Viruses

Editorial

Jump to: Research, Review

2 pages, 160 KiB

Open AccessEditorial

Special Issue “Insect Viruses and Pest Management”

by Miguel López-Ferber

Viruses 2020, 12(4), 431; https://doi.org/10.3390/v12040431 - 10 Apr 2020

Cited by 1 | Viewed by 1982

Abstract

Most revues consider the work on Lymantria monarcha in central Europe [...] Full article

(This article belongs to the Special Issue Insect Viruses and Pest Management)

Research

Jump to: Editorial, Review

23 pages, 3010 KiB

Open AccessArticle

Understanding the Evolutionary Ecology of host–pathogen Interactions Provides Insights into the Outcomes of Insect Pest Biocontrol

by David J. Páez and Arietta E. Fleming-Davies

Viruses 2020, 12(2), 141; https://doi.org/10.3390/v12020141 - 25 Jan 2020

Cited by 11 | Viewed by 3487

Abstract

The use of viral pathogens to control the population size of pest insects has produced both successful and unsuccessful outcomes. Here, we investigate whether those biocontrol successes and failures can be explained by key ecological and evolutionary processes between hosts and pathogens. Specifically, [...] Read more.

The use of viral pathogens to control the population size of pest insects has produced both successful and unsuccessful outcomes. Here, we investigate whether those biocontrol successes and failures can be explained by key ecological and evolutionary processes between hosts and pathogens. Specifically, we examine how heterogeneity in pathogen transmission, ecological and evolutionary tradeoffs, and pathogen diversity affect insect population density and thus successful control. We first review the existing literature and then use numerical simulations of mathematical models to further explore these processes. Our results show that the control of insect densities using viruses depends strongly on the heterogeneity of virus transmission among insects. Overall, increased heterogeneity of transmission reduces the effect of viruses on insect densities and increases the long-term stability of insect populations. Lower equilibrium insect densities occur when transmission is heritable and when there is a tradeoff between mean transmission and insect fecundity compared to when the heterogeneity of transmission arises from non-genetic sources. Thus, the heterogeneity of transmission is a key parameter that regulates the long-term population dynamics of insects and their pathogens. We also show that both heterogeneity of transmission and life-history tradeoffs modulate characteristics of population dynamics such as the frequency and intensity of “boom–bust" population cycles. Furthermore, we show that because of life-history tradeoffs affecting the transmission rate, the use of multiple pathogen strains is more effective than the use of a single strain to control insect densities only when the pathogen strains differ considerably in their transmission characteristics. By quantifying the effects of ecology and evolution on population densities, we are able to offer recommendations to assess the long-term effects of classical biocontrol. Full article

(This article belongs to the Special Issue Insect Viruses and Pest Management)

► Show Figures

Figure 1

11 pages, 3484 KiB

Open AccessArticle

Tracing Baculovirus AcMNPV Infection Using a Real-Time Method Based on ANCHOR^TM DNA Labeling Technology

by Aurélie Hinsberger, Benoît Graillot, Christine Blachère Lopez, Sylvie Juliant, Martine Cerutti, Linda A. King, Robert D. Possee, Franck Gallardo and Miguel Lopez Ferber

Viruses 2020, 12(1), 50; https://doi.org/10.3390/v12010050 - 2 Jan 2020

Cited by 8 | Viewed by 3535

Abstract

Many steps in the baculovirus life cycle, from initial ingestion to the subsequent infection of all larval cells, remain largely unknown; primarily because it has hitherto not been possible to follow individual genomes and their lineages. Use of ANCHOR^TM technology allows a [...] Read more.

Many steps in the baculovirus life cycle, from initial ingestion to the subsequent infection of all larval cells, remain largely unknown; primarily because it has hitherto not been possible to follow individual genomes and their lineages. Use of ANCHOR^TM technology allows a high intensity fluorescent labelling of DNA. When applied to a virus genome, it is possible to follow individual particles, and the overall course of infection. This technology has been adapted to enable labelling of the baculovirus Autographa californica Multiple NucleoPolyhedroVirus genome, as a first step to its application to other baculoviruses. AcMNPV was modified by inserting the two components of ANCHOR^TM: a specific DNA-binding protein fused to a fluorescent reporter, and the corresponding DNA recognition sequence. The resulting modified virus was stable, infectious, and replicated correctly in Spodoptera frugiperda 9 (Sf9) cells and in vivo. Both budded viruses and occlusion bodies were clearly distinguishable, and infecting cells or larvae allowed the infection process to be monitored in living cells or tissues. The level of fluorescence in the culture medium of infected cells in vitro showed a good correlation with the number of infectious budded viruses. A cassette that can be used in other baculoviruses has been designed. Altogether our results introduce for the first time the generation of autofluorescent baculovirus and their application to follow infection dynamics directly in living cells or tissues. Full article

(This article belongs to the Special Issue Insect Viruses and Pest Management)

► Show Figures

Graphical abstract

13 pages, 2067 KiB

Open AccessArticle

Occurrence and Molecular Phylogeny of Honey Bee Viruses in Vespids

by Sa Yang, Philippe Gayral, Hongxia Zhao, Yaojun Wu, Xuejian Jiang, Yanyan Wu, Diane Bigot, Xinling Wang, Dahe Yang, Elisabeth A. Herniou, Shuai Deng, Fei Li, Qingyun Diao, Eric Darrouzet and Chunsheng Hou

Viruses 2020, 12(1), 6; https://doi.org/10.3390/v12010006 - 19 Dec 2019

Cited by 26 | Viewed by 4084

Abstract

Since the discovery that honey bee viruses play a role in colony decline, researchers have made major breakthroughs in understanding viral pathology and infection processes in honey bees. Work on virus transmission patterns and virus vectors, such as the mite Varroa destructor, [...] Read more.

