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Faria M, Souza DA, Sanches MM, Schmidt FGV, Oliveira CM, Benito NP, Lopes RB. Evaluation of key parameters for developing a Metarhizium rileyi-based biopesticide against Spodoptera frugiperda (Lepidoptera: Noctuidae) in maize: laboratory, greenhouse, and field trials. PEST MANAGEMENT SCIENCE 2022; 78:1146-1154. [PMID: 34811883 DOI: 10.1002/ps.6729] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 11/17/2021] [Accepted: 11/23/2021] [Indexed: 06/13/2023]
Abstract
BACKGROUND The entomopathogenic fungus Metarhizium rileyi is known to cause natural infections in some caterpillars. In this multiyear study, we carried out laboratory, greenhouse and three field trials with the aim of developing a sustainable option for control of the fall armyworm (FAW) in maize. Association of M. rileyi with Spodoptera frugiperda baculovirus (SfMNPV) and delivery strategies were also investigated. RESULTS The selected isolate (CG381) was effective in the laboratory at a low concentration (~ 4 × 103 conidia cm-2 ), killing >95% of FAW larvae within 8 days. In the greenhouse assay, applications of conidia suspended in water or as dry powder in maize whorls (~ 6.3 × 106 conidia per plant) produced similar larval mortalities (88%-96%). In the field trials, conventional spraying of unformulated conidia (0.6 and 1.2 × 1012 conidia ha-1 ) caused low larval mortalities (27-31%). Simultaneous application of either unformulated or oil-based formulations of M. rileyi conidia and S. frugiperda baculovirus (SfMNPV) to plant rows caused larval mortalities comparable with each of the pathogens applied alone. However, when a formulation containing both pathogens was sprayed directly into the whorls, the overall mortality of S. frugiperda larvae due to pathogens (mostly to M. rileyi infections) reached ~ 59%, twofold higher than the other treatments with conventional spraying, whereas in the control, the overall mortality was only 1%. CONCLUSION Optimizing exposure of S. frugiperda larvae to an inoculum of virulent entomopathogens through directed applications to maize whorls is critical to produce satisfactory mortality levels and is promising for integrated pest management.
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Affiliation(s)
- Marcos Faria
- EMBRAPA Genetic Resources and Biotechnology, Brasília, Brazil
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Stinguel P, Paiva CEC, Zuim V, Azevedo ACT, Valicente FH, Dos Santos Júnior HJG. Optimization of In Vivo Production of Spodoptera frugiperda multiple nucleopolyhedrovirus (SfMNPV). NEOTROPICAL ENTOMOLOGY 2022; 51:122-132. [PMID: 34590293 DOI: 10.1007/s13744-021-00917-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Accepted: 09/15/2021] [Indexed: 06/13/2023]
Abstract
Insect viruses have been used to protect crops and forests worldwide for decades. Among insect viruses, isolates of Spodoptera frugiperda multiple nucleopolyhedrovirus (SfMNPV) have proven potential for the control of Spodoptera frugiperda (J. E. Smith) (FAW) (Lepidoptera: Noctuidae), a pest of many economically essential crops across several continents. Mass production of SfMNPV depends on an in vivo system using host insect rearing. However, many factors can limit its production, including abiotic factors and host characteristics, such as the stage of development and an antagonist intraspecific interaction. Thus, to improve in vivo production, we verified the most suitable larval age to inoculate the virus and the influence of incubation temperature on viral production. Subsequently, cannibal behavior was verified in FAW larvae reared at different densities, while reproducing the conditions of the best treatments. The highest viral yield occurred when FAW larvae were inoculated at 10 and 8 days old and incubated at 22 °C and 25 °C, respectively. Nonetheless, survival (lethal period in days) and cannibal behavior were positively influenced by larval development, which potentially increases the load of contamination and requires larval individualization for these production conditions. In contrast, 4-day-old larvae, which were inoculated and incubated at 31 °C, also demonstrated high viral production, with lower rates of cannibalism and death on the same day, thereby showing potential. The information presented in this study is useful for the optimization of the in vivo production systems of SfMNPV.
