Journal of invertebrate pathology最新文献

The genome of a new member of the Nimaviridae family has been sequenced. The Chionoecetes bairdi bacilliform virus (CbBV) causes Milky Hemolymph Syndrome (MHS) in Chionoecetes bairdi populations of the Pacific coast of Kamchatka. The CbBV genome is represented by double-stranded DNA with a length of 245,567 nucleotides containing 120 ORFs. Of these, 85 proteins had significant matches in the NCBI database, and 57 genes encoded capsid, envelope, tegument and nonstructural proteins. Comparative analysis of the genomes of CbBV and a number of representatives of the class nuclear arthropod large DNA viruses (NALDVs) made it possible to isolate 49 evolutionarily conserved orthologue core genes. Among them, 5 were multicopy genes, and 44 were single-copy genes. There were ancestral genes characteristic of all Naldaviricetes − per os infectivity complex genes, one DNA polymerase gene and one thymidylate synthase gene.

Phylogenetic analysis of representatives of the Nimaviridae family revealed that the CbBV and Chionoecetes opilio bacilliform virus (CoBV) form an independent clade within the family separate from the clade containing WSSV strains. This is supported by data on the order and arrangement of genes in the genomes of nimaviruses that were identical within each clade but differed between them. In addition, a high identity of the genomes and proteomes of CbBV and CoBV (approximately 99%) was shown, and their identity with WSSV strains was no more than 33%.

The data on the structure of the genome of the new virus that causes MHS in C. bairdi indicate that it belongs to the family Nimaviridae, genus Whispovirus. Thus, the CbBV infecting the commercially important species of Tanner crab in populations of the Pacific coast of Kamchatka is the second “wild” representative of replicating nimaviruses whose genome has been characterized after the CoBV that causes MHS in C. opilio in populations of the Sea of Japan. The discovery of a new member of the family that infects decapods indicates the prevalence of nimaviruses in marine ecosystems. The information obtained is important for understanding the evolution of representatives of the class of nuclear arthropod large DNA viruses. The discovery of a new nimavirus that causes MHS in Chionoecetes crabs, in contrast to the white spot syndrome (WSS) caused by WSSV strains, makes it relevant to identify two variants and possibly species within the family, namely, WSSV and Milky Hemolymph Syndrome virus (MHSV).

Because of the exoskeleton, arthropods must have flexible areas to be able to move. Such regions are called arthrodial membranes and are particularly vulnerable to bacteria and fungi. Here, we analyzed the secretion in the glands underneath it in a Neotropical harvester Mischonyx squalidus (Arachnida: Opiliones) and tested whether it has antiseptical properties. We punctured the membrane, collected and quantified in a spectrophotometer. We also fractionated and analyzed the samples in reversed-phase high-performance liquid chromatography (RP-HPLC) and then incubated the treated fractions and determined growth inhibition by measuring absorbance. The secretions resulted in 100 fractions, among which two had activity against the Gram-positive bacteria Micrococcus luteus and against the yeast Candida albicans. The low concentrations at which the secretions were active are relevant from a biotechnological point of view. For the organism, the secretions possibly prevent infections, including when they are attacked in these regions by predators that pick that spot to bite.

Insects are attacked by a diverse range of microbial pathogens in the wild. In herbivorous species, larval host plants frequently play a critical role in mediating susceptibility to infection. Characterizing such plant-mediated effects on herbivore-pathogen interactions can provide insight into patterns of infection across wild populations. In this study, we investigated the effects of host plant use by two North American butterflies, Euphydryas phaeton (Nymphalidae) and Anartia jatrophae (Nymphalidae), on entomopathogen infection across a range of three doses. Both of these herbivores recently incorporated the same exotic plant, Plantago lanceolata (Plantaginaceae), into their host range and are naturally infected by the same entomopathogen, Junonia coenia densovirus (Parvoviridae), in wild populations. We performed two factorial experiments in which E. phaeton and A. jatrophae were reared on either P. lanceolata or a native host plant [Chelone glabra (Plantaginaceae) for E. phaeton; Bacopa monnieri (Plantaginaceae) for A. jatrophae] and inoculated with either a low, medium, or high dose of the virus. In E. phaeton, the outcomes of infection were highly dose-dependent, with inoculation with higher viral doses resulting in faster time to death and greater mortality. However, neither survival nor postmortem viral burdens varied depending upon the host plant that was consumed. In contrast, host plant use had a strong effect on viral burdens in A. jatrophae, with consumption of the exotic plant appearing to enhance host resistance to infection. Together, these results illustrate the variable influences of host plant use on herbivore resistance to infection, highlighting the importance of investigating plant-herbivore relationships within a tritrophic framework.