Since the discovery that honey bee viruses play a role in colony decline, researchers have made major breakthroughs in understanding viral pathology and infection processes in honey bees. Work on virus transmission patterns and virus vectors, such as the mite Varroa destructor, has prompted intense efforts to manage honey bee health. However, little is known about the occurrence of honey bee viruses in bee predators, such as vespids. In this study, we characterized the occurrence of 11 honey bee viruses in five vespid species and one wasp from four provinces in China and two vespid species from four locations in France. The results showed that all the species from China carried certain honey bee viruses, notably Apis mellifera filamentous virus (AmFV), Deformed wing virus (DWV), and Israeli acute paralysis virus (IAPV); furthermore, in some vespid colonies, more than three different viruses were identified. In France, DWV was the most common virus; Sacbrood virus (SBV) and Black queen cell virus (BQCV) were observed in one and two samples, respectively. Phylogenetic analyses of IAPV and BQCV sequences indicated that most of the IAPV sequences belonged to a single group, while the BQCV sequences belonged to several groups. Additionally, our study is the first to detect Lake Sinai virus (LSV) in a hornet from China. Our findings can guide further research into the origin and transmission of honey bee viruses in Vespidae, a taxon of ecological, and potentially epidemiological, relevance. Full article

(This article belongs to the Special Issue Insect Viruses and Pest Management)

► Show Figures

Figure 1

11 pages, 1914 KiB

Open AccessArticle

Genome Analysis of a Novel Clade II.b Alphabaculovirus Obtained from Artaxa digramma

by Jiang Li, Xiaoyan Duan, Qianran Wang, Lei Zhang, Fei Deng, Hualin Wang, Zhihong Hu, Manli Wang and Jun Wang

Viruses 2019, 11(10), 925; https://doi.org/10.3390/v11100925 - 9 Oct 2019

Cited by 6 | Viewed by 3155

Abstract

Artaxa digramma is a lepidopteran pest distributed throughout southern China, Myanmar, Indonesia, and India. Artaxa digramma nucleopolyhedrovirus (ArdiNPV) is a specific viral pathogen of A. digramma and deemed as a promising biocontrol agent against the pest. In this study, the complete genome sequence [...] Read more.

Artaxa digramma is a lepidopteran pest distributed throughout southern China, Myanmar, Indonesia, and India. Artaxa digramma nucleopolyhedrovirus (ArdiNPV) is a specific viral pathogen of A. digramma and deemed as a promising biocontrol agent against the pest. In this study, the complete genome sequence of ArdiNPV was determined by deep sequencing. The genome of ArdiNPV contains a double-stranded DNA (dsDNA) of 161,734 bp in length and 39.1% G+C content. Further, 149 hypothetical open reading frames (ORFs) were predicted to encode proteins >50 amino acids in length, covering 83% of the whole genome. Among these ORFs, 38 were baculovirus core genes, 22 were lepidopteran baculovirus conserved genes, and seven were unique to ArdiNPV, respectively. No typical baculoviral homologous regions (hrs) were identified in the genome. ArdiNPV had five multi-copy genes including baculovirus repeated ORFs (bros), calcium/sodium antiporter B (chaB), DNA binding protein (dbp), inhibitor of apoptosis protein (iap), and p26. Interestingly, phylogenetic analyses showed that ArdiNPV belonged to Clade II.b of Group II Alphabaculoviruses, which all contain a second copy of dbp. The genome of ArdiNPV was the closest to Euproctis pseudoconspersa nucleopolyhedrovirus, with 57.4% whole-genome similarity. Therefore, these results suggest that ArdiNPV is a novel baculovirus belonging to a newly identified cluster of Clade II.b Alphabaculoviruses. Full article

(This article belongs to the Special Issue Insect Viruses and Pest Management)

► Show Figures

Figure 1

13 pages, 705 KiB

Open AccessArticle

Identification of Loci Associated with Enhanced Virulence in Spodoptera litura Nucleopolyhedrovirus Isolates Using Deep Sequencing

by Mark P. Zwart, Ghulam Ali, Elisabeth A. van Strien, Elio G. W. M. Schijlen, Manli Wang, Wopke van der Werf and Just M. Vlak

Viruses 2019, 11(9), 872; https://doi.org/10.3390/v11090872 - 17 Sep 2019

Cited by 8 | Viewed by 3860

Abstract

Spodoptera litura is an emerging pest insect in cotton and arable crops in Central Asia. To explore the possibility of using baculoviruses as biological control agents instead of chemical pesticides, in a previous study we characterized a number of S. litura nucleopolyhedrovirus (SpltNPV) [...] Read more.

