Pollinator attracting odour signals in sexually deceptive orchids of the Ophrys fusca group

We investigated patterns of volatiles of several allopatric and sympatric species of the Ophrys fusca group and one species of the O. mammosa/sphegodes group pollinated by either Andrena nigroaenea or A. flavipes, using electrophysiology (gas chromatography coupled with electroantennography; GC-EAD) and chemical analyses. We found 52 GC-EAD active compounds, mainly saturated and unsaturated hydrocarbons with chain lengths of 21 to 31, aldehydes, an ester, and an acid. Based on the relative proportions of all GC-EAD active compounds, the investigated species were compared using various statistical methods (ANOVA, principle component analyses, discriminant function analyses and cluster analyses). Our results show that Ophrys species with the same pollinator – independent of their phylogenetic relationship–use the same volatiles for pollinator attraction. Differences between the species mainly involve different quantitative patterns of volatiles. Our results are in congruence with previous studies that showed different odour bouquets to be responsible for the specific attraction of different pollinators and that alkanes and alkenes are most important for pollinator attraction.     

Role of nesting resources in organising diverse bee communities in a Mediterranean landscape

Abstract.  1. The habitat components determining the structure of bee communities are well known when considering foraging resources; however, there is little data with respect to the role of nesting resources.
2. As a model system this study uses 21 diverse bee communities in a Mediterranean landscape comprising a variety of habitats regenerating after fire. The findings clearly demonstrate that a variety of nesting substrates and nest building materials have key roles in organising the composition of bee communities.
3. The availability of bare ground and potential nesting cavities were the two primary factors influencing the structure of the entire bee community, the composition of guilds, and also the relative abundance of the dominant species. Other nesting resources shown to be important include availability of steep and sloping ground, abundance of plant species providing pithy stems, and the occurrence of pre-existing burrows.
4. Nesting resource availability and guild structure varied markedly across habitats in different stages of post-fire regeneration; however, in all cases, nest sites and nesting resources were important determinants of bee community structure.     

The ethnobotany of Christ's Thorn Jujube (Ziziphus spina-christi) in Israel

This article surveys the ethnobotany of Ziziphus spina-christi (L.) Desf. in the Middle East from various aspects: historical, religious, philological, literary, linguistic, as well as pharmacological, among Muslims, Jews, and Christians. It is suggested that this is the only tree species considered "holy" by Muslims (all the individuals of the species are sanctified by religion) in addition to its status as "sacred tree " (particular trees which are venerated due to historical or magical events related to them, regardless of their botanical identity) in the Middle East. It has also a special status as "blessed tree" among the Druze.     

Flower characteristics and breeding system of two phenological ecotypes of Cyclamen persicum Mill. (Myrsinaceae) in Israel

Cyclamen persicum Mill. in Israel consists of two discrete population types that differ in their flowering (fall versus winter) as well as leafing (hysteranthous versus synanthous) phenology. The two populations have similar pollen:ovule ratios, index of self incompatibility, stigma receptivity duration, pollen longevity, flower longevity, floral morphology and seed production rate. These data indicate no apparent selective pressure on floral characteristics or on the breeding system, which may be exerted by the pollinators. The two populations retained their autonomous blooming rhythm even after transplantation, which indicated that this character was genetically determined. There are no genetic barriers and the populations may share some pollinators (Schwartz-Tzachor et al. 2006). Thus the main potential restriction on gene flow is the incomplete phenological barrier. These findings may indirectly support our hypothesis that the phenological shift is due to environmental cues. Thus it was concluded that these two types are ‘phenological ecotypes’ in the sense of Turesson (1922) due to the unequivocal delineation of both types, as revealed by the timing of leaf appearance (synanthous versus hysteranthous) without any evidence of any intermediates.     

Pollination by deceit and floral mimesis inThelymitra antennifera (Orchidaceae)

Thelymitra antennifera is found to be a general mimic of the search image of other co-blooming yellow or cream-flowered species including members of the following genera:Hibbertia, Goodenia and, to a lesser extent,Helichrysum, Pimelia andStackhousia. The most common pollinators areLasioglossum (Chilalictus) spec. and the introducedSyrphus damaster (hover fly) as well as a solitary wasp,Eurys spec.—T. antennifera acts by deceit, involving opticals (yellow colour and pollen imitation) as well as olfactory (sweet odour) signals. Capsule production is low and density dependent, a situation demonstrated in other species which have evolved pollination syndromes involving deceitful mimicry.     

