settings. This has enabled this species to become established outside its natural range and it is now established in eastern Canada (New Brunswick, Nova Scotia, Prince Edward Island) and British Columbia. To date, the species has not been detected via field capture in the prairie provinces. NEW INFORMATION: Here we report on recent captures of B. impatiens workers and males from south-eastern Alberta and suggest that these specimens escaped from nearby commercial greenhouses. The risk that the presence and looming establishment of this species has on native bumble bees in the Canadian prairies is discussed.

Hymenoptera of Canada.

A summary of the numbers of species of the 83 families of Hymenoptera recorded in Canada is provided. In total, 8757 described species are recorded compared to approximately 6000 in 1979, which is a 46% increase. Of the families recognized in 1979, three have been newly recorded to Canada since the previous survey: Anaxyelidae (Anaxyleoidea), Liopteridae (Cynipoidea), and Mymarommatidae (Mymarommatoidea). More than 18,400 BINs of Canadian Hymenoptera are available in the Barcode of Life Data Systems (Ratnasingham and Hebert 2007) implying that nearly 9650 undescribed or unrecorded species of Hymenoptera may be present in Canada (and more than 10,300 when taking into account additional species that have not been DNA barcoded). The estimated number of unrecorded species is very similar to that of 1979 (10,637 species), but the percentage of the fauna described/recorded has increased from 36% in 1979 to approximately 45% in 2018. Summaries of the state of knowledge of the major groups of Hymenoptera are presented, including brief comments on numbers of species, biology, changes in classification since 1979, and relevant taxonomic references.

Trichoptera of Canada.

Trichoptera, or caddisflies, are common members of freshwater ecosystems as larvae and are important indicators of aquatic system health. As such, the species are relatively well studied, with keys available for larvae and adults of many of the taxa occurring in Canada. The number of species recorded from Canada since 1979 (Wiggins 1979) has increased from 546 to 636, an increase of 16.4%. Of those species newly recorded, 17 represent newly described taxa since 1979. Taking into consideration the species likely to be subsequently found in Canada based on records in adjacent parts of the United States and results from DNA barcoding, an estimated 129-181 species remain to be documented in Canada.

The arctic and alpine bumblebees of the subgenus Alpinobombus revised from integrative assessment of species' gene coalescents and morphology (Hymenoptera, Apidae, Bombus).

The bumblebees of the subgenus Alpinobombus of the genus Bombus are unusual among bees for specialising in many of the most northerly vegetated arctic habitats on Earth. Most named taxa in this group (37 available names from a total of 67 names) were described originally from differences in the colour patterns of the hair. Previous revisions have shown unusually little agreement, recognising a range of 6‒9 species, in part because of pronounced intraspecific variation in both skeletal morphology and in the colour patterns of the hair. Here we examine variation among 4622 specimens from throughout the group's global range. Bayesian inference of the gene tree for the fast evolving mitochondrial COI gene combined with Poisson-tree-process analysis of this tree shows support for 10 gene lineages as candidates for being putative species lineages. Integrative assessment shows that the interpretation of these results is not straightforward. Evidence from the fast evolving mitochondrial 16S ribosomal RNA gene supports two of the COI gene alleles (from the samples B. kluanensis s. str. and 'unnamed2') as being associated with just one 16S allele. Double COI bands on the PCR gels for these individuals and double peaks on sequence traces (in one case with both COI alleles sequenced from one individual) identifies this as a likely case of COI paralogy that has resulted in mitochondrial heteroplasmy. Evidence from morphology also supports only the remaining nine lineages as separate. Evidence from extracts of cephalic labial gland secretions (CLGS, with components believed to function as sex pheromones) reported by others shows small diagnostic differences between all of the candidate species examined (although B. kluanensis s. l. was not examined) and shows larger differences between all of the species pairs that we find are likely to have co-occurred at least in the past, revealing a likely limitation to the CLGS approach in cases of recent and continuously allopatric species. Consequently we infer nine species in the subgenus Alpinobombus (so that B. kluanensis s. str. and 'unnamed2' are interpreted as conspecific, as B. kluanensis s. l.). We provide distribution maps and identification keys for the nine species. The morphology of the male of B. kluanensis is described for the first time, including a unique, unusually dense pad of short hair on the mandible that may have a function involving CLGS in mate-searching behaviour. In seeking to identify the valid names for these species, seven new lectotypes are designated and support is provided for synonymizing 10 names as proposed in a recent summary table of names. The prevailing usage of Bombus balteatus Dahlbom is maintained as valid by proposing Bombus nivalis Dahlbom and Bombus tricolor Dahlbom as nomina oblita and by proposing Bombus balteatus Dahlbom as a nomen protectum. The prevailing usage of Bombus hyperboreus Schönherr is maintained as valid by supporting Apis arctica Quensel as a nomen oblitum and by supporting Bombus hyperboreus Schönherr as a nomen protectum. We then use sequence data from COI and 16S together with nuclear PEPCK and opsin genes to estimate dated phylogenetic relationships among the nine species, allowing for incongruent gene trees with *BEAST. If crown-group divergence within the subgenus Alpinobombus coincided with the global climate cooling and with the growth of the northern ice sheets at the end of the Miocene at ca 7.2 Ma, then divergences between each of the three pairs of sister species are likely to have coincided with fluctuations in vegetated land connections across the Bering Strait after ca 2.5 Ma.

