Antibacterial activity of Turkish propolis and its qualitative and quantitative chemical composition

The antibacterial activity of propolis from different regions of Turkey was studied, accompanied by TLC and GC-MS analyses of its chemical composition and spectrophotometric quantification of the most important active principles. All six samples were active against the bacterial test strains used; however, samples 1 (Yozgat), 2 (Izmir) and 3 (Kayseri) were more active than samples 4 (Adana), 5 (Erzurum) and 6 (Artvin). By TLC comparison all samples were found to contain poplar taxonomic markers but in samples 4 (Adana), 5 (Erzurum) and 6 (Artvin), different substances were observed, which were not present in P. nigra L. bud exudate. The typical poplar samples 1 (Yozgat), 2 (Izmir) and 3 (Kayseri) displayed very similar phenolic and flavonoid content. Samples 4 (Adana), 5 (Erzurum) and 6 (Artvin) were characterized by low phenolic and very low flavonoid concentrations. Qualitative analysis by GC-MS revealed that sample 4 (Adana) contained diterpenic acids and high percent of cinnamyl cinnamate, sample 5 (Erzurum)-significant amounts of hydroxy fatty acids and triterpenic alcohoLs, and sample 6 (Artvin)-phenolic glycerides, characteristic for the bud exudate of Populus euphratica Oliv. The results confirm the importance of phenolics for propolis antibacterial activity, and the significance of P. nigra L. as a propolis source, which provides the hive with the best defense against microorganisms.     

Phylogeny of the Augochlora clade with the description of four new species (Hymenoptera,Apoidea)

The Augochlora clade includes four genera: Augochlora Smith, Augochlorella Sandhouse, Ceratalictus Moure, and Pereirapis Moure. This is one of the richest and most widespread groups of Augochlorini bees. There are about 150 species, which occur from Argentina to Canada. The species of Augochlora clade are considered solitary to facultatively social, except Ceratalictus for which nothing is known. Wood nesting behavior arose once in the clade, in Augochlora sensu strictu. The objective of this study is to describe four new species and to present a revised phylogenetic analysis of the Augochlora clade for the placement of these species. The morphological matrix comprised 77 characters and 42 terminals, and resulted in two most parsimonious trees. The monophyly of the Augochlora clade is corroborated. Ceratalictus and Pereirapis are considered as sister groups and Ceratalictus inflexus sp. nov. came as sister to other species of Ceratalictus. Augochlora and Augochlorella are monophyletic and sister groups. Both extant subgenera of Augochlora were corroborated as monophyletic. Augochlorella comis is considered as sister group to the rest of Augochlorella species. All Augochlorella new species described belong to the Augochlorella ephyra group. Augochlorella kelliae sp. nov. is phylogenetically related to Augochlorella una. Augochlorella procliva sp. nov. and Augochlorella mavricera sp. nov. constitute a clade with Augochlorella acarinata. Including the new species, Augochlorella has 19 species and Ceratalictus 11 species. A revised key for species of Augochlorella and Ceratalictus is also presented in the Supplementary Information.     

Spectral cathodoluminescence analysis of hymenopteran mandibles with different levels of zinc enrichment in their teeth

The inclusion of Zn in insect mandibles affects their hardness and is functional to their use during feeding or reproducing. However, little is known on the chemical/structural base of Zn enrichment. Here, we found that cathodoluminescence (CL) technique revealed two different types of CL spectra in the mandibles of Hymenoptera, depending on the Zn enrichment level assessed by Energy Dispersive X-ray Spectroscopy (EDS). Individuals having negligible traces to low % of Zn in their mandible teeth (≤3 wt%) presented a wide band of luminescence in the visible range which resembled those observed in the CC structures of graphite. This spectrum is probably characteristic for un-enriched cuticle, since it did not differ from those obtained from the Zn-lacking inner part of mandibles. Individuals with moderate to high % of Zn in their mandible teeth (≥7 wt%), instead, presented additional CL peaks in the ultraviolet range. Comparisons with different minerals of Zn suggest that these peaks could be related with OZnO bonds, with hydroxyl groups and with zinc-chlorine links (in agreement with Cl high levels detected by the EDS). Being a non-destructive technique, CL allows large comparative studies of the chemistry of metal-enriched insect cuticle even using unique specimens, such as those deposited in Natural History Museums.     

