TABLE 3.
Cross-resistance between Cry1Ac-SEL, Cry1Ab-SEL, B. thuringiensis subsp. kurstaki-SEL, and B. thuringiensis subsp. aizawai-SEL subpopulations of P. xylostella
| Population (generation) | Insecticide | LC50a (95% FL) | Avg slope (SE) | RRb | RRc | nd |
|---|---|---|---|---|---|---|
| Cry1Ac-SEL (F9) | Cry1Ac | >20e | 1.45 (0.49) | >10,500 | >95 | 240 |
| Cry1Ac-SEL (F9) | Cry1Ab | 1.11 (0.85–1.43) | 3.91 (0.37) | 264 | 5 | 298 |
| Cry1Ac-SEL (F9) | B. thuringiensis subsp. kurstaki | 3.17 (2.25–5.96) | 2.31 (0.33) | 59 | 4 | 280 |
| Cry1Ac-SEL (F9) | B. thuringiensis subsp. aizawai | 0.12 (0.09–0.15) | 2.56 (0.55) | 10 | 1 | 238 |
| Cry1Ab-SEL (F9) | Cry1Ac | 13.20 (6.87–38.00) | 1.16 (0.21) | 7,000 | 60 | 282 |
| Cry1Ab-SEL (F9) | Cry1Ab | 2.13 (1.67–2.68) | 3.51 (0.49) | 500 | 10 | 240 |
| Cry1Ab-SEL (F9) | B. thuringiensis subsp. kurstaki | 4.37 (3.17–6.11) | 2.54 (0.32) | 81 | 5 | 242 |
| Cry1Ab-SEL (F9) | B. thuringiensis subsp. aizawai | 0.18 (0.14–0.25) | 2.27 (0.35) | 16 | 2 | 238 |
| B. thuringiensis subsp. kurstaki-SEL (F9) | Cry1Ac | 20.50 (14.60–33.00) | 2.20 (0.39) | 10,700 | 100 | 237 |
| B. thuringiensis subsp. kurstaki-SEL (F9) | Cry1Ab | 3.86 (2.60–7.44) | 2.18 (0.40) | 900 | 18 | 237 |
| B. thuringiensis subsp. kurstaki-SEL (F9) | B. thuringiensis subsp. kurstaki | 6.02 (4.78–7.39) | 3.81 (0.40) | 112 | 7 | 274 |
| B. thuringiensis subsp. kurstaki-SEL (F9) | B. thuringiensis subsp. aizawai | 0.09 (0.07–0.12) | 3.08 (0.40) | 8 | 1 | 280 |
| B. thuringiensis subsp. aizawai-SEL (F9) | Cry1Ac | 13.80 (4.86–129.00) | 0.77 (0.19) | 7,260 | 70 | 208 |
| B. thuringiensis subsp. aizawai-SEL (F9) | Cry1Ab | 1.78 (1.19–3.63) | 2.51 (0.47) | 420 | 8 | 178 |
| B. thuringiensis subsp. aizawai-SEL (F9) | B. thuringiensis subsp. kurstaki | 2.33 (1.57–3.80) | 2.10 (0.35) | 40 | 3 | 173 |
| B. thuringiensis subsp. aizawai-SEL (F9) | B. thuringiensis subsp. aizawai | 0.29 (0.21–0.42) | 2.56 (0.40) | 30 | 3 | 211 |
a
Cry1Ac and Cry1Ab data are in micrograms per milliliter; B. thuringiensis subsp. kurstaki and B. thuringiensis subsp. aizawai data are in international units per microgram.
b
Resistance ratio of LC50s for selected subpopulation compared with ROTH (Table 1).
c
Resistance ratio of LC50s for selected subpopulation compared with UNSEL-MEL at F9 (Table 2).
d
Number of larvae used in bioassay, including control.
e
Mortality at 20 μg ml−1 = 35%.