TABLE 1.

Toxicity of Cry1Ab protoxin to resistant (Cry1Ab-SEL) and susceptible (ROTH) populations, F₁, and back-cross progenies

Population	Nh	LC50 (μg/ml)	95% FL	Slope ± SE	RRa
Cry1Ab-SEL	182	14.73	12.60-17.64	6.52 ± 0.69	2,455
ROTH	182	0.006	0.002-0.009	2.67 ± 0.95
Reciprocal crosses
F1b	184	2.94	2.26-3.90	3.65 ± 0.63	490
F1c	154	1.38	1.25-1.72	5.4 ± 0.95	230
F1 (pooled)	338	2.02	1.66-2.45	3.62 ± 0.46	337
Backcrosses
BCd	214	0.12	0.019-0.22	2.36 ± 0.69	20
BCe	210	0.40	0.20-0.61	1.82 ± 0.40	67
BCf	182	0.18	0.04-0.31	2.09 ± 0.62	30
BCg	191	0.43	0.26-0.60	2.52 ± 0.47	72
BC (pooled)	660	0.24	0.17-0.31	2.21 ± 0.24	40

^aRR, resistance ratio (the LC₅₀ for the strain divided by the LC₅₀ for ROTH population).

^bProgeny of mass crosses between 40 males of Cry1Ab-SEL and 40 females of ROTH.

^cProgeny of mass crosses between 40 females of Cry1Ab-SEL and 40 males of ROTH.

^dProgeny of backcrosses between 40 females of Cry1Ab-SEL female F₁ progeny and 40 males of ROTH.

^eProgeny of backcrosses between 40 males of Cry1Ab-SEL female F₁ progeny and 40 females of ROTH.

^fProgeny of backcrosses between 40 females of Cry1Ab-SEL male F₁ progeny and 40 males of ROTH.

^gProgeny of backcrosses between 40 males of Cry1Ab-SEL male F₁ progeny and 40 females of ROTH.

^hN = number of larvae tested, including controls.