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Affiliation(s)
- Priscila Stinguel
- Federal University of Espírito Santo, Porto Alegre, ES, Brazil
- Federal Institute of Espírito Santo, Montanha, ES, Brazil
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Zanella-Saenz I, Herniou EA, Ibarra JE, Huerta-Arredondo IA, Del Rincón-Castro MC. Virulence and genetic characterization of six baculovirus strains isolated from different populations of Spodoptera frugiperda (Lepidoptera: Noctuidae). Arch Microbiol 2022; 204:108. [PMID: 34978619 DOI: 10.1007/s00203-021-02722-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 12/01/2021] [Accepted: 12/13/2021] [Indexed: 12/24/2022]
Abstract
Fall armyworm (FAW), Spodoptera frugiperda (Smith, 1797), is a polyphagous, voracious, and economically important agricultural pest. Biological control of FAW is a strategy that must be further explored. This study evaluated six baculovirus strains isolated from infected FAW larvae from Mexico, Argentina, Honduras, and the United States. Five alphabaculoviruses (SfNPV-An2, SfNPV-Arg, SfNPV-Fx, SfNPV-Ho, and SfNPV-Sin) and one betabaculovirus (SfGV-RV) were tested against FAW larvae, showing a wide diversity of virulence levels among strains when their estimated LC50s were compared, being SfNPV-Arg, SfNPV-Ho and SfNPV-Fx more virulent than SfNPV-An2, SfNPV-Sin, and SfGV-RV. To determine any virulence difference in vitro studies of these isolates, Sf9 cell cultures were used. Interestingly, only ODVs from four of the test SfNPV strains showed infectivity on Sf9 cell cultures, and some differences in virulence were observed. Genomic restriction analyses and partial sequences of lef-8, lef-9, and polh/granulin genes showed little variability among alphabaculoviruses, both, among them and with previously reported sequences. However, sequences from SfGV-RV were closer to previously reported sequences from the SfGV-VG008 strain than the SfGV-Arg and SfGV-VG014 strains. The great difference in the in vivo virulence was not correlated with great similarity among the isolates. The characterization of these six baculovirus isolates offers the basis for exploring their potential as biological control agents against S. frugiperda, as well the initial studies on their specific infection mechanisms, evolution, and ecology.
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Affiliation(s)
- Ingrid Zanella-Saenz
- División Ciencias de la Vida, Departamento de Alimentos, Posgrado en Biociencias, Universidad de Guanajuato, Campus Irapuato-Salamanca, Km. 9.0 Carr. Irapuato-León, C.P. 36500, Irapuato, Guanajuato, Mexico.,Instituto Tecnológico Superior de Abasolo, Blvd. Cuitzeo de los Naranjos No. 401, Abasolo, C.P. 36976, Guanajuato, Mexico
| | - Elisabeth A Herniou
- Faculté des Sciences Parc Grandmont, Institut de Recherche sur la Biologie de l'Insect, UMR 7261 CNRS-Université de Tours, 37200, Tours, France
| | - Jorge E Ibarra
- Departamento de Biotecnología y Bioquímica, Centro de Investigación y de Estudios Avanzados del I.P.N., 36500, Irapuato, Gto, Mexico
| | - Ilse Alejandra Huerta-Arredondo
- División Ciencias de la Vida, Departamento de Agronomía, Universidad de Guanajuato, Campus Irapuato-Salamanca, Km. 9.0 Carr. Irapuato-León, C.P. 36500, Irapuato, Guanajuato, Mexico
| | - Ma Cristina Del Rincón-Castro
- División Ciencias de la Vida, Departamento de Alimentos, Posgrado en Biociencias, Universidad de Guanajuato, Campus Irapuato-Salamanca, Km. 9.0 Carr. Irapuato-León, C.P. 36500, Irapuato, Guanajuato, Mexico.
