Selection of Atoxigenic Aspergillus flavus for Potential Use in Aflatoxin Prevention in Shandong Province, China

Aspergillus flavus is a common filamentous fungus widely present in the soil, air, and in crops. This facultative pathogen of both animals and plants produces aflatoxins, a group of mycotoxins with strong teratogenic and carcinogenic properties. Peanuts are highly susceptible to aflatoxin contamination and consumption of contaminated peanuts poses serious threats to the health of humans and domestic animals. Currently, the competitive displacement of aflatoxin-producers from agricultural environments by atoxigenic A. flavus is the most effective method of preventing crop aflatoxin contamination. In the current study, 47 isolates of A. flavus collected from peanut samples originating in Shandong Province were characterized with molecular methods and for aflatoxin-producing ability in laboratory studies. Isolates PA04 and PA10 were found to be atoxigenic members of the L strains morphotype. When co-inoculated with A. flavus NRRL3357 at ratios of 1:10, 1:1, and 10:1 (PA04/PA10: NRRL3357), both atoxigenic strains were able to reduce aflatoxin B1 (AFB1) levels, on both culture media and peanut kernels, by up to 90%. The extent to which atoxigenic strains reduced contamination was correlated with the inoculation ratio. Abilities to compete of PA04 and PA10 were also independently verified against local aflatoxin-producer PA37. The results suggest that the two identified atoxigenic strains are good candidates for active ingredients of biocontrol products for the prevention of aflatoxin contamination of peanuts in Shandong Province.

Overwintering, Cold Tolerance and Supercooling Capacity Comparison Between Liriomyza Sativae and L. Trifolii, Two Successively Invaded Leafminers in China

Liriomyza sativae Blanchard and Liriomyza trifolii (Burgess) are two highly polyphagous pests that successively invaded China in the 1990s and 2000s, respectively, threatening vegetable and horticultural plants. Competitive displacement of L. sativae by L. trifolii occurred during the expansion process of the latter in southern China. However, whether L. trifolii can expand their range to northern China and, if so, how they compete with L. sativae in northern China remains unclear. Overwintering and cold tolerance capacity largely determine the species distribution range and can affect species displacement through overwintering and phenology. In this study, we compared the overwintering potential, cold tolerance and supercooling point (SCP) between these two leafminer species. Our results showed that L. trifolii can overwinter at higher altitudes than L. sativae. In addition, we found that they can both successfully overwinter in greenhouses in northern China, and the overwintering capacity of L. trifolii was higher than that of L. sativae. Moreover, the extreme low-temperature survival of L. trifolii was significantly higher than that of L. sativae, and the SCP of the former was lower than that of the latter. We thus conclude that the overwintering and cold tolerance capacity of L. trifolii is much better than that of L. sativae. Our findings indicate that L. trifolii has the potential to displace L. sativae and expand its range to northern China. Moreover, our results have important implications for predicting overwinter ranges and developing management strategies for invasive leafminers in China.

Public service media in the age of SVoDs: A comparative study of PSM strategic responses in Flanders, Italy and the UK

Netflix and other transnational online video streaming services are disrupting long-established arrangements in national television systems around the world. In this paper we analyse how public service media (PSM) organisations (key purveyors of societal goals in broadcasting) are responding to the fast-growing popularity of these new services. Drawing on Philip Napoli’s framework for analysing strategic responses by established media to threats of competitive displacement by new media, we find that the three PSM organisations in our study exhibit commonalities. Their responses have tended to follow a particular evolution starting with different levels of complacency and resistance before settling into more coherent strategies revolving around efforts to differentiate PSM offerings, while also diversifying into activities, primarily across new platforms, that mimic SVoD approaches and probe production collaborations. Beyond these similarities, however, we also find that a range of contextual factors (including path-dependency, the role and status of PSM in each country, the degree of additional government support, cultural factors and market size) help explain nuances in strategic responses between our three cases.