Smells like aphids: orchid flowers mimic aphid alarm pheromones to attract hoverflies for pollination

Most insects are dependent on chemical communication for activities such as mate finding or host location. Several plants, and especially orchids, mimic insect semiochemicals to attract insects for unrewarded pollination. Here, we present a new case of pheromone mimicry found in the terrestrial orchid Epipactis veratrifolia. Flowers are visited and pollinated by several species of aphidophagous hoverflies, the females of which also often lay eggs in the flowers. The oviposition behaviour of these hoverflies is mainly guided by aphid-derived kairomones. We show that the flowers produce α- and β-pinene, β-myrcene and β-phellandrene, and that these compounds attract and induce oviposition behaviour in female hoverflies. This floral odour profile is remarkably similar to the alarm pheromone released by several aphid species, such as Megoura viciae. We therefore suggest that E. veratrifolia mimics aphid alarm pheromones to attract hoverflies for pollination; this is the first time, to our knowledge, that such a case of mimicry has been demonstrated.     

A Diverse Range of Bacterial and Eukaryotic Chitinases Hydrolyzes the LacNAc (Galβ1–4GlcNAc) and LacdiNAc (GalNAcβ1–4GlcNAc) Motifs Found on Vertebrate and Insect Cells

There is emerging evidence that chitinases have additional functions beyond degrading environmental chitin, such as involvement in innate and acquired immune responses, tissue remodeling, fibrosis, and serving as virulence factors of bacterial pathogens. We have recently shown that both the human chitotriosidase and a chitinase from Salmonella enterica serovar Typhimurium hydrolyze LacNAc from Galβ1–4GlcNAcβ-tetramethylrhodamine (LacNAc-TMR (Galβ1–4GlcNAcβ(CH₂)₈CONH(CH₂)₂NHCO-TMR)), a fluorescently labeled model substrate for glycans found in mammals. In this study we have examined the binding affinities of the Salmonella chitinase by carbohydrate microarray screening and found that it binds to a range of compounds, including five that contain LacNAc structures. We have further examined the hydrolytic specificity of this enzyme and chitinases from Sodalis glossinidius and Polysphondylium pallidum, which are phylogenetically related to the Salmonella chitinase, as well as unrelated chitinases from Listeria monocytogenes using the fluorescently labeled substrate analogs LacdiNAc-TMR (GalNAcβ1–4GlcNAcβ-TMR), LacNAc-TMR, and LacNAcβ1–6LacNAcβ-TMR. We found that all chitinases examined hydrolyzed LacdiNAc from the TMR aglycone to various degrees, whereas they were less active toward LacNAc-TMR conjugates. LacdiNAc is found in the mammalian glycome and is a common motif in invertebrate glycans. This substrate specificity was evident for chitinases of different phylogenetic origins. Three of the chitinases also hydrolyzed the β1–6 bond in LacNAcβ1–6LacNAcβ-TMR, an activity that is of potential importance in relation to mammalian glycans. The enzymatic affinities for these mammalian-like structures suggest additional functional roles of chitinases beyond chitin hydrolysis.     

Flybow: genetic multicolor cell labeling for neural circuit analysis in Drosophila melanogaster

To facilitate studies of neural network architecture and formation, we generated three Drosophila melanogaster variants of the mouse Brainbow-2 system, called Flybow. Sequences encoding different membrane-tethered fluorescent proteins were arranged in pairs within cassettes flanked by recombination sites. Flybow combines the Gal4-upstream activating sequence binary system to regulate transgene expression and an inducible modified Flp-FRT system to drive inversions and excisions of cassettes. This provides spatial and temporal control over the stochastic expression of one of two or four reporters within one sample. Using the visual system, the embryonic nervous system and the wing imaginal disc, we show that Flybow in conjunction with specific Gal4 drivers can be used to visualize cell morphology with high resolution. Finally, we demonstrate that this labeling approach is compatible with available Flp-FRT-based techniques, such as mosaic analysis with a repressible cell marker; this could further support the genetic analysis of neural circuit assembly and function.