Lasioglossum (Dialictus) tenax (Sandhouse) (Hymenoptera: Halictidae) as a solitary sweat bee

Summary Nine nests ofLasioglossum (Dialictus) tenax were excavated near Calgary, Alberta, Canada over a time period encompassing the entire brood production period in 1988. Each nest contained a maximum of one active adult female, nest productivity peaked in mid July, protandry was noted and no significant size difference between foundresses and the earlier emerging females was detected. These data suggest that this species is solitary. These results are compared with data for the sympatrically nesting eusocial speciesL. (D.) laevissimum.     

Invasion of Nests of Lasioglossum imitatum by a Social Parasite,Paralictus asteris (Hymenoptera: Halictidae)

Paralictus asteris Mitchell is a socially parasitic sweat bee that invades nests and becomes the dominant reproductive in colonies of a phylogenetically related host, Lasioglossum (Dialictus) imitatum (Smith). The parasite has a greatly enlarged quadrate head, with elongate scythe-like mandibles, and other morphological modifications apparently associated with a parasitic lifestyle. Nevertheless, the parasite did not forcefully enter nests. Host guards adopted a defensive posture at the nest entrance when they contacted a dead, frozen parasite, suggesting that they recognized the intruders as parasites. Living parasites, however, only sometimes induced this guarding response, while in other cases parasites entered host nests without obvious signs of aggression from the guard. Guards also responded aggressively to both frozen and living conspecifics from other nests, but were not aggressive to living or frozen nest-resident conspecifics, suggesting that the cues used for recognition of both unrelated conspecifics and parasites are chemical ones. More than one parasite can invade and occupy a nest, and successful invasion was not influenced by whether a parasitic female was mated or had developed ovaries.     

Taxonomic notes on Lasioglossum (Lasioglossum) subopacum (Smith) and L. (L.) okinawa Ebmer et Maeta (Hymenoptera, Halictidae) from Asia

Lasioglossum (Lasioglossum) subopacum (Smith) is recorded from the Korean Peninsula for the first time. Lasioglossum (Lasioglossum) okinawa Ebmer et Maeta from Japan is ranked to a subspecies of Lasioglossum (Lasioglossum) subopacum judging from the characteristics of the male. The male of Lasioglossum (Lasioglossum) subopacumokinawa is described for the first time. Some bionomical notes of both subspecies are presented.     

Colony dynamics in a primitively eusocial halictine beeLasioglossum (Dialictus) zephyrum (Hymenoptera: Halictidae)

Summary Proximate control of colony dynamics was studied in the primitively eusocial halictine beeLasioglossum (Dialictus) zephyrum using allozyme markers. The results indicate that workers produce on average 15% of the male brood (range=0–50%) in small laboratory colonies made up of unrelated, single-generation, uninseminated females. This proportion is not influenced by colony size, but is influenced by the relative size of the queen. Large queens are more successful in dominating their workers than are small queens, the queen being defined as the female that is the mother of most of the brood produced in the colony. Older and larger females tend to become queens. Thus, while small differences in age (up to 4 days) influence which female becomes a queen, her ability to control her workers is primarily influenced by her relative size. The proportion of reproduction that is co-opted by the queen is negatively correlated with colony reproductivity (the number of males/day/female). Colony reproductivity is also negatively correlated with the standard deviation in size among females.     

Nesting biology of tropical solitary and social sweat bees,Lasioglossum (Dialictus) figueresi Wcislo andL. (D.) aeneiventre (Friese) (Hymenoptera: Halictidae)

