TABLE 1.
Evaluation of the sensitivities of susceptible and Cry2A-resistant H. armigera larvae to M. anisopliaea
| Spore concn (no. of spores/ml) | H. armigera strain | No. of larvae exposed | No. of dead larvae (no. of larvae producing spores) | Mortality (%) | Mean wt (mg) | Distribution of larval instars (%)
|
||
|---|---|---|---|---|---|---|---|---|
| L3 | L4 | L5 | ||||||
| 0 | Susceptible | 60 | 6 (0) | 10.0 | 68.0 | 0 | 48.2 | 51.9 |
| Cry2A resistant | 60 | 6 (0) | 10.0 | 77.7 | 0 | 37.0 | 63.0 | |
| 9.6 × 105 | Susceptible | 59 | 11 (0) | 18.6 | 68.1 | 0 | 51.1 | 48.9 |
| Cry2A resistant | 59 | 5 (0) | 8.5 | 67.2 | 0 | 59.3 | 40.7 | |
| 4.8 × 106 | Susceptible | 61 | 24 (6) | 39.3 | 66.7 | 0 | 75.7 | 24.3 |
| Cry2A resistant | 61 | 6 (1) | 9.8 | 75.9 | 0 | 65.5 | 34.6 | |
| 2.4 × 107 | Susceptible | 55 | 19 (6) | 34.5 | 63.3 | 0 | 81.1 | 18.9 |
| Cry2A resistant | 57 | 8 (2) | 17.0 | 83.1 | 0 | 69.4 | 30.6 | |
| 1.2 × 108 | Susceptible | 59 | 25 (15) | 42.4 | 59.3 | 0 | 88.2 | 11.8 |
| Cry2A resistant | 58 | 16 (8) | 27.6 | 76.9 | 0 | 63.4 | 36.6 | |
| 6 × 108 | Susceptible | 60 | 37 (27) | 61.7 | 63.2 | 12.0 | 48.0 | 40.0 |
| Cry2A resistant | 57 | 26 (24) | 45.6 | 72.4 | 0 | 56.7 | 43.3 | |
| 3 × 109 | Susceptible | 59 | 51 (48) | 86.4 | 51.2 | 0 | 100 | 0 |
| Cry2A resistant | 59 | 47 (46) | 79.7 | 57.9 | 9.1 | 72.7 | 18.2 | |
a
Larvae were exposed to chickpea leaves treated with six different spore concentrations for 2 days, differing fivefold in their spore concentrations. Subsequently, the larvae were provided with untreated chickpea leaves every other day until day 8. Weight is shown as the mean weight of all survivors per treatment. The larval instar reached by surviving larvae at the completion of the experiment is given as the percentage of survivors. n = 55 to 61.