Transgenic crops producing Bacillus thuringiensis (Bt) proteins kill key insect pests, providing economic and environmental benefits. However, the evolution of pest resistance threatens the continued success of such Bt crops. To delay or counter resistance, transgenic plant "pyramids" producing two or more Bt proteins that kill the same pest have been adopted extensively. Field populations of t...

The biological potential of Vip and Cry proteins from Bacillus is well known and widely established. Thus, it is important to look for new genes showing different modes of action, selecting those with differentiated entomotoxic activity against Diatraea flavipennella and Elasmopalpus lignosellus, which are secondary pests of sugarcane. Therefore, Cry1 and Vip3 proteins were expressed in Escheri...

Insects exposed to genetically modified crops expressing Bacillus thuringiensis (Bt) toxins are under intense selection pressure that could result on widespread Bt resistance. Screening for early indications of Bt resistance developing in targeted Lepidoptera is conducted in many of the regions where genetically modified cotton and corn have been commercialized. Heliothis virescens (F.) (Lepido...

This experiment evaluated the effect of feeding dairy cows with cottonseeds containing BollGard r (Cry1Ac) and BollGard r II (Cry1Ac and Cry2Ab), Roundup Ready r (CP4 EPSPS) and control non-transgenic cottonseed on dry matter intake, milk yield and milk composition. Twelve lactating multiparous Argentinean Holstein cows weighing 570 kg (BW) were used in a 4x4 Latin square design, with 3 squares...

Cry1Aa, an insecticidal protein produced by Bacillus thuringiensis, has been shown to bind to cadherin-like protein, BtR175, in Bombyx mori (silkworm) midgut. We previously reported three variant alleles of BtR175 (BtR175a, b and c). When transiently expressed in COS7 cells, all the three BtR175 variants bound to Cry1Aa. We stably expressed BtR175b in HEK293 cells. These BtR175b-expressing cell...

A fluorescence-based approach was developed to analyze in vivo the function of Manduca sexta cadherin (Bt-R(1)) as a Cry1 toxin receptor. We cloned a Bt-R(1a) cDNA that differs from Bt-R(1) by 37 nucleotides and two amino acids and expressed it transiently in Drosophila melanogaster Schneider 2 (S2) cells. Cells expressing Bt-R(1a) bound Cry1Aa, Cry1Ab, and Cry1Ac toxins on ligand blots, and in...

Two candidate diagnostic concentrations of the Cry1Ab and Cry1Ac toxins from Bacillus thuringiensis corresponding to the LC99 and EC99 (effective concentration that causes 99% growth inhibition) for European corn borer, Ostrinia nubilalis (Hübner), were determined based on previously obtained baseline data. Validation experiments using field-collected European corn borer populations from across...

Transgenic corn expressing the Bacillus thuringiensis Cry1Ab gene is highly insecticidal to Ostrinia nubilalis (European corn borer) larvae. We ascertained whether Cry1F, Cry9C, or Cry9E recognizes the Cry1Ab binding site on the O. nubilalis brush border by three approaches. An optical biosensor technology based on surface plasmon resonance measured binding of brush border membrane vesicles (BB...

The heritability, stability, and fitness costs in a Cry1Ac-resistant Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae) colony (AR) were measured in the laboratory. In response to selection, heritability values for AR increased in generations 4-7 and decreased in generations 11-19. AR had significantly increased pupal mortality, a male-biased sex ratio, and lower mating success compared with the...