Halictidae Research Articles

Queen Recognition Signals in Two Primitively Eusocial Halictid Bees: Evolutionary Conservation and Caste-Specific Perception.

Queen signals are known to regulate reproductive harmony within eusocial colonies by influencing worker behavior and ovarian physiology. However, decades of research have resulted in the identification of just a few queen signals, and studies of their mode of action are rare. Our aim was to identify queen recognition signals in the halictid bee Lasioglossum pauxillum and to analyze caste differences in the olfactory perception of queen signals in L. pauxillum and the closely related species L. malachurum. We performed chemical analyses and bioassays to test for caste differences in chemical profiles and worker behavior influenced by queen-specific compounds in L. pauxillum. Our results indicated that caste differences in the chemical profiles were mainly attributable to higher amounts of macrocyclic lactones in queens. Bioassays demonstrated a higher frequency of subordinate behavior in workers elicited by queen-specific amounts of macrocyclic lactones. Thus, macrocyclic lactones function as queen recognition signals in L. pauxillum, as in L. malachurum. Using electrophysiological analyses, we have demonstrated that queens of both tested species lack antennal reactions to certain macrocyclic lactones. Therefore, we assume that this is a mechanism to prevent reproductive self-inhibition in queens. Our results should stimulate debate on the conservation and mode of action of queen signals.

Transient dehydration of pollen carried by hot bees impedes fertilization

In the intense solar radiation of an alpine climate, small black bees often experience extremely high thoracic temperatures when they are foraging on flowers, but flies forage at lower temperatures. To explore the hypothesis that seed set could be depressed by transient dehydration of pollen at the high temperatures reached by hot bees foraging in sunshine, we compared the effectiveness of single visits by different pollinators to a bowl-shaped flower Potentilla lancinata in alpine meadows, SW China. The ratio of seed set to pollen transferred in individual flowers was monitored over 2 years, indicating that pollen deposited on stigmas by halictid bees produced lower seed set than pollen carried by flies. Scopal pollen applied to stigmas by hand gave good seed set, but in germination tests it burst more frequently than pollen from anthers, implying dehydration. Pollen grains freshly taken from the scopae of solitary bees foraging in sunshine were smaller than those taken from anthers or foraging bees in early-morning overcast conditions, implying dehydration. The effect was reversible: hand pollination showed that scopal pollen was no less effective than fly pollen after removal from the bee. Pollen carried by such bees foraging in intense sunlight in flowers became dehydrated, causing an osmotic mismatch between the pollen and the stigmas. Transient heat-induced dehydration of pollen represents a novel pathway by which climate warming may disrupt plant reproduction, and helps us understand why flies could be more effective pollinators than bees in cool, high-radiation arctic or high-altitude sites.

RED BOWL-SHAPED FLOWERS: CONVERGENCE FOR BEETLE POLLINATION IN THE MEDITERRANEAN REGION

ABSTRACT Anemone coronaria, Papaver rhoeas, Ranunculus asiaticus, and Tulipa agenensis are pollinated primarily by scarabaeid beetles (Amphicoma, Glaphyridae) and secondarily by bees (Lasioglossum marginatum Br., Halictidae, and Synhalonia plumigera Kohl, Anthophoridae). The four plant species have large bowl-shaped flowers which are orange-red in color with a black center, radial symmetry, weak scent (to humans), and filamentous stamens. It is suggested that there is a convergent evolution of red bowl-shaped flowers in the East Mediterranean region, concordant with a center of diversity in the genus Amphicoma. The floral phenology of these “Poppy guild” species correlated positively with the amount of edible pollen produced by each of them and with the visiting frequencies of their pollinators. Field experiments showed that Amphicoma beetles also preferred red, odorless flower models over odorless models of different colors, and models with a dark center over plain red ones. This evidence extends the cla...

