Table 1.

Toxicity of crystalline Cry1Ac for ROTH, UNSEL, and Cry1Ac-SEL populations of P. xylostella

StrainForm of toxinLC50 (95% FL)aAvg slope (SE)RRb
ROTHCrystalc 0.0020 (0.0001–0.0085)0.69 (0.18)
Spore-crystald 0.0013 (0.0003–0.0039)0.85 (0.19)
NAT spore-crystald,e 0.0020 (0.0008–0.004)2.12 (0.53)
UNSELCrystal0.0880 (0.034–0.19)1.29 (0.24)44
Spore-crystal0.0920 (0.03–0.2)1.23 (0.24)71
NAT spore-crystal0.1110 (0.0003–0.315)1.64 (0.61)55
Cry1Ac-SELCrystal2.33 (0.14–29.62)0.54 (0.22)1,170
Spore-crystal3.60 (1.1–15.0)0.81 (0.24)2,770
NAT spore-crystal2.08 (0.56–6.01)0.64 (0.16)1,040
  • a Expressed in micrograms per milliliter. At least 150 larvae (F11) were used in each experiment. LC50, 50% lethal concentration FL, fiducial limits.

  • b Resistance ratio of 50% lethal concentrations for the UNSEL and Cry1Ac-SEL populations to those for the ROTH population.

  • c Expressed in E. coli.

  • d Expressed in B. thuringiensisIPS78/11 and applied as a spore-crystal mixture.

  • e NAT, N-terminally activated toxin.