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In 2000, resistance was again documented in tobacco budworm populations to pyrethroid insecticides. Over 686 tobacco budworm moths were bioassayed for pyrethroid resistance from May through August 2000 using a discriminating dose of 10 µg in the adult vial test. Pyrethroid resistance levels in 2000 were similar to those measured since 1997. Percent survival in May, June, July and August was 62, 22, 43, and 63, respectively. The high survival level in May and June indicates that a large percentage of the tobacco budworm population was resistant to pyrethroids before growers began to use pyrethroids for tobacco budworm control. The data indicates that pyrethroids no longer provide effective control of tobacco budworm populations. Over 1445 male bollworm moths were assayed against a 5µg/vial dose of cypermethrin. Bollworm moth survival levels were similar to 1998 and 1999 levels. Percent survival in May, June, July and August was 13, 20, 19 and 14%, respectively. This data indicates that bollworm susceptibility to pyrethroid insecticides is changing. |
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©National Cotton Council, Memphis TN |
Document last modified XXXXXX, XXX XX 2001
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