title: Interactions of recombinant and wild-type baculoviruses with classical insecticides and pyrethroid-resistant tobacco budworm (Lepidoptera: Noctuidae).
abstract: In tests with neonate Heliothis virescens (F.), we characterized interactions of all combinations of a recombinant Autographa californica (Speyer) nuclear polyhedrosis virus (AcAaIT) that expresses an insect-selective neurotoxin (AaIT) and wild-type AcNPV when combined with low concentrations of several conventional insecticides. All combinations of the recombinant virus AcAaIT and insecticides showed a positive interaction (decrease in the median lethal time (LT50) compared with the LT50 for either component alone). A type II pyrethroid (cypermethrin, which modifies currents of sodium channels) and a carbamate (methomyl, an inhibitor of acetylcholinesterase) were synergistic in combination with AcAaIT. Other insecticides also showed a positive interaction when tested in combination with the recombinant virus, but joint activity was slightly antagonistic (i.e., less than predicted activity when combined) with wild-type AcNPV. We also characterized the effectiveness of AcAaIT against pyrethroid-resistant H. virescens larvae. Our results show that a resistant strain of H. virescens is more sensitive to the recombinant virus compared with a susceptible strain. Results of these studies should be useful in planning of future field trials to increase the effectiveness of nuclear polyhedrosis viruses and to manage resistance to pyrethroids and other insecticides.
authors.affiliation: Department of Entomology, University of California, Davis 95616, USA.
authors.forename: B F
authors.initials: BF
authors.lastname: McCutchen
authors.forename: K
authors.initials: K
authors.lastname: Hoover
authors.forename: H K
authors.initials: HK
authors.lastname: Preisler
authors.forename: M D
authors.initials: MD
authors.lastname: Betana
authors.forename: R
authors.initials: R
authors.lastname: Herrmann
authors.forename: J L
authors.initials: JL
authors.lastname: Robertson
authors.forename: B D
authors.initials: BD
authors.lastname: Hammock
mesh_terms: D000818:Animals; D002800:Cholinesterase Inhibitors; D004357:Drug Synergism; D015870:Gene Expression; D007305:Insecticide Resistance; D007306:Insecticides; D007915:Lepidoptera / Q000821:virology; D008724:Methomyl; D009498:Neurotoxins; D017924:Nucleopolyhedroviruses / Q000235:genetics*; D011722:Pyrethrins; D011994:Recombinant Proteins; D012604:Scorpion Venoms / Q000235:genetics; D013997:Time Factors
chemical_list: D002800:Cholinesterase Inhibitors; D007306:Insecticides; D009498:Neurotoxins; D011722:Pyrethrins; D011994:Recombinant Proteins; D012604:Scorpion Venoms; C065634:AaIT neurotoxin, Androctonus australis; D008724:Methomyl; C017160:cypermethrin