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Hussain AG, Wennmann JT, Goergen G, Bryon A, Ros VI. Viruses of the Fall Armyworm Spodoptera frugiperda: A Review with Prospects for Biological Control. Viruses 2021; 13:v13112220. [PMID: 34835026 PMCID: PMC8625175 DOI: 10.3390/v13112220] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 10/29/2021] [Accepted: 10/30/2021] [Indexed: 11/17/2022] Open
Abstract
The fall armyworm (FAW), Spodoptera frugiperda, is a native pest species in the Western hemisphere. Since it was first reported in Africa in 2016, FAW has spread throughout the African continent and is now also present in several countries in Asia as well as Australia. The invasion of FAW in these areas has led to a high yield reduction in crops, leading to huge economic losses. FAW management options in the newly invaded areas are limited and mainly rely on the use of synthetic pesticides. Since there is a risk of resistance development against pesticides in addition to the negative environmental and human health impacts, other effective, sustainable, and cost-efficient control alternatives are desired. Insect pathogenic viruses fulfil these criteria as they are usually effective and highly host-specific with no significant harmful effect on beneficial insects and non-target organisms. In this review, we discuss all viruses known from FAW and their potential to be used for biological control. We specifically focus on baculoviruses and describe the recent advancements in the use of baculoviruses for biological control in the native geographic origin of FAW, and their potential use in the newly invaded areas. Finally, we identify current knowledge gaps and suggest new avenues for productive research on the use of viruses as a biopesticide against FAW.
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Affiliation(s)
- Ahmed G. Hussain
- Laboratory of Virology, Wageningen University and Research, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands; (A.G.H.); (A.B.)
| | - Jörg T. Wennmann
- Julius Kühn Institute (JKI)—Federal Research Centre for Cultivated Plants, Institute for Biological Control, Heinrichstr. 243, 64287 Darmstadt, Germany;
| | - Georg Goergen
- International Institute of Tropical Agriculture (IITA), Biological Control Centre for Africa, Cotonou 08 BP 0932, Benin;
| | - Astrid Bryon
- Laboratory of Virology, Wageningen University and Research, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands; (A.G.H.); (A.B.)
| | - Vera I.D. Ros
- Laboratory of Virology, Wageningen University and Research, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands; (A.G.H.); (A.B.)
- Correspondence:
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Yu H, Ou-Yang YY, Yang CJ, Li N, Nakai M, Huang GH. 3H-31, A Non-structural Protein of Heliothis virescens ascovirus 3h, Inhibits the Host Larval Cathepsin and Chitinase Activities. Virol Sin 2021; 36:1036-1051. [PMID: 33830433 DOI: 10.1007/s12250-021-00374-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Accepted: 11/16/2020] [Indexed: 11/29/2022] Open
Abstract
3h-31 of Heliothis virescens ascovirus 3h (HvAV-3h) is a highly conserved gene of ascoviruses. As an early gene of HvAV-3h, 3h-31 codes for a non-structural protein (3H-31) of HvAV-3h. In the study, 3h-31 was initially transcribed and expressed at 3 h post-infection (hpi) in the infected Spodoptera exigua fat body cells (SeFB). 3h-31 was further inserted into the bacmid of Autographa californica nucleopolyhedrovirus (AcMNPV) to generate an infectious baculovirus (AcMNPV-31). In vivo experiments showed that budded virus production and viral DNA replication decreased with the expression of 3H-31, and lucent tubular structures were found around the virogenic stroma in the AcMNPV-31-infected SeFB cells. In vivo, both LD50 and LD90 values of AcMNPV-31 were significantly higher than those of the wild-type AcMNPV (AcMNPV-wt) in third instar S. exigua larvae. An interesting finding was that the liquefaction of the larvae killed by the infection of AcMNPV-31 was delayed. Chitinase and cathepsin activities of AcMNPV-31-infected larvae were significantly lower than those of AcMNPV-wt-infected larvae. The possible regulatory function of the chitinase and cathepsin for 3H-31 was further confirmed by RNAi, which showed that larval cathepsin activity was significantly upregulated, but chitinase activity was not significantly changed due to the RNAi of 3h-31. Based on the obtained results, we assumed that the function of 3H-31 was associated with the inhibition of host larval chitinase and cathepsin activities, so as to restrain the hosts in their larval stages.
