Mise au point d'un milieu de culture pour le dénombrement deBeauveria tenella dans les sols

Résumé Un milieu de culture permettant d'isoler et de dénombrer les colonies deBeauveria tenella parmi d'autres champignons du sol a été mis au point en vue de faciliter l'étude du comportement d'un germe entomopathogène artificiellement introduit pour lutter contre les pullulations des larves du Hanneton commun.

---

Summary A culture medium composed of 8 vegetable juices, glucose, yeast extract, dried oxgall and antibiotics (actidione, streptomycine, tetracycline) allows the isolation ofBeauveria tenella blastospores or conidiospores artificialy introduced in soil when the concentration of this inoculum varies between 100 and 40,000 spores per gram.

     

Antibody response and therapy in COVID-19 patients: what can be learned for vaccine development?

Science China Life Sciences - The newly emerged severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has infected millions of people and caused tremendous morbidity and mortality worldwide....     

Soil amendment interacts with invasive grass and drought to uniquely influence aboveground versus belowground biomass in aridland restoration

Water‐holding soil amendments such as super‐absorbent polymer (SAP) may improve native species establishment in restoration but may also interact with precipitation or invasive species such as Bromus tectorum L. (cheatgrass or downy brome) to influence revegetation outcomes. We implemented an experiment at two sites in Colorado, U.S.A., in which we investigated the interactions of drought (66% reduction of ambient rainfall), B. tectorum seed addition (BRTE, 465 seeds/m²), and SAP soil amendment (25 g/m²) on initial plant establishment and 3‐year aboveground and belowground biomass and allocation. At one site, SAP resulted in higher native seeded species establishment but only with ambient precipitation. However, by the third year, we detected no SAP effects on native seeded species biomass. Treatments interacted to influence aboveground and belowground biomass and allocation differently. At one site, a SAP × precipitation interaction resulted in lower belowground biomass in plots with SAP and drought (61.7 ± 7.3 g/m²) than plots with drought alone (91.6 ± 18.1 g/m²). At the other site, a SAP × BRTE interaction resulted in higher belowground biomass in plots with SAP and BRTE (56.6 ± 11.2 g/m²) than BRTE alone (35.0 ± 3.7 g/m²). These patterns were not reflected in aboveground biomass. SAP should be used with caution in aridland restoration because initial positive effects may not translate to long‐term benefits, SAP may uniquely influence aboveground versus belowground biomass, and SAP can interact with environmental variables to impact developing plant communities in positive and negative ways.     

Exploring movement patterns and changing distributions of baleen whales in the western North Atlantic using a decade of passive acoustic data

Six baleen whale species are found in the temperate western North Atlantic Ocean, with limited information existing on the distribution and movement patterns for most. There is mounting evidence of distributional shifts in many species, including marine mammals, likely because of climate‐driven changes in ocean temperature and circulation. Previous acoustic studies examined the occurrence of minke (Balaenoptera acutorostrata) and North Atlantic right whales (NARW; Eubalaena glacialis). This study assesses the acoustic presence of humpback (Megaptera novaeangliae), sei (B. borealis), fin (B. physalus), and blue whales (B. musculus) over a decade, based on daily detections of their vocalizations. Data collected from 2004 to 2014 on 281 bottom‐mounted recorders, totaling 35,033 days, were processed using automated detection software and screened for each species' presence. A published study on NARW acoustics revealed significant changes in occurrence patterns between the periods of 2004–2010 and 2011–2014; therefore, these same time periods were examined here. All four species were present from the Southeast United States to Greenland; humpback whales were also present in the Caribbean. All species occurred throughout all regions in the winter, suggesting that baleen whales are widely distributed during these months. Each of the species showed significant changes in acoustic occurrence after 2010. Similar to NARWs, sei whales had higher acoustic occurrence in mid‐Atlantic regions after 2010. Fin, blue, and sei whales were more frequently detected in the northern latitudes of the study area after 2010. Despite this general northward shift, all four species were detected less on the Scotian Shelf area after 2010, matching documented shifts in prey availability in this region. A decade of acoustic observations have shown important distributional changes over the range of baleen whales, mirroring known climatic shifts and identifying new habitats that will require further protection from anthropogenic threats like fixed fishing gear, shipping, and noise pollution.     

Bioassessment of benthic macroinvertebrates in wetlands: a paired comparison of two standardized sampling protocols

Wetlands Ecology and Management - We compared a rapid bioassessment protocol (Traveling Sweep Approach [TSA]) with a more conventional time intensive protocol (Composite Transect Approach [CTA]) to...     

Effect of deltamethrin-incorporated nets on mobility and survivorship of Halyomorpha halys (Hemiptera: Pentatomidae) adults and nymphs in the laboratory

The brown marmorated stink bug, Halyomorpha halys Stål (Hemiptera: Pentatomidae), is an invasive pest that attacks specialty and row crops in North America and Europe. There has been a concerted effort to reduce frequent broad-spectrum insecticide applications made on vulnerable crops. One tool that has emerged recently is the use of long-lasting insecticide-treated nets (LLINs) as a killing agent. Here, we conducted bioassays to evaluate the effect of direct contact on deltamethrin-impregnated LLINs on the behaviour and survivorship of H. halys nymphs and adults in the laboratory. Following exposure at three different durations (1.25, 4.25 or 7.25 min), vertical and horizontal mobility of adults and nymphs and the flight capacity of adults were recorded and compared with individuals that were not exposed (control). Exposure to LLINs reduced the horizontal distance and velocity and increased the angular velocity of adults only but reduced vertical mobility of adults and nymphs. Adult flights were not significantly affected by LLIN exposure. Mortality of adults and nymphs at 7-day post-exposure ranged from 73% to 77% regardless of exposure time. We discuss our findings within the context of the potential for and limitations of deploying LLINs in vulnerable crops to manage H. halys populations.     

Increased diversity and concordant shifts in community structure of coral‐associated Symbiodiniaceae and bacteria subjected to chronic human disturbance

Both coral‐associated bacteria and endosymbiotic algae (Symbiodiniaceae spp.) are vitally important for the biological function of corals. Yet little is known about their co‐occurrence within corals, how their diversity varies across coral species, or how they are impacted by anthropogenic disturbances. Here, we sampled coral colonies (n = 472) from seven species, encompassing a range of life history traits, across a gradient of chronic human disturbance (n = 11 sites on Kiritimati [Christmas] atoll) in the central equatorial Pacific, and quantified the sequence assemblages and community structure of their associated Symbiodiniaceae and bacterial communities. Although Symbiodiniaceae alpha diversity did not vary with chronic human disturbance, disturbance was consistently associated with higher bacterial Shannon diversity and richness, with bacterial richness by sample almost doubling from sites with low to very high disturbance. Chronic disturbance was also associated with altered microbial beta diversity for Symbiodiniaceae and bacteria, including changes in community structure for both and increased variation (dispersion) of the Symbiodiniaceae communities. We also found concordance between Symbiodiniaceae and bacterial community structure, when all corals were considered together, and individually for two massive species, Hydnophora microconos and Porites lobata, implying that symbionts and bacteria respond similarly to human disturbance in these species. Finally, we found that the dominant Symbiodiniaceae ancestral lineage in a coral colony was associated with differential abundances of several distinct bacterial taxa. These results suggest that increased beta diversity of Symbiodiniaceae and bacterial communities may be a reliable indicator of stress in the coral microbiome, and that there may be concordant responses to chronic disturbance between these communities at the whole‐ecosystem scale.