The evolution of eusociality: no risk‐return tradeoff but the ecology matters

The origin of eusociality in the Hymenoptera is a question of major interest. Theory has tended to focus on genetic relatedness, but ecology can be just as important a determinant of whether eusociality evolves. Using the model of Fu et al. (2015), we show how ecological assumptions critically affect the conclusions drawn. Fu et al. inferred that eusociality rarely evolves because it faces a fundamental ‘risk‐return tradeoff’. The intuitive logic was that worker production represents an opportunity cost because it delays realising a reproductive payoff. However, making empirically justified assumptions that (1) workers take over egg‐laying following queen death and (2) productivity increases gradually with each additional worker, we find that the risk‐return tradeoff disappears. We then survey Hymenoptera with more specialised morphological castes, and show how the interaction between two common features of eusociality – saturating birth rates and group size‐dependent helping decisions – can determine whether eusociality outperforms other strategies.     

Plant–pollinator interactions in a Mexican Acacia community

Competition for pollination is thought to be an important factor structuring flowering in many plant communities, particularly among plant taxa with morphologically similar and easily accessible flowers. We examined the potential for heterospecific pollen transfer (HPT) in a community of four Acacia species in a highly seasonal tropical habitat in Mexico. Partitioning of pollen flow among sympatric species appears to be achieved, in part, through segregation of flowering in seasonal time, and interspecific differences in pollinator guilds. However, two coflowering species (Acacia macracantha and Acacia angustissima) shared multiple flower visitors, raising the possibility of HPT. Each of these coflowering species showed high intraspecific daily synchrony in pollen release, but dehisce at different times of day. Pollinators rapidly harvested available pollen from one species before abandoning it to visit the flowers of the second later in the day. The activity of shared pollinators, predominantly bees, is thus structured throughout the day, and potential for HPT reduced. Suggestive evidence in favour of a resource partitioning explanation for this pattern is provided by the fact that A. macracantha showed significantly greater intraspecific synchrony when coflowering with a potential competitor (A. angustissima) than when flowering alone. We discuss our results in light of previous work on coflowering acacia assemblages in Tanzania and Australia. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.

Tactile Conditioning And Movement Analysis Of Antennal Sampling Strategies In Honey Bees (Apis mellifera L.)

Honey bees (Apis mellifera L.) are eusocial insects and well known for their complex division of labor and associative learning capability^{1, 2}. The worker bees spend the first half of their life inside the dark hive, where they are nursing the larvae or building the regular hexagonal combs for food (e.g. pollen or nectar) and brood³. The antennae are extraordinary multisensory feelers and play a pivotal role in various tactile mediated tasks⁴, including hive building⁵ and pattern recognition⁶. Later in life, each single bee leaves the hive to forage for food. Then a bee has to learn to discriminate profitable food sources, memorize their location, and communicate it to its nest mates⁷. Bees use different floral signals like colors or odors^{7, 8}, but also tactile cues from the petal surface⁹ to form multisensory memories of the food source. Under laboratory conditions, bees can be trained in an appetitive learning paradigm to discriminate tactile object features, such as edges or grooves with their antennae^{10, 11, 12, 13}. This learning paradigm is closely related to the classical olfactory conditioning of the proboscis extension response (PER) in harnessed bees¹⁴. The advantage of the tactile learning paradigm in the laboratory is the possibility of combining behavioral experiments on learning with various physiological measurements, including the analysis of the antennal movement pattern.     

Consequences of warming up a hotspot: species range shifts within a centre of bee diversity