Aedes albopictus (Diptera: Culicidae) Has Not Become the Dominant Species in Artificial Container Habitats in a Temperate Forest More Than a Decade After Establishment

Aedes albopictus (Skuse) (Diptera: Culicidae) is one of the most invasive species globally, and has led to rapid declines and local extirpations of resident mosquitoes where it becomes established. A potential mechanism behind these displacements is the superior competitive ability of Ae. albopictus in larval habitats. Research on the context-dependent nature of competitive displacement predicts that Ae. albopictus will not replace native Aedes triseriatus (Say) (Diptera: Culicidae) in treeholes but could do so in artificial container habitats. Aedes albopictus remains rare in temperate treeholes but less is known about how Ae. albopictus fares in artificial containers in forests. Tyson Research Center (TRC) is a field station composed of mostly oak-hickory forest located outside Saint Louis, MO. The container community has been studied regularly at TRC since 2007 with permanently established artificial containers on the property since 2013. Aedes albopictus was detected each year when these communities were sampled; however, its abundance remains low and it fails to numerically dominate other species in these communities. We present data that show Ae. albopictus numbers have not increased in the last decade. We compare egg counts from 2007 to 2016 and combine larval sample data from 2012 to 2017.We present average larval densities and prevalence of Ae. albopictus and two competitors, Ae. triseriatus and Aedes japonicus (Theobald) (Diptera: Culicidae), as well as monthly averages by year. These data highlight a circumstance in which Ae. albopictus fails to dominate the Aedes community despite it doing so in more human-impacted habitats. We present hypotheses for these patterns based upon abiotic and biotic environmental conditions.

Investigation of the Interaction of Gadolinium with Several Organic Ligands and Humic Acid by Ligand Competition Using 4-(2-Pyridylazo)-Resorcinol (PAR)

Gd3+ forms a strongly colored complex with 4-(2-pyridylazo)-resorcinol (PAR) in aqueous solutions. We characterized the Gd3+-PAR complex in order to use it as a probe of Gd3+ speciation in the presence of environmentally relevant ligands. The formation of the Gd3+-PAR complex was investigated from pH 5 to 8 in the presence of excess PAR. The absorbance of the Gd3+-PAR complex dramatically increased from pH 5 to 8 and application of the method of continuous variation indicates that the complex was primarily 1:2 Gd(PAR)2 at pH 8. Stability constants for Gd3+ with other ligands can be quantified by competitive displacement of the PAR ligand. To establish the viability of this approach, we measured the stability constants between Gd3+ and several organic acids and carbonate. Our measurements show reasonable agreement with the literature values. We used the competitive displacement approach to establish that humic acids can competitively displace PAR from the Gd(PAR)2 complex.

A Reference Genome of Bursaphelenchus mucronatus Provides New Resources for Revealing Its Displacement by Pinewood Nematode

The Bursaphelenchus mucronatus, which was highly similar with Bursaphelenchus xylophilus in terms of morphological characteristics and biological properties—but had weaker pathogenicity to forests—was a native species often displaced by B. xylophilus when occupying the same niche. Since the draft genome of the invasive B. xylophilus has been published, the absence of a reference genome of B. mucronatus still prevents us from understanding the molecular evidences behind competitive displacement. In this study, we employed Single Molecule, Real-Time (SMRT) sequencing and a Hi-C scaffolding approach to yield a near chromosome-level assembly of B. mucronatus, including six pseudo-chromosomes. The assembly size is 73 Mb, with scaffold N50 of 11.50 Mb and contig N50 of 1.48 Mb. Comparative genomics results showed high similarity between B. xylophilus and B. mucronatus. However, the losing of orphan genes and species-specific orthologous genes in B. mucronatus may indicate weaker adaptability to the environment. The gene family contractions of GPCRs (G Protein-Coupled Receptors) and cellulases in B. mucronatus may jointly contribute to its displacement by B. xylophilus. Overall, we introduced a valuable genomic resource for molecular and evolutionary studies of B. mucronatus, especially for studying the competitive displacement by the pinewood nematode, which could help us control the pathogenicity of pine wilt diseases.