Floral biology of Scaphochlamys (Zingiberaceae) focusing on Bornean taxa

An overview of the floral biology including floral odour analyses of twenty‐two Bornean Scaphochlamys taxa and three ex Bornean Scaphochlamys taxa was undertaken. All Scaphochlamys species investigated bloom diurnally. Pollen is released gradually, either simultaneously with stigma secretion or later (mostly within one hour). Flowers of most Scaphochlamys species were found to emit a mild odour but a few are odourless. Stigmas and anther spurs (where present) differ among the taxa investigated. Natural fruit set percentages of all species investigated were very low, up to 14.29%. Scaphochlamys species are facultatively xenogamic as the pollen/ovule ratios (P/O ratios) were high. Analysis of floral odour revealed 102 identifiable floral volatile organic compounds (VOCs), representing 31.8% of the compounds found. The volatile fraction was characterized by the aliphatics class (21.5%), monoterpenes (3.4%), irregular terpenes (0.3%) and benzenoids and phenyl propanoids (0.6%). Two pollinator guilds were found: halictid bees and Amegilla bees.

Overcoming the pollination barrier through artificial pollination in the Wild Nutmeg Knema attenuata (Myristicaceae), an endemic tree of the Western Ghats, India

The barrier to pollination and pollinator assemblage were investigated in Knema attenuata, a dioecious tree species endemic to the Western Ghats of India. It occupies an intermediate canopy stratum of the low and mid-elevation wet evergreen forests. In order to observe floral display, insect foraging and fruit development, four populations of K. attenuata were selected. The population diagram of each population was constructed by marking one female tree as the centre and male trees available at different radii from the female tree. Direct observations and swap net trapping were used to sample insects in the canopy during the flowering season of 2016 and 2017. Knema attenuata exhibited generalised pollination through diverse insects: thysanopterans (thrips), coleopterans (beetles), halictid bees, and dipterans (syrphid and phorid flies), where thrips played the major role. On analysing the floral display, it was found that the male flowers provided no rewards and thus attracted less pollinators than the female flowers. Among the four populations studied, three showed more than 70% fruit setting and the rate of abscission in flowers and young fruits were negligible. One population was without fruit setting and trials on artificial pollination resulted in fruit setting. A very low frequency of seed germination was observed in natural conditions which was enhanced by a seed germinator.

The type specimens of bees (Hymenoptera, Apoidea) deposited in the ZoologicalInstitute of the Russian Academy of Sciences, St. Petersburg. Contribution II.Family Halictidae, subfamilies Rophitinae, Nomiinae, and Nomioidinae.

The type specimens for names of bee taxa in the subfamilies Rophitinae, Nomiinae, and Nomioidinae of family Halictidae deposited in the Zoological Institute, Russian Academy of Sciences (St. Petersburg) are reviewed. Primary types of 63 taxa are illustrated and detailed information is provided (taxa include 20 described by F. Morawitz; 15 by Yu. Pesenko (one of them with N. Davydova and one with A. Pauly); ten by V. Popov; nine by P. Blüthgen; four by E. Eversmann; three by Yu. Astafurova; one by H. Friese, one by A. Ponomareva). A lectotype is designated for Nomia squamata Morawitz, 1894.

Re-thinking the social ladder approach for elucidating the evolution and molecular basis of insect societies.

The evolution of large insect societies is a major evolutionary transition that occurred in the long-extinct ancestors of termites, ants, corbiculate bees, and vespid wasps. Researchers have long used 'social ladder thinking': assuming progressive stepwise phenotypic evolution and asserting that extant species with simple societies (e.g. some halictid bees) represent the ancestors of species with complex societies, and thus provide insight into general early steps of eusocial evolution. We discuss how this is inconsistent with data and modern evolutionary 'tree thinking'. Phylogenetic comparative methods with broad sampling provide the best means to make rigorous inferences about ancestral traits and evolutionary transitions that occurred within each lineage, and to determine whether consistent phenotypic and genomic changes occurred across independent lineages.

Draft Genome Assembly and Population Genetics of an Agricultural Pollinator, the Solitary Alkali Bee (Halictidae: Nomia melanderi).

