Short-term heat stress results in diminution of bacterial symbionts but has little effect on life history in adult female citrus mealybugs

Mealybugs are sap-feeding insect pests that pose a serious threat to horticulture. The citrus mealybug, Planococcus citri (Risso) (Hemiptera: Pseudococcidae), like most other mealybug species, harbours two obligate maternally transmitted bacterial endosymbionts, which are essential for nutrient acquisition and host survival. These are ‘Candidatus Tremblaya princeps’, a member of the β-Proteobacteria, and ‘Candidatus Moranella endobia’, a member of the γ-Proteobacteria. The density of symbionts in the hosts is now understood to be dynamic, being influenced by the age and gender of the host and by environmental conditions during development. Here, we examine the impact of short-term heat stress treatment on the obligate symbionts and life-history parameters of P. citri, using qPCR to measure changes in symbiont density. Heat stress killed juveniles and adult males, and significantly reduced levels of ‘Ca. Moranella endobia’ and ‘Ca. Tremblaya princeps’ in adult females. However, adult females were resilient to this and it did not affect their fecundity or brood survival, although the sex ratio of their brood was slightly, but significantly, more female biased. Our results suggest that ‘Ca. Tremblaya princeps’ and ‘Ca. Moranella endobia’ are not as essential to the survival of adult mealybugs as they are to the survival of immature mealybugs and that sub-lethal heat treatment alone is unlikely to be effective as a disinfestation tactic

Diurnal temperature variations affect development of a herbivorous arthropod pest and its predators

The impact of daily temperature variations on arthropod life history remains woefully understudied compared to the large body of research that has been carried out on the effects of constant temperatures. However, diurnal varying temperature regimes more commonly represent the environment in which most organisms thrive. Such varying temperature regimes have been demonstrated to substantially affect development and reproduction of ectothermic organisms, generally in accordance with Jensen's inequality. In the present study we evaluated the impact of temperature alternations at 4 amplitudes (DTR0, +5, +10 and + 15 degrees C) on the developmental rate of the predatory mites Phytoseiulus persimilis Athias-Henriot and Neoseiulus californicus McGregor (Acari: Phytoseiidae) and their natural prey, the two-spotted spider mite Tetranychus urticae Koch (Acari: Tetranychidae). We have modelled their developmental rates as a function of temperature using both linear and nonlinear models. Diurnally alternating temperatures resulted in a faster development in the lower temperature range as compared to their corresponding mean constant temperatures, whereas the opposite was observed in the higher temperature range. Our results indicate that Jensen's inequality does not suffice to fully explain the differences in developmental rates at constant and alternating temperatures, suggesting additional physiological responses play a role. It is concluded that diurnal temperature range should not be ignored and should be incorporated in predictive models on the phenology of arthropod pests and their natural enemies and their performance in biological control programmes

Adventitious rooting of Chrysanthemum is stimulated by a low red:far-red ratio

Adventitious rooting, a critical process in the vegetative propagation of many ornamentals, can be affected by both light intensity and light quality. We investigated the use of spectral light quality to improve adventitious rooting of Chrysanthemum morifolium cuttings by applying different combinations of blue, red and far-red light. Additionally, unrooted cuttings were treated before planting with two auxin transport inhibitors (TIBA and NPA) to study the effect of light quality on auxin biosynthesis and/or transport. Results showed that lowering the R:FR ratio (decreasing the phytochrome photostationary state, PSS) improved rooting significantly and decreased the inhibiting effect of the auxin transport inhibitor NPA. An extra decrease of PSS by adding blue light to a red + far-red spectrum further enhanced rooting. In contrast, adding blue light to solely red light decreased rooting, an effect which was more pronounced in combination with the auxin transport inhibitors TIBA and NPA. Our results show that phytochrome plays a role in adventitious root formation through the action of auxin, but that also blue light receptors interact in this process

Analyse de cycle de vie à l’échelle du quartier : un outil d’aide à la décision?