A new microsporidian disease of the pond-reared ridgetail white prawn, Palaemon carinicauda, was found in China. Light microscopy, pathology, and scanning electron microscopy showed that the parasite infected the host’s skeletal muscle tissue and formed spherical sporophorous vesicles (SPOVs). Electron microscopy revealed that its merogonic life stages developed in direct contact with the host cytoplasm. The sporogonic life stages underwent octosporoblastic sporogony with the formation of eight uninucleate spores in each SPOV. Fresh SPOVs were 5.4 ± 0.55 µm in diameter. The octospores were oval and measured 2.3 × 1.5 μm (fresh) and 1.96 × 1.17 μm (fixed). The isofilar polar filament was coiled with 9–10 turns and arranged in two rows. Phylogenetic analysis based on the SSU rRNA gene suggests that this microsporidium has close affinities with members of the genera Potaspora and Apotaspora, but represents an independent generic taxon. We therefore propose the establishment of a new genus and species (Paospora carinifang n. gen., n. sp.) within the family Spragueidae. We also propose a taxonomic revision to transfer Potaspora macrobrachium to this new genus and reclassify it as Paospora macrobrachium comb. nov.

Orius laevigatus (Hemiptera, Anthocoridae) is a generalist predator extensively used for the biocontrol of diverse agricultural pests. Previous studies on O. laevigatus have focused on the improvement of insect genetic traits, but little is known about its association with microbes, especially viruses that may influence its production and efficacy. More than 280 RNA viruses have been described in other Hemiptera insects, in line with the continuous discovery of insect-specific viruses (ISVs) boosted by next-generation sequencing. In this study, we characterized the repertoire of RNA viruses associated with O. laevigatus. Its virome comprises 27 RNA viruses, classified within fourteen viral families, of which twenty-three viruses are specific to O. laevigatus and four are likely associated with fungal microbiota. The analysis of viral abundance in five O. laevigatus populations confirmed the presence of simultaneous viral infections and highlighted the ubiquitous presence and high abundance of one solinvivirus and three totiviruses. Moreover, we identified 24 non-retroviral endogenous viral elements (nrEVEs) in the genome of O. laevigatus, suggesting a long-term relationship between the host and its virome. Although no symptoms were described in the insect populations under study, the high diversity of viral species and the high abundance of certain RNA viruses identified indicate that RNA viruses may be significant for the applicability and efficacy of O. laevigatus in biocontrol programs.

This study is the first to report ciliate infection on soft corals in the Northern Coral Triangle. Infected Briareum violacea will undergo tissue ulceration and death within a short period of time. This ciliate was identified as Scuticociliatia sp. through 18S rRNA gene identification. In this study, the body length of the ciliate was approximately 80–85 μm before parasitizing the B. violacea. After being parasitizing, the body length was approximately 200–250 μm, and the body width was 50 μm. Body size increased three times after parasitism. According to observations, ciliates will first parasitize the coral endoderm in the early stage of infection, and no ciliates were found in the ectoderm. Preliminary judgment suggests that it may invade the coral endoderm through the mouth for parasitism. After parasitism, the ciliate eats the coral tissue and zooxanthellae. The antioxidant enzymes SOD, CAT, and MDA of infected corals were significantly increased, which also means that the corals are in a stress response. Ciliates will eat the zooxanthellae in the coral body, resulting in a significant reduction in the number of zooxanthellae and chlorophyll a. To effectively prevent and treat this disease, Combretum indicum extract was used in this study. It is a tropical plant commonly used medicinally to treat roundworms, pinworms and parasitic diseases. The results showed that at a concentration of 1500–2500 ppm, Combretum indicum extract can be used to treat ciliates and can applied via medicinal bath therapy for long periods without causing coral stress reactions. The results of this study regarding coral disease prevention are in line with SDG 14 and promote the practical application of coral reef ecological sustainability and large-scale coral aquaculture.

