Abstract
Larvae of Helicoverpa zea and Heliothis virescens fed recombinant strains of two nucleopolyhedroviruses (AcMNPV, HzSNPV), genetically engineered to express two different scorpion toxins, produced significantly Lower numbers (ca. 4 to 10-fold lower) of occlusion bodies than larvae infected with the wild strain of these viruses. Lower yields of occlusion bodies were a manifestation of early larval paralysis caused by the toxin-expressing recombinant strains.