Season-long infection of diverse hosts by the entomopathogenic fungus Batkoa major

Populations of the entomopathogenic fungus Batkoa major were analyzed using sequences of four genomic regions and evaluated in relation to their genetic diversity, insect hosts and collection site. This entomophthoralean pathogen killed numerous insect species from 23 families and five orders in two remote locations during 2019. The host list of this biotrophic pathogen contains flies, true bugs, butterflies and moths, beetles, and barkflies. Among the infected bugs (Order Hemiptera), the spotted lanternfly ( Lycorma delicatula ) is a new invasive planthopper pest of various woody plants that was introduced to the USA from Eastern Asia. A high degree of clonality occurred in the studied populations and high gene flow was revealed using four molecular loci for the analysis of population structure. We did not detect any segregation in the population regarding host affiliation (by family or order), or collection site. This is the first description of population structure of a biotrophic fungus-generalist in the entomopathogenic Order Entomophthorales. This analysis aimed to better understand the potential populations of entomopathogen-generalists infecting emerging invasive hosts in new ecosystems.

More about the biodiversity of parasites in Vietnam: a first report of microsporidia (opistosporidia, microsporidia) in coral fish

This is the first report of microsporidia infection in marine fish from Vietnam. Microsporidia (Opistosporidia, Microsporidia) were identified in 4 species of coral fish Cheilinus chlorourus (Labridae), Abudefduf bengalensis (Pomacentridae), Pomacentrus brachialis (Pomacentridae), Atule mate (Carangidae) from Nha Trang Bay (East Sea), Khanh Hoa Province, Vietnam, in 2018 and 2019. Dry smears of blood, intestine and liver were stained using the Giemsa method. Gut and liver were fixed in Bouin’s fluid, processed for routine paraffin infiltration, and sections were stained with Hematoxylin and Eosin. Strong microsporidia infections were the same for all three species revealed in 1 of every 6 fish samples (prevalence 16.7%) of C. chlorourus, A. bengalensis, and P. brachialis. In C. chlorourus there were meronts, sporogonial plasmodia, and sporoblasts found in all layers of intestine (enterocytes, myocytes, mesotheliocytes), pancreas and liver. In A. bengalensis parasites were found in enterocytes of the small intestine and liver. In P. brachialis meronts, sporogonial plasmodia and sporoblasts were in enterocytes of the small intestine. Intracellular parasites are located in parasitophorous vacuoles covered with additional shell, which appeared to be in the process of forming xenoma. Microsporidia infection was revealed in 1 of 31 fish samples of A. mate (prevalence 3 %). Up to 30 of round and oval white xenomas were detected in the gills of fresh samples by microscopy. We tentatively assign the microsporidia to Glugeidae due to host affiliation (fish), localization (digestive system) and xenoma formation. They differ from Pleistophoridae by localization in non-muscular cells.

Polyphasic studies of new species of Diaporthe from native forest in Chile, with descriptions of Diaporthe araucanorum sp. nov., Diaporthe foikelawen sp. nov. and Diaporthe patagonica sp. nov.

During a survey of fungi in native forests in Chile, several unidentified isolates of Diaporthe were collected from different hosts. The isolates were characterized based on DNA comparisons, morphology, culture characteristics and host affiliation, in accordance with previous descriptions. Phylogenetic analysis of the ITS region, combined with partial tub2 and tef1 genes, showed that the isolates formed three distinct groups representing three new taxa. The three new species of Diaporthe, Diaporthe araucanorum on Araucaria araucana, Diaporthe foikelawen on Drimys winteri and Diaporthe patagonica on Aristotelia chilensis are described and illustrated in the present study.

An Ancient Lineage of Highly Divergent Parvoviruses Infects both Vertebrate and Invertebrate Hosts

Chapparvoviruses (ChPVs) comprise a divergent, recently identified group of parvoviruses (family Parvoviridae), associated with nephropathy in immunocompromised laboratory mice and with prevalence in deep sequencing results of livestock showing diarrhea. Here, we investigate the biological and evolutionary characteristics of ChPVs via comparative in silico analyses, incorporating sequences derived from endogenous parvoviral elements (EPVs) as well as exogenous parvoviruses. We show that ChPVs are an ancient lineage within the Parvoviridae, clustering separately from members of both currently established subfamilies. Consistent with this, they exhibit a number of characteristic features, including several putative auxiliary protein-encoding genes, and capsid proteins with no sequence-level homology to those of other parvoviruses. Homology modeling indicates the absence of a β-A strand, normally part of the luminal side of the parvoviral capsid protein core. Our findings demonstrate that the ChPV lineage infects an exceptionally broad range of host species, including both vertebrates and invertebrates. Furthermore, we observe that ChPVs found in fish are more closely related to those from invertebrates than they are to those of amniote vertebrates. This suggests that transmission between distantly related host species may have occurred in the past and that the Parvoviridae family can no longer be divided based on host affiliation.

