TOXICOLOGICAL RESPONSES OF TOBACCO BUDWORM (LEPIDOPTERA, NOCTUIDAE) FROM LOUISIANA, MISSISSIPPI, AND TEXAS TO SELECTED INSECTICIDES

Topical application bioassays of cypermethrin, methomyl, profenofos, a nd sulprofos were done with the Louisiana State University laboratory strain (LSU-LAB) and field-collected strains of tobacco budworm, Helio this virescens (F.), from Louisiana, Mississippi, and Texas. The field -collected strains showed low to high levels of resistance to cypermet hrin (2- to 41-fold), low to moderate levels of resistance to profenof os and sulprofos (2- to 8-fold) and low to moderate levels of resistan ce to methomyl (2- to 8-fold) compared with the LSU-LAB strain. Spray chamber bioassays indicated reduced efficacy of cypermethrin, endosulf an, profenofos, and thiodicarb against the field-collected strains of H. virescens when their responses were compared with responses of the Stoneville laboratory strain.