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Affiliation(s)
- Huan Yu
- Hunan Provincial Key Laboratory for Biology and Control of Plant Diseases and Insect Pests, Hunan Agricultural University, Changsha, 410128, China.,College of Plant Protection, Hunan Agricultural University, Changsha, 410128, China
| | - Yi-Yi Ou-Yang
- Hunan Provincial Key Laboratory for Biology and Control of Plant Diseases and Insect Pests, Hunan Agricultural University, Changsha, 410128, China.,College of Plant Protection, Hunan Agricultural University, Changsha, 410128, China
| | - Chang-Jin Yang
- Hunan Provincial Key Laboratory for Biology and Control of Plant Diseases and Insect Pests, Hunan Agricultural University, Changsha, 410128, China.,College of Plant Protection, Hunan Agricultural University, Changsha, 410128, China
| | - Ni Li
- Hunan Provincial Key Laboratory for Biology and Control of Plant Diseases and Insect Pests, Hunan Agricultural University, Changsha, 410128, China.,College of Plant Protection, Hunan Agricultural University, Changsha, 410128, China
| | - Madoka Nakai
- Tokyo University of Agriculture and Technology, Saiwai, Fuchu, Tokyo, 183-8509, Japan
| | - Guo-Hua Huang
- Hunan Provincial Key Laboratory for Biology and Control of Plant Diseases and Insect Pests, Hunan Agricultural University, Changsha, 410128, China. .,College of Plant Protection, Hunan Agricultural University, Changsha, 410128, China.
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Sosa-Gómez DR, Morgado FS, Corrêa RFT, Silva LA, Ardisson-Araújo DMP, Rodrigues BMP, Oliveira EE, Aguiar RWS, Ribeiro BM. Entomopathogenic Viruses in the Neotropics: Current Status and Recently Discovered Species. NEOTROPICAL ENTOMOLOGY 2020; 49:315-331. [PMID: 32358711 DOI: 10.1007/s13744-020-00770-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Accepted: 03/03/2020] [Indexed: 06/11/2023]
Abstract
The market for biological control of insect pests in the world and in Brazil has grown in recent years due to the unwanted ecological and human health impacts of chemical insecticides. Therefore, research on biological control agents for pest management has also increased. For instance, insect viruses have been used to protect crops and forests around the world for decades. Among insect viruses, the baculoviruses are the most studied and used viral biocontrol agent. More than 700 species of insects have been found to be naturally infected by baculoviruses, with 90% isolated from lepidopteran insects. In this review, some basic aspects of baculovirus infection in vivo and in vitro infection, gene content, viral replication will be discussed. Furthermore, we provide examples of the use of insect viruses for biological pest control and recently characterized baculoviruses in Brazil.
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Affiliation(s)
- D R Sosa-Gómez
- Empresa Brasileira de Pesquisa Agropecuária, Embrapa Soja, Londrina, PR, Brasil
| | - F S Morgado
- Depto de Biologia Celular, Univ of Brasília, Brasília, DF, Brasil
| | - R F T Corrêa
- Depto de Biotecnologia, Univ Federal de Tocantins, Gurupi, TO, Brasil
| | - L A Silva
- Depto de Biologia Celular, Univ of Brasília, Brasília, DF, Brasil
| | - D M P Ardisson-Araújo
- Depto de Bioquímica e Biologia Molecular, Univ Federal de Santa Maria, Santa Maria, RS, Brasil
| | - B M P Rodrigues
- Depto de Biologia Celular, Univ of Brasília, Brasília, DF, Brasil
| | - E E Oliveira
- Depto de Entomologia, Univ Federal de Viçosa, Viçosa, MG, Brasil
| | - R W S Aguiar
- Depto de Biotecnologia, Univ Federal de Tocantins, Gurupi, TO, Brasil
| | - B M Ribeiro
- Depto de Biologia Celular, Univ of Brasília, Brasília, DF, Brasil.
