title: Bacillus thuringiensis Vip3Aa Toxin Resistance in Heliothis virescens (Lepidoptera: Noctuidae).
abstract: Laboratory selection with Vip3Aa of a field-derived population ofHeliothis virescensproduced >2,040-fold resistance in 12 generations of selection. The Vip3Aa-selected (Vip-Sel)-resistant population showed little cross-resistance to Cry1Ab and no cross-resistance to Cry1Ac. Resistance was unstable after 15 generations without exposure to the toxin. F1reciprocal crosses between Vip3Aa-unselected (Vip-Unsel) and Vip-Sel insects indicated a strong paternal influence on the inheritance of resistance. Resistance ranged from almost completely recessive (mean degree of dominance [h] = 0.04 if the resistant parent was female) to incompletely dominant (meanh= 0.53 if the resistant parent was male). Results from bioassays on the offspring from backcrosses of the F1progeny with Vip-Sel insects indicated that resistance was due to more than one locus. The results described in this article provide useful information for the insecticide resistance management strategies designed to overcome the evolution of resistance to Vip3Aa in insect pests.IMPORTANCEHeliothis virescensis an important pest that has the ability to feed on many plant species. The extensive use ofBacillus thuringiensis(Bt) crops or spray has already led to the evolution of insect resistance in the field for some species of Lepidoptera and Coleoptera. The development of resistance in insect pests is the main threat to Bt crops. The effective resistance management strategies are very important to prolong the life of Bt plants. Lab selection is the key step to test the assumption and predictions of management strategies prior to field evaluation. Resistant insects offer useful information to determine the inheritance of resistance and the frequency of resistance alleles and to study the mechanism of resistance to insecticides.
authors.affiliation: Department of Life Sciences, Imperial College of Science, Technology and Medicine, London, Silwood Park Campus, Ascot, Berkshire, United Kingdom.|Syngenta, Jealott's Hill International Research Centre, Bracknell, Berkshire, United Kingdom.
authors.forename: Brian R
authors.initials: BR
authors.lastname: Pickett
authors.affiliation: Department of Life Sciences, Imperial College of Science, Technology and Medicine, London, Silwood Park Campus, Ascot, Berkshire, United Kingdom.|Department of Entomology, PMAS Arid Agriculture University, Rawalpindi, Pakistan.
authors.forename: Asim
authors.initials: A
authors.lastname: Gulzar
authors.affiliation: ERI de Biotecnología y Biomedicina (BIOTECMED), Department of Genetics, Universitat de València, Burjassot, Spain juan.ferre@uv.es.
authors.forename: Juan
authors.initials: J
authors.lastname: Ferré
authors.affiliation: Department of Life Sciences, Imperial College of Science, Technology and Medicine, London, Silwood Park Campus, Ascot, Berkshire, United Kingdom.
authors.forename: Denis J
authors.initials: DJ
authors.lastname: Wright
mesh_terms: D000818:Animals; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000633:toxicity*; D001681:Biological Assay; D003433:Crosses, Genetic; D004731:Endotoxins / Q000633:toxicity; D006460:Hemolysin Proteins / Q000633:toxicity; D007305:Insecticide Resistance; D007915:Lepidoptera / Q000187:drug effects* / Q000502:physiology*; D020412:Multifactorial Inheritance; D000072740:Paternal Inheritance; D012641:Selection, Genetic; D016019:Survival Analysis
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D004731:Endotoxins; D006460:Hemolysin Proteins; C447139:Vip3A protein, Bacillus thuringiensis; C030956:insecticidal crystal protein, Bacillus Thuringiensis
keywords: Bt toxins; insect resistance; selection for resistance