title: Bacillus thuringiensis Cry1Ac resistance frequency in tobacco budworm (Lepidoptera: Noctuidae).
abstract: The tobacco budworm, Heliothis virescens (F.) (Lepidoptera: Noctuidae), is one of the most important pests of cotton, Gossypium hirsutum L, that has become resistant to a wide range of synthetic insecticides. CrylAc-expressing cotton has proven its effectiveness against this insect since its introduction in North America in 1996. However, the constant exposure of tobacco budworm to this protein toxin may result in the development of resistance to it. To estimate the frequency of alleles that confer resistance to a 1.0 microg of Bacillus thuringiensis Cry1Ac diagnostic concentration in field-collected insects, the second generation (F2) of 1,001 single-pair families from seven geographical regions representing 2,202 alleles from natural populations was screened in 2006 and 2007 without finding major resistant alleles. Neonates of 56 single-pair families were able to develop to second instar on the diagnostic concentration in the initial screen, but only seven of these lines did so again in a second confirmatory screen. Minor resistance alleles to Cry1Ac may be quite common in natural populations of H. virescens. Our estimated resistance allele frequencies (0.0036-0.0263) were not significantly different from a previously published estimate from 1993. There is no evidence that H. virescens populations have become more resistant to Cry1Ac.
authors.affiliation: USDA-ARS, Southern Insect Management Research Unit, Stoneville, MS 38776, USA. carlos.blanco@ars.usda.gov
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Blanco
authors.forename: David A
authors.initials: DA
authors.lastname: Andow
authors.forename: Craig A
authors.initials: CA
authors.lastname: Abel
authors.forename: Douglas V
authors.initials: DV
authors.lastname: Sumerford
authors.forename: Gerardo
authors.initials: G
authors.lastname: Hernandez
authors.forename: Juan D
authors.initials: JD
authors.lastname: López
authors.forename: Larry
authors.initials: L
authors.lastname: Adams
authors.forename: Astrid
authors.initials: A
authors.lastname: Groot
authors.forename: Rogers
authors.initials: R
authors.lastname: Leonard
authors.forename: Roy
authors.initials: R
authors.lastname: Parker
authors.forename: Gregory
authors.initials: G
authors.lastname: Payne
authors.forename: O P
authors.initials: OP
authors.lastname: Perera
authors.forename: Antonio P
authors.initials: AP
authors.lastname: Terán-Vargas
authors.forename: Ausencio
authors.initials: A
authors.lastname: Azuara-Domínguez
mesh_terms: D000818:Animals; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D004731:Endotoxins; D005260:Female; D005787:Gene Frequency; D017344:Genes, Insect; D006460:Hemolysin Proteins; D007305:Insecticide Resistance / Q000235:genetics*; D008297:Male; D009036:Moths / Q000235:genetics*; D010572:Pest Control, Biological; D015144:Southeastern United States
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D004731:Endotoxins; D006460:Hemolysin Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis