TABLE 2.
Stability of resistance to B. thuringiensis subsp. kurstaki (Dipel) and Cry1Ac toxin (MVP) in the resistant field population Karak of P. xylostella
| Generation from field | Insecticide used | LC50 (95% FL)a | Avg slope (±SE) | RRb | Rc |
|---|---|---|---|---|---|
| G2 | B. thuringiensis subsp. kurstaki | 2.97 (2.18-4.15) | 3.30 (0.60) | 770 | |
| G2 | Cry1Ac | 9,800 (7,500-13,600) | 0.90 (0.28) | 363,000 | |
| G8 | B. thuringiensis subsp. kurstaki | 1.70 (1.03-2.75) | 0.96 (0.11) | 440 | −0.04 |
| G8 | Cry1Ac | 980 (420-2170) | 0.96 (0.11) | 36,900 | −0.17 |
| G13 | B. thuringiensis subsp. kurstaki | 2.98 (1.81-5.89) | 0.25 (0.08) | 770 | 0.00 |
| G13 | Cry1Ac | 3,220 (1,860-5,820) | 0.71 (0.08) | 119,000 | −0.04 |
a
Cry toxin concentrations are in micrograms per milliliter. B. thuringiensis subsp. kurstaki data are in international units per milligram per milliliter.
b
RR, resistance ratio of the LC50 for the selected subpopulation to those for the LAB-UK population.
c
R, log (final LC50 − initial LC50)n, where n is the number of generations in the population reared without insecticide exposure.