Genotype assembly, biological activity and adaptation of spatially separated isolates of Spodoptera litura nucleopolyhedrovirus

Ali, Ghulam Muhammad; Abma-Henkens, Marleen H. C.; Werf, Wopke Van der; Hemerik, Lia; Vlak, Just M.

doi:10.1016/j.jip.2018.01.009

Cited by 11 publications

(16 citation statements)

References 44 publications

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“…In a field survey in 2011–2013, 22 baculovirus isolates were obtained from S. litura from different cropping systems [4,5]. These isolates turned out to be nucleopolyhedroviruses (NPVs), members of the genus Alphabaculovirus within the Baculoviridae family [6,7].…”

Section: Introductionmentioning

confidence: 99%

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

Zwart

Ali

Strien

et al. 2019

Viruses

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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.

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Section: Introductionmentioning

confidence: 99%

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

Zwart

Ali

Strien

et al. 2019

Viruses

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“…A field survey has been set up to obtain further Splt-Pak NPV field isolates with improved insecticidal characteristics. The initial results have been reported and four isolates with improved speed of kill have been obtained (Ali, Abma-Henkens, Van der Werf, Hemerik, & Vlak, 2018). SpltNPV-Pak-BNG can be considered the prototype of Pakistani SpltNPV isolates, which form a separate regional clade (regiotype) within the SpltNPV species.…”

Section: Discussionmentioning

confidence: 99%

Biological activity of Pakistani isolate SpltNPV-Pak-BNG in second, third and fourth instar larvae of the leafwormSpodoptera litura

Ali¹,

Vlak

Werf

2018

Biocontrol Science and Technology

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Recently, a novel isolate of the baculovirus Spodoptera litura nucleopolyhedrovirus (SpltNPV) has been isolated from Pakistan, which is distinct from the type species SpltNPV-G2 (ICTV). Here, we examined the biological activity of this isolate (SpltNPV-Pak-BNG) in second (L2), third (L3) and fourth instar (L4) larvae of the leafworm S. litura, more specifically to measure biological properties that are relevant for use of this virus for pest control under field conditions. The median lethal dose for L2 and L3 instar larvae was similar, but significantly lower than for L4 larvae. Likewise, the survival time was similar for L2 and L3 larvae (84 h), but was significantly longer for L4 instar larvae (108 h). Thus, in terms of efficacy, S. litura L2 and L3 instar larvae are the preferred targets for S. litura control with SpltNPV-Pak-BNG in field crops in Pakistan. On the basis of our data spray regimes can be designed to control the leafworm in cotton and vegetable crops targeting L2 and L3 larvae.

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“…In addition, during the replication step of the infection process, the baculoviruses exchange genetic material with other virus and other co‐infecting microorganisms, resulting in a wide genetic diversity of isolates, which vary in pathogenicity and virulence (Ali, Abma‐Henkens, van der Werf, Hemerik, & Vlak, ). This might explain the effect of the geographical origin on the insecticidal activity of baculoviruses.…”

Section: Introductionmentioning

confidence: 99%

Molecular and Morphological characterization of multiple nucleopolyhedrovirus from Mexico and their insecticidal activity against Spodoptera frugiperda (Lepidoptera: Noctuidae)

Ordóñez-García

Rios‐Velasco

Ornelas‐Paz

et al. 2019

J Applied Entomology

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The fall armyworm (FAW), Spodoptera frugiperda (Lepidoptera: Noctuidae), is the most important pest of maize in many countries. Entomopathogenic viruses mainly Baculoviruses family are excellent biological control agents and therefore a viable alternative for managing this pest. The aim of this study was to determine the biological activity of eight native nucleopolyhedrovirus (NPVs) against FAW larvae.Additionally, two of the most virulent isolates (SfCH32 and SfCH15) were characterized biologically by bioassays to estimate their median lethal dose (LD 50 ) and median lethal time (LT 50 ), morphologically by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) and molecularly by restriction enzymes.Three (SfCH15, SfCH18 and SfCH32) of the eight tested native nucleopolyhedrovirus isolates caused mortalities ˃98% at 168-hr post-inoculation (hpi) with a dose of 9.2 × 10 4 OBs/larva. SfCH15 and SfCH32 isolates showed occlusion bodies (OBs) of irregular shape and size (1.02-2.24 μm). The SfCH15 and SfCH32 isolates showed similar median lethal dose (5.6 × 10 2 -6.4 × 10 2 OBs/larva). The lowest median lethal time (114.5 hpi) was observed with the SfCH15 isolate at the highest concentration (2.5 × 10 6 OBs/larva). The DNA restriction profiles for SfCH15 and SfCH32 were different, with their genome size being ~128,000 bp and 132,000 bp, respectively. SfCH15 and SfCH32 isolates showed similar morphological characteristics and the highest virulence against fall armyworm. This study showed that native isolates were highly virulent against S. frugiperda larvae, being similar to other reported strains; however, field studies are required to confirm their insecticidal effect. K E Y W O R D Sbaculovirus, biological control, fall armyworm, genetic variability, morphology, virulence

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Genotype assembly, biological activity and adaptation of spatially separated isolates of Spodoptera litura nucleopolyhedrovirus

Cited by 11 publications

References 44 publications

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

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

Biological activity of Pakistani isolate SpltNPV-Pak-BNG in second, third and fourth instar larvae of the leafwormSpodoptera litura

Molecular and Morphological characterization of multiple nucleopolyhedrovirus from Mexico and their insecticidal activity against Spodoptera frugiperda (Lepidoptera: Noctuidae)

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