title: Effect of maysin on wild-type, deltamethrin-resistant, and Bt-resistant Helicoverpa armigera (Lepidoptera: Noctuidae).
abstract: Larvae of the Old World corn earworm, Helicoverpa armigera (Hübner), were fed diets containing lyophilized silks from maize genotypes expressing varying levels of maysin, a flavone glycoside known to be toxic to the New World corn earworm, Helicoverpa zea Boddie. Three different H. armigera colonies were tested: a wild-type colony (96-S), a colony selected for resistance to deltamethrin (Del-R), and a colony selected for resistance to the Cry1Ac protoxin of Bacillus thuringiensis (Bt-R). A colony of H. zea was also tested as a control. High-maysin silk diets significantly slowed the growth and arrested the development of larvae from all H. armigera colonies compared with low-maysin silk diets, maysin-lacking silk diets, and no-silk control diets. The effects on the H. armigera and H. zea colonies were similar across maysin levels, although H. zea is a larger insect than H. armigera and this overall size difference was observed. Among the H. armigera colonies, maysin effects were generally similar, although 7-d-old Del-R larvae were significantly smaller than 7-d-old Bt-R and 96-S larvae for one no-silk control and two maysin-containing silk treatments. The toxic effect of maysin on the Bt-R and Del-R colonies suggests that physiological mechanisms of H. armigera resistance to Cry1Ac and deltamethrin do not confer cross-resistance to maysin.
authors.affiliation: USDA-ARS, Crop Genetics and Breeding Research Unit, Tifton, GA 31794, USA. rector@tifton.cpes.peachnet.edu
authors.forename: Brian G
authors.initials: BG
authors.lastname: Rector
authors.forename: Gemei
authors.initials: G
authors.lastname: Liang
authors.forename: Yuyuan
authors.initials: Y
authors.lastname: Guo
mesh_terms: D000818:Animals; D001413:Bacillus thuringiensis / Q000502:physiology*; D004032:Diet; D005419:Flavonoids / Q000008:administration & dosage* / Q000494:pharmacology*; D015870:Gene Expression; D005960:Glucosides / Q000008:administration & dosage* / Q000494:pharmacology*; D007300:Insect Control; D007305:Insecticide Resistance; D007306:Insecticides / Q000008:administration & dosage / Q000494:pharmacology*; D007814:Larva / Q000187:drug effects / Q000254:growth & development; D007915:Lepidoptera / Q000187:drug effects* / Q000235:genetics / Q000382:microbiology / Q000502:physiology*; D009570:Nitriles; D010572:Pest Control, Biological; D030821:Plants, Genetically Modified; D011722:Pyrethrins / Q000494:pharmacology*; D003313:Zea mays / Q000469:parasitology
chemical_list: D005419:Flavonoids; D005960:Glucosides; D007306:Insecticides; D009570:Nitriles; D011722:Pyrethrins; C114429:maysin; C017180:decamethrin