Daniel Mendes Pereira Ardisson-Araujo

Soybean production is a cornerstone of Brazilian agriculture but is heavily threatened by insect pests such as the soybean looper Chrysodeixis includens, capable of reducing yields by up to 70% if uncontrolled. Reliance on chemical insecticides is increasingly unsustainable due to environmental impacts and resistance, highlighting the need for eco-friendly alternatives. The alphabaculovirus Chrysodeixis includens nucleopolyhedrovirus (ChinNPV) is an important biocontrol agent largely used in Brazilian fields because of its host specificity and safety, although its persistence is limited by ultraviolet (UV) sensitivity. Here, we characterize two ChinNPV isolates, CNPSo-168 (C168) and Tabatinga (Tb), using genomic and phenotypic analyses. Whole-genome sequencing revealed circular dsDNA genomes of 139,290 bp (154 ORFs) for C168 and 139,131 bp (153 ORFs) for Tb, both encoding the 38 baculovirus core genes and sharing >98.9% identity with reference genomes. Comparative genomics identified 431 SNPs, including 132 nonsynonymous changes in structural, regulatory, and infection-related genes. At low concentrations, C168 showed an approximately 2-fold lower LC₅₀ than Tb (higher potency), while both achieved near-complete mortality within 8 days at higher concentrations. This greater potency at lower concentrations reinforces the efficacy-based rationale for selecting isolate C168 for biocontrol applications. Infection reduced larval growth, pupation, and adult emergence, often with developmental impairments. Despite genetic differences, both isolates were highly UV-sensitive, and formulation tests indicated that titanium dioxide combined with kaolin conferred partial protection. These results provide insights into ChinNPV diversity and support its development as a sustainable tool for soybean pest management.

Nudiviruses (family Nudiviridae) are a diverse group of enveloped, rod-shaped viruses with double-stranded DNA genomes that infect a wide range of insects and crustaceans. These viruses are of significance both as biological control agents in agriculture and as agents of disease in aquaculture and insect rearing. In this work, we found four segments of a novel and divergent nudivirus identified through RNA-seq data from the two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae). The sequences of this virus were detected only in a subset of mite transcriptomes. The assembled segments covered a total of 100,780 bp, with 122 annotated ORFs, including all the 28 conserved nudiviral core genes. Phylogenetic analysis based on the predicted amino acid sequences of 17 selected nudiviral core genes placed the virus within the Alphanudivirus genus, in a clade containing nudiviruses identified from flea transcriptomes. This placement was confirmed by phylogenies of segment-specific concatenated core gene alignments. Indeed, the virus was designated as Tetranychus urticae alphanudivirus (TuNV). Transcriptional profiling revealed variable levels of transcriptional activity among genomic segments and viral genes. Arthropod gene homologs were found interspersed among nudiviral genes across all segments along with several unique genes. This genomic and phylogenetic characterization enhances our understanding of nudivirus diversity and evolution within arthropod hosts.

Wasps are important parasitoids of stinkbugs and frequently exposed to various types of microorganisms through environmental contact and fecal–oral transmission route. Many parasitize stinkbug eggs and are commercially used in the field to control insect population. The parasitoid T. podisi is known for its high parasitism capacity and ability to target multiple species of stinkbugs. In this study we asked whether T. podisi exposed to eggs infected by a multispecies asymptomatic stinkbug virus, the Halyomorpha halys virus (HhV) would get infected. HhV is a geographically distributed multispecies iflavirus previously found to infect four stinkbug hosts, including three Brazilian species, Chinavia ubica, Euschistus heros and Diceraeus melacanthus, and T. posidi can parasitize all of them. As results, RT-PCR screening revealed positive samples for the HhV genome in two out of four tested pools of T. podisi, whereas the antigenome, indicative of replicative activity, was not detected. The wasps were raised in E. heros eggs that presented both the genome and the antigenome forms of the HhV genome. Subsequent RNA-deep sequencing of HhV positive T. podisi RNA pools yielded a complete genome of HhV with high coverage. Phylogenetic analysis positioned the isolate HhV-Tp (isolate Telenomus podisi) alongside with the stinkbug HhV. Analysis of transcriptomes from several hymenopteran species revealed HhV-Tp reads in four species. However, the transmission mechanism and the ecological significance of HhV remain elusive, warranting further studies to illuminate both the transmission process and its capacity for environmental propagation using T. podisi as a potential vector.

The decline in honey bee colonies in different parts of the world in recent years is due to different reasons, such as agricultural practices, climate changes, the use of chemical insecticides, and pests and diseases. Viral infections are one of the main causes leading to honey bee population declines, which have a major economic impact due to honey production and pollination. To investigate the presence of viruses in bees in southern Brazil, we used a metagenomic approach to sequence adults’ samples of concentrated extracts from Apis mellifera collected in fifteen apiaries of six municipalities in the Rio Grande do Sul state, Brazil, between 2016 and 2017. High-throughput sequencing (HTS) of these samples resulted in the identification of eight previously known viruses (Apis rhabdovirus 1 (ARV-1), Acute bee paralysis virus (ABPV), Aphid lethal paralysis virus (ALPV), Black queen cell virus (BQCV), Bee Macula-like virus (BeeMLV), Deformed wing virus (DWV), Lake Sinai Virus NE (LSV), and Varroa destructor virus 3 (VDV-3)) and a thogotovirus isolate. This thogotovirus shares high amino acid identities in five of the six segments with Varroa orthomyxovirus 1, VOV-1 (98.36 to 99.34% identity). In contrast, segment 4, which codes for the main glycoprotein (GP), has no identity with VOV-1, as observed for the other segments, but shares an amino acid identity of 34–38% with other glycoproteins of viruses from the Orthomyxoviridae family. In addition, the putative thogotovirus GP also shows amino acid identities ranging from 33 to 41% with the major glycoprotein (GP64) of insect viruses of the Baculoviridae family. To our knowledge, this is the second report of a thogotovirus found in bees and given this information, this thogotovirus isolate was tentatively named Apis thogotovirus 1 (ATHOV-1). The detection of multiple viruses in bees is important to better understand the complex interactions between viruses and their hosts. By understanding these interactions, better strategies for managing viral infections in bees and protecting their populations can be developed.