Spodoptera litura is an emerging pest insect in cotton and arable crops in Central Asia. To explore the possibility of using baculoviruses as biological control agents instead of chemical pesticides, in a previous study we characterized a number of S. litura nucleopolyhedrovirus (SpltNPV) isolates from Pakistan. We found significant differences in speed of kill, an important property of a biological control agent. Here we set out to understand the genetic basis of these differences in speed of kill, by comparing the genome of the fast-killing SpltNPV-Pak-TAX1 isolate with that of the slow-killing SpltNPV-Pak-BNG isolate. These two isolates and the SpltNPV-G2 reference strain from China were deep sequenced with Illumina. As expected, the two Pakistani isolates were closely related with >99% sequence identity, whereas the Chinese isolate was more distantly related. We identified two loci that may be associated with the fast action of the SpltNPV-Pak-TAX1 isolate. First, an analysis of rates of synonymous and non-synonymous mutations identified neutral to positive selection on open reading frame (ORF) 122, encoding a viral fibroblast growth factor (vFGF) that is known to affect virulence in other baculoviruses. Second, the homologous repeat region hr17, a putative enhancer of transcription and origin of replication, is absent in SpltNPV-Pak-TAX1 suggesting it may also affect virulence. Additionally, we found there is little genetic variation within both Pakistani isolates, and we identified four genes under positive selection in both isolates that may have played a role in adaptation of SpltNPV to conditions in Central Asia. Our results contribute to the understanding of the enhanced activity of SpltNPV-Pak-TAX1, and may help to select better SpltNPV isolates for the control of S. litura in Pakistan and elsewhere. Full article

(This article belongs to the Special Issue Insect Viruses and Pest Management)

► Show Figures

Figure 1

15 pages, 1818 KiB

Open AccessArticle

Generation of Virus- and dsRNA-Derived siRNAs with Species-Dependent Length in Insects

by Dulce Santos, Lina Mingels, Elise Vogel, Luoluo Wang, Olivier Christiaens, Kaat Cappelle, Niels Wynant, Yannick Gansemans, Filip Van Nieuwerburgh, Guy Smagghe, Luc Swevers and Jozef Vanden Broeck

Viruses 2019, 11(8), 738; https://doi.org/10.3390/v11080738 - 11 Aug 2019

Cited by 48 | Viewed by 7564

Abstract

Double-stranded RNA (dsRNA) molecules of viral origin trigger a post-transcriptional gene-silencing mechanism called RNA interference (RNAi). Specifically, virally derived dsRNA is recognized and cleaved by the enzyme Dicer2 into short interfering RNAs (siRNAs), which further direct sequence-specific RNA silencing, ultimately silencing replication of [...] Read more.

Double-stranded RNA (dsRNA) molecules of viral origin trigger a post-transcriptional gene-silencing mechanism called RNA interference (RNAi). Specifically, virally derived dsRNA is recognized and cleaved by the enzyme Dicer2 into short interfering RNAs (siRNAs), which further direct sequence-specific RNA silencing, ultimately silencing replication of the virus. Notably, RNAi can also be artificially triggered by the delivery of gene-specific dsRNA, thereby leading to endogenous gene silencing. This is a widely used technology that holds great potential to contribute to novel pest control strategies. In this regard, research efforts have been set to find methods to efficiently trigger RNAi in the field. In this article, we demonstrate the generation of dsRNA- and/or virus-derived siRNAs—the main RNAi effectors—in six insect species belonging to five economically important orders (Lepidoptera, Orthoptera, Hymenoptera, Coleoptera, and Diptera). In addition, we describe that the siRNA length distribution is species-dependent. Taken together, our results reveal interspecies variability in the (antiviral) RNAi mechanism in insects and show promise to contribute to future research on (viral-based) RNAi-triggering mechanisms in this class of animals. Full article

(This article belongs to the Special Issue Insect Viruses and Pest Management)

► Show Figures

Figure 1

12 pages, 2636 KiB

Open AccessArticle

A Combination of Real-Time PCR and High-Resolution Melting Analysis to Detect and Identify CpGV Genotypes Involved in Type I Resistance

by Aurélie Hinsberger, Stéphane Theulier Saint Germain, Patrice Guerrero, Christine Blachère-López, Miguel López-Ferber and Sandrine Bayle

Viruses 2019, 11(8), 723; https://doi.org/10.3390/v11080723 - 6 Aug 2019

Cited by 5 | Viewed by 3948

Abstract

Cydia pomonella granulovirus, in particular CpGV-M isolate, is used as a biological control against the codling moth (CM), Cydia pomonella. As a result of intensive control over the years, codling moth populations have developed resistance against this isolate. This resistance is now [...] Read more.

Cydia pomonella granulovirus, in particular CpGV-M isolate, is used as a biological control against the codling moth (CM), Cydia pomonella. As a result of intensive control over the years, codling moth populations have developed resistance against this isolate. This resistance is now called type I resistance. Isolates, among them, CpGV-R5, have been found that are able to overcome type I resistance. Both CpGV-M and CpGV-R5 are used in orchards to control the codling moth. High resolution melting (HRM) has been adapted to differentiate between CpGV-M and CpGV-R5 isolates. Specific PCR primers have been designed for the CpGV p38 gene, encompassing the variable region responsible for the ability to overcome resistance. Because each amplicon has a specific melting point, it is possible to identify the CpGV-M and CpGV-R5 genotypes and to quantify their relative proportion. This method has been validated using mixtures of occlusion bodies of each isolate at various proportions. Then, the HRM has been used to estimate the proportion of each genotype in infected larvae or in occlusion bodies (OBs) extracted from dead larvae. This method allows a rapid detection of genotype replication and enables the assessment of either success or failure of the infection in field conditions. Full article