Les collectivités territoriales s’engagent dans de nombreuses actions pour limiter leurs impacts environnementaux. La ville de Paris cherche à se doter de nouveaux outils permettant de mesurer l’incidence de choix urbains ou architecturaux sur l’environnement dès la phase de conception. Les outils d’analyse du cycle de vie (ACV) permettent aujourd’hui d’évaluer les performances tout au long de la vie d’un ouvrage : construction, exploitation, fin de vie. La recherche présentée dans cet article a permis d’effectuer l’ACV de la ZAC Claude Bernard à Paris et d’observer le potentiel d’aide à la décision pour la maitrise d’ouvrage d’un tel outil.Local authorities are engaged in numerous actions in favor of the environment. The City of Paris is interested in new tools to take into account environmental impacts of their urban planning projects during the different stages of the project design. Life Cycle Assessment (LCA) tools allow environmental impacts of a building to be evaluated during its life: construction, exploitation, end of life. In this article, we test an LCA tool on an urban planning project in Paris (France) in order to analyze the relevance of LCA for assessing district impacts and being a decision support tool

Clonal expansion of community-associated meticillin-resistant Staphylococcus aureus (MRSA) in people who inject drugs (PWID)::Prevalence, risk factors and molecular epidemiology, Bristol, United Kingdom, 2012 to 2017

Background: In 2015, Bristol (South West England) experienced a large increase in cases of meticillin-resistant Staphylococcus aureus (MRSA) infection in people who inject drugs (PWID). Aim: We aimed to characterise and estimate the prevalence of MRSA colonisation among PWID in Bristol and test evidence of a clonal outbreak. Methods: PWID recruited through an unlinked-anonymous community survey during 2016 completed behavioural questionnaires and were screened for MRSA. Univariable logistic regression examined associations with MRSA colonisation. Whole-genome sequencing used lineage-matched MRSA isolates, comparing PWID (screening and retrospective bacteraemia samples from 2012-2017) with non-PWID (Bristol screening) in Bristol and national reference laboratory database samples. Results: The MRSA colonisation prevalence was 8.7% (13/149) and was associated with frequently injecting in public places (odds ratio (OR): 5.5; 95% confidence interval (CI):1.34–22.70), recent healthcare contact (OR: 4.3; 95% CI: 1.34–13.80) and injecting in groups of three or more (OR: 15.8; 95% CI: 2.51–99.28). People reporting any one of: injecting in public places, injection site skin and soft tissue infection or hospital contact accounted for 12/13 MRSA positive cases (sensitivity 92.3%; specificity 51.5%). Phylogenetic analysis identified a dominant clade associated with infection and colonisation among PWID in Bristol belonging to ST5-SCCmecIVg. Conclusions: MRSA colonisation in Bristol PWID is substantially elevated compared with general population estimates and there is evidence of clonal expansion, community-based transmission and increased infection risk related to the colonising strain. Targeted interventions, including community screening and suppression therapy, education and basic infection control are needed to reduce MRSA infections in PWID

Marine Biodiversity in the Caribbean: Regional Estimates and Distribution Patterns

This paper provides an analysis of the distribution patterns of marine biodiversity and summarizes the major activities of the Census of Marine Life program in the Caribbean region. The coastal Caribbean region is a large marine ecosystem (LME) characterized by coral reefs, mangroves, and seagrasses, but including other environments, such as sandy beaches and rocky shores. These tropical ecosystems incorporate a high diversity of associated flora and fauna, and the nations that border the Caribbean collectively encompass a major global marine biodiversity hot spot. We analyze the state of knowledge of marine biodiversity based on the geographic distribution of georeferenced species records and regional taxonomic lists. A total of 12,046 marine species are reported in this paper for the Caribbean region. These include representatives from 31 animal phyla, two plant phyla, one group of Chromista, and three groups of Protoctista. Sampling effort has been greatest in shallow, nearshore waters, where there is relatively good coverage of species records; offshore and deep environments have been less studied. Additionally, we found that the currently accepted classification of marine ecoregions of the Caribbean did not apply for the benthic distributions of five relatively well known taxonomic groups. Coastal species richness tends to concentrate along the Antillean arc (Cuba to the southernmost Antilles) and the northern coast of South America (Venezuela – Colombia), while no pattern can be observed in the deep sea with the available data. Several factors make it impossible to determine the extent to which these distribution patterns accurately reflect the true situation for marine biodiversity in general: (1) highly localized concentrations of collecting effort and a lack of collecting in many areas and ecosystems, (2) high variability among collecting methods, (3) limited taxonomic expertise for many groups, and (4) differing levels of activity in the study of different taxa

Syndicalisme confédéral européen et projet de marché transatlantique USA-UE. Un discours et/ou une stratégie, un soutien, une méfiance ou une contestation ?

info:eu-repo/semantics/nonPublishe