Table 3. Concentration-response and growth inhibition response (MIC50 and EC50; ng/cm2) of S. frugiperda in diet-overlay bioassays with purified Cry1A.105 and Cry2Ab2 proteins.
| FAW strain | n | Slope ± SE | MIC50 (95% IC) a | χ2(df) b | Resistance Ratio c | EC50 (95% CI) d | Resistance Ratio c |
|---|---|---|---|---|---|---|---|
| Tests with Cry1A.105 protein | |||||||
| RR | 384 | - | > 16,000 | - | > 3368 | 138.40 (102.21–191.02) | 206.56 |
| S♂R♀ | 502 | 1.14 ± 0.11 | 25.05 (18.80–32.06) | 5.08 (6) | 5.27 | 8.80 (5.96–12.80) | 13.13 |
| S♀R♂ | 445 | 1.42 ± 0.12 | 32.62 (23.98–47.67) | 6.14 (6) | 6.86 | 18.37 (15.87–29.38) | 27.41 |
| SR Pooled | 947 | 1.16 ± 0.04 | 28.97 (20.53–39.90) | 8.53 (6) | 5.99 | 13.18 (12.39–13.97) | 19.7 |
| SS | 448 | 1.20 ± 0.19 | 4.75 (2.67–7.04) | 8.63 (4) | - | 0.67 (0.53–0.84) | - |
| Tests with Cry2Ab2 protein | |||||||
| RR | 540 | 0.96 ± 0.09 | 146.96 (83.37–330.35) | 16.83 (5) | 10.44 | 19.05 (10.77–35.56) | 10.82 |
| S♂R♀ | 448 | 1.51 ± 0.12 | 48.35 (26.17–90.48) | 18.07 (7) | 3.43 | 16.01 (12.72–24.36) | 9.09 |
| S♀R♂ | 512 | 1.07 ± 0.12 | 45.63 (28.48–76.28) | 17.24 (7) | 3.24 | 13.51 (8.68–20.53) | 7.67 |
| SR Pooled | 960 | 1.40 ± 0.10 | 45.36 (25.81–76.61) | 8.53 (6) | 3.10 | 13.52 (11.53–15.51) | 7.68 |
| SS | 576 | 1.27 ± 0.09 | 14.06 (11.64–16.96) | 7.63 (7) | - | 1.76 (1.23–2.49) | - |
a MIC50: Concentration that inhibits molting to second instar in 50% of individuals after 7 days.
b P > 0.05 in the goodness-of-fit test.
c Resistance Ratio = (MIC50 or EC50 of indicated strain)/(MIC50 or EC50 of SS strain).
d EC50: Effective concentration of protein required to cause 50% growth inhibition at 7 days.