Post-mortem incubation influences occlusion body production in nucleopolyhedrovirus-infected larvae of Spodoptera frugiperda

Ramírez-Arias, Fernando G.; Lasa, Rodrigo; Murillo, Rosa; Navarro-de-la-Fuente, Laura; Mercado, Gabriel; Williams, Trevor

doi:10.1016/j.biocontrol.2019.05.003

Cited by 11 publications

(5 citation statements)

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“…Various qPCR methods have been used previously for alphabaculovirus quantification in insect and environmental samples [ 45 , 46 , 47 ], as well as numerous baculovirus transcriptional studies. The SfMNPV-NIC isolate was previously subjected to qPCR assays using primers targeted at polyhedrin [ 48 , 49 ]. However, qPCR methods for quantification of genotypic variants in a nucleopolyhedrovirus isolate are scarce [ 50 ].…”

Section: Discussionmentioning

confidence: 99%

A qPCR Assay for the Quantification of Selected Genotypic Variants of Spodoptera frugiperda Multiple Nucleopolyhedrovirus (Baculoviridae)

Molina-Ruiz,

Zamora-Briseño,

Simón

et al. 2024

Viruses

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Alphabaculoviruses are lethal dsDNA viruses of Lepidoptera that have high genetic diversity and are transmitted in aggregates within proteinaceous occlusion bodies. This mode of transmission has implications for their efficacy as biological insecticides. A Nicaraguan isolate of Spodoptera frugiperda multiple nucleopolyhedrovirus (SfMNPV-NIC) comprising nine genotypic variants has been the subject of considerable study due to the influence of variant interactions on the insecticidal properties of mixed-variant occlusion bodies. As part of a systematic study on the replication and transmission of variant mixtures, a tool for the accurate quantification of a selection of genotypic variants was developed based on the quantitative PCR technique (qPCR). First, primer pairs were designed around a region of high variability in four variants named SfNic-A, SfNic-B, SfNic-C and SfNic-E to produce amplicons of 103–150 bp. Then, using cloned purified amplicons as standards, amplification was demonstrated over a dynamic range of 108–101 copies of each target. The assay was efficient (mean ± SD: 98.5 ± 0.8%), reproducible, as shown by low inter- and intra-assay coefficients of variation (<5%), and specific to the target variants (99.7–100% specificity across variants). The quantification method was validated on mixtures of genotype-specific amplicons and demonstrated accurate quantification. Finally, mixtures of the four variants were quantified based on mixtures of budded virions and mixtures of DNA extracted from occlusion-derived virions. In both cases, mixed-variant preparations compared favorably to total viral genome numbers by quantification of the polyhedrin (polh) gene that is present in all variants. This technique should prove invaluable in elucidating the influence of variant diversity on the transmission and insecticidal characteristics of this pathogen.

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Section: Discussionmentioning

confidence: 99%

A qPCR Assay for the Quantification of Selected Genotypic Variants of Spodoptera frugiperda Multiple Nucleopolyhedrovirus (Baculoviridae)

Molina-Ruiz,

Zamora-Briseño,

Simón

et al. 2024

Viruses

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“…Calibration of the soil bioassay indicated that the concentrations of OBs in virus-positive maize field samples were likely between 10 4 and 10 5 OBs/g soil. This is not an insignificant amount as the 50% lethal concentration of SfMNPV OBs by droplet feeding bioassay is approximately 2 × 10 4 OBs/mL in second instar larvae of S. frugiperda [ 44 ].…”

Section: Discussionmentioning

confidence: 99%

Presence of Spodoptera frugiperda Multiple Nucleopolyhedrovirus (SfMNPV) Occlusion Bodies in Maize Field Soils of Mesoamerica