(This article belongs to the Special Issue Insect Viruses and Pest Management)

► Show Figures

Figure 1

14 pages, 1631 KiB

Open AccessArticle

Bio-Insecticidal Potential of Nucleopolyhedrovirus and Granulovirus Mixtures to Control the Fall Armyworm Spodoptera frugiperda (J.E. Smith, 1797) (Lepidoptera: Noctuidae)

by Paola E. Cuartas-Otálora, Juliana A. Gómez-Valderrama, Andrea E. Ramos, Gloria P. Barrera-Cubillos and Laura F. Villamizar-Rivero

Viruses 2019, 11(8), 684; https://doi.org/10.3390/v11080684 - 26 Jul 2019

Cited by 20 | Viewed by 6359

Abstract

The ability of the isolate VG008 of S. frugiperda granulovirus (SpfrGV) to enhance the infectivity of the isolate SfCOL of S. frugiperda multiple nucleopolyhedrovirus (SpfrMNPV) was evaluated on S. frugiperda larvae. Bioassays were performed with mixtures by using different proportions 90%:10% (M1), 95%:5% [...] Read more.

The ability of the isolate VG008 of S. frugiperda granulovirus (SpfrGV) to enhance the infectivity of the isolate SfCOL of S. frugiperda multiple nucleopolyhedrovirus (SpfrMNPV) was evaluated on S. frugiperda larvae. Bioassays were performed with mixtures by using different proportions 90%:10% (M1), 95%:5% (M2) and 97.5%:2.5% (M3) of SfCOL:VG008, respectively. All mixtures showed higher insecticidal activity that SfCOL. The mixture M3 showed the highest enhancement of SfCOL reducing 11.40 times the Mean Lethal Concentration and 96 h in the Mean Time to Death. The enhancer activity of proteins derived from VG008 (GVPs) were also evaluated in mixture with SfCOL. The GVPs increased 27% larval mortality caused by SfCOL and damaged the peritrophic membrane of S. litura larvae, suggesting that the key point in this enhancing activity is the initial step of the larva colonization, the midgut infection. M3 was formulated and evaluated under greenhouse conditions in maize plants using different doses. The highest efficacy was obtained with the highest dose of M3 (8 × 10¹¹ OBs/ha), which was similar to that found when formulated SfCOL was applied using an approximately twofold higher dose. The viral mixture M3 was selected as the active ingredient for developing a new biopesticide for a more efficient management of the pest in the field. Full article

(This article belongs to the Special Issue Insect Viruses and Pest Management)

► Show Figures

Figure 1

19 pages, 3518 KiB

Open AccessArticle

Genetic Variation and Biological Activity of Two Closely Related Alphabaculoviruses during Serial Passage in Permissive and Semi-Permissive Heterologous Hosts

by Isabel M. Belda, Inés Beperet, Trevor Williams and Primitivo Caballero

Viruses 2019, 11(7), 660; https://doi.org/10.3390/v11070660 - 18 Jul 2019

Cited by 6 | Viewed by 3597

Abstract

Phylogenetic analyses suggest that Mamestra brassicae multiple nucleopolyhedrovirus (MbMNPV) and Helicoverpa armigera multiple nucleopolyhedrovirus (HearMNPV) may be strains of the same virus species. Most of the studies comparing their biological activities have been performed in their homologous hosts. A comparison of host range [...] Read more.

Phylogenetic analyses suggest that Mamestra brassicae multiple nucleopolyhedrovirus (MbMNPV) and Helicoverpa armigera multiple nucleopolyhedrovirus (HearMNPV) may be strains of the same virus species. Most of the studies comparing their biological activities have been performed in their homologous hosts. A comparison of host range and stability in alternative hosts was performed. The host range of these viruses was compared using high concentrations of inoculum to inoculate second instars of six species of Lepidoptera. One semi-permissive host (Spodoptera littoralis) and one permissive host (S. exigua) were then selected and used to perform six serial passages involving a concentration corresponding to the ~25% lethal concentration for both viruses. Restriction endonuclease analysis showed fragment length polymorphisms in every host-virus system studied. In S. littoralis, serial passage of MbMNPV resulted in decreased pathogenicity and an increase in speed-of-kill, whereas no significant changes were detected for HearMNPV with respect to the initial inoculum. In contrast, both viruses showed a similar trend in S. exigua. These results highlight the low genetic diversity and a high phenotypic stability of HearMNPV with respect to the original inoculum after six successive passages in both insect hosts. This study concludes that host-baculovirus interactions during serial passage are complex and the process of adaptation to a novel semi-permissive host is far from predictable. Full article

(This article belongs to the Special Issue Insect Viruses and Pest Management)

► Show Figures

Figure 1

10 pages, 811 KiB

Open AccessCommunication

Genome Analysis of A Novel South African Cydia pomonella granulovirus (CpGV-SA) with Resistance-Breaking Potential

by Boitumelo Motsoeneng, Michael D. Jukes, Caroline M. Knox, Martin P. Hill and Sean D. Moore

Viruses 2019, 11(7), 658; https://doi.org/10.3390/v11070658 - 18 Jul 2019

Cited by 5 | Viewed by 4237

Abstract

The complete genome of an endemic South African Cydia pomonella granulovirus isolate was sequenced and analyzed. Several missing or truncated open reading frames (ORFs) were identified, including a 24 bp deletion in the pe38 gene which is reported to be associated with type [...] Read more.