Alkali bees (Nomia melanderi) are solitary relatives of the halictine bees, which have become an important model for the evolution of social behavior, but for which few solitary comparisons exist. These ground-nesting bees defend their developing offspring against pathogens and predators, and thus exhibit some of the key traits that preceded insect sociality. Alkali bees are also efficient native pollinators of alfalfa seed, which is a crop of major economic value in the United States. We sequenced, assembled, and annotated a high-quality draft genome of 299.6 Mbp for this species. Repetitive content makes up more than one-third of this genome, and previously uncharacterized transposable elements are the most abundant type of repetitive DNA. We predicted 10,847 protein coding genes, and identify 479 of these undergoing positive directional selection with the use of population genetic analysis based on low-coverage whole genome sequencing of 19 individuals. We found evidence of recent population bottlenecks, but no significant evidence of population structure. We also identify 45 genes enriched for protein translation and folding, transcriptional regulation, and triglyceride metabolism evolving slower in alkali bees compared to other halictid bees. These resources will be useful for future studies of bee comparative genomics and pollinator health research.

Unique Metasomal Musculature in Sweat Bees (Hymenoptera: Apoidea: Halictidae) Revealed by Micro-CT Scanning

Bees of the family Halictidae (Apoidea: Anthophila) have three pairs of thick, bundled muscles that are circular to subcircular in cross section within the first metasomal segment, as revealed by micro-CT scanning of 16 species in 15 genera of five bee families. In nonhalictids and the basal halictid subfamily Rophitinae, these muscles are planar (flat and sheetlike), typically lying between the anterior air sacs and abdominal wall. In Nomiinae and Halictinae, these muscles, especially the dorsal-ventral pair, bulge into air-sac space, partly enveloped by air-sac membrane. A possible function may be to facilitate metasomal compression and contraction, and thus air flow. The bundled shape of these derived halictid muscles is similar to that of flight muscles, but further data is needed to determine if they are fibrillar, which would suggest a completely different function.

Pollination biology and reproductive phenology of the federally endangered endemic Physaria globosa (Brassicaceae) in Tennessee1

A study on the reproductive biology of the federally endangered Physaria globosa was conducted near Hartsville, TN, at one of the largest known populations of the species from February through July 2016. Objectives included (a) establishment of baseline reproductive phenology for P. globosa, (b) documentation of the diversity and frequency of floral visitors, and (c) determination of effective insect pollen vectors. Flowers were open for three days and displayed characteristics typical of outcrossing. Six insect species were identified as effective vectors for P. globosa pollen, including two dipterans and four halictid bees. While pollen loads were not significantly different among the vectors, floral visitors were ranked by frequency in descending order as follows: Nemotelus bruesii, Toxomerus geminatus, Lasioglossum illinoense, Halictus ligatus, Lasioglossum versatus, and Augochlorella striata. Information on natural history of this species is vital to aiding conservation efforts for P. globosa across its range.

The genetic basis of a social polymorphism in halictid bees.

The emergence of eusociality represents a major evolutionary transition from solitary to group reproduction. The most commonly studied eusocial species, honey bees and ants, represent the behavioral extremes of social evolution but lack close relatives that are non-social. Unlike these species, the halictid bee Lasioglossum albipes produces both solitary and eusocial nests and this intraspecific variation has a genetic basis. Here, we identify genetic variants associated with this polymorphism, including one located in the intron of syntaxin 1a (syx1a), a gene that mediates synaptic vesicle release. We show that this variant can alter gene expression in a pattern consistent with differences between social and solitary bees. Surprisingly, syx1a and several other genes associated with sociality in L. albipes have also been implicated in autism spectrum disorder in humans. Thus, genes underlying behavioral variation in L. albipes may also shape social behaviors across a wide range of taxa, including humans.

Nesting biology, seasonality and host range of sweat bee, Hoplonomia westwoodi (Gribodo) (Hymenoptera: Halictidae: Nomiinae)

Nesting biology and Seasonal dynamics of Halictid bee, Hoplonomia westwoodi (Nomiinae: Halictidae) was studied at ICAR-National Bureau of Agricultural Insect Resources (NBAIR) Bengaluru, Yelahanka Campus (13.096792N, 77.565976E) India from July 2016 to May 2017. The bee built subterranean nests on a leveled soil surface with turrets with main shaft running to a depth of 70.1 cm. In total, nineteen cells were observed in clusters at diferente depths. Different life stages of the bee were observed in the cells. The life cycle of the bee was completed in 41.80 days. The bees were found actively foraging on different flora belonging to the different families like Acanthaceae, Asteraceae, Convolvulaceae, Fabaceae, Lamiaceae, Malpighiaceae, Polygonaceae, Rubiaceae and Solanceae throughout the year with the peak population during the months of June to November. Marked preference and behavior of buzz pollination was observed on the flowers of Solanaceous crops like tomato and eggplant.

