Molecular and Biological Characterization of Spodoptera frugiperda Multiple Nucleopolyhedrovirus Field Isolate and Genotypes from China

Abstract

The fall armyworm, Spodoptera frugiperda, is a new invading pest in China. The baculovirus Spodoptera frugiperda multiple nucleopolyhedrovirus (SfMNPV) is a pathogenic agent of the fall armyworm and a potential agent for its control in integrated pest management strategies. In this work, we analyze the molecular and biological characteristics of an SfMNPV isolate collected from maize in China (SfMNPV-Hub). Two genotypes were further isolated from SfMNPV-Hub by an in vivo cloning method. The PstI profile of one genotype (SfHub-A) was similar to genotype A of the SfMNPV Colombian isolate, and the other (SfHub-E) was similar to genotype E of the Colombian isolate. The bioactivity of SfHub-A against second-instar S. frugiperda larvae was not significantly different from that of SfMNPV-Hub, whereas SfHub-E was 2.7–5.5 fold less potent than SfMNPV-Hub. The speed of kill of SfHub-E was quicker than SfMNPV-Hub, while SfHub-A acted slower than SfMNPV-Hub. Occlusion body (OB) production of SfHub-A in an S. frugiperda cadaver was significantly higher than that of SfMNPV-Hub, while SfHub-E yielded far fewer occlusion bodies (OBs) in the host larvae. These results provide basic information for developing a virus-based pesticide against the invading pest S. frugiperda.

Viruses of the Fall Armyworm Spodoptera frugiperda: A Review with Prospects for Biological Control

“…Knowledge on the occurrence of SfMNPV and SfGV in association with the invading population of FAW is still limited. However, naturally occurring field isolates of SfMNPV have been found in newly invaded areas like China [108], India [50,109,110], and Nigeria [111]. Initial characterization of an SfMNPV field isolate from China (SfHub) shows that there are two naturally occurring genotypes (SfHub-A and -E) that differ in their biological characteristics [108].…”

“…However, naturally occurring field isolates of SfMNPV have been found in newly invaded areas like China [108], India [50,109,110], and Nigeria [111]. Initial characterization of an SfMNPV field isolate from China (SfHub) shows that there are two naturally occurring genotypes (SfHub-A and -E) that differ in their biological characteristics [108]. Commercial isolates of SfMNPV have been registered and successfully employed to control S. frugiperda in North and South America, and more recently in some African and Asian countries (Table 4) [28,32,35,72].…”

“…It is therefore desirable to purify the single genotypes from such field isolates and test the characteristics of each genotype separately. Studies have exploited the use of in vivo (passage in live larvae) or in vitro (in competent insect cell lines) plaque purification techniques to purify the different genotypes and used DNA restriction endonuclease analysis to characterize these [76,104,108,114,115]. One of the genotypes derived from a field isolate from United State isolate 3AP2 possesses desired traits like fast killing properties and is currently commercialized for usage in America and in some countries in Africa and Asia [66,72].…”

Genetic diversity in Chrysodeixis includens nucleopolyhedrovirus and factors involved in its generation

“…In spite of this, the possible interactions among variants were not examined in this thesis although mixtures of genotypes can have better insecticidal characteristics than individual genotypic variants Bernal et al, 2013). This is an interesting issue, as baculovirus genotypic variants often present lower OB pathogenicity than the original isolate from which they originated (Lei et al, 2020;Redman et al, 2016). In the case of ChinNPV, the variants purified from natural isolates may compete for host resources or perhaps the different combinations of variants within natural isolates result in the mortality differences observed.…”

Caracterización de baculovirus autóctonos para el control de la oruga militar tardía (<i>Spodoptera frugiperda</i>)

“…166,167 Mas aún, ensayos biológicos comparativos entre distintas variantes genotípicas presentes dentro de un mismo aislamiento de SfMNPV han demostrado que estos genotipos pueden diferir en sus propiedades biológicas. 33,34,90,92,168 La innovación genética es una de las mayores fuentes de adaptación durante el proceso de coevolución entre el virus y su hospedador. 169,170 Para el caso del baculovirus modelo, Autographa californica Multiple Nucleopolyhedrovirus (AcMNPV), los polimorfismos presentes en la población viral se han demostrado como fuente relevante de diversidad funcional para las proteínas virales.…”