Epizootiology and Phylogenetics of Entomopathogenic Fungi Associated with Fiorinia externa ferris(Hemiptera: Diaspididae) in the Northeastern USA

The eastern hemlock [Tsuga canadensis (L.) Carrière] is one of the native dominant forest components of northeastern US. At present, these valuable stands face an alarming decline, in part due to the Fiorinia externa, elongate hemlock scale (EHS), (Hemiptera: Coccoidea: Diaspididae). The armored shield of F. externa provides an excellent defense against insecticides, natural enemies and adverse conditions. Chemical and classical biocontrol methods have been unable to stop the spread of this pest. Recently, the occurrence of an epizootic within the F. externa population in the Mianus River Gorge Preserve in Bedford, NY revealed a promising opportunity for control of this scale. Entomopathogenic fungi represent a valuable, although under-utilized, group of organisms with unique capabilities for self-sustaining pest management. Given the significant impact of this epizootic on F. externa, we have conducted extensive research on the biology, genetics and biological control potential of this epizootic. We molecularly identified a complex of entomopathogenic, phytopathogenic, and endophytic fungi associated with the epizootic in 36 localities within the states of New York, Pennsylvania, Connecticut and New Jersey. One fungus, Colletotrichum sp., was the most commonly isolated organism in populations of F. externa within areas of the epizootic. The host range of this Colletotrichum species comprised both insects and plants, although diverse life cycles occured in the different hosts. Endophytic growth was observed in 28 species of plants comprising 18 families (52% of the sampling), whereas in F. externa biotrophic and necotrophic growth was detected. Colletotrichum is a widely known phytopathogenic genus and reports of entomopathogenic activity are extremely rare. In order to understand the biological processes involved in the host-pathogen interactions we quantified the pathogenicity and virulence of this Colletotrichum sp. to four insect families and six plants families as well as the occurrence of sexual recombination in this Colletotrichum sp., both in vitro and in planta. We observed that this Colletotrichum sp. displays a propensy to induce rapid disease and mortality in F. externa hosts. Phylogenetic analysis comprising six of the most commonly studied nuclear genes in molecular phylogenetics (D1/D2 domain of the 28 rDNA gene, ITS region, β-Tubulin 2, GPDH gene, GS gene and HMG box at the MAT1-2 mating-type gene) and RAPDs showed this fungus is closely related to phytopathogenic strains of Colletotrichum acutatum and that it may represent a single population lineage of this species (i.e., Colletotrichum acutatum forma specialis fiorinia). Though a large body of information exists regarding the phytopathogenic genus Colletotrichum, ours is only the second reported entomopathogenic strain. It is not clear whether the colonization of an insect by this fungus is truly rare or a common but undetected event. Sexual recombination, observed in planta and in vitro, could be the means by which new genetic variants are generated leading to new biotypes with a selective advantage to colonize new hosts, which in this case is a novel host in a different kingdom

Oxygen Chemistry in the Circumstellar Envelope of the Carbon-Rich Star IRC+10216

In this paper we study the oxygen chemistry in the C-rich circumstellar shells of IRC+10216. The recent discoveries of oxygen bearing species (water, hydroxyl radical and formaldehyde) toward this source challenge our current understanding of the chemistry in C-rich circumstellar envelopes. The presence of icy comets surrounding the star or catalysis on iron grain surfaces have been invoked to explain the presence of such unexpected species. This detailed study aims at evaluating the chances of producing O-bearing species in the C-rich circumstellar envelope only by gas phase chemical reactions. For the inner hot envelope, it is shown that although most of the oxygen is locked in CO near the photosphere (as expected for a C/O ratio greater than 1), some stellar radii far away species such as H2O and CO2 have large abundances under the assumption of thermochemical equilibrium. It is also shown how non-LTE chemistry makes very difficult the CO-->H2O,CO2 transformation predicted in LTE. Concerning the chemistry in the outer and colder envelope, we show that formaldehyde can be formed through gas phase reactions. However, in order to form water vapor it is necessary to include a radiative association between atomic oxygen and molecular hydrogen with a quite high rate constant. The chemical models explain the presence of HCO+ and predict the existence of SO and H2CS (which has been detected in a 3 mm line survey to be published). We have modeled the line profiles of H2CO, H2O, HCO+, SO and H2CS using a non-local radiative transfer model and the abundance profiles predicted by our chemical model. The results have been compared to the observations and discussed.Comment: 20 pages, 9 figures, accepted for publication in the Astrophysical Journa