The complete genome of an endemic South African Cydia pomonella granulovirus isolate was sequenced and analyzed. Several missing or truncated open reading frames (ORFs) were identified, including a 24 bp deletion in the pe38 gene which is reported to be associated with type I resistance-breaking potential. Comparison of single nucleotide polymorphisms (SNPs) with five other fully sequenced CpGV isolates identified 67 unique events, 47 of which occurred within ORFs, leading to several amino acid changes. Further analysis of single nucleotide variations (SNVs) within CpGV-SA revealed that this isolate consists of mixed genotypes. Phylogenetic analysis using complete genome sequences placed CpGV-SA basal to M, I12 and E2 and distal to S and I07 but with no distinct classification into any of the previously defined CpGV genogroups. These results suggest that CpGV-SA is a novel and genetically distinct isolate with significant potential as a biopesticide for management of codling moth (CM), not only in South Africa, but potentially in other pome fruit producing countries, particularly where CM resistance to CpGV has been reported. Full article

(This article belongs to the Special Issue Insect Viruses and Pest Management)

► Show Figures

Figure 1

19 pages, 1829 KiB

Open AccessArticle

Identification of Multiple Replication Stages and Origins in the Nucleopolyhedrovirus of Anticarsia gemmatalis

by Solange A.B. Miele, Carolina S. Cerrudo, Cintia N. Parsza, María Victoria Nugnes, Diego L. Mengual Gómez, Mariano N. Belaich and P. Daniel Ghiringhelli

Viruses 2019, 11(7), 648; https://doi.org/10.3390/v11070648 - 15 Jul 2019

Cited by 3 | Viewed by 3395

Abstract

To understand the mechanism of replication used by baculoviruses, it is essential to describe all the factors involved, including virus and host proteins and the sequences where DNA synthesis starts. A lot of work on this topic has been done, but there is [...] Read more.

To understand the mechanism of replication used by baculoviruses, it is essential to describe all the factors involved, including virus and host proteins and the sequences where DNA synthesis starts. A lot of work on this topic has been done, but there is still confusion in defining what sequence/s act in such functions, and the mechanism of replication is not very well understood. In this work, we performed an AgMNPV replication kinetics into the susceptible UFL-Ag-286 cells to estimate viral genome synthesis rates. We found that the viral DNA exponentially increases in two different phases that are temporally separated by an interval of 5 h, probably suggesting the occurrence of two different mechanisms of replication. Then, we prepared a plasmid library containing virus fragments (0.5–2 kbp), which were transfected and infected with AgMNPV in UFL-Ag-286 cells. We identified 12 virus fragments which acted as origins of replication (ORI). Those fragments are in close proximity to core genes. This association to the core genome would ensure vertical transmission of ORIs. We also predict the presence of common structures on those fragments that probably recruit the replication machinery, a structure also present in previously reported ORIs in baculoviruses. Full article

(This article belongs to the Special Issue Insect Viruses and Pest Management)

► Show Figures

Graphical abstract

11 pages, 1488 KiB

Open AccessArticle

Importance of the Host Phenotype on the Preservation of the Genetic Diversity in Codling Moth Granulovirus

by Benoit Graillot, Christine Blachere-López, Samantha Besse, Myriam Siegwart and Miguel López-Ferber

Viruses 2019, 11(7), 621; https://doi.org/10.3390/v11070621 - 5 Jul 2019

Cited by 5 | Viewed by 2751

Abstract

To test the importance of the host genotype in maintaining virus genetic diversity, five experimental populations were constructed by mixing two Cydia pomonella granulovirus isolates, the Mexican isolate CpGV-M and the CpGV-R5, in ratios of 99% M + 1% R, 95% M + [...] Read more.

To test the importance of the host genotype in maintaining virus genetic diversity, five experimental populations were constructed by mixing two Cydia pomonella granulovirus isolates, the Mexican isolate CpGV-M and the CpGV-R5, in ratios of 99% M + 1% R, 95% M + 5% R, 90% M + 10% R, 50% M + 50% R, and 10% M + 90% R. CpGV-M and CpGV-R5 differ in their ability to replicate in codling moth larvae carrying the type I resistance. This ability is associated with a genetic marker located in the virus pe38 gene. Six successive cycles of replication were carried out with each virus population on a fully-permissive codling moth colony (CpNPP), as well as on a host colony (R_GV) that carries the type I resistance, and thus blocks CpGV-M replication. The infectivity of offspring viruses was tested on both hosts. Replication on the CpNPP leads to virus lineages preserving the pe38 markers characteristic of both isolates, while replication on the R_GV colony drastically reduces the frequency of the CpGV-M pe38 marker. Virus progeny obtained after replication on CpNPP show consistently higher pathogenicity than that of progeny viruses obtained by replication on R_GV, independently of the host used for testing. Full article

(This article belongs to the Special Issue Insect Viruses and Pest Management)

► Show Figures

Figure 1

14 pages, 1637 KiB

Open AccessArticle

Genetic Variability of Chrysodeixis Includens Nucleopolyhedrovirus (ChinNPV) and the Insecticidal Characteristics of Selected Genotypic Variants

by Eduardo Aguirre, Inés Beperet, Trevor Williams and Primitivo Caballero

Viruses 2019, 11(7), 581; https://doi.org/10.3390/v11070581 - 26 Jun 2019

Cited by 6 | Viewed by 3422

Abstract

Genetic variation in baculoviruses is recognized as a key factor, not only due to the influence of such variation on pathogen transmission and virulence traits, but also because genetic variants can form the basis for novel biological insecticides. In this study, we examined [...] Read more.

