Table 4. Efficacy of Bt toxins Cry1AbMod, Cry1Ac and Cry2Ab singly and in combinations against a susceptible strain of pink bollworm (APHIS-S) (see Methods for details).
| Concentration | Mortality (%)a
|
||||
|---|---|---|---|---|---|
| Toxin set | (µg per ml diet) | Obsb | Expc | Obs - Expd | P e |
| Cry1AbMod | 0.1 | 4 | — | — | — |
| 1.0 | 45 | — | — | — | |
| Cry1Ac | 0.03 | 7 | — | — | — |
| 0.1 | 4 | — | — | — | |
| Cry2Ab | 0.1 | 16 | — | — | — |
| 0.3 | 53 | — | — | — | |
| Cry1AbMod + Cry1Ac | 0.1 + 0.03 | 11 | 11 | 0 | 1.0 |
| 0.1 + 0.1 | 20 | 7 | 13 | 0.01 | |
| 1.0 + 0.03 | 44 | 49 | -6 | 0.52 | |
| 1.0 + 0.1 | 53 | 47 | 5 | 0.53 | |
| Mean | 32 | 29 | 3 | 0.39 | |
| Cry1AbMod + Cry2Ab | 0.1 + 0.1 | 44 | 19 | 25 | 0.0004 |
| 0.1 + 0.3 | 64 | 55 | 9 | 0.27 | |
| 1.0 + 0.1 | 56 | 54 | 2 | 0.87 | |
| 1.0 + 0.3 | 87 | 74 | 13 | 0.06 | |
| Mean | 63 | 51 | 12 | 0.002 | |
| Cry1Ac + Cry2Ab | 0.03 + 0.1 | 22 | 22 | 0 | 1.0 |
| Cry1AbMod + Cry1Ac + Cry2Ab | 0.1 + 0.03 + 0.1 | 22 | 25 | -3 | 0.71 |
| 1.0 + 0.03 + 0.1 | 59 | 58 | 1 | 1.0 | |
| Mean | 40 | 41 | -1 | 0.91 | |
a
All mortality values are adjusted for control mortality.
b
Observed mortality
c
Expected mortality for combinations of two or three toxins
d
Observed mortality - expected mortality; synergism causes positive values and antagonism causes negative values
e
Probability that the difference between observed and expected mortality occurred by chance based on Fisher’s exact test