Summary The nesting biology of a mainly solitary bee,Lasioglossum (Dialictus) figueresi, is compared with that of a possible relative and mainly eusocial bee,L. (D.) aeneiventre. These bees nest in the ground in highly disturbed areas in the Meseta Central of Costa Rica. Information is provided on social organization, male production, diel and seasonal activity patterns, pollen utilization, natural enemies and nest architecture. L. (D.) figueresi nests within aggregations in vertical earthen banks, and 80–90 % of females are solitary during the nest-provisioning phase. Social nests contain two (or rarely three) females which may be either equal or unequal in reproductive status (i.e. mated with developed ovaries or not). Solitary nests and two-female nests do not experience different rates of parasitism. Mid-way through the dry season, females cease provisioning at a time when otherL. (Dialictus) remain active. Females typically remain within their nests, although they occasionally forage for nectar. This behavior is similar of that of spring gynes of temperate eusocial species. The egg-to-adult developmental rate ofL. (D.) figueresi is unusually slow for halictine bees, however, so that all the adult females die before their brood eclose in April and May, precluding overlap of generations. The eclosed offspring remain in open cells within their natal nests until mid-June, when both males and females emerge to mate. These newly mated females either establish new nests or re-use old ones. L. (D.) aeneiventre nests within aggregations in horizontal ground or in vertical banks. A foundress female digs a nest at the beginning of the dry season, although some re-activate old nests. Foundress nests develop into colonies with various kinds of social organization. In contrast toL. (D.) figueresi, L. (D.) aeneiventre is active nearly all year round, except during periods of heavy rain, and produces up to three broods per year.Sweat bees (Hymenoptera: Halictinae) are a socially heterogeneous group of mainly ground-nesting bees which are abundant world-wide. Intra-specific variation in social behavior is prevalent both within and among populations, presumably indicating social and environmental control of behavioral modifications (see e.g. Sakagami and Munakata, 1972; Eickwort, 1986; Packer, 1990; Yanega, 1988; reviewed in Michener, 1990). The initial stages of hymenopteran social evolution are represented by solitary individuals and those in undifferentiated societies, yet their biology is not well known, as is true for the numerous tropical halictine species or populations (see Michener, 1990).The subgenusDialictus ofLasioglossum is a primarily New World group of several hundred species (Moure and Kurd, 1987). These bees are monotonously similar in structure and appearance, yet diverse in social behavior. FemaleLasioglossum (Dialictus) figueresi are usually solitary, and structurally are very similar to their social relativeL. (D.) aeneiventre (Wcislo, 1990 a). The systematic placement of these species with respect to otherL. (Dialictus) is uncertain, but they have no obvious affinities to other recognized species groups (G. C. Eickwort, pers. comm.). Unusual morphological features, such as large size, yellowish wings and pubescence, and features of the genital organs, may indicate thatL. (D.) figueresi is the more derived of the pair, and may therefore be secondarily solitary, as is known for other sweat bees (Packer, 1991).     

Structure of reef fish communities in Catalinas Islands and Ocotal beach, North Pacific of Costa Rica

The reefs are heterogeneous systems that maintain a high diversity of organisms. Fish community structure varies within and among reefs, so it would be expected that reef structure and heterogeneity should affect fish communities inhabiting reefs. Four reef patches at Catalinas Islands (Sur, La Pared, Roca Sucia and Sombrero) and one in Ocotal beach (10 degrees 28'45" N; 85 degrees 52'35" W) were studied with visual censuses (July-December 2003). The structure and composition of fishes between Catalinas islands and Ocotal beach were different, and habitat structure and composition explain most of the variance founded. The presence of the fleshy algae Caulerpa sertularioides in Ocotal, and the corals Tubastrea coccinea and Pocillopora spp. at Catalinas Island explained the variability among sites and how it affected fish community structure and composition. The butterfly fish Johnrandallia nigrirostris, damselfish Microspathodon dorsalis, and surgeon fish Prionurus punctatus were directly correlated with the ahermatipic coral Tubastrea coccinea in Roca Sucia reef, while the angel fish Holacanthus passer was associated to reefs with a major percentage of rocky substrate. Other species such as the damselfish Abudefduf troschelli and Halichoeres dispilus were more abundant at Ocotal, where the algae C sertularioides dominated. The number and abundance of reef fishes was directly correlated with the rugosity index at the reefs of Roca Sucia and Ocotal, but not at reefs of La Pared and Sombrero.     

中国淡脉隧蜂亚属二新种记述(膜翅目,隧蜂科)

记述隧蜂科淡脉隧蜂属淡脉隧蜂亚属2新种,横皱淡脉隧蜂Lasioglossum(Lasioglossum)transruginosum Zhang,Niu et Zhu,sp.nov.和内蒙淡脉隧蜂L.(L.)neimengensis Zhang,Niu et Li,sp.nov.,模式标本保存于中国科学院动物研究所动物标本馆和云南农业大学昆虫标本室。     

Australian Lasioglossum + Homalictus form a monophyletic group: resolving the "Australian enigma"

