Microsatellite loci for the eusocial Lasioglossum malachurum and other sweat bees (Hymenoptera, Halictidae)

Sweat bees (family Halictidae) comprise a numerous and diverse group that are arguably among the most socially labile of all insect taxa. Given the lack of highly variable markers for eusocial species of the family, we developed a suite of dinucleotide and trinucleotide markers for one of its members, the Eurasian Lasioglossum malachurum, and used them to amplify DNA from other halictids. Loci were highly variable in L. malachurum and amplified DNA from many other halictids.

Characterization of 14 polymorphic microsatellite loci for the facultatively eusocial sweat bee Halictus rubicundus (Hymenoptera, Halictidae) and their variability in related species

Sweat bees display considerable variation in social organization and a few species, such as Halictus rubicundus, are even facultatively eusocial. Fourteen polymorphic, unlinked microsatellite loci were isolated from H. rubicundus and characterized in 45 females. The number of alleles per locus ranged from two to 18 (mean 10.1), observed heterozygosity ranged from 0.24 to 0.98 (mean 0.71) and expected heterozygosity ranged from 0.24 to 0.98 (mean 0.70). Six or more loci cross-amplified in four other sweat bees. These loci will be useful for the study of social evolution and population genetic structure in H. rubicundus and many other sweat bees.

Orchid bee baits attracting bees of the genus Megalopta (Hymenoptera, Halictidae) in Bauru region, São Paulo, Brazil: abundance, seasonality, and the importance of odors for dim-light bees

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

The Importance of Bees for Eggplant Cultivations (Hymenoptera: Apidae, Andrenidae, Halictidae)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

New species of North American bees of the genus Dufourea (Hymenoptera, Halictidae) with descriptions of two previously undescribed females /

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Complex sociogenetic organization and reproductive skew in a primitively eusocial sweat bee, Lasioglossum malachurum, as revealed by microsatellites

The sweat bees (Family Halictidae) are a socially diverse taxon in which eusociality has arisen independently numerous times. The obligate, primitively eusocial Lasioglossum malachurum, distributed widely throughout Europe, has been considered the zenith of sociality within halictids. A single queen heads a colony of smaller daughter workers which, by mid-summer, produce new sexuals (males and gynes), of which only the mated gynes overwinter to found new colonies the following spring. We excavated successfully 18 nests during the worker- and gyne-producing phases of the colony cycle and analysed each nest's queen and either all workers or all gynes using highly variable microsatellite loci developed specifically for this species. Three important points arise from our analyses. First, queens are facultatively polyandrous (queen effective mating frequency: range 1–3, harmonic mean 1.13). Second, queens may head colonies containing unrelated individuals (n = 6 of 18 nests), most probably a consequence of colony usurpation during the early phase of the colony cycle before worker emergence. Third, nonqueen's workers may, but the queen's own workers do not, lay fertilized eggs in the presence of the queen that successfully develop into gynes, in agreement with so-called 'concession' models of reproductive skew

Is big best? Queen size, usurpation and nest closure in a primitively eusocial sweat bee (Lasioglossum malachurum).

For primitively eusocial insects in which a single foundress establishes a nest at the start of the colony cycle, the solitary provisioning phase before first worker emergence represents a risky period when other, nestless foundresses may attempt to usurp the nest. In the primitively eusocial sweat bee Lasioglossum malachurum (Hymenoptera, Halictidae), spring foundresses compete for nests which are dug into hard soil. Nest-searching foundresses (‘floaters’) frequently inspected nests during this solitary phase and thereby exerted a usurpation pressure on resident queens. Usurpation has been hypothesised to increase across the solitary provisioning phase and favour closure of nests at an aggregation, marking the termination of the solitary provisioning phase by foundresses, before worker emergence. However, our experimental and observational data suggest that usurpation pressure may remain constant or even decrease across the solitary provisioning phase and therefore cannot explain nest closure before first worker emergence. Levels of aggression during encounters between residents and floaters were surprisingly low (9% of encounters across 2 years), and the outcome of confrontations was in favour of residents (resident maintains residency in 94% of encounters across 2 years). Residents were significantly larger than floaters. However, the relationship between queen size and offspring production, though positive, was not statistically significant. Size therefore seems to confer a considerable advantage to a queen during the solitary provisioning phase in terms of nest residency, but its importance in terms of worker production appears marginal. Factors other than intraspecific usurpation need to be invoked to explain the break in provisioning activity of a foundress before first worker emergence.

