Evaluation of Bacillus thuringiensis -Spray Adjuvant-Viral Insecticide Combinations Against Heliothis spp. (Lepidoptera: Noctuidae) 1

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Abstract
Mortality of Heliothis zea (Boddie) and Heliothis virescens (Fabricius) larvae after treatment with Bacillus thuringiensis (Berliner) was determined in bioassays with treated cotton leaves. Larval mortality depended upon dosage, species, and size of larvae tested. Bacillus thuringiensis was also found to reduce the weight of larvae surviving treatment (7 days) when compared with the untreated check. Bioassays failed to detect differences between two commercial B. thuringiensis formulations, Dipel (Abbott Laboratories, North Chicago, III.) and Thuricide (Sandoz, Inc., San Diego, Calif.). Effectiveness of B. thuringiensis was usually increased when treatments were made in combination with the commercial spray adjuvants, Coax (Trader Oil Mill Co., Ft. Worth, Tex.) and Gustol (Sandoz, Inc., San Diego, Calif.). Combinations of B. thuringiensis and nuclear polyhedrosis viruses of H. zea and Autographa californica (Speyer) usually resulted in mortality levels greater than that of B. thuringiensis alone but not greater than that of either virus alone. Advantages for combining B. thuringiensis with the nuclear polyhedrosis virus of H. zea or A. californica were not detected in this study.1