Elevated rates of dietary generalization in eusocial lineages of the secondarily herbivorous bees.

BACKGROUND: Within the Hymenoptera, bees are notable for their relationship with flowering plants, being almost entirely dependent on plant pollen and nectar. Though functionally herbivorous, as a result of their role as pollinators, bees have received comparatively little attention as models for insect herbivory. Bees often display dietary specialization, but quantitative comparison against other herbivorous insects has not previously been conducted. RESULTS: In the most comprehensive analysis to date for 860 bee species, dietary specialization amounted to 50.1% of studied species collecting pollen from between 1 and 2 botanical families with a relatively long tail of dietary generalists, with 11.1% of species collecting from more than 10 botanical families. This distribution deviated from the truncated Pareto distribution of dietary breadth seen in other herbivorous insect lineages. However, this deviation was predominantly due to eusocial bee lineages, which show a range of dietary breadths that conformed to a normal distribution, while solitary bees show a typical truncated distribution not strongly different from other herbivorous insects. We hypothesize that the relatively low level of dietary specialization in bees as a whole reflects the relaxation of the constraints typically observed in herbivorous insects with a comparatively reduced importance of plant chemistry and comparatively increased importance of phenology and foraging efficiency. The long flight periods of eusocial bees that are necessary to allow overlapping generations both allows and necessitates the use of multiple flowering resources, whereas solitary bees with short flight periods have more limited access to varied resources within a constrained activity period. CONCLUSIONS: Collectively, solitary bees show slightly lower specialization compared to other herbivorous insects, possibly due to their balanced relationship with plants, rather than direct antagonism such as seen in the direct consumption of plant tissues. An additional factor may be the mediocre diversity of bees at low latitudes combined with low levels of dietary specialization, whereas these areas typically display a high rate of specialization by herbivorous insects in general. Though the most important factors structuring dietary specialization in bees appear to differ from many other herbivorous insects, solitary bees show a surprisingly similar overall pattern of dietary specialization.

Phenological shifts alter the seasonal structure of pollinator assemblages in Europe.

Pollinators play an important role in terrestrial ecosystems by providing key ecosystem functions and services to wild plants and crops, respectively. The sustainable provision of such ecosystem functions and services requires diverse pollinator communities over the seasons. Despite evidence that climate warming shifts pollinator phenology, a general assessment of these shifts and their consequences on pollinator assemblages is still lacking. By analysing phenological shifts of over 2,000 species, we show that, on average, the mean flight date of European pollinators shifted to be 6 d earlier over the last 60 yr, while their flight period length decreased by 2 d. Our analysis further reveals that these shifts have probably altered the seasonal distribution of pollination function and services by decreasing the overlap among pollinators' phenologies within European assemblages, except in the most northeastern part of Europe. Such changes are expected to decrease the functional redundancy and complementarity of pollinator assemblages and, therefore, might alter the performance of pollination function and services and their robustness to ongoing pollinator extinctions.

Author Correction: Phenological shifts alter the seasonal structure of pollinator assemblages in Europe.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Localized hypertrophy of the semimembranosus muscle in a young athlete: a case report.

Popliteal fossa and distal thigh swellings have many causes in young active adult. Cysts are the main cause, but they may also evolve from fatty tissue, lymph nodes or the popliteal artery. Semimembranosus muscle hypertrophy, found in athletes and young active adults, is only rarely the main or only cause of swelling, and only four such cases are reported in the literature. The present article reports our experience in the management of a case of semimembranosus hypertrophy as the only cause of a swelling above the popliteal fossa, and its favorable evolution.

Pollen dispersal and fruit production in Vaccinium oxycoccos and comparison with its sympatric congener V. uliginosum.