Complex sociogenetic organization and the origin of unrelated workers in a eusocial sweat bee, Lasioglossum malachurum

Sweat bees (Halictidae) exhibit great interspecific and intraspecific diversity in their social organisation, yet there is remarkably little information on the sociogenetic organisation of any species. Lasioglossum malachurum is a eusocial sweat bee with an annual lifecycle that exhibits considerable variation in its social organisation across its wide geographic range from northern to southern Europe. We collected all adults from 31 L. malachurum nests at Eichkogl, Austria, near the latitudinal centre of its distribution, and genotyped 148 workers using 5 highly variable microsatellite loci developed for this species. Nests were often queenless (48% of nests) during the second phase of worker activity, when colonies were provisioning the sexual brood. Pedigree reconstruction and estimates of nestmate genetic relatedness demonstrated that nests often (32% of nests) contained alien workers, probably as a result of worker drifting from their natal to a foreign nest. Queen effective mating frequency was variable (harmonic mean m(e) = 1.24), but sometimes high (maximum 2.7). These data demonstrate that nests of L. malachurum do not have a classical eusocial sociogenetic organisation (monogyny, monandry) and thereby pose a challenge to exclusively relatedness based arguments for the evolution of eusociality in the taxon.

Intraspecific and interspecific social variation in the sweat bee Lasioglossum Malachurum and other members of the subgenus Evylaeus

Sweat bees exhibit a range of social behaviours, from solitary nesting, in which no workers are produced, to strong eusociality, in which workers exhibit a high degree of altruism, behaviour that is measured by the degree of personal reproductive sacrifice. Field studies were carried out for seven weeks during May-June 2000 in southern Greece in order to investigate intraspecific social variation, and test the hypothesis of a north-south cline of decreasing eusociality in the obligately eusocial sweat bee L. (E.) malachurum. A comparative study, using principal components analysis, was performed to determine if patterns of intraspecific social variation in L. malachurum reflect the patterns of social variation within the subgenus, Evylaeus, as a whole. The results of the field study reveal that, in Greece, two worker broods were produced followed by a third brood consisting of gynes, males and some workers, indicating that there was an overlap in worker and gyne production. There was strong caste distinction between queens and workers. Workers actively foraged and participated in nest construction as most workers (58%, n=303) had a high degree of mandibular wear. Workers did not participate in the oviposition of Brood 3 gynes since only 0.7% (n=278) of workers were mated. Furthermore, queen survival until the end of Brood 3 and a substantial size differential of 10.6% between queens and workers suggested that queen domination over worker behaviour during the early to mid-part of the colony cycle was plausible. Male production in Brood 3 by some workers was likely, since the timing of worker ovarian development corresponded with the timing of male production. These findings suggest that workers of the first two broods were primarily altruistic, but some (28%) Brood 1 (9%) and Brood 2 (19%) workers produced males, indicating that the degree of altruistic behaviour declined during the lifetime of the colony. In comparison with other L. malachurum populations in Europe, the Greek population of L. malachurum had a weaker social level as a result of the higher proportion of workers potentially involved in male production, thus 3 supporting the hypothesis of a southerly cline of decreasing eusociality. Furthermore, intraspecific variation in social level across Europe appears to be due to longer breeding seasons in more southerly locations that would promote the production of larger colonies and provide opportunities for workers to evade queen control. The comparative study using principal components analysis on 20 solitary (of the subgenera Evylaeus and Lasioglossum), eusocial and socially polymorphic Evylaeus species and populations reveals that six traits are closely associated with stronger eusociality in Evylaeus. These traits are: (1) a reduction in the proportion of males in the early brood(s); (2) a reduction in the proportion of females that mate; (3) an increase in the mean number of first brood workers; (4) a reduction in the proportion of females with developed ovaries; (5) an increase in size dimorphism between castes, and (6) nest guarding. These are traits that most significantly define principal component one and therefore distinguish social type as indicated by a clear separation of the eusocial and the solitary populations, with a socially polymorphic species falling in between. Furthermore, most of these traits are under foundress control and may suggest that the evolutionary loss or gain of eusociality is based on selection pressures on a founding female. Colony size and female ovarian development are common factors distinguishing social variation in L. malachurum and within the subgenus as a whole. The principal components analysis excluding the solitary species and the socially aberrant L. marginatum populations show the L. malachurum populations separated based on an increasing proportion of workers with developed ovaries as populations are found more south, lending further support to the hypothesis of a north-south cline of decreasing eusociality.

Annual Variation in Bee Community Structure in the Context of Disturbance (Niagara Region, South-Western Ontario)

This study examined annual variation in phenology, abundance and diversity of a bee community during 2003, 2004, 2006, and 2008 in recovered landscapes at the southern end of St. Catharines, Ontario, Canada. Overall, 8139 individuals were collected from 26 genera and sub-genera and at least 57 species. These individuals belonged to the 5 families found in eastern North America (Andrenidae, Apidae, Colletidae, Halictidae and Megachilidae). The bee community was characterized by three distinct periods of flight activity over the four years studied (early spring, late spring/early summer, and late summer). The number of bees collected in spring was significantly higher than those collected in summer. In 2003 and 2006 abundance was higher, seasons started earlier and lasted longer than in 2004 and 2008, as a result of annual rainfall fluctuations. Differences in abundance for low and high disturbance sites decreased with years. Annual trends of generic richness resembled those detected for species. Likewise, similarity in genus and species composition decreased with time. Abundant and common taxa (13 genera and 18 species) were more persistent than rarer taxa being largely responsible for the annual fluctuations of the overall community. Numerous species were sporadic or newly introduced. The invasive species Anthidium oblongatum was first recorded in Niagara in 2006 and 2008. Previously detected seasonal variation patterns were confirmed. Furthermore, this study contributed to improve our knowledge of temporal dynamics of bee communities. Understanding temporal variation in bee communities is relevant to assessing impacts caused on their habitats by diverse disturbances.

