Invasive Drosophila suzukii facilitates Drosophila melanogaster infestation and sour rot outbreaks in the vineyards.

How do invasive pests affect interactions between members of pre-existing agrosystems? The invasive pest Drosophila suzukii is suspected to be involved in the aetiology of sour rot, a grapevine disease that otherwise develops following Drosophila melanogaster infestation of wounded berries. We combined field observations with laboratory assays to disentangle the relative roles of both Drosophila in disease development. We observed the emergence of numerous D. suzukii, but no D. melanogaster flies, from bunches that started showing mild sour rot symptoms days after field collection. However, bunches that already showed severe rot symptoms in the field mostly contained D. melanogaster. In the laboratory, oviposition by D. suzukii triggered sour rot development. An independent assay showed the disease increased grape attractiveness to ovipositing D. melanogaster females. Our results suggest that in invaded vineyards, D. suzukii facilitates D. melanogaster infestation and, consequently, favours sour rot outbreaks. Rather than competing with close species, the invader subsequently permits their reproduction in otherwise non-accessible resources and may cause more frequent, or more extensive, disease outbreaks.

Landscape genetics highlights the role of bank vole metapopulation dynamics in the epidemiology of Puumala hantavirus.

Rodent host dynamics and dispersal are thought to be critical for hantavirus epidemiology as they determine pathogen persistence and transmission within and between host populations. We used landscape genetics to investigate how the population dynamics of the bank vole Myodes glareolus, the host of Puumala hantavirus (PUUV), vary with forest fragmentation and influence PUUV epidemiology. We sampled vole populations within the Ardennes, a French PUUV endemic area. We inferred demographic features such as population size, isolation and migration with regard to landscape configuration. We next analysed the influence of M. glareolus population dynamics on PUUV spatial distribution. Our results revealed that the global metapopulation dynamics of bank voles were strongly shaped by landscape features, including suitable patch size and connectivity. Large effective size in forest might therefore contribute to the higher observed levels of PUUV prevalence. By contrast, populations from hedge networks highly suffered from genetic drift and appeared strongly isolated from all other populations. This might result in high probabilities of local extinction for both M. glareolus and PUUV. Besides, we detected signatures of asymmetric bank vole migration from forests to hedges. These movements were likely to sustain PUUV in fragmented landscapes. In conclusion, our study provided arguments in favour of source-sink dynamics shaping PUUV persistence and spread in heterogeneous, Western European temperate landscapes. It illustrated the potential contribution of landscape genetics to the understanding of the epidemiological processes occurring at this local scale.

Does natural larval parasitism of Lobesia botrana (Lepidoptera: Tortricidae) vary between years, generation, density of the host and vine cultivar?

Populations of European grapevine moth Lobesia botrana Denis & Schiffermüller and its larval parasitoids were studied for two consecutive years on an experimental insecticide-free vineyard in France planted with adjacent plots of five grape cultivars (Merlot, Cabernet Franc, Sauvignon, Cabernet Sauvignon and Sémillon) using a natural L. botrana population during the first year, and a natural population supplemented with artificially inoculated individuals during the second year. Levels of natural populations of larval parasitoids were measured by their parasitism rate. The ichneumonid Campoplex capitator Aubert was the most common species collected from L. botrana larvae. Its incidence was higher during the spring compared to summer. The overall parasitism rate found on the experimental vineyard varied from 23% in 2000 to 53% in 2001, and was mainly due to C. capitator. Parasitism was not affected by the grape cultivar on which the host developed but was positively correlated with the host density, per bunch or per stock, suggesting that among the five grape cultivars tested, C. capitator females probably do not discriminate between hosts feeding on different grape cultivars, but rather the densities of L. botrana larvae.

Changes in bone collagen markers and in bone density in hormone treated and untreated postmenopausal women.

OBJECTIVE: This study aims to compare bone mineral density measurements (BMD), pyridinium crosslink levels and pyridinium crosslink levels in untreated and hormone treated postmenopausal women. METHODS: A cross-sectional study comparing biophysical (BMD) and biochemical (pyridinium crosslink and PCICP) parameters in a group of untreated postmenopausal women (n = 145) to a group of postmenopausal women on hormone replacement therapy (HRT) (n = 92). RESULTS: Untreated postmenopausal women compared to postmenopausal women on HRT had higher Osteoblastic and Osteoclastic activity. Procollagen I C-end terminal peptide (PCICP) was 11.3% lower in the women on HRT compared to controls whilst crosslinks were 27.2% lower than in controls. This seems to indicate that women on HRT had a bone balance that was higher compared to the control group (15.9%). The difference in bone density of L2-L4 between the two groups was (16.1%). CONCLUSIONS: This study seems to indicate that postmenopausal women receiving HRT readjust their bone remodelling so that although osteoblastic function is reduced, there is a much greater deduction in osteoclastic function and this results in an overall higher bone mass observed in the BMD of women on HRT.

Stereological study of tissue compartments of the human spleen.

Morphometric reports on animal and human spleen are very few and no studies have been carried out using stereological methods to investigate all of the tissue compartments of the human spleen. Eighteen samples of spleens, which were either surgically removed after traumatic injury or during treatment for early stage carcinoma or gastric ulcer, were investigated. The point-counting method was used to study the volume densities of the following tissue compartments: red pulp, perifollicular zone, white pulp (this tissue compartment was divided in two subcompartments: follicles and periarteriolar lymphatic sheath), marginal zone and connective tissue of trabeculas. The following stereological parameters of the follicles were investigated: the number of follicles per mm2 of spleen section, numerical density, volume density, and the mean follicular diameter. The identity of spleen tissue compartments was verified using immunohistochemical staining for B- and T-lymphocytes. The volume densities of tissue compartments, as well as stereological parameters of lymphoid follicles, were similar in both groups of splenic samples, except for the volume densities of perifollicular zone and periarteriolar lymphatic sheath, where a statistically significant difference was registered.

Stereologic study of splenic tissue compartments from traumatically injured and cancer patients.

Carefully age-matched groups of patients, surgically treated for either traumatic injury (n = 5; mean = 71.2 years) or for early stage carcinoma (n = 5; mean = 74.2 years), were used to investigate all the splenic tissue compartments applying model-based stereology. The point-counting method was utilized to study the volume densities of following tissue compartments: red pulp, perifollicular zone, white pulp (this compartment was divided into two subcompartments: follicles and periarteriolar lymphatic sheath), marginal zone and connective tissue. The following stereologic parameters of lymphoid follicles were determined: areal numerical density (the number of follicles per mm2 of tissue section), the numerical density (number of follicles per mm3 of tissue), and the mean follicle diameter. The identity of tissue compartments was verified using immunohistochemical staining for B- and T- lymphocytes. Significantly increased volume densities of perifollicular zone and periarteriolar lymphatic sheath were registered in patients treated for traumatic spleen injury. On the other hand, the significantly increased number of lymphoid follicles per mm2 and per mm3 of splenic tissue were registered in the group of cancer patients. The differences observed, whether attributable to the immune stimulation of the ruptured spleen or the alterations of the immune system due to malignant disease, suggest that this issue deserves further attention.