Table 2.

Toxicity of in vitro solubilized and activated Cry1Ac for ROTH, UNSEL, and Cry1Ac-SEL populations of P. xylostella

StrainForm of toxincLC50 (95% FL)aAvg slope (SE)RRb
ROTHCrystal15 (8–64)0.69 (0.18)
Solubilizedd 10 (8–22)1.11 (0.29)
Activatedd 15 (15–45)1.18 (0.39)
UNSELCrystal660 (255–1425)1.29 (0.24)44
Solubilized3,150 (975–6300)2.02 (0.43)315
Activated375 (135–750)1.99 (0.44)25
Cry1Ac-SELCrystal17,475 (1,050–222,150)0.54 (0.22)1,170
Solubilized>150,0000.44 (0.15)>15,000
Activated1,410 (465–3,150)0.65 (0.14)94
  • a Values are expressed as picomolar concentrations due to differences in mass between the protoxin and activated forms of Cry1Ac. 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 Solubilized in 50 mM Na2CO3 and, where indicated, activated with 1 mg of trypsin per ml.