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Interaction of Cotesia Marginiventris Parasitization and Field Applied Bacillus Thuringiensis, Thiodicarb, and Their Combination on Tobacco Budworm Mortality and Parasitoid Emergence

D.W. Atwood, S.Y. Young, III, T.J. Kring


Bacillus thuringiensis var. kurstaki and thiodicarb were evaluated in field tests to determine the effect on Heliothis virescens larvae and the parasitoid Cotesia marginiventris. Tests were conducted using B. thuringiensis rates and thiodicarb rate, independently and in combination, as recommended for resistance management in Arkansas. Results indicate that neither B. thuringiensis nor thiodicarb, alone or in combination, provide acceptable control of late second to early third instar H. virescens larvae (< 32%). However, thiodicarb and thiodicarb/B. thuringiensis mixes provided significantly greater control of H. virescens than did B. thuringiensis application alone. In addition, no significant advantage was determined for tank mixes as compared to thiodicarb application alone. Parasitization was only observed to increase early mortality in conjunction with the application of B. thuringiensis. Neither insecticide applied independently nor in combination had a significant impact on the emergence of C. marginiventris from H. virescens. Overall, while results indicate poor control of H. virescens, findings indicate no detrimental effect on the parasitoid population at rates suggested for resistance management.

Reprinted from Proceedings of the 1996 Beltwide Cotton Conferences pp. 905 - 908
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998