Natural Coinfection between Novel Species of Baculoviruses in Spodoptera ornithogalli Larvae

Abstract

Spodoptera ornithogalli (Guenée) (Lepidoptera: Noctuidae) is an important pest in different crops of economic relevance in America. For its control, strategies that include chemicals are usually used; so, the description of entomopathogens would be very useful for the formulation of biopesticides. In this regard, two different baculoviruses affecting S. ornithogalli were isolated in Colombia, with one of them being an NPV and the other a GV. Ultrastructural, molecular, and biological characterization showed that both isolates possess the 38 core genes and are novel species in Baculoviridae, named as Spodoptera ornithogalli nucleopolyhedrovirus (SporNPV) and Spodoptera ornithogalli granulovirus (SporGV). The bioassays carried out in larvae of S. ornithogalli and S. frugiperda showed infectivity in both hosts but being higher in the first. In addition, it was observed that SporGV potentiates the insecticidal action of SporNPV (maximum value in ratio 2.5:97.5). Both viruses are individually infective but coexist in nature, producing mixed infections with a synergistic effect that improves the performance of the NPV and enables the transmission of the GV, which presents a slowly killing phenotype.

Effects of Mixed Baculovirus Infections in Biological Control: A Comprehensive Historical and Technical Analysis

“…The first recorded case of co-infection of a lepidopteran larva with polyhedrosis and granulosis viruses was in the cutworm Euxoa segetum in 1936 [ 19 ]. Similar findings were reported in Pieris rapae , Pseudaletia unipuncta , Nephelodes emmedonia , Mythimna unipuncta , Choristoneura fumiferana , Spodoptera frugiperda, and Spodoptera Ornithogalli [ 20 , 21 , 22 , 23 , 24 , 25 ]. On the other hand, the experimental co-infection with two baculoviruses isolated from the same host started with the work of Tanada [ 22 , 23 ].…”

“…However, this synergy was observed only when the proportion of SpfrGV in the mixture did not exceed 2.5% [ 24 ]. Similar results were obtained through bioassays using SporNPV and SporGV on neonate larvae of Spodoptera ornithogalli [ 25 ].…”

“…Enhancin genes are absent in some GVs that have shown synergistic effects on the infectivity of NPVs [ 25 , 41 ]. This raises the question of which proteins, other than enhancins, could act in a similar way at the primary infection site.…”

Biological Control of Two Date Fruit Insect Pests Using Entomopathogenic Viruses

“…Several studies (e.g., Hodgson, et al, 2004;Simon, et al, 2005 ) have shown that combination of wild type viruses has always more pathogenic than any of the individual one, suggesting a positive interaction between them. Barrera, et al (2021), mentioned that, the both viruses NPV and GV are individually infective to Spodoptera ornithogalli (Guenée) larvae but coexist in nature, producing mixed infections with a synergistic effect that improves the performance of the NPV and enables the transmission of the GV, which presents a slowly killing phenotype.…”

Protein-Gene Orthology in Baculoviridae: An Exhaustive Analysis to Redefine the Ancestrally Common Coding Sequences

“…Out of the 297 genomes thus selected, 1 sequence (Lymantria dispar multiple nucleopolyhedrovirus isolate T3; accession number MF311096.1) was discarded because, according to the database file, it did not encode LEF-5 (core gene) due to mutations (“nonfunctional lef-5 due to mutation”), without an associated scientific publication endorsing this particularity. In addition, a novel sequence (SporGV) [ 23 ], obtained by our working group and not yet submitted to GenBank, was included. Therefore, a database (hereafter identified by the acronym BPDB for Baculovirus Proteome DataBase ) containing 297 complete baculoviral genomes and proteomes was generated as an input to determine homologous gene groups and phylogenetic inferences ( Table S1 ).…”