Résumé
Covert infection with Spodoptera frugiperda multiple nucleopolyhedrovirus, detected by reverse transcription-PCR of virus gene transcripts (ie-0 and polh), was not significantly affected by the presence of an optical brightener (Tinopal UNPA-GX), indicating no change in virus virulence. Detection of the covert infection was dependent on insect life stage and the viral mRNA used for diagnosis.