General distribution of different arthropods species associated with sunflower in Khyber Pakhtunkhwa: (A survey of Peshawar, Mardan and Swabi District:)

A field survey was carried out to record different insect pests, pollinators and natural enemies associated with sunflower, in three districts of Khyber Pakhtunkhwa i.e. Peshawar, Mardan and Swabi during 2012 and 2013. The collection was focused to recored insect pest, pollinators and natural enemies in spring and autum season on weekly basis from various sunflower fields till crop maturity. The districts were assigned as Site A (Peshawar), Site B (Mardan) and Site C (Swabi). Results showed that. Seedling and root feeding pests includedcutworm, Field crickets, Black field earwig and Grasshopper spp. Stem feeders insect included stem weevil and tree hoppers. Sucking pests were Whitefly, Leaf hoppers, Aphids and Green stink bug), defoliators included leaf beetle, Tobacco caterpillar, Cabbage semilooper and Hairy caterpillar and (Capitulum borer, Thrips, Brown stink bug and Seed Weevil recorded as capitulum or seed feeders. Apart from insect pests, honeybees, bumble bees, carpenter bees and halictid bees were recorded as pollinator associated with sunflower. Among the recorded insect pest, Lepidopterous insect were the most dominant (( milkweed butterfly, cabbage butterfly, yellow butterfly, diamondback moth and swallowtail butterflies) Followed by Dipterous insect that include, syrphid fly as pollinating agent of sunflower. Furthermore, ladybird beetle, green lacewing, praying mantis, syrphid flies, tachinid flies and certain species of spiders were the natural enemies associated insect complex of sunflower. Keywords: Arthropods; Natural enemies; Pests; Pollinators Sunflower http://dx.doi.org/10.19045/bspab.2018.700134

Evolution of Caste-Specific Chemical Profiles in Halictid Bees.

Chemical communication is crucial for the maintenance of colony organization in eusocial insects and chemical signals are known to mediate important aspects of their social life, including the regulation of reproduction. Sociality is therefore hypothesized to be accompanied by an increase in the complexity of chemical communication. However, little is known about the evolution of odor signals at the transition from solitary living to eusociality. Halictid bees are especially suitable models to study this question as they exhibit considerable variability in social behavior. Here we investigated whether the dissimilarities in cuticle chemical signals in females of different castes and life stages reflect the level of social complexity across halictid bee species. Our hypothesis was that species with a higher social behavior ergo obligate eusocial species possess a more distinct chemical profile between castes or female life stages. We analyzed cuticular chemical profiles of foundresses, breeding females and workers of ancestrally solitary species, facultative and obligate eusocial halictid species. We also tested whether social complexity was associated with a higher investment in chemical signals. Our results revealed higher chemical dissimilarity between castes in obligate than in facultative eusocial species, especially regarding macrocyclic lactones, which were the single common compound class overproduced in queens compared with workers. Chemical dissimilarities were independent of differences in ovarian status in obligate eusocial species but were dependent on ovarian status in facultative eusocial species, which we discuss in an evolutionary framework.