Bee Communities in Restored Landfill Sites of Niagara Region

This study examined the impact of habitat restoration on bee communities (Hymenoptera: Apidae) of the Niagara Region, Ontario, Canada. Bee abundance and diversity was studied in three restored landfill sites: the Glenridge Quarry Naturalization Site (GQNS) in St. Catharines, Elm Street Naturalization Site in Port Colborne, and Station Road Naturalization Site in Wainfleet during 2011 and 2012. GQNS represented older sites restored from 2001-2003. Elm and Station sites represented newly restored landfills as of 2011. These sites were compared to control sites at Brock University where bee communities are well established and again to other landfills where no stable habitat was available before restoration. The objective of this study is to investigate the impact of restoration level on bee abundance and diversity in restored landfill sites of the Niagara Region. Based on the increased disturbance hypothesis (InDH) and the intermediate disturbance hypothesis (IDH), I hypothesized that bee abundance and diversity will follow two patterns. First pattern according to InDH suggest that as the disturbance decrease the bee abundance and diversity will increased. Second pattern according to the IDH bee abundance and diversity will be the highest at the intermediate level of disturbance. A total of 7 173 bees were collected using pan traps and flower collections, from May to October 2011 and 2012. Bees were classified to five families, 21 genera and sub-genera, containing at least 78 species. In 2011 bee abundance was not significantly different among restoration levels while in 2012 bee abundance was significant difference among restoration level. According to family there were no significant difference in Halictidae and Apidae abundance among restoration level while Colletidae and Megachilidae abundance were varied among restoration levels. The bee species richness was highest in the newly restored sites followed by restored control sites, and then the control site. The current study demonstrates that habitat restoration results in rapid increases in bee abundance and diversity for newly restored sites, and, further, that it takes only 2-3 years for bee assemblages in newly restored sites to arrive at the same levels of abundance and diversity as in nearby control sites where bee communities are well established.

The effects of cattle grazing on plant-pollinator communities in a fragmented Mediterranean landscape

The main aims of this study were to assess grazing impacts on bee communities in fragmented mediterranean shrubland (phrygana) and woodland habitats that also experience frequent wildfires, and to explain the mechanisms by which these impacts occur. Fieldwork was carried out in 1999 and 2000 on Mount Carmel, in northern Israel, a known hot-spot for bee diversity. Habitats with a range of post-burn ages and varying intensities of cattle grazing were surveyed by transect recording, grazing levels, and the diversity and abundance of both flowers and bees were measured. The species richness of both bees and flowers were highest at moderate to high grazing intensities, and path-analysis indicated that the effects of both grazing and fire on bee diversity were mediated mainly through changes in flower diversity, herb flowers being more important than shrubs. The abundance of bees increased with intensified grazing pressure even at the highest levels surveyed. Surprisingly though, changes in bee abundance at high grazing levels were not caused directly by changes in flower cover. The variation in bee abundance may have been due to higher numbers of solitary bees from the family Halictidae in grazed sites, where compacted ground (nesting resource) and composites (forage resource) were abundant. The effects of grazing on plants were clearest in the intermediate-aged sites, where cattle inhibited the growth of some of the dominant shrubs, creating or maintaining more open patches where light-demanding herbs could grow, thus allowing a diverse flora to develop. Overall, bee communities benefit from a relatively high level of grazing in phrygana. Although bee and flower diversity may decrease under very heavy grazing, the present levels of grazing on Mount Carmel appear to have only beneficial effects on the bee community.

New species of the bee genus Augochlorodes Moure (Hymenoptera, Apidae s. I., Halictinae)

Five new species of the bee genus Augochlorodes from Brazil are described and the type species, A. turrifaciens Moure, 1958, is redescribed. The new species are: A. clementis sp. nov. (from the states of Parana, Santa Catarina and Rio Grande do Sul), A. incomitatus sp. nov. (Rio Grande do Sul), A. politus sp. nov. (Parana), A. rostratus sp. nov. (Rio Grande do Sul) and A. vachali sp. nov. (Parana, Santa Catarina, Sao Paulo). A discriminant function analysis using head measurements is presented to help distinguish the species. An identification key for the species is provided.