Frequency of alleles conferring resistance to Bacillus thuringiensis maize in Louisiana populations of the southwestern corn borer

Laboratory studies were conducted to compare the response of Diatraea grandiosella (Dyar) larvae to lyophilized transgenic corn tissue expressing the Cry1Ab endotoxin protein of Bacillus thuringiensis (Berliner) (Bt) with conventional corn tissue incorporated into a BioServ™ artificial diet. Whorl leaf, stalk, shank, husk, silk or kernel tissues were tested independently in the diet. Larvae fed diet containing conventional corn weighed more and were longer in length than larvae fed diet containing Bt corn for all tissue types included in the study. The number of larvae that survived depended on the tissue type and age of the tissue. Larvae fed diet with kernel tissue expressing Bt toxin had greater weight and body length than larvae fed the other Bt tissue types. The negative effects of Bt corn tissues expressing the Cry1Ab endotoxin protein on growth of D. grandiosella was observed, even at the diluted concentrations of toxic tissues incorporated into the diet in this study.

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Field Resistance of Bacillus thuringiensis Berliner Transformed Maize to Fall Armyworm (Lepidoptera: Noctuidae) and Southwestern Corn Borer (Lepidoptera: Crambidae) Leaf Feeding

Journal of Entomological Science ◽

10.18474/0749-8004-39.3.325 ◽

2004 ◽

Vol 39 (3) ◽

pp. 325-336 ◽

Cited By ~ 4

Author(s):

Craig A. Abel ◽

Melanie C. Pollan

Keyword(s):

Bacillus Thuringiensis ◽

Fall Armyworm ◽

Field Resistance ◽

Economic Damage ◽

Yield Reduction ◽

Insecticidal Proteins ◽

Corn Borer ◽

Field Efficacy ◽

Southwestern Corn Borer ◽

Hybrid Maize

The fall armyworm, Spodoptera frugiperda (J. E. Smith), and the southwestern corn borer, Diatraea grandiosella (Dyar), can cause economic damage to maize, Zea mays L., grown in the southeastern United States. Maize hybrids are commercially available that have been transformed to express insecticidal crystalline proteins from Bacillus thuringiensis (Bt) Berliner. The field efficacy of seven Bt hybrids were tested for control of leaf-feeding fall armyworm and southwestern corn borer. All Bt hybrids performed better than their conventional near-isolines for control of both insects. In general, the Bt hybrids provided intermediate resistance to the fall armyworm and near immunity to the southwestern corn borer. Based on larval establishment and weights, the fall armyworm was more tolerant of the insecticidal proteins expressed by the Bt hybrids than the southwestern corn borer. There was no difference in expression of insecticidal proteins among the Bt hybrids. Bt hybrids should be advantageous for the production of maize in areas that are affected by southwestern corn borer. The moderate level of resistance in the Bt hybrids to fall armyworm should be further examined to determine if amplifying the expression of insecticidal proteins or integrating other control methods along with the use of current Bt hybrid maize is needed to protect the crop from yield reduction by this pest.

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