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Bentivenha JPF, Rodrigues JG, Lima MF, Marçon P, Popham HJR, Omoto C. Baseline Susceptibility of Spodoptera frugiperda (Lepidoptera: Noctuidae) to SfMNPV and Evaluation of Cross-Resistance to Major Insecticides and Bt Proteins. JOURNAL OF ECONOMIC ENTOMOLOGY 2019; 112:91-98. [PMID: 30395231 DOI: 10.1093/jee/toy342] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2018] [Indexed: 06/08/2023]
Abstract
The resistance evolution of Spodoptera frugiperda (J.E. Smith) to insecticides and Bt proteins along with the intensive crop production systems adopted in Brazil make it challenging to implement integrated pest management. The adoption of alternative methods to manage pests is fundamental to the implementation of favorable integrated pest management and insect resistance management. Spodoptera frugiperda multiple nucleopolyhedrovirus (SfMNPV) is a valuable tool for S. frugiperda control. The characterization of the baseline susceptibility of S. frugiperda populations and cross-resistance involving SfMNPV and major insecticides and Bt proteins have not yet been conducted. The objective of this study was to characterize the baseline susceptibility of S. frugiperda populations from five Brazilian States to SfMNPV (Cartugen, AgBiTech, Fort Worth, TX). Possible cross-resistance to insecticides and Bt proteins among resistant S. frugiperda strains was also assessed. There were no differences in the susceptibility of the studied populations to SfMNPV. The estimated diagnostic concentration may be utilized in future monitoring studies to SfMNPV. The SfMNPV presented no cross-resistance to the chemical insecticides and to the Bt proteins tested. Our results provide evidence of the biological activity and high potential of SfMNPV as a distinct insecticidal mode of action for use in rotation with other tools. This biological insecticide is known to have a favorable toxicological and ecotoxicological profile and will be a valuable tool in insect resistance management and integrated pest management programs for control of S. frugiperda.
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Affiliation(s)
- José P F Bentivenha
- Department of Entomology and Acarology, Luiz de Queiroz College of Agriculture, University of São Paulo, Piracicaba, São Paulo, Brazil
| | - Juliana G Rodrigues
- Department of Entomology and Acarology, Luiz de Queiroz College of Agriculture, University of São Paulo, Piracicaba, São Paulo, Brazil
| | | | | | | | - Celso Omoto
- Department of Entomology and Acarology, Luiz de Queiroz College of Agriculture, University of São Paulo, Piracicaba, São Paulo, Brazil
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Within-host interactions of Metarhizium rileyi strains and nucleopolyhedroviruses in Spodoptera frugiperda and Anticarsia gemmatalis (Lepidoptera: Noctuidae). J Invertebr Pathol 2019; 162:10-18. [PMID: 30735762 DOI: 10.1016/j.jip.2019.01.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Revised: 01/31/2019] [Accepted: 01/31/2019] [Indexed: 11/21/2022]
Abstract
Members of the family Baculoviridae have been quite successfully used as biocontrol agents against some lepidopterans. Likewise, a number of fungi are important natural enemies of these pests. An interesting approach to increase control efficacy could be the combination of a given nucleopolyhedrovirus (NPV) and a fungus, since they possess distinct modes of action. As a first step towards this goal, we assessed the interaction between NPV (either AgMNPV-79 or SfMNPV-6nd) and the entomopathogenic fungus Metarhizium rileyi (either CG1153 or CG381), using Anticarsia gemmatalis and Spodoptera frugiperda as hosts. In sequential applications of these pathogens, per os inoculation of an NPV (leaf discs with 2.5 × 104 occlusion bodies) either two days before or two days post-spraying of its counterpart fungal strain (5 × 103 conidia.cm-2 sprays) usually resulted in an antagonistic effect. When both pathogens were simultaneously applied at different combined dosages, usually an additive effect was seen. Interestingly, a number of dead larvae showing signs of co-infections (partially with soft integument and partially mummified) were recorded. However, mixes with lower dosages of both pathogens did not cause significantly higher insect mortalities compared to low dosages of the fungus applied alone. The advantages and disadvantages of the simultaneous applications of NPV and M. rileyi aiming at the management of either A. gemmatalis or S. frugiperda were discussed.
