Persistent Link:
http://hdl.handle.net/10150/197706
Title:
Susceptibility of Arizona Pink Bollworm to Cry1Ac
Author:
Sims, Maria A.; Dennehy, Timothy J.; Shriver, Laura; Holley, Danny; Carrière, Yves; Tabashnik, Bruce; Antilla, Larry; Whitlow, Mike
Affiliation:
Department of Entomology, University of Arizona, Tucson, AZ; Arizona Cotton Research and Protection Council, Phoenix, AZ
Issue Date:
Jun-2002
Publisher:
College of Agriculture, University of Arizona (Tucson, AZ)
Journal:
Cotton: A College of Agriculture and Life Sciences Report
Abstract:
Genetically modified cotton expressing the Cry1Ac toxin has been used in Arizona since 1996 with exceptionally positive results in terms of economic returns to growers and reductions in insecticide use in cotton. Since 1995, average insecticide use in Arizona cotton has declined from greater than six applications per acre to less than two in 2000. Bt cotton has contributed greatly to these savings to growers, as have insect growth regulators used for whitefly control. Collections of pink bollworm, Pectinophora gossypiella, made in 1997 and subsequently exposed to Cry1Ac in the laboratory from 1998 to 2000, yielded a laboratory strain with susceptibility to Cry1Ac reduced 1,000 to 3,000- fold, relative to highly susceptible field populations. Unparalleled measures have been taken to detect and manage this resistance. In this report we summarize results of statewide monitoring of pink bollworm susceptibility to Cry1Ac conducted from 1997 to 2000, and results of field evaluations of the effectiveness of Bt cotton from 1995 to 2001. Susceptibility of Arizona pink bollworm to Cry1Ac, increased from 1997 to 2000. Mean corrected mortality in 1μg/ml Cry1Ac assays was 57.4% in 1997, 90.6% in 1998, 97.9% in 1999 and 97.4% in 2000. Mean corrected mortality in bioassays of 10 μg/ml also increased: it was 94.1% in 1997, 99.9% in 1998, 100% in 1999 and 100 % in 2000. Field performance of Bt cotton in 2000 continued to be excellent at 39 locations throughout Arizona cotton at which paired Bt and non-Bt fields were evaluated. Whereas non-Bt cotton fields had mean infestations of over 15% infested bolls, Bt cotton fields averaged less than 0.15% infested bolls. Thus, after six years of intensive use of Bt cotton in Arizona, pink bollworm populations show no signs of being resistant to Bollgard cotton. Indeed, for reasons that are not understood at this time, they have been found to be significantly more susceptible to the Bt toxin in Bollgard cotton at the end of the 2000 season than they were in 1997.
Keywords:
Agriculture -- Arizona; Cotton -- Arizona; Resistance management
Series/Report no.:
AZ1283; Series P-130

Full metadata record

DC FieldValue Language
dc.titleSusceptibility of Arizona Pink Bollworm to Cry1Acen_US
dc.contributor.authorSims, Maria A.en_US
dc.contributor.authorDennehy, Timothy J.en_US
dc.contributor.authorShriver, Lauraen_US
dc.contributor.authorHolley, Dannyen_US
dc.contributor.authorCarrière, Yvesen_US
dc.contributor.authorTabashnik, Bruceen_US
dc.contributor.authorAntilla, Larryen_US
dc.contributor.authorWhitlow, Mikeen_US
dc.contributor.departmentDepartment of Entomology, University of Arizona, Tucson, AZen_US
dc.contributor.departmentArizona Cotton Research and Protection Council, Phoenix, AZen_US
dc.date.issued2002-06-
dc.publisherCollege of Agriculture, University of Arizona (Tucson, AZ)en_US
dc.identifier.journalCotton: A College of Agriculture and Life Sciences Reporten_US
dc.description.abstractGenetically modified cotton expressing the Cry1Ac toxin has been used in Arizona since 1996 with exceptionally positive results in terms of economic returns to growers and reductions in insecticide use in cotton. Since 1995, average insecticide use in Arizona cotton has declined from greater than six applications per acre to less than two in 2000. Bt cotton has contributed greatly to these savings to growers, as have insect growth regulators used for whitefly control. Collections of pink bollworm, Pectinophora gossypiella, made in 1997 and subsequently exposed to Cry1Ac in the laboratory from 1998 to 2000, yielded a laboratory strain with susceptibility to Cry1Ac reduced 1,000 to 3,000- fold, relative to highly susceptible field populations. Unparalleled measures have been taken to detect and manage this resistance. In this report we summarize results of statewide monitoring of pink bollworm susceptibility to Cry1Ac conducted from 1997 to 2000, and results of field evaluations of the effectiveness of Bt cotton from 1995 to 2001. Susceptibility of Arizona pink bollworm to Cry1Ac, increased from 1997 to 2000. Mean corrected mortality in 1μg/ml Cry1Ac assays was 57.4% in 1997, 90.6% in 1998, 97.9% in 1999 and 97.4% in 2000. Mean corrected mortality in bioassays of 10 μg/ml also increased: it was 94.1% in 1997, 99.9% in 1998, 100% in 1999 and 100 % in 2000. Field performance of Bt cotton in 2000 continued to be excellent at 39 locations throughout Arizona cotton at which paired Bt and non-Bt fields were evaluated. Whereas non-Bt cotton fields had mean infestations of over 15% infested bolls, Bt cotton fields averaged less than 0.15% infested bolls. Thus, after six years of intensive use of Bt cotton in Arizona, pink bollworm populations show no signs of being resistant to Bollgard cotton. Indeed, for reasons that are not understood at this time, they have been found to be significantly more susceptible to the Bt toxin in Bollgard cotton at the end of the 2000 season than they were in 1997.en_US
dc.subjectAgriculture -- Arizonaen_US
dc.subjectCotton -- Arizonaen_US
dc.subjectResistance managementen_US
dc.identifier.urihttp://hdl.handle.net/10150/197706-
dc.relation.ispartofseriesAZ1283en_US
dc.relation.ispartofseriesSeries P-130-
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