Differences in activity enhancement of a baculovirus by an optical brightener between Choristoneura fumiferana and Choristoneura occidentalis (Lepidoptera: Tortricidae)

Abstract

Optical brighteners were recently discovered to function as UV protectants for baculoviruses of insects (Shapiro 1992) and, also, to enhance entomopathogenic activity of these viruses (Hamm and Shapiro 1992; Li and Otvos 1999a). Enhancement of viral activity by brighteners varied greatly from one virus–host system to another: for example, from 1500-fold in LdMNPV against Lymantria dispar (L.) (Lepidoptera: Lymantriidae) (Argauer and Shapiro 1997) to 2- to 13-fold in a multicapsid nuclear polyhedrosis virus of Choristoneura fumiferana (Clemens) (Lepidoptera: Tortricidae) (CfMNPV) against Choristoneura occidentalis Freeman (Li and Otvos 1999a). The reason for this variation in enhancement of viral activity is still unknown. In this study, we used CfMNPV to compare the levels of viral enhancement by an optical brightener between C. occidentalis and C. fumiferana.