Investigating plant-pollinator interactions and pollen dispersal are particularly relevant for understanding processes ensuring long-term viability of fragmented plant populations. Pollen dispersal patterns may vary strongly, even between similar congeneric species, depending on the mating system, pollinator assemblages and floral traits. We investigated pollen dispersal and fruit production in a population of Vaccinium oxycoccos, an insect-pollinated shrub, and compared the pollen dispersal pattern with a co-flowering, sympatric congener, V. uliginosum. We examined whether they share pollinators (through interspecific fluorescent dye transfers) and may differently attract pollinators, by comparing their floral colour as perceived by insects. Fluorescent dyes were mainly dispersed over short distances (80% within 40.4 m (max. 94.5 m) for V. oxycoccos and 3.0 m (max. 141.3 m) for V. uliginosum). Dye dispersal in V. oxycoccos was not significantly affected by plant area, floral display or the proximity to V. uliginosum plants. Interspecific dye transfers were observed, indicating pollinator sharing. The significantly lower dye deposition on V. oxycoccos stigmas suggests lower visitation rates by pollinators, despite higher flower density and local abundance. The spectral reflectance analysis indicates that bees are unlikely to be able to discriminate between the two species based on floral colour alone. Fruit production increased with increasing floral display, but was not affected by proximity to V. uliginosum plants. Our study highlights that fragmented populations of V. oxycoccos, when sympatric with co-flowering V. uliginosum, might incur increased competition for the shared pollinators in the case of pollination disruption, which might then reduce outcrossed seed set.

Factors limiting the species richness of bees in Saharan Africa.

There is a severe shortage of knowledge of bee biogeography. Some former studies have highlighted a link between bee diversity and xeric ecosystems, but we know practically nothing of the macro-ecological factors driving bee diversity. The present study aims to analyse the main macro-ecological factors driving bee species-richness in the Saharan region. Our dataset includes 25,000+ records for localities in Africa, between 37 degrees and 10 degrees N. Maps and GIS were used to get a first overview of the distribution of the studied taxa. Partial least squares analysis (PLS) was used to study the impact of a set of ecological factors on the bee species richness (SR). The mapping highlighted the clustering of the highest bee SR values in some parts of the Saharan area (e.g. Maghreb, western Africa). In Central Sahara, there is an obvious topological coincidence of the high SR, the local mountain chains and the inland waters. The PLS helped to quantify the relationships between bee SR and a set of eco-climatic variables. It also highlighted a residual variance not explained by the considered descriptors. Our results recover the tight link between bee SR and xeric ecosystems. They also suggest that, within these ecosystems, bee SR is driven by an optimum of the energy-water balance (on which adjustment is allowed by the above gradients).

[Peripheral thrombopenic purpura associated with acquired toxoplasmosis]. / Purpura thrombopénique périphérique associé à une toxoplasmose acquise.

Acquired Toxoplasma Gondii infection has a benign course in adults and children immunologically competent. Thrombocytopenia is much more common during congenital toxoplasma infection and the rare cases of purpura associated with acquired toxoplasmosis are usually not thrombocytopenic. We report a case of thrombocytopenic purpura in an immunocompetent child, associated with active acquired toxoplasmosis. In rare circumstances, acquired toxoplasmosis in an immunocompetent patient may be associated with severe thrombocytopenia. However, the low incidence of such cases makes a therapeutic consensus difficult.

[Pneumatosis cystoides intestinalis. Diagnostic elements and therapeutic approach]. / La pneumatose kystique intestinale. Eléments diagnostiques et attitudes thérapeutiques.

Pneumatosis cystoides intestinalis is an uncommon condition characterised by multiple gas-filled cysts within the small intestine or colonic wall. Clinical manifestations are unspecific and often found in many other abdominal diseases. To avoid unnecessary laparotomy, radiologic and endoscopic findings are essential to be known. The present case associates symptoms highly suspect of neoplasia like weight loss, rectal mass, bloody stools and tenesmus. Treatment of choice is medical. In the absence of an acute abdomen, surgery is only reserved when it is not responsive to medical treatment.

[Cervico-facial non-Hodgkin's lymphomas. Apropos of a case of orbital localization]. / Les lymphomes non-hodgkiniens cervico-faciaux. A propos d'une localisation orbitaire.

The orbital localization of the non-Hodgkin's lymphoma is not the more common site of presentation. The most classical sites in the head and neck are the cervical lymph nodes and Waldeyer's ring. The treatment is depending on the Staging and includes radiation therapy, chemotherapy and surgery or a combination of these modalities. We describe here an orbital localization of intermediate-grade. The clinical and pathological features are discussed, and the literature is summarized.