Williams¹,

Melo-Molina²,

Jiménez-Fernández³

et al. 2023

Insects

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The occlusion bodies (OBs) of lepidopteran nucleopolyhedroviruses can persist in soil for extended periods before being transported back on to the foliage for transmission to the host insect. A sensitive insect bioassay technique was used to detect OBs of Spodoptera frugiperda multiple nucleopolyhedrovirus (SfMNPV) in 186 soil samples collected from maize fields in the southern Mexican states of Chiapas, Tabasco, Campeche, Yucatán, and Quintana Roo, as well Belize and Guatemala. Overall, 35 (18.8%) samples proved positive for SfMNPV OBs. The frequency of OB-positive samples varied significantly among Mexican states and countries (p < 0.05). Between 1.7 and 4.4% of S. frugiperda larvae that consumed OB-positive samples died from polyhedrosis disease. Restriction endonuclease analysis using PstI and HindIII confirmed that the soil-derived isolates were strains of SfMNPV and that genetic diversity was evident among the isolates. The prevalence of OB-positive soil samples did not differ with altitude or extension (area) of the maize field, but it was significantly higher in fields with the presence of living maize plants compared to those containing dead plants or crop residues (p < 0.05). Georeferenced soil samples were used to identify soil types on digitized soil maps. Lithosol and Luvisol soils had a higher than average prevalence of OB-positive samples (42–45% positive) (p = 0.006), as did Andosol, Gleysol, and Vertisol soils (33–60% OB-positive), although the sample sizes were small (<5 samples) for the latter three soils. In contrast, Cambisol soils had a lower than average prevalence of OB-positive samples (5% positive). Bioassays on Acrisol, Fluvisol, Phaeozem, and Rendzina soils resulted in intermediate levels of OB-positive samples. We conclude that certain soil types may favor OB persistence and virus-mediated biological pest control. The soil is also likely to provide a valuable source of genetic diversity for the design of virus-based insecticides against this pest.

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“…The commercial production of baculovirus OBs currently uses in vivo procedures that require rearing and harvesting large numbers of host larvae 11 . As a result, the production of baculovirus‐based insecticides at low cost and large quantities represents a challenge for a commercial‐scale up manufacturing 12–14 …”

Section: Introductionmentioning

confidence: 99%

“…11 As a result, the production of baculovirus-based insecticides at low cost and large quantities represents a challenge for a commercial-scale up manufacturing. [12][13][14] Baculoviruses have the potential to infect, multiply, spread (both horizontally and vertically) and persist in populations that constantly fluctuate. 6,15 When using baculoviruses in huge amounts with a curative strategy, the virus reduces pest population levels, but its reproductive success decreases because transmission to new host is a fundamental process in disease ecology; in the end, this reduces the persistence of the virus because of the speed of the death of the host.…”

Section: Introductionmentioning

confidence: 99%

A novel use of Nesidiocoris tenuis (Reuter) (Hemiptera: Miridae) as inoculative agent of baculoviruses

Gutiérrez-Cárdenas

Adán

Medina

et al. 2023

Pest Management Science

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BackgroundAlphabaculoviruses are Lepidoptera‐specific virulent pathogens that infect numerous pests, including the Spodoptera complex. Due to their low environmental persistence, the traditional use of Alphabaculoviruses as bioinsecticides consist in high‐rate spray applications with repeated treatments. Several abiotic and biotic factors can foster its dispersion, promoting their persistence in the agroecosystem. Amongst biotic factors, predatory arthropods can disperse the viruses by excretion after preying on infected individuals. Therefore, this study focused on promoting predator's ingestion of nucleopolyhedrovirus (NPV)‐treated diets, and the later exposition of the insect host to leaf surfaces contaminated with predator excreta. The virus–host–predator system studied was Spodoptera littoralis nucleopolyhedrovirus (SpliNPV), Spodoptera littoralis (Boisduval) and Nesidiocoris tenuis (Reuter). The infective potential of N. tenuis feces and the retention time of SpliNPV were assessed under laboratory conditions after feeding on treated diets (sucrose solution and Ephestia kuehniella eggs).ResultsMortality of S. littoralis larvae was lower via N. tenuis excretion than in positive control (spray application) in the first infection cycle, together with a delay in host death. In the second infection cycle, both SpliNPV‐treated diets triggered 100% mortality. Both diets allowed the transmission of SpliNPV, with a faster excretion via sucrose solution compared to E. kuehniella eggs. SpliNPV remained in N. tenuis digestive tract and was viable after excretion at least for 9 days for both diets.ConclusionsThis study demonstrated the potential of the predator N. tenuis as inoculative agent of baculoviruses, representing a new alternative that, along with inundative applications, might contribute to improve pest management strategies. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

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Post-mortem incubation influences occlusion body production in nucleopolyhedrovirus-infected larvae of Spodoptera frugiperda

Cited by 11 publications

References 50 publications

A qPCR Assay for the Quantification of Selected Genotypic Variants of Spodoptera frugiperda Multiple Nucleopolyhedrovirus (Baculoviridae)

A qPCR Assay for the Quantification of Selected Genotypic Variants of Spodoptera frugiperda Multiple Nucleopolyhedrovirus (Baculoviridae)

Presence of Spodoptera frugiperda Multiple Nucleopolyhedrovirus (SfMNPV) Occlusion Bodies in Maize Field Soils of Mesoamerica

A novel use of Nesidiocoris tenuis (Reuter) (Hemiptera: Miridae) as inoculative agent of baculoviruses

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