Consistent patterns of common species across tropical tree communities

Trees structure the Earth’s most biodiverse ecosystem, tropical forests. The vast number of tree species presents a formidable challenge to understanding these forests, including their response to environmental change, as very little is known about most tropical tree species. A focus on the common species may circumvent this challenge. Here we investigate abundance patterns of common tree species using inventory data on 1,003,805 trees with trunk diameters of at least 10 cm across 1,568 locations1,2,3,4,5,6 in closed-canopy, structurally intact old-growth tropical forests in Africa, Amazonia and Southeast Asia. We estimate that 2.2%, 2.2% and 2.3% of species comprise 50% of the tropical trees in these regions, respectively. Extrapolating across all closed-canopy tropical forests, we estimate that just 1,053 species comprise half of Earth’s 800 billion tropical trees with trunk diameters of at least 10 cm. Despite differing biogeographic, climatic and anthropogenic histories7, we find notably consistent patterns of common species and species abundance distributions across the continents. This suggests that fundamental mechanisms of tree community assembly may apply to all tropical forests. Resampling analyses show that the most common species are likely to belong to a manageable list of known species, enabling targeted efforts to understand their ecology. Although they do not detract from the importance of rare species, our results open new opportunities to understand the world’s most diverse forests, including modelling their response to environmental change, by focusing on the common species that constitute the majority of their trees.Publisher PDFPeer reviewe

The continuity of effect of schizophrenia polygenic risk score and patterns of cannabis use on transdiagnostic symptom dimensions at first-episode psychosis: findings from the EU-GEI study

Abstract: Diagnostic categories do not completely reflect the heterogeneous expression of psychosis. Using data from the EU-GEI study, we evaluated the impact of schizophrenia polygenic risk score (SZ-PRS) and patterns of cannabis use on the transdiagnostic expression of psychosis. We analysed first-episode psychosis patients (FEP) and controls, generating transdiagnostic dimensions of psychotic symptoms and experiences using item response bi-factor modelling. Linear regression was used to test the associations between these dimensions and SZ-PRS, as well as the combined effect of SZ-PRS and cannabis use on the dimensions of positive psychotic symptoms and experiences. We found associations between SZ-PRS and (1) both negative (B = 0.18; 95%CI 0.03–0.33) and positive (B = 0.19; 95%CI 0.03–0.35) symptom dimensions in 617 FEP patients, regardless of their categorical diagnosis; and (2) all the psychotic experience dimensions in 979 controls. We did not observe associations between SZ-PRS and the general and affective dimensions in FEP. Daily and current cannabis use were associated with the positive dimensions in FEP (B = 0.31; 95%CI 0.11–0.52) and in controls (B = 0.26; 95%CI 0.06–0.46), over and above SZ-PRS. We provide evidence that genetic liability to schizophrenia and cannabis use map onto transdiagnostic symptom dimensions, supporting the validity and utility of the dimensional representation of psychosis. In our sample, genetic liability to schizophrenia correlated with more severe psychosis presentation, and cannabis use conferred risk to positive symptomatology beyond the genetic risk. Our findings support the hypothesis that psychotic experiences in the general population have similar genetic substrates as clinical disorders

Novel eDNA approaches to monitor Western honey bee (Apis mellifera L.) microbial and arthropod communities

Abstract Pests and pathogens are a continuous threat to the health of Western honey bee Apis mellifera L. Monitoring honey bee colonies for arthropod pests, disease‐causing bacteria and fungi, and early detection of new invasions is essential to maintain the pollination services provided by honey bees. We investigated the feasibility of using eDNA metabarcoding to detect pests and pathogens in bee hives and across their foraging environment. We sampled 13 sources for eDNA within and outside hives from our test apiary to determine where the most informative eDNA could be obtained, with most sources sampled thrice. This resulted in 61 samples, 20 negative controls, and three positive controls. Furthermore, we compared two eDNA collection techniques—wiping surfaces with moistened forensic swabs and using a spray/wash technique that aggregated surface eDNA into a container, before collecting the eDNA on a filter. We used DNA metabarcoding with universal primer sets to target arthropod, bacterial, and fungal communities. Our results showed that most sources yielded sufficient eDNA and that results of the swab and spray/wash methods were similar when they could be applied to the same surface. We detected DNA from honey bee bacterial symbionts, mycotoxin‐producing fungi and Brachymyrmex sp. rover ants. Common pests and pathogens of concern to honey bees (i.e., [small hive beetle (Aethina tumida), Varroa destructor, and Melissococcus plutonius]) were detected. This matched our visual observations of clinical signs of these pests and pathogens in the hives we tested. DNA from some species was source specific, which has implications for using eDNA as a monitoring tool. Collectively, our data show that eDNA metabarcoding can accurately detect DNA from arthropods and microbes honey bees contact and can be used as a comprehensive molecular predictor tool for colony health surveys