A new western Canadian record of Epeoloides pilosulus (Cresson), with discussion of ecological associations, distribution and conservation status in Canada.

BACKGROUND: Epeoloides pilosulus, one of the rarest bees in North America, is a cleptoparasite of Macropis bees which themselves are uncommon oligoleges of oil-producing Lysimachia flowers. Only two specimens of the cleptoparasite have been reported from Canada since the 1960s, both from Nova Scotia. NEW INFORMATION: A recently collected specimen of Epeoloides pilosulus from Alberta, Canada confirms this species from that province and greatly increases its known range in western North America. This record and additional specimens from southern Ontario (one collected in 1978) have implications for the conservation status of this COSEWIC assessed species in Canada, which are discussed.

Assessing Wild Bee Biodiversity in Cranberry Agroenvironments: Influence of Natural Habitats.

The conservation of bee populations for pollination in agricultural landscapes has attracted a lot of recent research interest, especially for crop industries undergoing expansion to meet increased production demands. In Canada, much growth has been occurring with commercial cranberry production, a field crop which is largely dependent on bee pollination. Wild bee pollinators could be negatively impacted by losses of natural habitat surrounding cranberry fields to accommodate increased production, but growers have little insight on how to manage their lands to maximize the presence of wild bees. Here, we described a 2-yr study where bee diversity and species composition were investigated to better understand the dynamic between natural habitat and cranberry fields. Bees were sampled using pan-traps and hand netting both within cranberry fields and in one of the three adjacent natural habitat types once a week during the crop flowering period. We found that bee community composition among cranberry fields did not differ based on the respective adjacent habitat type, but fields bordered by meadows were marginally less diverse than fields bordered by forest. As one would expect, field and natural habitat communities differed in terms of species composition and species richness. There was no evidence that one type of natural habitat was more favorable for the bees than another. Future agrobiodiversity studies should simultaneously examine bee diversity comprised in both crop fields and adjacent natural environments to better understand the species dynamics essential to the preservation of pollination services.

Genes Suggest Ancestral Colour Polymorphisms Are Shared across Morphologically Cryptic Species in Arctic Bumblebees.

