title: Susceptibility of Cry1Ab maize-resistant and -susceptible strains of sugarcane borer (Lepidoptera: Crambidae) to four individual Cry proteins.
abstract: Sugarcane borer, Diatraea saccharalis (F.), is a major target of Bt maize in South America and many areas of the US mid-south region. Six laboratory strains of D. saccharalis were established from six single-pair F(2) families possessing major resistance alleles to Cry1Ab maize hybrids. Susceptibility of the six strains was evaluated on diet treated with each of four purified trypsin-activated Bt proteins, Cry1Ab, Cry1Aa, Cry1Ac and Cry1F. Bt susceptibility of the six strains was compared with that of known Cry1Ab-susceptible and -resistant strains of D. saccharalis. At least two of the six strains demonstrated a similar level (>526-fold) of resistance to Cry1Ab as shown in the known Cry1Ab-resistant strain, while resistance levels were relatively lower for other strains (116- to 129-fold). All the six strains were highly cross-resistant to Cry1Aa (71- to 292-fold) and Cry1Ac (30- to 248-fold), but only with a low level to Cry1F (<7-fold). Larval growth of all six strains was also inhibited on Bt-treated diet, but, except for Cry1F, the growth inhibition of the six strains was considerably less than that of the Cry1Ab-susceptible larvae. The results provide clear evidence that the observed resistance to Cry1Ab maize in the six strains is a result of resistance to the Cry1Ab protein in the plants. The low level of cross-resistance between Cry1A and Cry1F suggests that pyramiding these two types of Bt proteins into a plant could be a good strategy for managing D. saccharalis.
authors.affiliation: Department of Entomology, Louisiana State University Agricultural Center, Baton Rouge, LA 70803, USA.
authors.forename: Liping
authors.initials: L
authors.lastname: Zhang
authors.forename: Fangneng
authors.initials: F
authors.lastname: Huang
authors.forename: B
authors.initials: B
authors.lastname: Rogers Leonard
authors.forename: Mao
authors.initials: M
authors.lastname: Chen
authors.forename: Thomas
authors.initials: T
authors.lastname: Clark
authors.forename: Yu Cheng
authors.initials: YC
authors.lastname: Zhu
authors.forename: David S
authors.initials: DS
authors.lastname: Wangila
authors.forename: Fei
authors.initials: F
authors.lastname: Yang
authors.forename: Ying
authors.initials: Y
authors.lastname: Niu
mesh_terms: D000818:Animals; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000235:genetics*; D004731:Endotoxins / Q000235:genetics*; D006460:Hemolysin Proteins / Q000235:genetics*; D007306:Insecticides; D007814:Larva; D009036:Moths; D010572:Pest Control, Biological; D030821:Plants, Genetically Modified; D003313:Zea mays / Q000235:genetics*
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D004731:Endotoxins; D006460:Hemolysin Proteins; D007306:Insecticides; C030956:insecticidal crystal protein, Bacillus Thuringiensis