ABSTRACT
The rates of loss for beet armyworm pupae were examined in three different cotton fields: (1) treated with pyrethroid insecticide as needed for heliothine control, (2) untreated throughout the season, and (3) Bt-transgenic cotton that received no insecticide applications. Studies were conducted in 1994 and 1995, with 100 pupae placed in each field for each trial (2 trials in 1994 and 1 in 1995). Rates of pupal loss were highest in the untreated and Bt-transgenic cotton fields and were lowest in the pyrethroid-treated field in all trials, although the difference was not so great in 1995. The agents causing this loss were not apparent in the study, although fire ants were observed to remove pupae from their shallow cells in the ground. Fire ant activity was found to be reduced considerably by insecticide application -- repeated applications essentially eliminated fire ant activity. Other factors besides fire ants are apparently involved, as the reduction in fire ants did not correlate well with any increase in pupal survival.
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