BACULOVIRUS-MEDIATED EXPRESSION OF A SCORPION DEPRESSANT TOXIN IMPROVES THE INSECTICIDAL EFFICACY ACHIEVED WITH EXCITATORY TOXINS

The insecticidal efficacy towards Helicoverpa armigera lepidopteran la rvae of recombinant Autographs californica M nucleopolyhedroviruses, e xpressing depressant and excitatory scorpion anti-insect selective tox ins, was investigated. The ET50 (effective paralysis time 50%) values obtained with the recombinant viruses expressing the depressant toxin, LqhIT2, and the excitatory toxin, LqhIT1, were 59 h and 66 h, respect ively, whereas the ET50 value of the wild-type virus was longer, 87 h post infection. The insecticidal effects obtained when using two disti nct temporally regulated viral promoters revealed advantage for the la te p10 promoter over the p35 early promoter. The higher insecticidity of the virus expressing the depressant toxin compared to the excitator y toxin suggests that pharmacokinetic factors and/or promoter efficien cy may play a role during infection of insect pest larvae by recombina nt baculoviruses. (C) 1998 Federation of European Biochemical Societie s.