Genetic variation in baculoviruses is recognized as a key factor, not only due to the influence of such variation on pathogen transmission and virulence traits, but also because genetic variants can form the basis for novel biological insecticides. In this study, we examined the genetic variability of Chrysodeixis includens nucleopolyhedrovirus (ChinNPV) present in field isolates obtained from virus-killed larvae. Different ChinNPV strains were identified by restriction endonuclease analysis, from which genetic variants were isolated by plaque assay. Biological characterization studies were based on pathogenicity, median time to death (MTD), and viral occlusion body (OB) production (OBs/larva). Nine different isolates were obtained from eleven virus-killed larvae collected from fields of soybean in Mexico. An equimolar mixture of these isolates, named ChinNPV-Mex1, showed good insecticidal properties and yielded 23 genetic variants by plaque assay, one of which (ChinNPV-R) caused the highest mortality in second instars of C. includens. Five of these variants were selected: ChinNPV-F, ChinNPV-J, ChinNPV-K, ChinNPV-R, and ChinNPV-V. No differences in median time to death were found between them, while ChinNPV-F, ChinNPV-K, ChinNPV-R and ChinNPV-V were more productive than ChinNPV-J and the original mixture of field isolates ChinNPV-Mex1. These results demonstrate the high variability present in natural populations of this virus and support the use of these new genetic variants as promising active substances for baculovirus-based bioinsecticides. Full article

(This article belongs to the Special Issue Insect Viruses and Pest Management)

► Show Figures

Figure 1

18 pages, 6191 KiB

Open AccessArticle

A Novel Alphabaculovirus from the Soybean Looper, Chrysodeixis includens, that Produces Tetrahedral Occlusion Bodies and Encodes Two Copies of he65

by Robert L. Harrison, Daniel L. Rowley and Holly J. R. Popham

Viruses 2019, 11(7), 579; https://doi.org/10.3390/v11070579 - 26 Jun 2019

Cited by 3 | Viewed by 3267

Abstract

Isolates of the alphabaculovirus species, Chrysodeixis includens nucleopolyhedrovirus, have been identified that produce polyhedral occlusion bodies and infect larvae of the soybean looper, Chrysodeixis includens. In this study, we report the discovery and characterization of a novel C. includens-infecting alphabaculovirus, [...] Read more.

Isolates of the alphabaculovirus species, Chrysodeixis includens nucleopolyhedrovirus, have been identified that produce polyhedral occlusion bodies and infect larvae of the soybean looper, Chrysodeixis includens. In this study, we report the discovery and characterization of a novel C. includens-infecting alphabaculovirus, Chrysodeixis includens nucleopolyhedrovirus #1 (ChinNPV#1), that produces tetrahedral occlusion bodies. In bioassays against C. includens larvae, ChinNPV #1 exhibited a degree of pathogenicity that was similar to that of other ChinNPV isolates, but killed larvae more slowly. The host range of ChinNPV#1 was found to be very narrow, with no indication of infection occurring in larvae of Trichoplusia ni and six other noctuid species. The ChinNPV#1 genome sequence was determined to be 130,540 bp, with 126 open reading frames (ORFs) annotated but containing no homologous repeat (hr) regions. Phylogenetic analysis placed ChinNPV#1 in a clade with other Group II alphabaculoviruses from hosts of lepidopteran subfamily Plusiinae, including Chrysodeixis chalcites nucleopolyhedrovirus and Trichoplusia ni single nucleopolyhedrovirus. A unique feature of the ChinNPV#1 genome was the presence of two full-length copies of the he65 ORF. The results indicate that ChinNPV#1 is related to, but distinct from, other ChinNPV isolates. Full article

(This article belongs to the Special Issue Insect Viruses and Pest Management)

► Show Figures

Figure 1

11 pages, 607 KiB

Open AccessArticle

Partial Loss of Inheritable Type I Resistance of Codling Moth to Cydia pomonella granulovirus

by Jiangbin Fan, Jörg T. Wennmann and Johannes A. Jehle

Viruses 2019, 11(6), 570; https://doi.org/10.3390/v11060570 - 20 Jun 2019

Cited by 4 | Viewed by 3114

Abstract

Current knowledge of the field resistance of codling moth (CM, Cydia pomonella, L) against Cydia pomonella granulovirus (CpGV) is based mainly on the interaction between the Mexican isolate CpGV-M and CpRR1, a genetically homogeneous CM inbreed line carrying type I resistance. The [...] Read more.

