ABSTRACT
in 1990, continued field evaluation of Heliothis virescens moths with the adult vial technique (AVT) showed moderately increased tolerance to cypermethrin compared to 1989. Early season testing demonstrated the benefits of the pyrethroid management program in reducing the tolerance of the field population prior to late season intensive use of pyrethroids. In spite of significant suppression of pyrethroid field failures in areas complying with use management programs there has been an annual increase in the late season survival values at the 10 µg ai/vial dose rate. Increases in these late season values indicate that we are merely suppressing the inevitable. Laboratory evaluation of field collected Heliothis virescens indicates that the AVT test does a good job of predicting tolerance of subsequent field populations. Lab tests also found that PBO was not an effective pyrethroid synergist against this tolerance. This implies that this is not an alternative management tool.
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