FIELD TESTS ON CONTROL OF THE IMPORTED CABBAGEWORM (LEPIDOPTERA: PIERIDAE) AND THE CABBAGE LOOPER (LEPIDOPTERA: NOCTUIDAE) BY MIXTURES OF MICROBIAL AND CHEMICAL INSECTICIDES

Abstract The efficacy of mixtures of permethrin and Bacillus thuringiensis var. kurstaki Berliner (B.t.), Autographa californica (Speyer) nuclear polyhedrosis virus (ACNPV), or Pieris (= Artogeia) rapae (L.) granulosis virus (PRGV) against the cabbage looper, Trichoplusia ni (Hübner), and the imported cabbageworm, P. rapae, was assessed by field plot tests. Protection of the crop and yield by plots treated with several of the reduced-dosage mixtures were similar to protection and yield by plots treated with permethrin at the full rate, demonstrating a feasible procedure for reducing the amount of chemical insecticide applied without sacrificing protection of the crop. Furthermore, efficacy of the biological component of the mixtures, B.t. or viruses, was frequently enhanced by low concentrations of the chemical component on the mixture.