Current knowledge of the field resistance of codling moth (CM, Cydia pomonella, L) against Cydia pomonella granulovirus (CpGV) is based mainly on the interaction between the Mexican isolate CpGV-M and CpRR1, a genetically homogeneous CM inbreed line carrying type I resistance. The resistance level of laboratory-reared CpRR1 to CpGV-M was recently found to have decreased considerably, compared to the initially high resistance. To understand the background of this phenomenon, CpRR1 larvae were exposed over several generations to CpGV-M for re-selection of the original resistance level. After five and seven generations of selection, new CpRR1_F5 and CpRR1_F7 lines were established. The resistance ratio of these selected lines was determined by full range bioassays. The CpRR1_F5 strain regained a higher level of resistance against CpGV up to 10⁴-fold based on LC₅₀ values compared to susceptible larvae (CpS), which indicated that the absence of virus selection had resulted in a reduction of resistance under laboratory rearing conditions. In addition, some fitness costs of fecundity were observed in CpRR1_F5. Single-pair crossings between CpRR1_F5 or CpRR1_F7 with susceptible CpS moths revealed a dominant but not fully sex-linked inheritance, which suggests a partial loss of previous resistance traits in CpRR1. Full article

(This article belongs to the Special Issue Insect Viruses and Pest Management)

► Show Figures

Figure 1

12 pages, 2994 KiB

Open AccessArticle

DWV-A Lethal to Honey Bees (Apis mellifera): A Colony Level Survey of DWV Variants (A, B, and C) in England, Wales, and 32 States across the US

by Jessica L. Kevill, Flaviane S. de Souza, Christopher Sharples, Randy Oliver, Declan C. Schroeder and Stephen J. Martin

Viruses 2019, 11(5), 426; https://doi.org/10.3390/v11050426 - 9 May 2019

Cited by 70 | Viewed by 8414

Abstract

The strong association between Varroa destructor, deformed wing virus (DWV), and high overwintering colony losses (OCL) of honey bees is well established. Three DWV master variants (DWV-A, -B, and -C) have been described, and their role in colony mortality remains an open [...] Read more.

The strong association between Varroa destructor, deformed wing virus (DWV), and high overwintering colony losses (OCL) of honey bees is well established. Three DWV master variants (DWV-A, -B, and -C) have been described, and their role in colony mortality remains an open question. Therefore, the aim of this study is to investigate the seasonal prevalence, viral load, and changing distribution of the three DWV master variants within honey bee colonies from England, Wales, and 32 states across the United States. Here, we report that in 2016, DWV-B was prevalent (100%, n = 249) and dominant (95%) in England and Wales, compared to the US. (56%, n = 217 and 23%, respectively), where DWV-A was prevalent (83%, n = 217) and dominant (63%). DWV-C was regularly detected in low viral loads (<1 × 10⁷ genome equivalents per bee) and at lower prevalence (58% in England and Wales, n = 203, and 14% across the United States, n = 124) compared to DWV-A and -B. DWV-B prevalence and dominance in England and Wales coincided with low OCL (6%). Meanwhile, a 60% loss was reported by participating U.S. beekeepers. In the United States, DWV-A prevalence (89%, n = 18) and viral load were significantly (p = 0.002) higher (1 × 10 ⁸–1 × 10¹¹) in colonies that died when compared to the surviving colonies (49% (n = 27), 1 × 10⁶–1 × 10¹⁰). DWV-B had low prevalence (56%, n = 18) in the colonies that died with viral loads of <1 × 10¹⁰. However, DWV-B was routinely detected in high viral loads (>1 × 10¹⁰) in surviving colonies from all sample locations, providing further supporting evidence of DWV-A exhibiting increased virulence over DWV-B at the colony level. Full article

(This article belongs to the Special Issue Insect Viruses and Pest Management)

► Show Figures

Figure 1

16 pages, 3211 KiB

Open AccessArticle

Effects of a Covert Infection with Phthorimaea operculella granulovirus in Insect Populations of Phthorimaea operculella

by Andreas Larem, Saoussen Ben Tiba, Eva Fritsch, Karin Undorf-Spahn, Jörg T. Wennmann and Johannes A. Jehle

Viruses 2019, 11(4), 337; https://doi.org/10.3390/v11040337 - 9 Apr 2019

Cited by 7 | Viewed by 3989

Abstract

Virus infections of insects can easily stay undetected, neither showing typical signs of a disease, nor being lethal. Such a stable and most of the time covert infection with Phthorimaea operculella granulovirus (PhopGV) was detected in a Phthorimaea operculella laboratory colony, which originated [...] Read more.

Virus infections of insects can easily stay undetected, neither showing typical signs of a disease, nor being lethal. Such a stable and most of the time covert infection with Phthorimaea operculella granulovirus (PhopGV) was detected in a Phthorimaea operculella laboratory colony, which originated from Italy (Phop-IT). This covert virus (named PhopGV-R) was isolated, purified and characterized at the genetic level by full genome sequencing. Furthermore, the insect colony Phop-IT was used to study the crowding effect, double infection with other PhopGV isolates (CR3 and GR1), and co-infection exclusion. An infection with a second homologous virus (PhopGV-CR3) activated the covert virus, while a co-infection with another virus isolate (PhopGV-GR1) led to its suppression. This study shows that stable virus infections can be common for insect populations and have an impact on population dynamics because they can suppress or enable co-infection with another virus isolate of the same species. Full article

(This article belongs to the Special Issue Insect Viruses and Pest Management)

► Show Figures

Figure 1

8 pages, 612 KiB

Open AccessArticle

Multiple Virus Infections in Western Honeybee (Apis mellifera L.) Ejaculate Used for Instrumental Insemination

by Jana Prodělalová, Romana Moutelíková and Dalibor Titěra

Viruses 2019, 11(4), 306; https://doi.org/10.3390/v11040306 - 29 Mar 2019

Cited by 18 | Viewed by 3562

Abstract

Instrumental insemination of Apis mellifera L. queens is a widely employed technique used in honeybee breeding that enables the effective control of mating. However, drone semen represents a potential source of honeybee viruses. In this study, 43 semen doses collected from apparently healthy [...] Read more.