Our grasp of biodiversity is fine-tuned through the process of revisionary taxonomy. If species do exist in nature and can be discovered with available techniques, then we expect these revisions to converge on broadly shared interpretations of species. But for the primarily arctic bumblebees of the subgenus Alpinobombus of the genus Bombus, revisions by some of the most experienced specialists are unusual for bumblebees in that they have all reached different conclusions on the number of species present. Recent revisions based on skeletal morphology have concluded that there are from four to six species, while variation in colour pattern of the hair raised questions as to whether at least seven species might be present. Even more species are supported if we accept the recent move away from viewing species as morphotypes to viewing them instead as evolutionarily independent lineages (EILs) using data from genes. EILs are recognised here in practice from the gene coalescents that provide direct evidence for their evolutionary independence. We show from fitting both general mixed Yule/coalescent (GMYC) models and Poisson-tree-process (PTP) models to data for the mitochondrial COI gene that there is support for nine species in the subgenus Alpinobombus. Examination of the more slowly evolving nuclear PEPCK gene shows further support for a previously unrecognised taxon as a new species in northwestern North America. The three pairs of the most morphologically similar sister species are separated allopatrically and prevented from interbreeding by oceans. We also find that most of the species show multiple shared colour patterns, giving the appearance of mimicry among parts of the different species. However, reconstructing ancestral colour-pattern states shows that speciation is likely to have cut across widespread ancestral polymorphisms, without or largely without convergence. In the particular case of Alpinobombus, morphological, colour-pattern, and genetic groups show little agreement, which may help to explain the lack of agreement among previous taxonomic revisions.

A new species of Megachile Latreille subgenus Megachiloides (Hymenoptera, Megachilidae).

A new species of leafcutter bee, Megachile (Megachiloides) chomskyi, is described from Texas, United States. Megachile chomskyi is one of the four known species of the oenotherae species group of Megachiloides, all members sharing the long tongue, and is most similar to Megachile (Megachiloides) amica Cresson. Like other members of the oenotherae species group, this species probably shows oligolecty with Onagraceae (Evening-Primrose Family). A diagnosis, full description of both sexes and a key to the species of the oenotherae species group are provided.

DNA barcoding a regional bee (Hymenoptera: Apoidea) fauna and its potential for ecological studies.

DNA barcoding has been evaluated for many animal taxa and is now advocated as a reliable and rapid means for species-level identification. The coming-to-light of this identification tool is timely as we are now facing perhaps the greatest rate of species loss in recent millennia. This study contributes to an ever-increasing number of published accounts of DNA barcoding successfully and accurately distinguishing animal taxa, in this instance, the bee fauna of Nova Scotia, Canada. Most members of this well-known fauna were resolved with particular clarity; the average intraspecific divergence was less than 0.5%, and COI sequences from over 75% of the province's species are now in the Barcodes of Life Data System. DNA barcoding also revealed some surprises within this fauna, including the possible recognition of two undescribed genetically unique species, one in the genus Ceratina (subgenus Zadontomerus), the second in the genus Andrena (subgenus Larandrena); both are presently receiving further taxonomic study. In addition, DNA barcoding has allowed sex-associations among two pairs of cleptoparasitic species. The resulting utility of DNA barcoding for ecological studies of bee communities is discussed.

Perfect syncarpy in apple (Malus x domestica 'Summerland McIntosh') and its implications for pollination, seed distribution and fruit production (Rosaceae: Maloideae).

BACKGROUND AND AIMS: The gynoecium of the domestic apple, Malus x domestica, has been assumed to be imperfectly syncarpic, whereby pollination of each stigmatic surface can result in fertilization within only one of the five carpels. Despite its implied effect on fruit quantity and quality, the resulting influence of flower form on seed set and distribution within the apple fruit has seldom been investigated. Instead, poor fruit quality is usually attributed to problems with pollination, such as low bee numbers and/or ineffective pollinators within apple agro-ecosystems. The objective of this study was to determine the true nature of gynoecial structure and its influence on fruit production in the apple cultivar 'Summerland McIntosh'. METHODS: A stigma-excision method was used to determine the effects of uneven pollination among the five stigmas on fruit quantity (as measured by fruit set), and quality (seed number and distribution). In addition, flowers were examined microscopically to determine pollen tube pathways. KEY RESULTS: Fruit set, seed number, seed distribution, and the microscopic examination of flower gynoecial structure reported in this study indicated that the gynoecium of the cultivar Summerland McIntosh is perfectly syncarpic and not imperfectly syncarpic as previously thought. CONCLUSIONS: Pollination levels among the five stigmas need not be uniform to obtain full seed development within Summerland McIntosh fruit; even if one stigmatic surface is adequately pollinated, a full complement of seeds is likely. The importance of perfect syncarpy in recognizing true causes of poor fruit quality in apple is discussed.