Comparative Toxicity of Four Commonly Used Insecticides to Field-Collected Beet Armyworm Larvae from the Southeastern United States

L. D. Chandler and J. R. Ruberson


Toxicity of chlorpyrifos, cypermethrin, diflubenzuron, and thiodicarb against 1993 field-collected beet armyworm, Spodoptera exigua (H�bner), larvae infesting cotton from Alabama, Georgia, and Mississippi was determined. Various levels of insecticide tolerance were observed dependent upon collection location. In general, beet armyworm populations collected in Ben Hill Co., GA, Bartow Co., GA, Macon Co., AL, and Yazoo Co., MS were more tolerant to chlorpyrifos, cypermethrin, and thiodicarb than the susceptible laboratory colony. Larvae from Bartow Co., GA, Decatur Co., GA, and Macon Co., AL were significantly more tolerant to diflubenzuron than the laboratory colony. In most instances, LC(50)'s decreased in value from the first to third generation of tested progeny of field collected beet armyworm larvae.

Reprinted from Proceedings of the 1994 Beltwide Cotton Conferences pp. 860 - 864
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998