Aim Bees are the most important pollinators of flowering plants and essential ecological keystone species contributing to the integrity of most terrestrial ecosystems. Here, we examine the potential impact of climate change on bees’ geographic range in a global biodiversity hotspot. Location South Africa with a focus on the Cape Floristic Region (CFR) diversity hotspot. Methods  Geographic ranges of 12 South African bee species representing dominant distribution types were studied, and the climate change impacts upon bees were examined with A2 and B2 climate scenarios of HadCM3 model, using MaxEnt for species distribution modelling. Results The predicted levels of climate change‐induced impacts on species ranges varied from little shifts and range expansion of 5–50% for two species to substantial range contractions between 32% and 99% in another six species. Four species show considerable range shifts. Bees of the winter rainfall area in the west of South Africa generally have smaller range sizes than in the summer rainfall area and generally show eastward range contractions toward the dry interior. Bee species prevalent in summer rainfall regions show a tendency for a south‐easterly shift in geographic range. Main conclusions The bee fauna of the CFR is identified as the most vulnerable to climate change due to the high level of endemism, the small range sizes and the island‐like isolation of the Mediterranean‐type climate region at the SW tip of Africa. For monitoring climate change impact on bees, we suggest to establish observatories in the coastal plains of the west coast that are predicted to be worst affected and areas where persistence of populations is most likely. Likely impacts of climate change on life history traits of bees (phenology, sociality, bee‐host plant synchronization) are discussed but require further investigation.     

Butterfly, bee and forb community composition and cross-taxon incongruence in tallgrass prairie fragments

Pollinators provide an important class of ecological services for crop plants and native species in many ecosystems, including the tallgrass prairie, and their conservation is essential to sustaining prairie remnants. In Iowa these remnants are typically either block-shaped or long, linear strips along transportation routes. In this study we examined differences in the butterfly, bee, and forb community composition in linear and block prairie remnants, determined correlations between species diversity among butterflies, bees and forbs in the 20 prairie remnants sampled, and examined correlations of community similarity among butterflies, bees and forbs. Correspondence analysis showed that distinct communities exist for butterflies and forbs in block versus linear sites and discriminant analysis showed that the bee and forb communities in block and linear sites can be distinguished on the basis of a few species. Diversity of one group was a poor predictor of diversity in another, except for a significant inverse relationship between bees and butterflies. These two pollinator taxa may be responding very differently to microhabitat components within fragmented ecosystems. Our studies show that there need to be differences in conservation strategies for bees and butterflies to maintain both pollinator communities.     

Visual ecology of Indian carpenter bees I: Light intensities and flight activity

Bees are mostly active during the daytime, but nocturnality has been reported in some bee families. We studied temporal flight activity in three species of carpenter bees (genus Xylocopa) in relation to light intensities. X. leucothorax is diurnal, X. tenuiscapa is largely diurnal being only occasionally crepuscular, while X. tranquebarica is truly nocturnal. Occasional forays into dim light by X. tenuiscapa are likely to be due to the availability of richly rewarding Heterophragma quadriloculare (Bignoniaceae) flowers, which open at night. X. tranquebarica can fly even during the moonless parts of nights when light intensities were lower than 10⁻⁵ cd m⁻², which makes this species the only truly nocturnal bee known so far. Other known dim-light species fly during crepuscular or moonlit periods. We compare eye and body sizes with other known diurnal and dim-light bees. We conclude that while extremely large ocellar diameters, large eye size:body size ratio, large number of ommatidia and large ommatidial diameters are all adaptations to dim-light foraging, these alone do not sufficiently explain the flights of X. tranquebarica in extremely dim light. We hypothesise that additional adaptations must confer extreme nocturnality in X. tranquebarica.     

Reward partitioning in Capparis spp. along ecological gradient

Summary The genus Capparis is represented in Israel by three taxons of the section spinosa. The pollinators of the three taxa are hawkmoths, crepuscular bees of the genus Proxylocopa and various daily bees. However, the efficiency of the different pollinators is very varied with respect to the individual taxons. Hawkmoths were frequently observed as pollinators of C. spinosa var. aravensis and C. ovata, but rarely on C. spinosa var. aegyptia. All the other bees, on the other hand, were found abundantly on all three taxons, all over the country. The three taxa all provide different rewards for their particular pollinators. Bees visiting C. spinosa var. aegyptia are provided with a lot of pollen but a relatively small amount of nectar, with a low sugar content. C. spinosa var. aravensis and C. ovata (the flowers visited more by hawkmoths), have less pollen but a higher amount of nectar which has a higher concentration of sugar. In drier habitats the emphasis of the reward provided by the flowers is nectar, whilst in the Mediterranean habitats it is the pollen which is the reward, without any connection to the systematic origin of the plant.