Laboratory and field populations of Spodoptera exigua are nautrally infected by multiple viruses

Abstract

Covert infections of Spodoptera exigua multiple nucleopoliedrovirus (SeMNPV) have been detected in laboratory or field populations of the homologous host, S. exigua. Recently, RNA viruses belonging to the Iflaviridae family were identified in S. exigua transcriptome from different laboratory colonies (S. exigua iflavirus-1: SeIV-1; S. exigua iflavirus-2: SeIV-2). The three viruses are vertically transmited and establish persistent infections, and coinfection ofindividual insects by these viruses is considered likely. Very little is known about iflaviruses but they have been reported in association with NPVs in previous studies. In this study, we determined the prevalence of covert infections caused by iflaviruses and SeMNPV in order to identify virus associations in natural S. exigua populations. Field adults were captured with UV light traps and their offspring reared in laboratory conditions. RT PCR and qPCR were used to detect iflaviruses and SeMNPV, respectively. SeMNPV was detected in the 20% of field adults, whereas 15% and 5% of insects were infected by SeIV-1 and SeIV-2, respectively. The adults of F1 are now being analyzed to determine the prevalence of each of the viruses. A laboratory colony used as reference, showed 74% (n=39) and 84% (n=19) of adults were infected by SeIV-1 and SeIV-2; non SeMNPV amplifications were detected by qPCR (n=20).