Intraguild predation between an exotic and a native coccinellid in Argentina: the role of prey density

Journal of Pest Science - Harmonia axyridis Pallas is a generalist predator native to Asia. It has been released both for classical and neoclassical biological control programs worldwide. Its...     

Biofilm development in micro-irrigation emitters for wastewater reuse

Laboratory experiments were carried out to investigate bioclogging on three types of online emitters using synthetic wastewater filtered at 10 μm (COD = 200 mg L^?1). The three types of emitters were as follows: non-pressure-compensating emitters delivering 2 L h^?1 (NPC2), non-pressure-compensating emitters delivering 4 L h^?1 (NPC4) and pressure-compensating emitters delivering 2.2 L h^?1 (PC). They were plugged on two parallel pipe diameters (16 and 20 mm). Emitter performance was followed by flow rate measurements. The results showed that PC emitters seemed to be more sensitive to clogging than NPC emitters. Biofilm was observed mainly on NPC flow paths and PC membranes; its presence was also confirmed by the assessment of different water quality parameters such as total organic carbon and pH. Experimental results compared with a model designed with computational fluid dynamics Software (ANSYS Fluent^®) showed relations between biofilm development and velocity distribution on NPC flow paths. Finally, pipe diameter also appeared to be a parameter inducing emitter clogging.     

Quantitative transmission characteristics of different H5 low pathogenic avian influenza viruses in Muscovy ducks

EU annual serosurveillance programs show that domestic duck flocks have the highest seroprevalence of H5 antibodies, demonstrating the circulation of notifiable avian influenza virus (AIV) according to OIE, likely low pathogenic (LP). Therefore, transmission characteristics of LPAIV within these flocks can help to understand virus circulation and possible risk of propagation. This study aimed at estimating transmission parameters of four H5 LPAIV (three field strains from French poultry and decoy ducks, and one clonal reverse-genetics strain derived from one of the former), using a SIR model to analyze data from experimental infections in SPF Muscovy ducks. The design was set up to accommodate rearing on wood shavings with a low density of 1.6 ducks/m²: 10 inoculated ducks were housed together with 15 contact-exposed ducks. Infection was monitored by RNA detection on oropharyngeal and cloacal swabs using real-time RT-PCR with a cutoff corresponding to 2–7 EID50. Depending on the strain, the basic reproduction number (R₀) varied from 5.5 to 42.7, confirming LPAIV could easily be transmitted to susceptible Muscovy ducks. The lowest R₀ estimate was obtained for a H5N3 field strain, due to lower values of transmission rate and duration of infectious period, whereas reverse-genetics derived H5N1 strain had the highest R₀. Frequency and intensity of clinical signs were also variable between strains, but apparently not associated with longer infectious periods. Further comparisons of quantitative transmission parameters may help to identify relevant viral genetic markers for early detection of potentially more virulent strains during surveillance of LPAIV.     

IMAGING DIAGNOSIS—EXTRAHEPATIC BILIARY TRACT OBSTRUCTION SECONDARY TO A BILIARY FOREIGN BODY IN A CAT

An 11‐year‐old, neutered female British Shorthair cat was referred with a 4‐week history of abdominal pain and vomiting. Abdominal ultrasonography revealed a dilated common bile duct containing a spindle‐shaped structure with several reflecting interfaces. Differentials that were considered included an intraluminal foreign body, or helminth parasites within the common bile duct. Surgical exploration of the abdominal cavity demonstrated the presence of two grass awns obstructing the common bile duct. Anomalies of the portal vasculature were noted during surgery and were considered an incidental finding. The clinical signs resolved following surgical removal of the grass awns.     

Timing of atmospheric CO2 and Antarctic temperature changes across termination III

The analysis of air bubbles from ice cores has yielded a precise record of atmospheric greenhouse gas concentrations, but the timing of changes in these gases with respect to temperature is not accurately known because of uncertainty in the gas age-ice age difference. We have measured the isotopic composition of argon in air bubbles in the Vostok core during Termination III (approximately 240,000 years before the present). This record most likely reflects the temperature and accumulation change, although the mechanism remains unclear. The sequence of events during Termination III suggests that the CO2 increase lagged Antarctic deglacial warming by 800 +/- 200 years and preceded the Northern Hemisphere deglaciation.     

A reservoir of ionized gas in the galactic halo to sustain star formation in the Milky Way

Without a source of new gas, our Galaxy would exhaust its supply of gas through the formation of stars. Ionized gas clouds observed at high velocity may be a reservoir of such gas, but their distances are key for placing them in the galactic halo and unraveling their role. We have used the Hubble Space Telescope to blindly search for ionized high-velocity clouds (iHVCs) in the foreground of galactic stars. We show that iHVCs with 90 ≤ |v(LSR)| ? 170 kilometers per second (where v(LSR) is the velocity in the local standard of rest frame) are within one galactic radius of the Sun and have enough mass to maintain star formation, whereas iHVCs with |v(LSR)| ? 170 kilometers per second are at larger distances. These may be the next wave of infalling material.     

Saturation of the southern ocean CO2 sink due to recent climate change

Based on observed atmospheric carbon dioxide (CO2) concentration and an inverse method, we estimate that the Southern Ocean sink of CO2 has weakened between 1981 and 2004 by 0.08 petagrams of carbon per year per decade relative to the trend expected from the large increase in atmospheric CO2. We attribute this weakening to the observed increase in Southern Ocean winds resulting from human activities, which is projected to continue in the future. Consequences include a reduction of the efficiency of the Southern Ocean sink of CO2 in the short term (about 25 years) and possibly a higher level of stabilization of atmospheric CO2 on a multicentury time scale.     

Functional genomic analysis of RNA interference in C. elegans

RNA interference (RNAi) of target genes is triggered by double-stranded RNAs (dsRNAs) processed by conserved nucleases and accessory factors. To identify the genetic components required for RNAi, we performed a genome-wide screen using an engineered RNAi sensor strain of Caenorhabditis elegans. The RNAi screen identified 90 genes. These included Piwi/PAZ proteins, DEAH helicases, RNA binding/processing factors, chromatin-associated factors, DNA recombination proteins, nuclear import/export factors, and 11 known components of the RNAi machinery. We demonstrate that some of these genes are also required for germline and somatic transgene silencing. Moreover, the physical interactions among these potential RNAi factors suggest links to other RNA-dependent gene regulatory pathways.