Table 3.

Selected list of insect species and strains with resistance to Cry toxins

SpeciesLocationEnvironmentGeneration (n)aSelective agent(s)bResistancecResistance mechanism(s)eReference(s)
P. interpunctellaOklahomaLaboratory13DipelDipel (100)261
36Dipel (>250)263
Dipel (>30)396
Cry1Ab (866)dReduced binding396
P. interpunctellaKansasLaboratoryB. thuringiensis subsp. entomocidus HD-198Cry1Ab (13)284, 285
Cry1Ac (128)Reduced protoxin activation284, 285
Cry1Ca (6)284, 285
P. interpunctellaKansasLaboratoryB. thuringiensis subsp.,aizawaiCry1Aa (17)264
Cry1Ab (226)264
Cry1Ac (789)Reduced binding243, 264
Cry1Ba (44)264
Cry1Ca (19)264
Cry2A (24)264
P. xylostellaPhilippinesFieldDipelCry1Ab (>200)Reduced binding113
Cry1Ba (2)113
Cry1Ca (0.5)113
P. xylostellaPhilippinesFieldDipelCry1Aa (1.3)21
Cry1Ab (236)Reduced binding21, 368
Cry1Ac (1)21
P. xylostellaHawaiiField/laboratoryB. thuringiensis, DipelCry1Ac (>59)Reduced binding365
Dipel (>130)365
Cry1Aa (>100)369
Cry1Ab (>100)369
Cry1Ac (>100)369
Cry1Ba (3)369
Cry1Bb (6)369
Cry1Ca (2)369
Cry1Da (3)369
Cry1Fa (>100)369
Cry1Ia (3)369
Cry1Ja (>140)369
Cry2A (6)369
P. xylostellaHawaiiField/laboratoryB. thuringiensis, B. thuringiensis subsp.aizawai, DipelCry1C (22)228
B. thuringiensis subsp.kurstaki HD-1 (134)228
B. thuringiensis subsp.aizawai (3)228
P. xylostellaFloridaFieldB. thuringiensisJavelin (1,640)341
Dipel (22)341
Cry1Aa (>200)372
Cry1Ab (>200)Reduced binding372
Cry1Ac (>200)372
Cry1Ba (2.5)372
Cry1Ca (3.4)372
Cry1Da (1)372
P. xylostellaPennsylvaniaField/laboratoryB. thuringiensis subsp.kurstakiCry1Aa (high)368
Cry1Ab (high)Reduced binding368
Cry1Ac (high)368
Cry1Ca (none)368
Cry1Fa (high)368
Cry1Ja (high)368
H. virescensNorth CarolinaLaboratoryCry1A(c)Cry1AaReduced binding210
Cry1Ab (2,300)No altered binding144, 210
Cry1Ac (10,000)No altered binding144, 210
Cry1Fa (3,700)144
Cry2A (25)144
H. virescensNorth CarolinaLaboratoryCry1A(b), DipelCry1Ab  (71)Slightly altered binding240
Cry1Ac (16)Slightly altered binding240
Dipel (57)240
H. virescensNorth CarolinaLaboratory17Cry1A(c)Cry1Ab (13)Decreased protoxin activation;117, 145
Increased toxin degradation
17Cry1Ac (50)No altered binding145
17Cry2A (53)145
S. exiguaAlabamaLaboratory10B. thuringiensis subsp. kurstaki HD-1B. thuringiensis subsp. kurstakiHD-1 (1)272
Laboratory24Cry1CaCry1Ca (100)Reduced total binding; increased nonspecific binding272
20Cry1Ab (20)d272
34Cry2A (73)272
34Cry9Ca (12)272
  • a When available, the number of generations of selection at which the insects were tested is given.

  • b Some commercial formulations of B. thuringiensis were used; Dipel and Javelin are tradenames of formulations of B. thuringiensis subsp. kurstaki.

  • c Given are the agent to which resistance was developed and (in parentheses) the resistance ratio (LC50or 50% lethal dose LC50 [LD50] of resistant strain divided by LC50 [or LD50] of susceptible control strain).

  • d Estimated ratio.

  • e When available, the mechanism(s) of resistance to the particular toxin is given. In the case of binding, only the results of binding experiments to native BBMV or to tissue sections are given.