Fast recognition of Lecanicillium spp. and its virulence against Frankliniella occidentalis

Background: Frankliniella occidentalis (Thysanoptera: Thripidae) is a highly destructive sucking pest of numerous crops. The entomogenous fungi of Lecanicillium spp. are important pathogens of insect pests, and some have been developed as commercial biopesticides. In order to explore the wild resources of Lecanicillium spp. in the development of more effective F. occidentalis controls, efficient gene combinations for strain identification were screened from internal transcribed spacer (ITS) and the genes SSU, LSU, TEF, RPB1, and RPB2.Results: In this study, six genes were used to reconstruct the phylogeny of Lecanicillium genus respectively. Among these, only four events (ITS, TEF, RPB1, RPB2) were validated using the gold standard for identifying the strains. All the phylogenetic trees reconstruct by free combination of these four events exhibited the same topology. Bioassay studies of a purified conidial suspension further confirmed the infection of second-instar nymphs and adult female F. occidentalis by seven strains of Lecanicillium. L. attenuatum strains GZUIFR-lun1405 was the most virulent, approximately 8.33% of adult and 23.33% of nymphs F. occidentalis survived after a 7-d exposure. Two strains were selected to compare the effects on the amount of eggs laid by F. occidentalis. The number of nymphs of F. occidentalis significantly decreased when adult F. occidentalis were treated with L. cauligalbarum strain GZUIFR-ZHJ01 compared to the controls.Conclusions: We found that combination of ITS and TEF could be used for fast recognition of Lecanicillium spp. We demonstrated that L. attenuatum, L. cauligalbarum, L araneogenum, and L. aphanocladii had various efficacies against F. occidentalis which were the first to demonstrate efficient control of F. occidentalis. In addition, the L. cauligalbarum strain GZUIFR-ZHJ01 not only caused high mortality in F. occidentalis but also inhibited the fecundity of the pest.

Reconstruction and functional annotation of Ascosphaera apis full-length transcriptome via PacBio single-molecule long-read sequencing

Ascosphaera apis is a widespread fungal pathogen of honeybee larvae that results in chalkbrood disease, leading to heavy losses for the beekeeping industry in China and many other countries. This work was aimed at generating a full-length transcriptome of A. apis using PacBio single-molecule real-time (SMRT) sequencing. Here, more than 23.97 Gb of clean reads was generated from long-read sequencing of A. apis mecylia, including 464,043 circular consensus sequences (CCS) and 394,142 full-length non-chimeric (FLNC) reads. In total, we identified 174,095 high-confidence transcripts covering 5141 known genes with an average length of 2728 bp. We also discovered 2405 genic loci and 11,623 isoforms that have not been annotated yet within the current reference genome. Additionally, 16,049, 10,682, 4520 and 7253 of the discovered transcripts have annotations in the Non-redundant protein (Nr), Clusters of Eukaryotic Orthologous Groups (KOG), Gene Ontology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases. Moreover, 1205 long non-coding RNAs (lncRNAs) were identified, which have less exons, shorter exon and intron lengths, shorter transcript lengths, lower GC percent, lower expression levels, and fewer alternative splicing (AS) evens, compared with protein-coding transcripts. A total of 253 members from 17 transcription factor (TF) families were identified from our transcript datasets. Finally, the expression of A. apis isoforms was validated using a molecular approach. Overall, this is the first report of a full-length transcriptome of entomogenous fungi including A. apis. Our data offer a comprehensive set of reference transcripts and hence contributes to improving the genome annotation and transcriptomic study of A. apis.

Secondary metabolites (SMs) of Isaria cicadae and Isaria tenuipes

Isaria cicadae (A–D) and Isaria tenuipes (E–F) are important medical and food entomogenous fungi, but some of their secondary metabolites are toxic. FB: fruiting bodies, HI: host insects, and CS: conidial structures.

Ophiocordyceps neonutans sp. nov., a new neotropical species from O. nutans complex (Ophiocordycipitaceae, Ascomycota)

Ophiocordyceps nutans is an entomogenous fungus growing on true bugs (Hemiptera), which has a presumed worldwide distribution. During forays of entomogenous fungi in Brazil, specimens morphologically similar to O. nutans were collected from the Atlantic Forest and Cerrado domains of Neotropical region. Morphological comparisons, as well as molecular phylogenetic analyses using ITS, led us to conclude that the neotropical specimens represent a new species Ophiocordyceps neonutans. The Neotropical occurrence of this taxon and its taxonomic implications are re-evaluated here. We discuss O. nutans as a species complex with distinct geographic lineages and host specificity. In addition, Barcoding gap analysis suggests that the different lineages have a great genetic distance between them.

Introducing Ophiocordyceps thanathonensis, a new species of entomogenous fungi on ants, and a reference specimen for O. pseudolloydii

Ophiocordyceps pathogens of ants (Hymenoptera) are considered to have a worldwide distribution. Species of Ophiocordyceps have been relatively poorly studied and there is little molecular data available in GenBank. Thus, fresh collections and sequence data are needed to improve the understanding of species in the genus. In this study, infected ant species were collected in northern Thailand and carefully studied. As a result, O. thanathonensis is introduced as a new species. The morphology of O. thanathonensis differs from related species in the genus in having smaller ascomata, shorter asci, shorter ascospores and curved secondary ascospores. A reference specimen for O. pseudolloydii is also designated with sequence data. Phylogenetic analyses using maximum likelihood and Bayesian combined LSU, SSU, ITS, TEF1α and RPB1 sequence data show the placement of O. thanathonensis (new species) and O. pseudolloydii (reference specimen) within the Ophiocordyceps clade.