Acute hepatopancreatic necrosis disease (AHPND) is a highly contagious and lethal disease of shrimp caused by Vibrio strains carrying the virulence plasmid (pAHPND) containing the pirAB virulence genes. Through analysis of plasmid sequence similarity, clustering, and phylogeny, a horizontal transfer element similar to IS91 was discovered within the pAHPND plasmid. Additionally, two distinct clades of plasmids related to pAHPND (designated as pAHPND-r1 and pAHPND-r2) were identified, which may serve as potential parental plasmids for pAHPND. The available evidence, including the difference in G+C content between the plasmid and its host, codon usage preference, and plasmid recombination event prediction, suggests that the formation of the pAHPND plasmid in the Vibrio owensii strain was likely due to the synergistic effect of the recombinase RecA and the associated proteins RecBCD on the pAHPND-r1 and pAHPND-r2, resulting in the recombination and formation of the precursor plasmid for pAHPND (pre-pAHPND). The emergence of pAHPND was found to be a result of successive insertions of the horizontal transfer elements of pirAB-Tn903 and IS91-like segment, which led to the deletion of one third of the pre-pAHPND. This plasmid was then able to spread horizontally to other Vibrio strains, contributing to the epidemics of AHPND. These findings shed light on previously unknown mechanisms involved in the emergence of pAHPND and improve our understanding of the disease’s spread.

The Manila clam Ruditapes philippinarum on the west coast of Korea harbors several digenetic trematodes. However, most studies in this region have been restricted to a few sampling sites and the current species designation of some trematodes is largely based on morphology, leaving the molecular phylogenetic position among the Digenea unsolved. Thus, we first provide both morphology and molecular phylogeny of some components in the trematodes community in the Manila clam based on a large-scale survey of 26 sites on the west coast, where well-developed tidal flats serve as large commercial clam culture beds. Our study revealed that the trematodes community in the clams consisted of at least 5 species that belong to 3 families (Himasthlidae, Gymnophallidae, Baccigeridae) and 1 superfamily (Monorchioidea). The life mode of the 5 different species included the metacercaria and sporocyst, with one species (Parvatrema duboisi) utilizing the clams as both the first and/or second intermediate host. Trematode infection prevalences were not evenly distributed among the study sites, although the reasons behind this are yet to be determined. Morphological identification was confirmed with the molecular analyses based on ITS and 28S rDNA; phylogenetic analysis also revealed that Cercaria pectinata infecting the clam gonad should be referred to as Bacciger bacciger hereafter. The present preliminary study provides a crucial baseline that could be further developed in a future study on the digenean trematodes community in the Manila clam.

Honey bees are economically important insects. However, they face multiple biotic and abiotic stresses, such as diseases, pesticides, climate change, and pests, which cause the loss of honey bee colonies worldwide. Among these factors, viruses have been identified as the major cause of colony loss. Research on honey bee viruses in Uzbekistan is limited. This study investigated the viruses affecting honey bees in Uzbekistan. Virome analysis was conducted for each sample using high-throughput sequencing and bioinformatics. Nine honey bee viruses have been identified: the acute bee paralysis virus, aphid lethal paralysis virus, Apis rhabdovirus 1 and 2, black queen cell virus, deformed wing virus, Lake Sinai virus 10, sacbrood virus, and Hubei partiti-like virus 34. Additionally, 15 plant viruses were identified, 7 of which were novel. This study is the first virome analysis of Uzbekistan honey bees and provides a foundation for understanding the viruses affecting honey bees and plants in Uzbekistan.

Honey bees utilize queen mandibular pheromone (QMP) for maintaining social hierarchy and colony development. In controlled cage studies, synthetic QMP is often introduced to mimic natural conditions. However, questions have arisen about the effects of QMP on nosema disease studies. This short report identifies significant early-stage suppression effects of QMP on Nosema (Vairimorpha) ceranae infections. QMP was found to significantly lower infection rates below the reported infectious dose for 50 % infectivity (ID50) and to slow disease development in a dose-independent manner. These effects diminished at doses exceeding ID100. We recommend that studies investigating treatment effects using caged bees avoid QMP to ensure unambiguous results. Additionally, employing multiple infectious doses with shorter incubation times would be useful for evaluating other treatments that may have subtle effects. Furthermore, our findings support previous field studies suggesting that queen replacement reduces nosema disease at levels similar to treatment with fumagillin.