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Beperet I, Simón O, Williams T, López-Ferber M, Caballero P. The “11K” gene family members sf68, sf95 and sf138 modulate transmissibility and insecticidal properties of Spodoptera frugiperda multiple nucleopolyhedrovirus. J Invertebr Pathol 2015; 127:101-9. [DOI: 10.1016/j.jip.2015.03.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Revised: 03/03/2015] [Accepted: 03/11/2015] [Indexed: 11/29/2022]
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Ishimwe E, Hodgson JJ, Clem RJ, Passarelli AL. Reaching the melting point: Degradative enzymes and protease inhibitors involved in baculovirus infection and dissemination. Virology 2015; 479-480:637-49. [PMID: 25724418 DOI: 10.1016/j.virol.2015.01.027] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2014] [Revised: 01/13/2015] [Accepted: 01/30/2015] [Indexed: 10/24/2022]
Abstract
Baculovirus infection of a host insect involves several steps, beginning with initiation of virus infection in the midgut, followed by dissemination of infection from the midgut to other tissues in the insect, and finally culminating in "melting" or liquefaction of the host, which allows for horizontal spread of infection to other insects. While all of the viral gene products are involved in ultimately reaching this dramatic infection endpoint, this review focuses on two particular types of baculovirus-encoded proteins: degradative enzymes and protease inhibitors. Neither of these types of proteins is commonly found in other virus families, but they both play important roles in baculovirus infection. The types of degradative enzymes and protease inhibitors encoded by baculoviruses are discussed, as are the roles of these proteins in the infection process.
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Affiliation(s)
- Egide Ishimwe
- Division of Biology, Kansas State University, 116 Ackert Hall, Manhattan, KS 66506-4901, United States
| | - Jeffrey J Hodgson
- Division of Biology, Kansas State University, 116 Ackert Hall, Manhattan, KS 66506-4901, United States
| | - Rollie J Clem
- Division of Biology, Kansas State University, 116 Ackert Hall, Manhattan, KS 66506-4901, United States.
| | - A Lorena Passarelli
- Division of Biology, Kansas State University, 116 Ackert Hall, Manhattan, KS 66506-4901, United States.
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Deletion genotypes reduce occlusion body potency but increase occlusion body production in a Colombian Spodoptera frugiperda nucleopolyhedrovirus population. PLoS One 2013; 8:e77271. [PMID: 24116220 PMCID: PMC3792916 DOI: 10.1371/journal.pone.0077271] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2013] [Accepted: 09/02/2013] [Indexed: 11/19/2022] Open
Abstract
A Colombian field isolate (SfCOL-wt) of Spodoptera frugiperda multiple nucleopolyhedrovirus (SfMNPV) is a mixture of different genotypes. To evaluate the insecticidal properties of the different genotypic variants, 83 plaque purified virus were characterized. Ten distinct genotypes were identified (named A through J). SfCOL-A was the most prevalent (71±2%; mean ± SE) showing a PstI restriction profile indistinguishable to that of SfCOL-wt. The remaining nine genotypes presented genomic deletions of 3.8 - 21.8 Kb located mainly between nucleotides 11,436 and 33,883 in the reference genome SfMNPV-B, affecting the region between open reading frames (ORFs) sf20 and sf33. The insecticidal activity of each genotype from SfCOL-wt and several mixtures of genotypes was compared to that of SfCOL-wt. The potency of SfCOL-A occlusion bodies (OBs) was 4.4-fold higher than SfCOL-wt OBs, whereas the speed of kill of SfCOL-A was similar to that of SfCOL-wt. Deletion genotype OBs were similarly or less potent than SfCOL-wt but six deletion genotypes were faster killing than SfCOL-wt. The potency of genotype mixtures co-occluded within OBs were consistently reduced in two-genotype mixtures involving equal proportions of SfCOL-A and one of three deletion genotypes (SfCOL-C, -D or -F). Speed of kill and OB production were improved only when the certain genotype mixtures were co-occluded, although OB production was higher in the SfCOL-wt isolate than in any of the component genotypes, or mixtures thereof. Deleted genotypes reduced OB potency but increased OB production of the SfCOL-wt population, which is structured to maximize the production of OBs in each infected host.
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