The bee genus Lasioglossum includes > 1,000 species of bees distributed on all continents except Antarctica. Lasioglossum is a major component of the bee fauna in the Holarctic, Ethiopian, and Asian regions and is an important group for investigating the evolution of social behavior in bees. Given its cosmopolitan distribution, the historical biogeography of the genus is of considerable interest. We reconstructed phylogenetic relationships among the subgenera and species within Lasioglossum s.s., using DNA sequence data from a slowly evolving nuclear gene, elongation factor-1 alpha. The entire data set includes > 1,604 aligned nucleotide sites (including three exons plus two introns) for 89 species (17 outgroups plus 72 ingroups). Parsimony and maximum likelihood analyses provide strong evidence that the primarily Indoaustralian subgenera (Homalictus, Chilalictus, Parasphecodes) form a monophyletic group. Bootstrap support for the Australian clade ranged from 73% to 77%, depending on the method of analysis. Monophyly of the Australian Lasioglossum suggests that a single colonization event (by way of Southeast Asia and New Guinea) gave rise to a lineage of > 350 native Indoaustralian bees. We discuss the implications of Australian monophyly for resolving the "Australian enigma"--the similarity in social behavior among the Australian halictine bees relative to that of Holarctic groups.     

Osmotic adjustment as a mechanism of dehydration postponement in chickpea (Cicer arietinum L.) leaves

The objectives of this study were to test the existence of osmotic adjustment in a field-grown chickpea (Cicer arietinum L.) and to reproduce it in controlled conditions for a more complete study. In a first experiment, carried out in the field with the cultivar Casoar, we described two types of drought stress that a field-grown chickpea could experience during flowering in our conditions. They were characterized with soil and plant water status. Osmotic adjustment was taking place when the stress increased progressively. This evidence was obtained with the measurement of plant water potential and relative water content during a drying-rewatering cycle. In a second experiment, carried out in pots with rain shelter, with cultivars Casoar and Sombrero, we reproduced this particular type of drought stress, on the basis of soil water potential. Measurement of plant water status was based on water, osmotic, and turgor potentials, and relative water content. It showed that chickpea is able to realize osmotic adjustment during a controlled drying-rewatering cycle limited in intensity and duration. The analysis of a broad range of solutes (nitrate, sucrose, glucose, proline, malic acid and six other organic acids) gave a good explanation of the measured reduction of osmotic potential. Organic acids accounted for most of this reduction: 97% for Casoar and 96% for Sombrero. Malic acid, which represented about half of these acids, and malonic acid significantly accumulated during the drought stress. They explained 78.2% (for Casoar) and 75.8% (for Sombrero) of the reduction of osmotic potential. Cultivar Sombrero was the only one able to accumulate some sucrose.     

Characterization of microsatellite loci from the solitary sweat bees Lasioglossum leucozonium and Lasioglossum oenotherae (Hymenoptera,Halictidae)

Microsatellite loci were isolated from two solitary sweat bees: the polylectic Lasioglossum leucozonium (10 loci) and the oligolectic Lasioglossum oenotherae (9 loci) (Hymenoptera, Halictidae). All loci were polymorphic with high observed heterozygosities (0.07–0.75 for L. leucozonium; 0.06–0.92 for L. oenotherae). These loci will be used to study the consequences of diet specialization on the population and conservation genetics of bees.     

Hybridization and asymmetric introgression between <Emphasis Type="Italic">Rhododendron eriocarpum</Emphasis> and <Emphasis Type="Italic">R. indicum</Emphasis> on Yakushima Island,southwest Japan

We examined natural hybridization between two morphologically and ecologically divergent species on Yakushima Island-the light-purple flowered Rhododendron eriocarpum native to seaside habitats and the red flowered R. indicum native to riverside habitats. By investigation of morphological traits and amplified fragment length polymorphisms (AFLP) we found that hybrid individuals morphologically and genetically intermediate between the two species grow mainly in the seaside areas of the island. The degree of morphological and genetic variation was different among the seaside hybrid populations. Although most pollinator species were exclusive to one of the two flower color groups, the halictine bees of Lasioglossum were observed in both the color types. The crucial interspecific incompatibility after pollination has not been previously described. Geographic distance between the populations is likely to be an important primary factor in bringing about natural hybridization and determining the degree of introgression between R. eriocarpum and R. indicum. The fact that hybrids occur mostly in the seaside area on Yakushima Island indicates that asymmetrical introgression occurs from R. indicum to R. eriocarpum. Alternatively, strong habitat-mediated selection from recurrent floods may prevent the hybrids from colonizing riverside habitats.     