Parapygmephorus crossi (Acari, Heterostigmata, Neopygmephoridae), a mite species new to fauna of Iran

There are 21 genera in the family Neopygmephoridae (Acari: Heterostigmata: Pygmephoroidea) (Khaustov and Mandelshtam 2017) in which many of them are associated with various arthropods including Chilopods, spiders, bees, ants, beetles and termites (Khaustov 2017). One of the neopygmephorid genera is Parapygmephorus encompassing eight species, associated with bees of the families Halictidae, Apidae, Colletidae and Megachilidae, and in one case on a spider wasp, Pompilidae (Fan et al . 2014). These phoretic mites feed on fungi in the nests of their bee hosts and are clinging them by a large and strong single claw on their first tibiotarsus (Cross 1965). During a sampling of bees and their associate mites in Iran, the mite Parapygmephorus crossi Mahunka, 1974 (Figures 1A and 1B) recovered from Halictus ( Halictus ) resurgens Nurse, 1903 (Halictidae) (Figure 1C and 1D) in city park (Park Jangali) close to Yasouj, capital of Kohgiluyeh and Boyer Ahmad province (Southwestern Iran) on 7 Septamber 2014. Twelve specimens of phoretic mites were found attaching to body hairs of a bee host. The materials are deposited in the Acarological Collection, Department of Entomology, Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran. Mite Parapygmephorus crossi was collected and described for the first time on Halictus holtzi (Schultz) from Afghanistan (Mahunka 1974) characterized by setae ps 1 longer than ps 2 and setae ps 3 distinctly shorter than ps 2 . So, it is first record of this species in Iran and second record in the world including Palaearctic. Previously, three other species of the Parapygmephorus were collected from Iran: P . khorasanicus Hajiqanbar and Khaustov, 2011 on Halictus quadricinctus (Fabricius); P . delyorum Mahunka, 1980 on an unidentified halictid bee; and P . magnisetosus Khaustov and Zaloznaya, 2011 on Amigella sp. and Eucera sp. (Apidae), Halictus spp. and Lasioglossum sp. (Halictidae), and Lithurgus chrysurus Fonscolombe, 1834 (Megachilidae) (Hajiqanbar et al. 2011a; Hajiqanbar et al. 2011b; Hajiqanbar and Rakhshani 2011; Loghmani et al . 2014; Sobhi et al . 2017).

Social behaviour in bees influences the abundance of Sodalis (Enterobacteriaceae) symbionts.

Social interactions can facilitate transmission of microbes between individuals, reducing variation in gut communities within social groups. Thus, the evolution of social behaviours and symbiont community composition have the potential to be tightly linked. We explored this connection by characterizing the diversity of bacteria associated with both eusocial and solitary bee species within the behaviourally variable family Halictidae using 16S amplicon sequencing. Contrary to expectations, we found few differences in bacterial abundance or variation between social forms; most halictid species appear to share similar gut bacterial communities. However, several strains of Sodalis, a genus described as a symbiont in a variety of insects but yet to be characterized in bees, differ in abundance between eusocial and solitary bees. Phylogenetic reconstructions based on whole-genome alignments indicate that Sodalis has independently colonized halictids at least three times. These strains appear to be mutually exclusive within individual bees, although they are not host-species-specific and no signatures of vertical transmission were observed, suggesting that Sodalis strains compete for access to hosts. The symbiosis between halictids and Sodalis therefore appears to be in its early stages.

Does reproductive isolation reflect the segregation of color forms in Spiranthes sinensis (Pers.) Ames complex (Orchidaceae) in the Chinese Himalayas?

Isolation between species, or taxa sharing a common lineage, depends primarily on the relative strengths of various reproductive barriers. Previous studies on reproductive isolation between orchids emphasized mechanical and ethological barriers in flowers of species showing food and/or sexual mimicry. In this study, we investigated and quantified a series of prepollination and postpollination barriers between pink and white forms of Spiranthes sinensis sl, a nectar‐secreting complex. We generated ML trees based on trnS‐G and matK to explore phylogenetic relationships in this species complex. Spiranthes sinensis sl segregated from some other congeners, but the white form constituted a distinct clade in relation to the pink form. The white form secreted 2‐Phenylethanol as it is a single‐scent compound and was pollinated almost exclusively by native, large‐bodied Apis cerana and Bombus species (Apidae). Apis cerana showed a high floral constancy to this form. The scentless, pink form was pollinated primarily by smaller bees in the genera Ceratina (Apidae), and members of the family Halictidae, with infrequent visits by A. cerana and Bombus species. Fruit set and the production of large embryos following interform pollination treatments were significantly lower compared to intraform pollination results for the white form. Our results suggested that pollinator isolation, based on color and scent cues, may result in greater floral constancy in white populations when both forms are sympatric as two different, guilds of pollinators forage selectively preventing or reducing prospective gene flow. Postpollination barriers appear weaker than prepollination barriers but they also play a role in interform isolation, especially in the white form. Our findings suggest that floral color forms in S. sinensis do not represent an unbalanced polymorphism. Interpretations of the evolutionary status of these forms are discussed.