The Phylogeny and Pathogenesis of Sacbrood Virus (SBV) Infection in European Honey Bees, Apis mellifera

RNA viruses that contain single-stranded RNA genomes of positive sense make up the largest group of pathogens infecting honey bees. Sacbrood virus (SBV) is one of the most widely distributed honey bee viruses and infects the larvae of honey bees, resulting in failure to pupate and death. Among all of the viruses infecting honey bees, SBV has the greatest number of complete genomes isolated from both European honey bees Apis mellifera and Asian honey bees A. cerana worldwide. To enhance our understanding of the evolution and pathogenicity of SBV, in this study, we present the first report of whole genome sequences of two U.S. strains of SBV. The complete genome sequences of the two U.S. SBV strains were deposited in GenBank under accession numbers: MG545286.1 and MG545287.1. Both SBV strains show the typical genomic features of the Iflaviridae family. The phylogenetic analysis of the single polyprotein coding region of the U.S. strains, and other GenBank SBV submissions revealed that SBV strains split into two distinct lineages, possibly reflecting host affiliation. The phylogenetic analysis based on the 5′UTR revealed a monophyletic clade with the deep parts of the tree occupied by SBV strains from both A. cerane and A. mellifera, and the tips of branches of the tree occupied by SBV strains from A. mellifera. The study of the cold stress on the pathogenesis of the SBV infection showed that cold stress could have profound effects on sacbrood disease severity manifested by increased mortality of infected larvae. This result suggests that the high prevalence of sacbrood disease in early spring may be due to the fluctuating temperatures during the season. This study will contribute to a better understanding of the evolution and pathogenesis of SBV infection in honey bees, and have important epidemiological relevance.

Flexibility of co-evolutionary patterns in ectoparasite populations: genetic structure and diversity in Apodemus mice and their lice

Host-parasite co-evolution belongs among the major processes governing evolution of biodiversity on the global scale. Numerous studies performed at inter-specific level revealed variety of patterns from strict co-speciation to lack of co-divergence and frequent host-switching, even in species tightly linked to their hosts. To explain these observations and formulate ecological hypotheses, we need to acquire better understanding to parasites’ population genetics and dynamics, and their main determinants. Here, we analyse the impact of co-evolutionary processes on genetic diversity and structure of parasite populations, using a model composed of the louse Polyplax serrata and its hosts, mice of the genus Apodemus, collected from several dozens of localities across Europe. We use mitochondrial DNA sequences and microsatellite data to describe the level of genealogical congruence between hosts and parasites and to assess genetic diversity of the populations. We also explore links between the genetic assignment of the parasite and its host affiliation, and test the prediction that populations of the parasite possessing narrower host specificity show deeper pattern of population structure and lower level of genetic diversity as a result of limited dispersal and smaller effective population size. We demonstrate an overall complexity of the co-evolutionary processes and their variability even among closely related lineages of the parasites. In the analysis of several sympatric parasite populations, we find strong evidence for the link between the width of host specificity and genetic diversity of parasites.

Molecular Differentiation of Fusarium solani f. sp. glycines from Other F. solani Based on Mitochondrial Small Subunit rDNA Sequences

Fusarium solani is a soilborne plant pathogen that infects many different hosts. Within the species, there is some specialization, and a number of forma specialis have been described based on host affiliation. One of these, F. solani f. sp. glycines, infects soybean and causes sudden death syndrome. To differentiate between F. solani f. sp. glycines and other F. solani isolates, a partial sequence of the mitochondrial small subunit (mtSSU) rRNA gene was amplified by polymerase chain reaction and sequenced from 14 F. solani f. sp. glycines and 24 F. solani isolates from various plant hosts. All F. solani f. sp. glycines isolates had identical sequences. A single, unique insertion of cytosine occurred in all F. solaniisolates but not in any of the F. solani f. sp. glycines isolates. Two major lineages, distinguished by sequence divergence and the presence or absence of multiple insertions, occurred in F. solani isolates. Cladistic analysis produced a single most-parsimonious tree with three major clades. The first clade contained all F. solani f. sp. glycines isolates. A second clade grouped together all of the F. solani isolates that had only a single nucleotide insertion difference from the first clade. Genetic distance between these two clades was 0.016. A third clade was formed by five F. solaniisolates that had multiple insertions. Isolates in the third clade had a genetic distance of 0.040 from the first and second clades. Based on the sequence data, it is likely that F. solani f. sp. glycineshas a shorter evolutionary history than other F. solaniisolates that have either single or multiple nucleotide insertions. The differences in nucleotide insertions in part of the mtSSU rRNA gene between F. solani f. sp. glycinesand other F. solani isolates provide a direct and reliable way to distinguish isolates of F. solani.