Table 2.
Survival on commercial Bt crops relative to survival on non-Bt crop counterparts for strains of four pest species selected in the laboratory or greenhouse for resistance to Bt toxins. Only studies reporting survival of lab- or greenhouse-selected strains from neonate to either pupa or adult are shown. Survival was measured in the greenhouse or using plants from the greenhouse unless noted otherwise. Diatraea saccharalis, Helicoverpa armigera, and Pectinophora gossypiella are lepidopterans; Diabrotica virgifera virgifera is a coleopteran
| Toxin(s), conditions | Insect species | Insect strain | Adjusted survival* | Reference |
|---|---|---|---|---|
| Corn | ||||
| Cry1Ab | D. saccharalis | B1F2 | 0.10 | Huang et al. (2007b) |
| Cry34Ab/Cry35Ab | D. v. virgifera | Rochelle-S | 0.18† | Lefko et al. (2008) |
| Cry34Ab/Cry35Ab | D. v. virgifera | York-S | 0.19† | Lefko et al. (2008) |
| Cry3Bb, field tested | D. v. virgifera | Constant-exposure | 0.44‡ | Meihls et al. (2008) |
| Cry3Bb, field tested | D. v. virgifera | Late-exposure | 0.14‡ | Meihls et al. (2008) |
| Cry3Bb, field tested | D. v. virgifera | Neonate-exposure | 0.015‡ | Meihls et al. (2008) |
| Cotton | ||||
| Cry1Ac | H. armigera | Cry1Ac-sel | 0.25 | Fan et al. (2000) |
| Cry1Ac, 5 to 6-leaf stage | H. armigera | ISOC4 | 0.37–0.39 | Bird and Akhurst (2004) |
| Cry1Ac, 15-leaf stage | H. armigera | ISOC4 | 0.91 | Bird and Akhurst (2005) |
| Cry1Ac + Cry2Ab, pre-square | H. armigera | SP15 | 0.029 | Mahon and Olsen (2009) |
| Cry1Ac + Cry2Ab, early square | H. armigera | SP15 | 0.044 | Mahon and Olsen (2009) |
| Cry1Ac + Cry2Ab, fruiting | H. armigera | SP15 | 0.52 | Mahon and Olsen (2009) |
| Cry1Ac + Cry2Ab, pre-square, field plants | H. armigera | SP15 | 0 | Mahon and Olsen (2009) |
| Cry1Ac + Cry2Ab, fruiting, field plants | H. armigera | SP15 | 0.17 | Mahon and Olsen (2009) |
| Cry1Ac | P. gossypiella | AZP-R | 0.46 | Liu et al. (2001) |
| Cry1Ac | P. gossypiella | AZP-R | 0.43 | Morin et al. (2003) |
| Cry1Ac | P. gossypiella | MOV97-R | 1.10 | Tabashnik et al. (2005b) |
| Cry1Ac | P. gossypiella | SAF97-R | 1.50 | Tabashnik et al. (2005b) |
| Cry1Ac | P. gossypiella | MOV97-H2, r1r3§ | 0.30 | Carrière et al. (2006) |
| Cry1Ac | P. gossypiella | MOV97-H2, r3r3§ | 0.38 | Carrière et al. (2006) |
| Cry1Ac | P. gossypiella | SAF97-H2, r1r2§ | 0.57 | Carrière et al. (2006) |
| Cry1Ac | P. gossypiella | SAF97-H2, r2r2§ | 0.20 | Carrière et al. (2006) |
Adjusted survival = survival of selected strain on Bt crop/survival of selected strain on non-Bt crop unless noted otherwise. Adjusted survival <1 indicates incomplete resistance (see text).
Survival of the selected Rochelle-S strain on Bt corn (0.137)/survival of the unselected parent strain (Rochelle-US) on non-Bt corn (0.762). Survival of the selected York-S strain on Bt corn (0.156)/survival of the unselected parent strain (York-US) on non-Bt corn (0.827). If survival on non-Bt corn was lower for the selected strain (data not reported) than for the unselected strain, these calculations would underestimate adjusted survival on Bt corn for the selected strains.
Adjusted survival of an unselected strain on Bt corn was 0.038. Survival was significantly higher than 0.038 in the constant-exposure and late-exposure strains, but not in the neonate-exposure strain.
Three cadherin alleles linked with resistance to Cry1Ac in P. gossypiella are denoted r1, r2, and r3. Adjusted survival is given for genotypes based on combinations of these alleles.