Instrumental insemination of Apis mellifera L. queens is a widely employed technique used in honeybee breeding that enables the effective control of mating. However, drone semen represents a potential source of honeybee viruses. In this study, 43 semen doses collected from apparently healthy drones, and consequently used in instrumental insemination, were analysed using PCR or RT-PCR to detect the presence of viral genome of 11 honeybee viruses. In 91% of samples, viral infection was detected. The survey revealed genomes of five viruses, namely Deformed wing virus (DWV), Acute bee paralysis virus (ABPV), Black queen cell virus (BQCV), Sacbrood virus (SBV), and A. mellifera filamentous virus (AmFV) in 84%, 19%, 14%, 2%, and 67% of samples, respectively. Single infection (30% of samples) as well as multiple infection (61% of samples) of two, three or four pathogens were also evaluated. To the best of our knowledge, this is the first study describing the presence of the BQCV and SBV genome sequence in drone ejaculate. Phylogenetic analysis of BQCV partial helicase gene sequence revealed the high similarity of nucleotide sequence of described Czech strains, which varied from 91.4% to 99.6%. The findings of our study indicate the possibility of venereal transmission of BQCV and SBV. Full article

(This article belongs to the Special Issue Insect Viruses and Pest Management)

► Show Figures

Figure 1

16 pages, 5651 KiB

Open AccessArticle

New Method for Differentiation of Granuloviruses (Betabaculoviruses) Based on Real-Time Polymerase Chain Reaction (Real-Time PCR)

by Martyna Krejmer-Rabalska, Lukasz Rabalski, Michael D. Jukes, Marlinda Lobo de Souza, Sean D. Moore and Boguslaw Szewczyk

Viruses 2019, 11(2), 115; https://doi.org/10.3390/v11020115 - 29 Jan 2019

Cited by 1 | Viewed by 3936

Abstract

Baculoviridae is a highly diverse family of rod-shaped viruses with double-stranded DNA. To date, almost 100 species have had their complete genomic sequences deposited in the GenBank database, a quarter of which comprises granuloviruses (GVs). Many of the genomes are sequenced using next-generation [...] Read more.

Baculoviridae is a highly diverse family of rod-shaped viruses with double-stranded DNA. To date, almost 100 species have had their complete genomic sequences deposited in the GenBank database, a quarter of which comprises granuloviruses (GVs). Many of the genomes are sequenced using next-generation sequencing, which is currently considered the best method for characterizing new species, but it is time-consuming and expensive. Baculoviruses form a safe alternative to overused chemical pesticides and therefore there is a constant need for identifying new species that can be active components of novel biological insecticides. In this study, we have described a fast and reliable method for the detection of new and differentiation of previously analyzed granulovirus species based on a real-time polymerase chain reaction (PCR) technique with melting point curve analysis. The sequences of highly conserved baculovirus genes, such as granulin and late expression factors 8 and 9 (lef-8 and lef-9), derived from GVs available to date have been analyzed and used for degenerate primer design. The developed method was tested on a representative group of eight betabaculoviruses with comparisons of melting temperatures to allow for quick and preliminary granulovirus detection. The proposed real-time PCR procedure may be a very useful tool as an easily accessible screening method in a majority of laboratories. Full article

(This article belongs to the Special Issue Insect Viruses and Pest Management)

► Show Figures

Figure 1

Review

Jump to: Editorial, Research

9 pages, 687 KiB

Open AccessReview

Nucleocapsid Assembly of Baculoviruses

by Shuling Zhao, Guanghui He, Yiheng Yang and Changyong Liang

Viruses 2019, 11(7), 595; https://doi.org/10.3390/v11070595 - 1 Jul 2019

Cited by 14 | Viewed by 4244

Abstract

The baculovirus nucleocapsid is formed through a rod-like capsid encapsulating a genomic DNA molecule of 80~180 kbp. The viral capsid is a large oligomer composed of many copies of various protein subunits. The assembly of viral capsids is a complex oligomerization process. The [...] Read more.

The baculovirus nucleocapsid is formed through a rod-like capsid encapsulating a genomic DNA molecule of 80~180 kbp. The viral capsid is a large oligomer composed of many copies of various protein subunits. The assembly of viral capsids is a complex oligomerization process. The timing of expression of nucleocapsid-related proteins, transport pathways, and their interactions can affect the assembly process of preformed capsids. In addition, the selection of viral DNA and the injection of the viral genome into empty capsids are the critical steps in nucleocapsid assembly. This paper reviews the replication and recombination of baculovirus DNA, expression and transport of capsid proteins, formation of preformed capsids, DNA encapsulation, and nucleocapsid formation. This review will provide a basis for further study of the nucleocapsid assembly mechanism of baculovirus. Full article

(This article belongs to the Special Issue Insect Viruses and Pest Management)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Insect Viruses and Pest Management

Share This Special Issue

Special Issue Editor

Special Issue Information

Benefits of Publishing in a Special Issue

Related Special Issues

Published Papers (21 papers)

Editorial

Research

Review

Further Information

Guidelines

MDPI Initiatives

Follow MDPI