Phylogeny of eusocial Lasioglossum reveals multiple losses of eusociality within a primitively eusocial clade of bees (Hymenoptera: Halictidae)

We performed a phylogenetic analysis of the species, species groups, and subgenera within the predominantly eusocial lineage of Lasioglossum (the Hemihalictus series) based on three protein coding genes: mitochondrial cytochrome oxidase I, nuclear elongation factor 1alpha and long-wavelength rhodopsin. The entire data set consisted of 3421 aligned nucleotide sites, 854 of which were parsimony informative. Analyses by equal weights parsimony, maximum likelihood, and Bayesian methods yielded good resolution among the 53 taxa/populations, with strong bootstrap support and high posterior probabilities for most nodes. There was no significant incongruence among genes, and parsimony, maximum likelihood, and Bayesian methods yielded congruent results. We mapped social behavior onto the resulting tree for 42 of the taxa/populations to infer the likely history of social evolution within Lasioglossum. Our results indicate that eusociality had a single origin within Lasioglossum. Within the predominantly eusocial clade, however, there have been multiple (six) reversals from eusociality to solitary nesting, social polymorphism, or social parasitism, suggesting that these reversals may be more common in primitively eusocial Hymenoptera than previously anticipated. Our results support the view that eusociality is hard to evolve but easily lost. This conclusion is potentially important for understanding the early evolution of the advanced eusocial insects, such as ants, termites, and corbiculate bees.     

The response to fire by two eusocial bee species

相似文献   

Disease in scleractinian corals: a new problem in the reef at Cayo Sombrero, Morrocoy National Park, Venezuela?

At the beginning of 1996 coral reefs in Morrocoy National Park, Venezuela, suffered an unprecedented mass mortality event. As a consequence, live coral cover dropped to 2-10%. One of the few reefs that kept live coral cover over 35% was Cayo Sombrero; nonetheless, the presence of some coral diseases has been detected within the past 2 years, representing a new source of coral mortality. Due to this situation, this study started a monitoring program on the incidence of coral diseases and syndromes in the reef of Cayo Sombrero. The CARICOMP protocol was used in order to evaluate reef health. Ten parallel band-transects (20 x 2m) where established at two depth intervals: Five between 3-8 m and five between 8-12 m, and the frequency of both, healthy and unhealthy colonies of each coral species was recorded along each band transect. In addition to other sources of coral damage (predation, siltation, etc), significant differences in disease incidence between the two depths intervals were tested with a Kruskall-Wallis test. The main problems observed were coral diseases such as yellow band (4.2%), dark spots (1.61%) and white plague-II (1.4%), mainly affecting Montastraea faveolata, M. annularis and Siderastrea siderea. Siltation, affecting massive colonies, such as Colpophyllia natans and Diploria strigosa; algae overgrowth, predation, anchor damage, and bleaching. Significant differences were found in the incidence of unhealthy (Kruskall-Wallis, p < 0.05) bleached (Kruskall-Wallis, p < 0.05) and colonies affected by siltation (Kruskall-Wallis, p < 0.05). More than 60% of the 585 coral colonies surveyed at both depths were found to be healthy, indicating that the Cayo Sombrero reef is still in good conditions compared to other localities in the Park. This study stresses the need to conduct early monitoring programs that survey coral disease incidence as a source of mortality for this coral reef.     

Pollination of the lady's slipper Cypripedium henryi Rolfe (Orchidaceae)

The pollination ecology of Cypripedium henryi Rolfe, a slipper orchid endemic to west China, was investigated, and its floral shape, size, colour, and scent were analysed. Examination of the breeding system suggests that the flowers are self-compatible, but need pollen vectors for successful reproduction. The flower is rewardless; over 15 insects belonging to Araneida, Hymenoptera, Diptera, Lepidoptera, and Coleoptera were recorded as flower visitors, but most only alighted or rested on the flower. In the total 32 h of observations over 2 years, female Lasioglossum bees were found to be the most frequent visitors and the only pollinators. They showed a high visitation frequency and, surprisingly, re-visited the same flowers frequently. Cypripedium henryi probably attracts pollinators visiting the flowers through general food deception (odour components, colour, false nectar guides), as well as special structures (slippery labellum, slippery staminode). Although three Lasioglossum species visited the flowers, only L. sauterum Fan et Ebmer was found with pollen. Lasioglossum flavohirtum Ebmer was large and climbed out from the entrance. Morphologically, L. sichuanense Fan et Ebmer could be considered as a potential pollinator, but the collected specimens were found to have no pollen of C. henryi on their bodies. It was speculated that the particular floral scent of C. henryi discouraged the entrance of L. sichuanense bees. Lasioglossum sauterum was matched morphologically to the flower, but not all of the visitations resulted in effective pollinations, as some flowers of C. henryi were frequently re-visited and the pollen mass had been taken away by bees on previous visitations. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society , 2008, 156 , 491–499.     

