The insecticidal efficacy towards Helicoverpa armigera lepidopteran larvae of recombinant Autographa californica M nucleopolyhedroviruses, expressing depressant and excitatory scorpion anti-insect selective toxins, 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, respectively, whereas the ET50 value of the wild-type virus was longer, 87 h post infection. The insecticidal effects obtained when using two distinct temporally regulated viral promoters revealed advantage for the very late p10 promoter over the p35 early promoter. The higher insecticidity of the virus expressing the depressant toxin compared to the excitatory toxin suggests that pharmacokinetic factors and/or promoter efficiency may play a role during infection of insect pest larvae by recombinant baculoviruses.
Bibliographical noteFunding Information:
This work was supported by grants IS-2139-92, IS-2530-95C, IS-2486-94C from BARD, The United States–Israel Binational Agricultural Research and Development Fund, and 891-0112-95 from The Israeli Ministry of Agriculture. We thank Dr. B.D. Hammock from the University of California, Davis for providing the plasmid pUW51P2, and Mrs. H. Rivkin for her excellent technical assistance. Contribution from the Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel No. 2313.
- Depressant anti-insect toxin
- Excitatory anti-insect toxin
- Insect cell
- Lepidopteran larva