Table 3. Responses to Bt toxin Cry2Ab of pink bollworm larvae from a resistant strain (Bt4-R2), a susceptible strain (APHIS-S), and their F1 progeny.
| Strain | na | LC50 (95% FL)b | RRc | Survival (%)d |
|---|---|---|---|---|
| Bt4-R2e | 192 | 679 (NA)f | 18,000 | 75.0 |
| F1Ag | 192 | 0.0780 (NA) | 2.0 | 0.00 |
| F1Bh | 192 | 0.0580 (0.038–0.074) | 1.5 | 0.00 |
| F1 pooled | 384 | 0.0620 (0.012–0.078) | 1.6 | 0.00 |
| APHIS-S | 192 | 0.0385 (0.028–0.050) | 1.0 | 0.00 |
aNumber of larvae tested including controls on untreated diet.
bConcentration killing 50% with 95% fiducial limits in parentheses, in μg Cry2Ab per mL of diet.
cResistance ratio, the LC50 for a strain divided by the LC50 for APHIS-S (susceptible).
dSurvival at 10 μg Cry2Ab per mL diet, adjusted for control mortality, n = 64 larvae for F1 pooled, 32 for all other estimates.
eF22 generation of Bt4-R2 was tested in October 2012 and used in crosses with APHIS-S.
fNot available.
gMale Bt4-R2 X female APHIS-S.
hFemale Bt4-R2 X male APHIS-S.