Seasonal changes in ovarian state in a eusocial halictine bee,Lasioglossum duplex,based on stages of the oldest oocytes in each ovariole (Hymenoptera: Halictidae)

Summary The changes in ovarian activity in the life cycle of the eusocial halictine beeLasioglossum (Evylaeus) duplex (Dalla Torre) was studied in both queens and workers by examining the stages of the terminal follicle in each of the six ovarioles. By this method, ovarian activities of both queens and workers were more quantitatively determined than by observation of gross ovarian features as usually conducted. Queen ovaries clearly exhibited two active periods, corresponding to the spring solitary phase and the summer eusocial phase, with distinctly greater activity in the latter. In ovaries of overwintering queens oosorption of young follicle was observed. Worker ovaries were found more active in orphan than in queenright colonies. The order of ovarian activity obtained from pooled data, summer queens>spring queens>orphan workers>queenright workers, was also recognized by comparison of individual females. Bionomics of the eusocial halictine beeLasioglossum duplex IX. Contribution No. 3107 from the Inst. Low Temp. Sci.     

Foraging ecology of a local wild bee community in an abandoned Satoyama system in Kanazawa, Central Japan

Satoyama is a traditional land management system in Japan that emphasizes the importance of a harmonious relationship between humans and their environment. It has been in a state of abandonment and destruction since the late 1960s. In 2000, the Japanese government initiated a new environment policy encouraging the use of Satoyama in biodiversity reservation areas. Before the initiation of active restoration works, an assessment of the potential of the Satoyama system is needed. To assess this potential, a study that focused on the foraging ecology of wild bees in a small abandoned Satoyama terraced paddy was carried out from June to October 2003. A total of 372 foraging bees belonging to 35 species in nine families was collected: two species of social bee ( Apis cerana and Bombus diversus ) and two of solitary bee ( Lasioglossum japonicum and Lasioglossum ohei ) dominated. The foraging activities of wild bees were highly influenced by the requirement of food for the colony and the active time of solitary bees. In the study, most wild bees showed a strong preference for abundant flowering plant species that produced a large number of flowers ( Achyranthes japonica and Polygonum thunbergii ). The results showed that an abandoned Satoyama system was an agricultural system that benefited pollinating bees. Careful and planned restoration practices to increase the diversity of foraging resources, microenvironment diversity and potential nesting areas for wild bees are needed to improve the ability of the Satoyama system to support more diverse and abundant wild bee populations.     

Pollination of Cypripedium plectrochilum (Orchidaceae) by Lasioglossum spp. (Halictidae): the roles of generalist attractants versus restrictive floral architecture

The pollination of Cypripedium plectrochilum Franch. was studied in the Huanglong Nature Reserve, Sichuan, China. Although large bees (Bombus, Apis), small bees (Ceratina, Lasioglossum), ants (Formica sp.), true flies (Diptera) and a butterfly were all found to visit the flowers, only small bees, including three Lasioglossum spp. (L. viridiclaucum, L. sichuanense and L. sp.; Halictidae) and one Ceratina sp., carried the flower's pollen and contacted the receptive stigma. Measurements of floral architecture showed that interior floral dimensions best fit the exterior dimensions of Lasioglossum spp., leading to the consistent deposition and stigmatic reception of dorsally-placed, pollen smears. The floral fragrance was dominated by one ketone, 3-methyl-Decen-2-one. The conversion rate of flowers into capsules in open (insect) pollinated flowers at the site was more than 38%. We conclude that, while pigmentation patterns and floral fragrance attracted a wide variety of insect foragers, canalization of interior floral dimensions ultimately determined the spectrum of potential pollinators in this generalist, food-mimic flower. A review of the literature showed that the specialised mode of pollination-by-deceit in C. plectrochilum, limiting pollinators to a narrow and closely related guild of 'dupes' is typical for other members of this genus.     

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.