Concentration- and time-response characteristics of plaque isolates of Agrotis ipsilon multiple nucleopolyhedrovirus derived from a field isolate.

Plaque isolates derived from the Illinois field isolate of Agrotis ipsilon multiple nucleopolyhedrovirus are distinguished by the presence or absence of a small deletion in the baculovirus egt (ecdysteroid UDP-glucosyltransferase) coding sequence. In concentration-response and time-response bioassays with both plaque and field isolates, plaque isolates with a mutated egt gene were less pathogenic against A. ipsilon larvae than other isolates, but killed larvae faster. Mixed infections with isolates representing the two different egt genotypes caused the same level of mortality as the field isolate and a plaque isolate with a wild-type egt gene.