ABSTRACT
In 1979 FMC Corporation initiated a pyrethroid susceptibility monitoring program for the tobacco budworm, Heliothis virescens. Annual collections of H. virescens were made in GA, MS, LA, TX, AZ and CA to determine if any changes in population susceptibility had occurred. Until 1986 no consistent or generalized decrease in H. virescens susceptibility vas detected. However, data from Texas, as well as other sources indicated pyrethroid susceptibility was changing in certain areas. In view of these data and the importance of the pyrethroids to the cotton industry, FMC along with DuPont, ICI, Mobay and Hoechst-Roussel Agri-vet agreed to cooperate to establish a larger and more effective monitoring program. The result was the PEG-US Monitoring Program. Three test methods are being utilized and evaluated. The results of this effort, primarily from topical tests, are presented in this paper with summary data from the larval foliar and adult vial tests being shown for comparison. Overall, no area-wide control failures could be attributed to pyrethroid resistance in 1987. Tolerance levels varied throughout the Cotton Belt and during the season. However, LD values tended to be somewhat higher in areas west of Mississippi than in previous years. The highest LD values occurred in Louisiana and Texas; the greatest tolerance was detected with H. virescens collected during the latter part of the season in the Brazos River Valley of Texas. No significant changes in susceptibility were observed in other areas.
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