Experimental small‐scale flower patches increase species density but not abundance of small urban bees

Abstract Large flower plantings are often used to combat negative effects of habitat loss on pollinators, but whether these floral additions are effective at smaller scales remains unclear, particularly in urban settings. To test the effectiveness of small‐scale floral additions on enhancing urban bee populations, as well as their impact from 1 year to the next, different quantities of potted sweet alyssum (Lobularia maritima) flowers were placed across sites in Ann Arbor, Michigan for two consecutive years and the resulting Halictid bee visitors were monitored. Overall, we found the number of flowers added at the local level was significantly and positively correlated with small Halictid bee abundance and species density in an urban landscape. At smaller flower quantities, dynamics were clearly linear, where incremental increases in number of flowers showed significant increases in bee abundance and species density. At larger quantities of floral additions, however, dynamics were nonlinear in that incremental increases in flower quantity had no effect on bee abundance and highly variable effects on bee species density. When comparing the change in small Halictid bee abundance and species density from 1 year to the next, we found a significant increase in bee species density in the second year of small‐scale floral additions, but no significant difference in bee abundance. Synthesis and applications. Our results show that small flower plantings can have positive effects on small bee communities in urban systems even over a short period of time and therefore confirm that encouraging citizens to plant flowers can be an effective conservation strategy for certain urban pollinator populations. In addition, our finding that smaller flower plantings may have higher impacts on small pollinators than larger plantings suggests resource managers interested in pollinator conservation should consider spreading multiple, smaller floral plantings across the urban landscape, rather than pooling all resources into one large flower patch.

Studies on characters for identification of Apis and non Apis bees on coriander

Coriander is used as a strip crop to attract pollinators in order to facilitate pollination of major crops. This strip crop planting is important in determining the occurrence and abundance of pollinators in a locality. Amongst various insect pollinators, bees accomplish more than 80% of insect pollination. The wild bees including bumble bees, leaf cutting bees, alkali bees and carpenter bees are especially adapted for gathering pollen and nectar from flowers. In the present study insect pollinators were collected by fluorescent pan traps, scan sampling and sweep net during March, 2013–2014. An effort was made to study and develop keys for identification of Apis and non Apis bees. All the samples were identified on the basis of tongue length as long tongue and short tongue bees. The bees collected on coriander bloom represent the family Megachilidae, Halictidae and Apidae were found on coriander bloom. Most of the bees belong to genus Halictus having 3 different species (Family Halictidae), one species of family Megachilidae and two species of family Apidae.

Bee Contribution to Partridge Pea (Chamaecrista fasciculata) Pollination in Florida

Partridge pea (Chamaecrista fasciculata) is a common annual legume that has many important uses for humans and wildlife. During the growing season, partridge pea produces numerous flowers that are visited by many bee and wasp species. However, which bees/wasps act as the principle pollinators of partridge pea has not been explored thoroughly. We used mesh cages with different hole sizes (2.5, 0.64, 0.32, and 0.16 cm2) to screen out different sized pollinators and collected data on pod length, seed number, and percentage of pods formed per flower number (pod set). We also collected partridge pea flower insect visitors and estimated pollen loads on their bodies to determine the amount of pollen available for pollination services. Overall, partridge peas in cages with larger holes produced longer pods and more seeds compared to those in cages with smaller holes. However, no significant difference in pod set was observed among plants grown in the various size cages. Thirteen flower visitors were observed to visit open partridge pea flowers. The most common insect visitors were Bombus spp., Agapostemon splendens, and Apis mellifera. Apis mellifera contained significantly less pollen on its body compared to that on all other common bees. Likely pollinators of partridge pea in Florida are larger bees such as Xylocopa and Bombus and possibly Agapostemon splendens, a smaller halictid bee.